Fix bug where nil cells would sometimes render without styling

The code has also been reorganized and cleaned up a bit, with more
comments added.

application.go

@@ -33,42 +33,60 @@ func (application *Application) Run () (
 	return
 }
 
+// OnQuit registers an event handler to be called just before the application
+// quits. This can happen when the user closes the application, or the backend
+// experiences an unrecoverable error.
 func (application *Application) OnQuit (
 	onQuit func (),
 ) {
 	application.callbackManager.onQuit = onQuit
 }
 
+// OnPress registers an event handler to be called when a key or mouse button
+// is pressed.
 func (application *Application) OnPress (
-	onPress func (button Button),
+	onPress func (button Button, modifiers Modifiers),
 ) {
 	application.callbackManager.onPress = onPress
 }
 
+// OnPress registers an event handler to be called when a key or mouse button
+// is released.
 func (application *Application) OnRelease (
 	onRelease func (button Button),
 ) {
 	application.callbackManager.onRelease = onRelease
 }
 
+// OnResize registers an event handler to be called when the application window
+// is resized. After the event handler is called, any updates it makes will
+// automatically be pushed to the screen.
 func (application *Application) OnResize (
 	onResize func (),
 ) {
 	application.callbackManager.onResize = onResize
 }
 
+// OnMouseMove registers an event handler to be called when mouse motion is
+// detected. The coordinates of the cell that the mouse now hovers over are
+// given as input.
 func (application *Application) OnMouseMove (
 	onMouseMove func (x, y int),
 ) {
 	application.callbackManager.onMouseMove = onMouseMove
 }
 
+// OnScroll registers an event handler to be called when the user uses the mouse
+// scroll wheel. Horizontal and vertical amounts are given as input.
 func (application *Application) OnScroll (
 	onScroll func (x, y int),
 ) {
 	application.callbackManager.onScroll = onScroll
 }
 
+// OnStart registers an event handler to be called once when the application
+// starts, right before the first time updates are pushed to the screen.
+// Anything done in here will be the first thing to appear on screen.
 func (application *Application) OnStart (
 	onStart func (),
 ) {

backend.go

@@ -3,13 +3,51 @@ package stone
 import "image"
 import "errors"
 
+// Backend represents a backend for stone. Backends can be registered for use
+// with the RegisterBackend() function. All of the below methods MUST be thread
+// safe!
 type Backend interface {
+	// Run is the backend's event loop. It must cleanly exit when the user
+	// closes the window, but not before calling the OnQuit event. Run
+	// must call event handlers within its own event loop in a
+	// non-concurrent fashion.
+	//
+	// The OnStart event handler must run after the backend has been fully
+	// initialized, and right before updates are first pushed to the screen.
+	// Whatever the application draws from within this event handler must be
+	// the first thing that appears on-screen.
+	//
+	// The OnResize event handler must run whenever the window is resized.
+	// The backend must push updates to the screen after OnResize has been
+	// run.
+	//
+	// The backend must not push updates to the screen in any other case,
+	// except when its Draw() method is specifically called.
+	//
+	// The OnPress, OnRelease, OnMouseMove, and OnMouseScroll events are to
+	// be called when such events happen. It is reccommended to compress
+	// resize, mouse move, and mouse scroll events whenever possible to
+	// reduce the likelihood of event buildup.
 	Run ()
+
+	// SetTitle sets the application title. This will most often be the
+	// window title. This method may not always produce an effect, depending
+	// on the backend.
 	SetTitle (title string) (err error)
+
+	// SetIcon takes in a set of images of different sizes and sets the
+	// window's icon to them. This method may not always produce an effect,
+	// depending on the backend.
 	SetIcon (icons []image.Image) (err error)
+
+	// Draw pushes all updates made to the application's buffer to the
+	// screen.
 	Draw ()
 }
 
+// BackendFactory must completely initialize a backend, and return it. If
+// anything goes wrong, it must stop, clean up any resources and return an
+// error so another backend can be chosen.
 type BackendFactory func (
 	application *Application,
 	callbackManager *CallbackManager,
@@ -20,6 +58,7 @@ type BackendFactory func (
 
 var factories []BackendFactory
 
+// RegisterBackend registers a backend factory.
 func RegisterBackend (factory BackendFactory) {
 	factories = append(factories, factory)
 }

backends/x/draw.go

@@ -49,11 +49,25 @@ func (backend *Backend) drawCells (forceRedraw bool) (areas []image.Rectangle) {
 
 		cell := backend.application.GetForRendering(x, y)
 		content := cell.Rune()
+		style   := cell.Style()
 
-		if forceRedraw && content < 32 { continue }
+		if
+			forceRedraw &&
+			content < 32 &&
+			style & (
+				stone.StyleHighlight |
+				stone.StyleUnderline) == 0 {
+			
+			continue
+		}
 
 		areas = append(areas, backend.boundsOfCell(x, y))
-		backend.drawRune(x, y, content, cell.Color(), !forceRedraw)
+		backend.drawRune (
+			x, y,
+			content,
+			cell.Color(),
+			cell.Style(),
+			!forceRedraw)
 	}}
 
 	if backend.drawBufferBounds && forceRedraw {
@@ -74,37 +88,87 @@ func (backend *Backend) drawRune (
 	x, y int,
 	character rune,
 	runeColor stone.Color,
+	runeStyle stone.Style,
 	drawBackground bool,
 ) {
 	// TODO: cache these draws as non-transparent buffers with the
 	// application background color as the background. that way, we won't
 	// need to redraw the characters *or* composite them.
 
-	if drawBackground {
+	face := backend.font.normal
+
+	highlight := runeStyle & stone.StyleHighlight > 0
+	bold      := runeStyle & stone.StyleBold      > 0
+	italic    := runeStyle & stone.StyleItalic    > 0
+
+	boldTransform   := false
+	italicTransform := false
+
+	switch {
+	case bold && italic:
+		if backend.font.boldItalic == nil {
+			switch {
+			case
+				backend.font.bold == nil && backend.font.italic != nil,
+				backend.font.bold != nil && backend.font.italic != nil:
+				
+				boldTransform = true
+				face = backend.font.italic
+			case backend.font.italic == nil && backend.font.bold != nil:
+				italicTransform = true
+				face = backend.font.bold
+			default:
+				boldTransform   = true
+				italicTransform = true
+			}
+		} else {
+			face = backend.font.boldItalic
+		}
+	case bold:
+		if backend.font.bold == nil {
+			boldTransform = true
+		} else {
+			face = backend.font.bold
+		}
+	case italic:
+		if backend.font.italic == nil {
+			italicTransform = true
+		} else {
+			face = backend.font.italic
+		}
+	}
+	
+	var background xgraphics.BGRA
+	var foreground xgraphics.BGRA
+
+	if highlight {
+		background = backend.colors[runeColor]
+		foreground = backend.colors[stone.ColorBackground]
+	} else {
+		background = backend.colors[stone.ColorBackground]
+		foreground = backend.colors[runeColor]
+	}
+
+	if drawBackground || highlight {
 		fillRectangle (
-			&image.Uniform {
-				C: backend.config.Color(stone.ColorBackground),
-			},
+			&image.Uniform { C: background },
 			backend.canvas,
 			backend.boundsOfCell(x, y))
 	}
 
-	if character < 32 { return }
-	
 	origin := backend.originOfCell(x, y + 1)
-	destinationRectangle, mask, maskPoint, _, ok := backend.font.face.Glyph (
+
+	if character >= 32 {
+		destinationRectangle, mask, maskPoint, _, ok := face.Glyph (
 			fixed.Point26_6 {
 				X: fixed.I(origin.X),
-			Y: fixed.I(origin.Y - backend.metrics.descent),
+				Y: fixed.I(origin.Y),
 			},
 			character)
 
 		if !ok {
-		println("warning")
 			strokeRectangle (
-			&image.Uniform {
-				C: backend.config.Color(stone.ColorForeground),
-			},
+				&image.Uniform { C: foreground },
 				backend.canvas,
 				backend.boundsOfCell(x, y))
 			return
@@ -112,25 +176,118 @@ func (backend *Backend) drawRune (
 
 		if backend.drawCellBounds {
 			strokeRectangle (
-			&image.Uniform {
-				C: backend.config.Color(stone.ColorForeground),
-			},
+				&image.Uniform { C: foreground },
 				backend.canvas,
 				backend.boundsOfCell(x, y))
 		}
 
-	draw.DrawMask (
-		backend.canvas,
-		destinationRectangle,
-		&image.Uniform {
-			C: backend.config.Color(runeColor),
-		},
-		image.Point { },
-		mask,
-		maskPoint,
-		draw.Over)
+		// alphaMask, isAlpha := mask.(*image.Alpha)
+		// if isAlpha {
+			// backend.sprayRuneMaskAlpha (
+				// alphaMask, destinationRectangle,
+				// maskPoint, foreground, background)
+		// } else {
+			backend.sprayRuneMask (
+				mask, destinationRectangle,
+				maskPoint, foreground, background,
+				italicTransform, boldTransform)
+		// }
+	}
+
+	// underline
+	if runeStyle & stone.StyleUnderline > 0 {
+		maxX := origin.X + backend.metrics.cellWidth
+		y :=
+			origin.Y -
+			backend.metrics.descent
+		for x := origin.X; x < maxX; x ++ {
+			backend.canvas.SetBGRA(x, y, foreground)
+		}
+	}
 }
 
+func (backend *Backend) sprayRuneMask (
+	mask       image.Image,
+	bounds     image.Rectangle,
+	maskPoint  image.Point,
+	fill       xgraphics.BGRA,
+	background xgraphics.BGRA,
+	italic     bool,
+	bold       bool,
+) {
+	maxX := bounds.Max.X - bounds.Min.X
+	maxY := bounds.Max.Y - bounds.Min.Y
+	
+	for y := 0; y < maxY; y ++ {
+		var previousAlpha uint32
+		offset := 0
+		if italic {
+			offset = (maxY - y) / 4
+		}
+		for x := 0; x < maxX; x ++ {
+			_, _, _,
+			alpha := mask.At(x + maskPoint.X, y + maskPoint.Y).RGBA()
+			currentAlpha := alpha
+			if bold && previousAlpha > alpha {
+				alpha = previousAlpha
+			}
+			backend.canvas.SetBGRA (
+				x + bounds.Min.X + offset,
+				y + bounds.Min.Y - backend.metrics.descent,
+				xgraphics.BlendBGRA (
+					background,
+					xgraphics.BGRA {
+						R: fill.R,
+						G: fill.G,
+						B: fill.B,
+						A: uint8(alpha >> 8),
+					}))
+			previousAlpha = currentAlpha
+		}
+
+		if bold {
+			backend.canvas.SetBGRA (
+				bounds.Max.X + offset,
+				y + bounds.Min.Y - backend.metrics.descent,
+				xgraphics.BlendBGRA (
+					background,
+					xgraphics.BGRA {
+						R: fill.R,
+						G: fill.G,
+						B: fill.B,
+						A: uint8(previousAlpha >> 8),
+					}))
+		}
+	}
+}
+
+// func (backend *Backend) sprayRuneMaskAlpha (
+	// mask       *image.Alpha,
+	// bounds     image.Rectangle,
+	// maskPoint  image.Point,
+	// fill       xgraphics.BGRA,
+	// background xgraphics.BGRA,
+// ) {
+	// maxX := bounds.Max.X - bounds.Min.X
+	// maxY := bounds.Max.Y - bounds.Min.Y
+	// 
+	// for y := 0; y < maxY; y ++ {
+	// for x := 0; x < maxX; x ++ {
+		// alpha := mask.AlphaAt(x + maskPoint.X, y + maskPoint.Y).A
+		// backend.canvas.SetBGRA (
+			// x + bounds.Min.X,
+			// y + bounds.Min.Y - backend.metrics.descent,
+			// xgraphics.BlendBGRA (
+				// background,
+				// xgraphics.BGRA {
+					// R: fill.R,
+					// G: fill.G,
+					// B: fill.B,
+					// A: alpha,
+				// }))
+	// }}
+// }
+
 func fillRectangle (
 	source      image.Image,
 	destination draw.Image,

backends/x/encoding.go

@@ -0,0 +1,339 @@
+package x
+
+import "unicode"
+import "github.com/jezek/xgb/xproto"
+import "github.com/jezek/xgbutil/keybind"
+import "git.tebibyte.media/sashakoshka/stone"
+
+// when making changes to this file, look at keysymdef.h and
+// https://tronche.com/gui/x/xlib/input/keyboard-encoding.html
+
+var buttonCodeTable = map[xproto.Keysym] stone.Button {
+	0xFFFFFF: stone.ButtonUnknown,
+
+	0xFF63: stone.KeyInsert,
+	0xFF67: stone.KeyMenu,
+	0xFF61: stone.KeyPrintScreen,
+	0xFF6B: stone.KeyPause,
+	0xFFE5: stone.KeyCapsLock,
+	0xFF14: stone.KeyScrollLock,
+	0xFF7F: stone.KeyNumLock,
+	0xFF08: stone.KeyBackspace,
+	0xFF09: stone.KeyTab,
+	0xFF0D: stone.KeyEnter,
+	0xFF1B: stone.KeyEscape,
+	
+	0xFF52: stone.KeyUp,
+	0xFF54: stone.KeyDown,
+	0xFF51: stone.KeyLeft,
+	0xFF53: stone.KeyRight,
+	0xFF55: stone.KeyPageUp,
+	0xFF56: stone.KeyPageDown,
+	0xFF50: stone.KeyHome,
+	0xFF57: stone.KeyEnd,
+	
+	0xFFE1: stone.KeyLeftShift,
+	0xFFE2: stone.KeyRightShift,
+	0xFFE3: stone.KeyLeftControl,
+	0xFFE4: stone.KeyRightControl,
+
+	0xFFE7: stone.KeyLeftMeta,
+	0xFFE8: stone.KeyRightMeta,
+	0xFFE9: stone.KeyLeftAlt,
+	0xFFEA: stone.KeyRightAlt,
+	0xFFEB: stone.KeyLeftSuper,
+	0xFFEC: stone.KeyRightSuper,
+	0xFFED: stone.KeyLeftHyper,
+	0xFFEE: stone.KeyRightHyper,
+	
+	0xFFFF: stone.KeyDelete,
+	
+	0xFFBE: stone.KeyF1,
+	0xFFBF: stone.KeyF2,
+	0xFFC0: stone.KeyF3,
+	0xFFC1: stone.KeyF4,
+	0xFFC2: stone.KeyF5,
+	0xFFC3: stone.KeyF6,
+	0xFFC4: stone.KeyF7,
+	0xFFC5: stone.KeyF8,
+	0xFFC6: stone.KeyF9,
+	0xFFC7: stone.KeyF10,
+	0xFFC8: stone.KeyF11,
+	0xFFC9: stone.KeyF12,
+
+	// TODO: send this whenever a compose key, dead key, etc is pressed,
+	// and then send the resulting character while witholding the key
+	// presses that were used to compose it. As far as the program is
+	// concerned, a magical key with the final character was pressed and the
+	// KeyDead key is just so that the program might provide some visual
+	// feedback to the user while input is being waited for.
+	0xFF20: stone.KeyDead,
+}
+
+var keypadCodeTable = map[xproto.Keysym] stone.Button {
+	0xff80: stone.Button(' '),
+	0xff89: stone.KeyTab,
+	0xff8d: stone.KeyEnter,
+	0xff91: stone.KeyF1,
+	0xff92: stone.KeyF2,
+	0xff93: stone.KeyF3,
+	0xff94: stone.KeyF4,
+	0xff95: stone.KeyHome,
+	0xff96: stone.KeyLeft,
+	0xff97: stone.KeyUp,
+	0xff98: stone.KeyRight,
+	0xff99: stone.KeyDown,
+	0xff9a: stone.KeyPageUp,
+	0xff9b: stone.KeyPageDown,
+	0xff9c: stone.KeyEnd,
+	0xff9d: stone.KeyHome,
+	0xff9e: stone.KeyInsert,
+	0xff9f: stone.KeyDelete,
+	0xffbd: stone.Button('='),
+	0xffaa: stone.Button('*'),
+	0xffab: stone.Button('+'),
+	0xffac: stone.Button(','),
+	0xffad: stone.Button('-'),
+	0xffae: stone.Button('.'),
+	0xffaf: stone.Button('/'),
+
+	0xffb0: stone.Button('0'),
+	0xffb1: stone.Button('1'),
+	0xffb2: stone.Button('2'),
+	0xffb3: stone.Button('3'),
+	0xffb4: stone.Button('4'),
+	0xffb5: stone.Button('5'),
+	0xffb6: stone.Button('6'),
+	0xffb7: stone.Button('7'),
+	0xffb8: stone.Button('8'),
+	0xffb9: stone.Button('9'),
+}
+
+// keycodeToButton converts an X keycode to a stone button code. It implements
+// a more fleshed out version of some of the logic found in
+// xgbutil/keybind/encoding.go to get a full keycode to keysym conversion, but
+// eliminates redundant work by going straight to a button code.
+func (backend *Backend) keycodeToButton (
+	keycode xproto.Keycode,
+	state   uint16,
+) (
+	button    stone.Button,
+	numberPad bool,
+) {
+	// PARAGRAPH 3
+	//
+	// A list of KeySyms is associated with each KeyCode. The list is
+	// intended to convey the set of symbols on the corresponding key. If
+	// the list (ignoring trailing NoSymbol entries) is a single KeySym
+	// ``K'', then the list is treated as if it were the list ``K NoSymbol
+	// K NoSymbol''. If the list (ignoring trailing NoSymbol entries) is a
+	// pair of KeySyms ``K1 K2'', then the list is treated as if it were the
+	// list ``K1 K2 K1 K2''. If the list (ignoring trailing NoSymbol
+	// entries) is a triple of KeySyms ``K1 K2 K3'', then the list is
+	// treated as if it were the list ``K1 K2 K3 NoSymbol''. When an
+	// explicit ``void'' element is desired in the list, the value
+	// VoidSymbol can be used.
+	symbol1 := keybind.KeysymGet(backend.connection, keycode, 0)
+	symbol2 := keybind.KeysymGet(backend.connection, keycode, 1)
+	symbol3 := keybind.KeysymGet(backend.connection, keycode, 2)
+	symbol4 := keybind.KeysymGet(backend.connection, keycode, 3)
+	switch {
+	case symbol2 == 0 && symbol3 == 0 && symbol4 == 0:
+		symbol3 = symbol1
+	case symbol3 == 0 && symbol4 == 0:
+		symbol3 = symbol1
+		symbol4 = symbol2
+	case symbol4 == 0:
+		symbol4 = 0
+	}
+	symbol1Rune := keysymToRune(symbol1)
+	symbol2Rune := keysymToRune(symbol2)
+	symbol3Rune := keysymToRune(symbol3)
+	symbol4Rune := keysymToRune(symbol4)
+
+	// PARAGRAPH 4
+	//
+	// The first four elements of the list are split into two groups of
+	// KeySyms. Group 1 contains the first and second KeySyms; Group 2
+	// contains the third and fourth KeySyms. Within each group, if the
+	// second element of the group is NoSymbol , then the group should be
+	// treated as if the second element were the same as the first element,
+	// except when the first element is an alphabetic KeySym ``K'' for which
+	// both lowercase and uppercase forms are defined. In that case, the
+	// group should be treated as if the first element were the lowercase
+	// form of ``K'' and the second element were the uppercase form of
+	// ``K.''
+	cased := false
+	if symbol2 == 0 {
+		upper := unicode.IsUpper(symbol1Rune)
+		lower := unicode.IsLower(symbol1Rune)
+		if upper || lower {
+			symbol1Rune = unicode.ToLower(symbol1Rune)
+			symbol2Rune = unicode.ToUpper(symbol1Rune)
+			cased = true
+		} else {
+			symbol2     = symbol1
+			symbol2Rune = symbol1Rune
+		}
+	}
+	if symbol4 == 0 {
+		upper := unicode.IsUpper(symbol3Rune)
+		lower := unicode.IsLower(symbol3Rune)
+		if upper || lower {
+			symbol3Rune = unicode.ToLower(symbol3Rune)
+			symbol4Rune = unicode.ToUpper(symbol3Rune)
+			cased = true
+		} else {
+			symbol4     = symbol3
+			symbol4Rune = symbol3Rune
+		}
+	}
+
+	// PARAGRAPH 5
+	//
+	// The standard rules for obtaining a KeySym from a KeyPress event make
+	// use of only the Group 1 and Group 2 KeySyms; no interpretation of/
+	// other KeySyms in the list is given. Which group to use is determined
+	// by the modifier state. Switching between groups is controlled by the
+	// KeySym named MODE SWITCH, by attaching that KeySym to some KeyCode
+	// and attaching that KeyCode to any one of the modifiers Mod1 through
+	// Mod5. This modifier is called the group modifier. For any KeyCode,
+	// Group 1 is used when the group modifier is off, and Group 2 is used
+	// when the group modifier is on.
+	modeSwitch := state & backend.modifierMasks.modeSwitch > 0
+	if modeSwitch {
+		symbol1     = symbol3
+		symbol1Rune = symbol3Rune
+		symbol2     = symbol4
+		symbol2Rune = symbol4Rune
+		
+	}
+	
+	// PARAGRAPH 6
+	// 
+	// The Lock modifier is interpreted as CapsLock when the KeySym named
+	// XK_Caps_Lock is attached to some KeyCode and that KeyCode is attached
+	// to the Lock modifier. The Lock modifier is interpreted as ShiftLock
+	// when the KeySym named XK_Shift_Lock is attached to some KeyCode and
+	// that KeyCode is attached to the Lock modifier. If the Lock modifier
+	// could be interpreted as both CapsLock and ShiftLock, the CapsLock
+	// interpretation is used.
+	shift :=
+		state & xproto.ModMaskShift                > 0 ||
+		state & backend.modifierMasks.shiftLock    > 0
+	capsLock := state & backend.modifierMasks.capsLock > 0
+
+	// PARAGRAPH 7
+	//
+	// The operation of keypad keys is controlled by the KeySym named
+	// XK_Num_Lock, by attaching that KeySym to some KeyCode and attaching
+	// that KeyCode to any one of the modifiers Mod1 through Mod5 . This
+	// modifier is called the numlock modifier. The standard KeySyms with
+	// the prefix ``XK_KP_'' in their name are called keypad KeySyms; these
+	// are KeySyms with numeric value in the hexadecimal range 0xFF80 to
+	// 0xFFBD inclusive. In addition, vendor-specific KeySyms in the
+	// hexadecimal range 0x11000000 to 0x1100FFFF are also keypad KeySyms.
+	numLock  := state & backend.modifierMasks.numLock  > 0
+	
+	// PARAGRAPH 8
+	//
+	// Within a group, the choice of KeySym is determined by applying the
+	// first rule that is satisfied from the following list:
+	var selectedKeysym xproto.Keysym
+	var selectedRune   rune
+	_, symbol2IsNumPad := keypadCodeTable[symbol2]
+	switch {
+	case numLock && symbol2IsNumPad:
+		// The numlock modifier is on and the second KeySym is a keypad
+		// KeySym. In this case, if the Shift modifier is on, or if the
+		// Lock modifier is on and is interpreted as ShiftLock, then the
+		// first KeySym is used, otherwise the second KeySym is used.
+		if shift {
+			selectedKeysym = symbol1
+			selectedRune   = symbol1Rune
+		} else {
+			selectedKeysym = symbol2
+			selectedRune   = symbol2Rune
+		}
+
+	case !shift && !capsLock:
+		// The Shift and Lock modifiers are both off. In this case, the
+		// first KeySym is used.
+		selectedKeysym = symbol1
+		selectedRune   = symbol1Rune
+
+	case !shift && capsLock:
+		// The Shift modifier is off, and the Lock modifier is on and is
+		// interpreted as CapsLock. In this case, the first KeySym is
+		// used, but if that KeySym is lowercase alphabetic, then the
+		// corresponding uppercase KeySym is used instead.
+		if cased && unicode.IsLower(symbol1Rune) {
+			selectedRune = symbol2Rune
+		} else {
+			selectedKeysym = symbol1
+			selectedRune   = symbol1Rune
+		}
+
+	case shift && capsLock:
+		// The Shift modifier is on, and the Lock modifier is on and is
+		// interpreted as CapsLock. In this case, the second KeySym is
+		// used, but if that KeySym is lowercase alphabetic, then the
+		// corresponding uppercase KeySym is used instead.
+		if cased && unicode.IsLower(symbol2Rune) {
+			selectedRune = unicode.ToUpper(symbol2Rune)
+		} else {
+			selectedKeysym = symbol2
+			selectedRune   = symbol2Rune
+		}
+
+	case shift:
+		// The Shift modifier is on, or the Lock modifier is on and is
+		// interpreted as ShiftLock, or both. In this case, the second
+		// KeySym is used.
+		selectedKeysym = symbol2
+		selectedRune   = symbol2Rune
+	}
+
+	/////////////////////////////////////////////////////////////////
+	// all of the below stuff is specific to stone's button codes. //
+	/////////////////////////////////////////////////////////////////
+
+	// look up in control code table
+	var isControl bool
+	button, isControl = buttonCodeTable[selectedKeysym]
+	if isControl { return }
+
+	// look up in keypad table
+	button, numberPad = keypadCodeTable[selectedKeysym]
+	if numberPad { return }
+
+	// otherwise, use the rune
+	button = stone.Button(selectedRune)
+	
+	return
+}
+
+// keysymToRune takes in an X keysym and outputs a utf32 code point. This
+// function does not and should not handle keypad keys, as those are handled
+// by Backend.keycodeToButton.
+func keysymToRune (keysym xproto.Keysym) (character rune) {
+	// X keysyms like 0xFF.. or 0xFE.. are non-character keys. these cannot
+	// be converted so we return a zero.
+	if (keysym >> 8) == 0xFF || (keysym >> 8) == 0xFE {
+		character = 0
+		return
+	}
+	
+	// some X keysyms have a single bit set to 1 here. i believe this is to
+	// prevent conflicts with existing codes. if we mask it off we will get
+	// a correct utf-32 code point.
+	if keysym & 0xF000000 == 0x1000000 {
+		character = rune(keysym & 0x0111111)
+		return
+	}
+
+	// if none of these things happened, we can safely (i think) assume that
+	// the keysym is an exact utf-32 code point.
+	character = rune(keysym)
+	return
+}

backends/x/event.go

@@ -91,7 +91,9 @@ func (backend *Backend) handleButtonPress (
 		backend.compressScrollSum(&sum)
 		backend.callbackManager.RunScroll(sum.x, sum.y)
 	} else {
-		backend.callbackManager.RunPress(stone.Button(buttonEvent.Detail + 127))
+		backend.callbackManager.RunPress (
+			stone.Button(buttonEvent.Detail + 127),
+			stone.Modifiers { })
 	}
 }
 
@@ -109,8 +111,18 @@ func (backend *Backend) handleKeyPress (
 	event xevent.KeyPressEvent,
 ) {
 	keyEvent    := *event.KeyPressEvent
-	button   := backend.keycodeToButton(keyEvent.Detail, keyEvent.State)
-	backend.callbackManager.RunPress(button)
+	button, num := backend.keycodeToButton(keyEvent.Detail, keyEvent.State)
+	backend.callbackManager.RunPress (button, stone.Modifiers {
+		Shift:
+			(keyEvent.State & xproto.ModMaskShift)             > 0 ||
+			(keyEvent.State & backend.modifierMasks.shiftLock) > 0,
+		Control: (keyEvent.State & xproto.ModMaskControl)       > 0,
+		Alt:     (keyEvent.State & backend.modifierMasks.alt)   > 0,
+		Meta:    (keyEvent.State & backend.modifierMasks.meta)  > 0,
+		Super:   (keyEvent.State & backend.modifierMasks.super) > 0,
+		Hyper:   (keyEvent.State & backend.modifierMasks.hyper) > 0,
+		NumberPad: num,
+	})
 }
 
 func (backend *Backend) handleKeyRelease (
@@ -118,7 +130,7 @@ func (backend *Backend) handleKeyRelease (
 	event xevent.KeyReleaseEvent,
 ) {
 	keyEvent  := *event.KeyReleaseEvent
-	button   := backend.keycodeToButton(keyEvent.Detail, keyEvent.State)
+	button, _ := backend.keycodeToButton(keyEvent.Detail, keyEvent.State)
 	backend.callbackManager.RunRelease(button)
 }
 

backends/x/factory.go

@@ -32,11 +32,20 @@ func factory (
 	}
 
 	// load font
-	backend.font.face = findAndLoadFont (
-		backend.config.FontName(),
+	backend.font.normal = findAndLoadFont (
+		backend.config.FontNameNormal(),
 		float64(backend.config.FontSize()))
-	if backend.font.face == nil {
-		backend.font.face = basicfont.Face7x13
+	backend.font.bold = findAndLoadFont (
+		backend.config.FontNameBold(),
+		float64(backend.config.FontSize()))
+	backend.font.italic = findAndLoadFont (
+		backend.config.FontNameItalic(),
+		float64(backend.config.FontSize()))
+	backend.font.boldItalic = findAndLoadFont (
+		backend.config.FontNameBoldItalic(),
+		float64(backend.config.FontSize()))
+	if backend.font.normal == nil {
+		backend.font.normal = basicfont.Face7x13
 	}
 
 	// pre-calculate colors
@@ -56,8 +65,8 @@ func factory (
 	}
 
 	// calculate metrics
-	metrics := backend.font.face.Metrics()
-	glyphAdvance, _ := backend.font.face.GlyphAdvance('M')
+	metrics := backend.font.normal.Metrics()
+	glyphAdvance, _ := backend.font.normal.GlyphAdvance('M')
 	backend.metrics.cellWidth  = glyphAdvance.Round()
 	backend.metrics.cellHeight = metrics.Height.Round()
 	backend.metrics.descent    = metrics.Descent.Round()
@@ -74,7 +83,18 @@ func factory (
 	if err != nil { return }
 	backend.window, err = xwindow.Generate(backend.connection)
 	if err != nil { return }
+
+	// get keyboard mapping information
 	keybind.Initialize(backend.connection)
+	backend.modifierMasks.capsLock   = backend.keysymToMask(0xFFE5)
+	backend.modifierMasks.shiftLock  = backend.keysymToMask(0xFFE6)
+	backend.modifierMasks.numLock    = backend.keysymToMask(0xFF7F)
+	backend.modifierMasks.modeSwitch = backend.keysymToMask(0xFF7E)
+	
+	backend.modifierMasks.hyper = backend.keysymToMask(0xffed)
+	backend.modifierMasks.super = backend.keysymToMask(0xffeb)
+	backend.modifierMasks.meta  = backend.keysymToMask(0xffe7)
+	backend.modifierMasks.alt   = backend.keysymToMask(0xffe9)
 
 	// create the window
 	backend.window.Create (
@@ -158,6 +178,38 @@ func findAndLoadFont (name string, size float64) (face font.Face) {
 	return
 }
 
+func (backend *Backend) keysymToKeycode (
+	symbol xproto.Keysym,
+) (
+	code xproto.Keycode,
+) {
+	mapping := keybind.KeyMapGet(backend.connection)
+	
+	for index, testSymbol := range mapping.Keysyms {
+		if testSymbol == symbol {
+			code = xproto.Keycode (
+				index /
+				int(mapping.KeysymsPerKeycode) +
+				int(backend.connection.Setup().MinKeycode))
+			break
+		}
+	}
+	
+	return
+}
+
+func (backend *Backend) keysymToMask (
+	symbol xproto.Keysym,
+) (
+	mask uint16,
+) {
+	mask = keybind.ModGet (
+		backend.connection,
+		backend.keysymToKeycode(symbol))
+	
+	return
+}
+
 // init registers this backend when the program starts.
 func init () {
 	stone.RegisterBackend(factory)

backends/x/unicode.go

@@ -1,187 +0,0 @@
-package x
-
-import "unicode"
-import "github.com/jezek/xgb/xproto"
-import "github.com/jezek/xgbutil/keybind"
-import "git.tebibyte.media/sashakoshka/stone"
-
-// when making changes to this file, look at keysymdef.h and
-// https://tronche.com/gui/x/xlib/input/keyboard-encoding.html
-
-var buttonCodeTable = map[xproto.Keysym] stone.Button {
-	0xFFFFFF: stone.ButtonUnknown,
-
-	0xFF63: stone.KeyInsert,
-	0xFF67: stone.KeyMenu,
-	0xFF61: stone.KeyPrintScreen,
-	0xFF6B: stone.KeyPause,
-	0xFFE5: stone.KeyCapsLock,
-	0xFF14: stone.KeyScrollLock,
-	0xFF7F: stone.KeyNumLock,
-	0xFF08: stone.KeyBackspace,
-	0xFF09: stone.KeyTab,
-	0xFF0D: stone.KeyEnter,
-	0xFF1B: stone.KeyEscape,
-	
-	0xFF52: stone.KeyUp,
-	0xFF54: stone.KeyDown,
-	0xFF51: stone.KeyLeft,
-	0xFF53: stone.KeyRight,
-	0xFF55: stone.KeyPageUp,
-	0xFF56: stone.KeyPageDown,
-	0xFF50: stone.KeyHome,
-	0xFF57: stone.KeyEnd,
-	
-	0xFFE1: stone.KeyLeftShift,
-	0xFFE2: stone.KeyRightShift,
-	0xFFE3: stone.KeyLeftControl,
-	0xFFE4: stone.KeyRightControl,
-	0xFFE9: stone.KeyLeftAlt,
-	0xFFEA: stone.KeyRightAlt,
-	0xFFEB: stone.KeyLeftSuper,
-	0xFFEC: stone.KeyRightSuper,
-	
-	0xFFFF: stone.KeyDelete,
-	
-	0xFFBE: stone.KeyF1,
-	0xFFBF: stone.KeyF2,
-	0xFFC0: stone.KeyF3,
-	0xFFC1: stone.KeyF4,
-	0xFFC2: stone.KeyF5,
-	0xFFC3: stone.KeyF6,
-	0xFFC4: stone.KeyF7,
-	0xFFC5: stone.KeyF8,
-	0xFFC6: stone.KeyF9,
-	0xFFC7: stone.KeyF10,
-	0xFFC8: stone.KeyF11,
-	0xFFC9: stone.KeyF12,
-}
-
-func (backend *Backend) keycodeToButton (
-	keycode xproto.Keycode,
-	state   uint16,
-) (
-	button stone.Button,
-) {
-	// FIXME: also set shift to true if the lock modifier is on and the lock
-	// modifier is interpreted as shiftLock
-	shift    := state & xproto.ModMaskShift > 0
-
-	// FIXME: only set this to true if the lock modifier is on and the lock
-	// modifier is interpreted as capsLock
-	capsLock := state & xproto.ModMaskLock  > 0
-
-	symbol1 := keybind.KeysymGet(backend.connection, keycode, 0)
-	symbol2 := keybind.KeysymGet(backend.connection, keycode, 1)
-	symbol3 := keybind.KeysymGet(backend.connection, keycode, 2)
-	symbol4 := keybind.KeysymGet(backend.connection, keycode, 3)
-
-	cased := false
-
-	// third paragraph
-	switch {
-	case symbol2 == 0 && symbol3 == 0 && symbol4 == 0:
-		symbol3 = symbol1
-	case symbol3 == 0 && symbol4 == 0:
-		symbol3 = symbol1
-		symbol2 = symbol2
-	case symbol4 == 0:
-		symbol4 = 0
-	}
-
-	symbol1Rune := keysymToRune(symbol1)
-	symbol2Rune := keysymToRune(symbol2)
-	symbol3Rune := keysymToRune(symbol3)
-	symbol4Rune := keysymToRune(symbol4)
-
-	// FIXME: we ignore mode switch stuff
-	_ = symbol4Rune
-
-	// fourth paragraph
-	if symbol2 == 0 {
-		upper := unicode.IsUpper(symbol1Rune)
-		lower := unicode.IsLower(symbol1Rune)
-		if upper || lower {
-			symbol1Rune = unicode.ToLower(symbol1Rune)
-			symbol2Rune = unicode.ToUpper(symbol1Rune)
-			cased = true
-		} else {
-			symbol2 = symbol1
-		}
-	}
-	if symbol4 == 0 {
-		upper := unicode.IsUpper(symbol3Rune)
-		lower := unicode.IsLower(symbol3Rune)
-		if upper || lower {
-			symbol3Rune = unicode.ToLower(symbol3Rune)
-			symbol4Rune = unicode.ToUpper(symbol3Rune)
-			cased = true
-		} else {
-			symbol4 = symbol3
-		}
-	}
-
-	var selectedKeysym xproto.Keysym
-	var selectedRune   rune
-	
-	// big ol list in the middle
-	switch {
-	// FIXME: take into account numlock
-	case !shift && !capsLock:
-		selectedKeysym = symbol1
-		selectedRune   = symbol1Rune
-		
-	case !shift && capsLock:
-		if cased && unicode.IsLower(symbol1Rune) {
-			selectedRune = symbol2Rune
-		} else {
-			selectedKeysym = symbol1
-			selectedRune   = symbol1Rune
-		}
-		
-	case shift && capsLock:
-		if cased && unicode.IsLower(symbol2Rune) {
-			selectedRune = unicode.ToUpper(symbol2Rune)
-		} else {
-			selectedKeysym = symbol2
-			selectedRune   = symbol2Rune
-		}
-		
-	case shift:
-		selectedKeysym = symbol2
-		selectedRune   = symbol2Rune
-	}
-
-	// look up in table
-	var isControl bool
-	button, isControl = buttonCodeTable[selectedKeysym]
-
-	// if it wasn't found, 
-	if !isControl {
-		button = stone.Button(selectedRune)
-	}
-	
-	return
-}
-
-func keysymToRune (keysym xproto.Keysym) (character rune) {
-	// X keysyms like 0xFF.. or 0xFE.. are non-character keys. these cannot
-	// be converted so we return a zero.
-	if (keysym >> 8) == 0xFF || (keysym >> 8) == 0xFE {
-		character = 0
-		return
-	}
-	
-	// some X keysyms have a single bit set to 1 here. i believe this is to
-	// prevent conflicts with existing codes. if we mask it off we will get
-	// a correct utf-32 code point.
-	if keysym & 0xF000000 == 0x1000000 {
-		character = rune(keysym & 0x0111111)
-		return
-	}
-
-	// if none of these things happened, we can safely (i think) assume that
-	// the keysym is an exact utf-32 code point.
-	character = rune(keysym)
-	return
-}

backends/x/x.go

@@ -27,7 +27,10 @@ type Backend struct {
 	lock sync.Mutex
 
 	font struct {
-		face font.Face
+		normal     font.Face
+		bold       font.Face
+		italic     font.Face
+		boldItalic font.Face
 	}
 
 	colors [8]xgraphics.BGRA
@@ -43,6 +46,18 @@ type Backend struct {
 		descent      int
 	}
 
+	modifierMasks struct {
+		capsLock   uint16
+		shiftLock  uint16
+		numLock    uint16
+		modeSwitch uint16
+
+		alt   uint16
+		meta  uint16
+		super uint16
+		hyper uint16
+	}
+
 	windowBoundsClean bool
 }
 

buffer.go

@@ -8,8 +8,8 @@ type Color uint8
 const (
 	ColorBackground  Color = 0x0
 	ColorForeground  Color = 0x1
-	ColorRed         Color = 0x2
-	ColorOrange      Color = 0x3
+	ColorDim         Color = 0x2
+	ColorRed         Color = 0x3
 	ColorYellow      Color = 0x4
 	ColorGreen       Color = 0x5
 	ColorBlue        Color = 0x6
@@ -21,11 +21,11 @@ const (
 type Style uint8
 
 const (
-	StyleNormal     Style = iota
-	StyleBold       Style = iota >> 1
-	StyleItalic
-	StyleUnderline
-	StyleHighlight
+	StyleNormal     Style = 0
+	StyleBold       Style = 1
+	StyleItalic     Style = 2
+	StyleUnderline  Style = 4
+	StyleHighlight  Style = 8
 	StyleBoldItalic Style = StyleBold | StyleItalic
 )
 
@@ -44,7 +44,7 @@ func (cell Cell) Color () (color Color) {
 }
 
 // Style returns the styling information associated with the cell
-func (cell Cell) Style (style Style) {
+func (cell Cell) Style () (style Style) {
 	style = cell.style
 	return
 }
@@ -192,9 +192,13 @@ func (buffer *DamageBuffer) Write (bytes []byte) (bytesWritten int, err error) {
 	bytesWritten = len(bytes)
 	
 	for _, character := range text {
+		if character == '\n' {
+			buffer.dot.x = 0
+			buffer.dot.y ++
+		} else {
 			buffer.setRune(buffer.dot.x, buffer.dot.y, character)
 			buffer.dot.x ++
-		if buffer.dot.x > buffer.width { break }
+		}
 	}
 	
 	return

config.go

@@ -1,171 +1,139 @@
 package stone
 
-import "os"
-import "bufio"
-import "strings"
-import "strconv"
 import "image/color"
-import "path/filepath"
 
-// Config stores configuration parameters. Backends only should honor parameters
-// that they can support.
+import "git.tebibyte.media/sashakoshka/stone/config"
+
+// Config stores global, read-only configuration parameters that apply to all
+// applications. Backends only should honor parameters that they can support.
 type Config struct {
+	private  config.Config
 	colors   [8]color.Color
 	padding  int
 	center   bool
 	fontSize int
-	fontName string
+	fontNameNormal     string
+	fontNameBold       string
+	fontNameItalic     string
+	fontNameBoldItalic string
 }
 
 // Color returns the color value at the specified index.
-func (config *Config) Color (index Color) (value color.Color) {
-	value = config.colors[index]
+func (public *Config) Color (index Color) (value color.Color) {
+	value = public.colors[index]
 	return
 }
 
 // Padding specifies how many cell's worth of padding should be on all sides of
 // the buffer.
-func (config *Config) Padding () (padding int) {
-	padding = config.padding
+func (public *Config) Padding () (padding int) {
+	padding = public.padding
 	return
 }
 
 // Center returns whether the buffer should be displayed in the center of the
 // window like in kitty, or aligned to one corner like in gnome-terminal.
-func (config *Config) Center () (center bool) {
-	center = config.center
+func (public *Config) Center () (center bool) {
+	center = public.center
 	return
 }
 
 // FontSize specifies how big the font should be.
-func (config *Config) FontSize () (fontSize int) {
-	fontSize = config.fontSize
+func (public *Config) FontSize () (fontSize int) {
+	fontSize = public.fontSize
 	return
 }
 
-// FontName specifies the name of the font to use.
-func (config *Config) FontName () (fontName string) {
-	fontName = config.fontName
+// FontNameNormal specifies the name of the font to use for normal text.
+func (public *Config) FontNameNormal () (fontName string) {
+	fontName = public.fontNameNormal
 	return
 }
 
-func (config *Config) load () {
-	config.colors = [8]color.Color {
-		// background
+// FontNameBold specifies the name of the font to use for bold text.
+func (public *Config) FontNameBold () (fontName string) {
+	fontName = public.fontNameBold
+	return
+}
+
+// FontName specifies the name of the font to use for  text.
+func (public *Config) FontNameItalic () (fontName string) {
+	fontName = public.fontNameItalic
+	return
+}
+
+// FontName specifies the name of the font to use for  text.
+func (public *Config) FontNameBoldItalic () (fontName string) {
+	fontName = public.fontNameBoldItalic
+	return
+}
+
+func (public *Config) load () {
+	public.private = config.Config {
+		LegalParameters: map[string] config.Type {
+			"fontNormal":      config.TypeString,
+			"fontBold":        config.TypeString,
+			"fontItalic":      config.TypeString,
+			"fontBoldItalic":  config.TypeString,
+			"fontSize":        config.TypeInteger,
+			"padding":         config.TypeInteger,
+			"center":          config.TypeBoolean,
+			"colorBackground": config.TypeColor,
+			"colorForeground": config.TypeColor,
+			"colorDim":        config.TypeColor,
+			"colorRed":        config.TypeColor,
+			"colorYellow":     config.TypeColor,
+			"colorGreen":      config.TypeColor,
+			"colorBlue":       config.TypeColor,
+			"colorPurple":     config.TypeColor,
+		},
+		
+		Parameters: map[string] any {
+			"fontNormal":     "",
+			"fontBold":       "",
+			"fontItalic":     "",
+			"fontBoldItalic": "",
+			"fontSize":       11,
+			"padding":        2,
+			"center":         false,
+			"colorBackground":
 				color.RGBA { R: 0, G: 0, B: 0, A: 0 },
-		// foreground
+			"colorForeground":
 				color.RGBA { R: 0xFF, G: 0xFF, B: 0xFF, A: 0xFF },
-		// red
+			"colorDim":
+				color.RGBA { R: 0x80, G: 0x80, B: 0x80, A: 0xFF },
+			"colorRed":
 				color.RGBA { R: 0xFF, G: 0x00, B: 0x00, A: 0xFF },
-		// orange
-		color.RGBA { R: 0xFF, G: 0x80, B: 0x00, A: 0xFF },
-		// yellow
+			"colorYellow":
 				color.RGBA { R: 0xFF, G: 0xFF, B: 0x00, A: 0xFF },
-		// green
+			"colorGreen":
 				color.RGBA { R: 0x00, G: 0xFF, B: 0x00, A: 0xFF },
-		// blue
+			"colorBlue":
 				color.RGBA { R: 0x00, G: 0x80, B: 0xFF, A: 0xFF },
-		// purple
+			"colorPurple":
 				color.RGBA { R: 0x80, G: 0x40, B: 0xFF, A: 0xFF },
+		},
 	}
-	config.fontName = ""
-	config.fontSize = 11
-	config.padding = 2
 
-	config.loadFile("/etc/stone/stone.conf")
-	homeDirectory, err := os.UserHomeDir()
-	if err != nil { return }
-	config.loadFile(filepath.Join(homeDirectory, "/.config/stone/stone.conf"))
+	public.private.Load("stone")
+	params := public.private.Parameters
+
+	public.fontNameNormal     = params["fontNormal"].(string)
+	public.fontNameBold       = params["fontBold"].(string)
+	public.fontNameItalic     = params["fontItalic"].(string)
+	public.fontNameBoldItalic = params["fontBoldItalic"].(string)
+	public.fontSize           = params["fontSize"].(int)
+	public.padding            = params["padding"].(int)
+	public.center             = params["center"].(bool)
+	
+	public.colors[ColorBackground] = params["colorBackground"].(color.RGBA)
+	public.colors[ColorForeground] = params["colorForeground"].(color.RGBA)
+	public.colors[ColorDim]        = params["colorDim"       ].(color.RGBA)
+	public.colors[ColorRed]        = params["colorRed"       ].(color.RGBA)
+	public.colors[ColorYellow]     = params["colorYellow"    ].(color.RGBA)
+	public.colors[ColorGreen]      = params["colorGreen"     ].(color.RGBA)
+	public.colors[ColorBlue]       = params["colorBlue"      ].(color.RGBA)
+	public.colors[ColorPurple]     = params["colorPurple"    ].(color.RGBA)
 	
 	return
 }
-
-func (config *Config) loadFile (path string) {
-	file, err := os.Open(path)
-	if err != nil { return }
-
-	scanner := bufio.NewScanner(file)
-	for scanner.Scan() {
-		line := strings.TrimSpace(scanner.Text())
-		
-		if len(line) == 0 {
-			continue
-		}
-
-		if line[0] == '#' {
-			continue
-		}
-	
-		key, value, found := strings.Cut(scanner.Text(), ":")
-		if !found {
-			println (
-				"config: error in file", path +
-				": key-value separator missing")
-			println(scanner.Text())
-			continue
-		}
-		key   = strings.TrimSpace(key)
-		value = strings.TrimSpace(value)
-
-		var valueInt int
-		var valueColor color.Color
-		var valueBoolean bool
-		
-		if value == "true" {
-			valueBoolean = true
-		}
-
-		if value[0] == '#' {
-			if len(value) != 7  {
-				println (
-					"config: error in file", path +
-					": malformed color literal")
-				continue
-			}
-
-			colorInt, err := strconv.ParseUint(value[1:7], 16, 24)
-			if err != nil  {
-				println (
-					"config: error in file", path +
-					": malformed color literal")
-				continue
-			}
-
-			valueColor = color.RGBA {
-				R: uint8(colorInt >> 16),
-				G: uint8(colorInt >> 8),
-				B: uint8(colorInt),
-				A: 0xFF,
-			}
-		} else {
-			valueInt, _ = strconv.Atoi(value)
-		}
-
-		switch key {
-		case "fontNormal":
-			config.fontName = value
-		case "fontSize":
-			config.fontSize = valueInt
-		case "padding":
-			config.padding = valueInt
-		case "center":
-			config.center = valueBoolean
-		case "colorBackground":
-			config.colors[ColorBackground] = valueColor
-		case "colorForeground":
-			config.colors[ColorForeground] = valueColor
-		case "colorRed":
-			config.colors[ColorRed] = valueColor
-		case "colorOrange":
-			config.colors[ColorOrange] = valueColor
-		case "colorYellow":
-			config.colors[ColorYellow] = valueColor
-		case "colorGreen":
-			config.colors[ColorGreen] = valueColor
-		case "colorBlue":
-			config.colors[ColorBlue] = valueColor
-		case "colorPurple":
-			config.colors[ColorPurple] = valueColor
-		}
-	}
-}

config/config.go

@@ -0,0 +1,324 @@
+package config
+
+import "io"
+import "os"
+import "fmt"
+import "sort"
+import "bufio"
+import "strings"
+import "strconv"
+import "image/color"
+import "path/filepath"
+
+// when making changes to this file, look at
+// https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
+
+// Error represents an error that can be returned by functions or methods in
+// this module.
+type Error int
+
+const (
+	// ErrorIllegalName is thrown when an application name contains illegal
+	// characters such as a slash.
+	ErrorIllegalName Error = iota
+
+	// ErrorNoSeparator is thrown when a configuration file has an
+	// incorrectly formatted key-value pair.
+	ErrorNoSeparator
+
+	// ErrorUnknownParameter is thrown when an unknown key is encountered in
+	// a configuration file.
+	ErrorUnknownParameter
+
+	// ErrorWrongColorLength is thrown when a configuration file has a color
+	// literal with a total length unequal to 7.
+	ErrorWrongColorLength
+
+	// ErrorMalformedColorLiteral is thrown when a configuration file has an
+	// improperly formatted color literal, or a color literal was expected
+	// and something else was encountered.
+	ErrorMalformedColorLiteral
+	
+	// ErrorMalformedIntegerLiteral is thrown when a configuration file has
+	// an improperly formatted integer literal, or an integer literal was
+	// expected and something else was encountered.
+	ErrorMalformedIntegerLiteral
+	
+	// ErrorMalformedFloatLiteral is thrown when a configuration file has
+	// an improperly formatted float literal, or a float literal was
+	// expected and something else was encountered.
+	ErrorMalformedFloatLiteral
+)
+
+// Error returns a description of the error.
+func (err Error) Error () (description string) {
+	switch err {
+	case ErrorIllegalName:
+		description = "name contains illegal characters"
+	case ErrorNoSeparator:
+		description = "key:value pair has no separator"
+	case ErrorUnknownParameter:
+		description = "unknown parameter"
+	case ErrorWrongColorLength:
+		description = "color literal has the wrong length"
+	case ErrorMalformedColorLiteral:
+		description = "malformed color literal"
+	case ErrorMalformedIntegerLiteral:
+		description = "malformed integer literal"
+	case ErrorMalformedFloatLiteral:
+		description = "malformed float literal"
+	}
+
+	return
+}
+
+// Type represents the data type of a configuration parameter.
+type Type int
+
+const (
+	// string
+	// It is just a basic string with inner whitespace preserved. No quotes
+	// should be used in the file.
+	TypeString Type = iota
+
+	// Type: image/color.RGBA
+	// Represented as a 24 bit hexadecimal number (case insensitive)
+	// preceded with a # sign where the first two digits represent the red
+	// channel, the middle two digits represent the green channel, and the
+	// last two digits represent the blue channel.
+	TypeColor
+
+	// Type: int
+	// An integer literal, like 123456789
+	TypeInteger
+
+	// Type: float64
+	// A floating point literal, like 1234.56789
+	TypeFloat
+
+	// Type: bool
+	// Values true, yes, on, and 1 are all truthy (case insensitive) and
+	// anything else is falsy.
+	TypeBoolean
+)
+
+// Config holds a list of configuration parameters.
+type Config struct {
+	// LegalParameters holds the names and types of all parameters that can
+	// be parsed. If the parser runs into a parameter that is not listed
+	// here, it will print out an error message and keep on parsing.
+	LegalParameters map[string] Type
+
+	// Parameters holds the names and values of all parsed parameters. If a
+	// value is non-nil, it can be safely type asserted into whatever type
+	// was requested.
+	Parameters map[string] any
+}
+
+// Load loads and parses the files /etc/xdg/<name>/<name>.conf and
+// <home>/.config/<name>/<name>.conf, unless the corresponding XDG environment
+// variables are set - then it uses those.
+func (config *Config) Load (name string) (err error) {
+	if nameIsIllegal(name) {
+		err = ErrorIllegalName
+		return
+	}
+
+	for _, directory := range configDirs {
+		path := filepath.Join(directory, name, name + ".conf")
+		
+		file, fileErr := os.Open(path)
+		if fileErr != nil { continue }
+		parseErr := config.LoadFrom(file)
+		defer file.Close()
+		
+		if parseErr != nil {
+			println (
+				"config: error in file", path +
+				":", parseErr.Error())
+		}
+	}
+
+	return
+}
+
+// LoadFrom parses a configuration file from an io.Reader. Configuration files
+// are divided into lines where each line may be blank, a comment, or a
+// key-value pair. If the line is blank or begins with a # character, it is
+// ignored. Else, the line must have a key and a value separated by a colon.
+// Before they are processed, leading and trailing whitespace is trimmed from
+// the key and the value. Keys are case sensitive.
+func (config *Config) LoadFrom (reader io.Reader) (err error) {
+	if config.LegalParameters == nil {
+		config.LegalParameters = make(map[string] Type)
+	}
+	
+	if config.Parameters == nil {
+		config.Parameters = make(map[string] any)
+	}
+	
+	scanner := bufio.NewScanner(reader)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		
+		if len(line) == 0 {
+			continue
+		}
+
+		if line[0] == '#' {
+			continue
+		}
+	
+		key, value, found := strings.Cut(scanner.Text(), ":")
+		if !found {
+			err = ErrorNoSeparator
+			return
+		}
+		key   = strings.TrimSpace(key)
+		value = strings.TrimSpace(value)
+
+		what, isKnown := config.LegalParameters[key]
+		if !isKnown {
+			err = ErrorUnknownParameter
+			return
+		}
+
+		switch what {
+		case TypeString:
+			config.Parameters[key] = value
+			
+		case TypeColor:
+			var valueColor color.Color
+			valueColor, err = parseColor(value)
+			if err != nil { return }
+			config.Parameters[key] = valueColor
+		
+		case TypeInteger:
+			var valueInt int
+			valueInt, err = strconv.Atoi(value)
+			if err != nil {
+				err = ErrorMalformedIntegerLiteral
+				return
+			}
+			config.Parameters[key] = valueInt
+			
+		case TypeFloat:
+			var valueFloat float64
+			valueFloat, err = strconv.ParseFloat(value, 64)
+			if err != nil {
+				err = ErrorMalformedFloatLiteral
+				return
+			}
+			config.Parameters[key] = valueFloat
+			
+		case TypeBoolean:
+			value = strings.ToLower(value)
+			truthy :=
+				value == "true" ||
+				value == "yes"  ||
+				value == "on"   ||
+				value == "1"
+			config.Parameters[key] = truthy
+		}
+	}
+
+	return
+}
+
+// Save overwrites the main user configuration file, which is located at
+// <home>/.config/<name>/<name>.conf unless $XDG_CONFIG_HOME has been set, in
+// which case the value of that variable is used instead.
+func (config *Config) Save (name string) (err error) {
+	if nameIsIllegal(name) {
+		err = ErrorIllegalName
+		return
+	}
+
+	err = os.MkdirAll(configHome, 0755)
+	if err != nil { return }
+	
+	file, err := os.OpenFile (
+		filepath.Join(configHome, name, name + ".conf"),
+		os.O_WRONLY | os.O_CREATE | os.O_TRUNC, 0744)
+	if err != nil { return }
+	defer file.Close()
+
+	err = config.SaveTo(file)
+	if err != nil { return }
+
+	return
+}
+
+// SaveTo writes the configuration data to the specified io.Writer. Keys are
+// alphabetically sorted.
+func (config *Config) SaveTo (writer io.Writer) (err error) {
+	keys := make([]string, len(config.Parameters))
+	index := 0
+	for key, _ := range config.Parameters {
+		keys[index] = key
+		index ++
+	}
+	sort.Strings(keys)
+
+	for _, key := range keys {
+		value := config.Parameters[key]
+		switch value.(type) {
+		case string:
+			fmt.Fprintf(writer,"%s: %s\n", key, value.(string))
+			
+		case color.RGBA:
+			colorValue := value.(color.RGBA)
+			colorInt := 
+				uint64(colorValue.R) << 16 |
+				uint64(colorValue.G) << 8  |
+				uint64(colorValue.B)
+			fmt.Fprintf(writer,"%s: #%06x\n", key, colorInt)
+			
+		case int:
+			fmt.Fprintf(writer,"%s: %d\n", key, value.(int))
+			
+		case float64:
+			fmt.Fprintf(writer,"%s: %f\n", key, value.(float64))
+			
+		case bool:
+			fmt.Fprintf(writer,"%s: %t\n", key, value.(bool))
+		default:
+			fmt.Fprintf(writer,"# %s: unknown type\n", key)
+		}
+	}
+
+	return
+}
+
+func parseColor (value string) (valueColor color.Color, err error) {
+	if value[0] == '#' {
+		if len(value) != 7  {
+			err = ErrorWrongColorLength
+			return
+		}
+
+		var colorInt uint64
+		colorInt, err = strconv.ParseUint(value[1:7], 16, 24)
+		if err != nil  {
+			err = ErrorMalformedColorLiteral
+			return
+		}
+
+		valueColor = color.RGBA {
+			R: uint8(colorInt >> 16),
+			G: uint8(colorInt >> 8),
+			B: uint8(colorInt),
+			A: 0xFF,
+		}
+	} else {
+		err = ErrorMalformedColorLiteral
+		return
+	}
+
+	return
+}
+
+func nameIsIllegal (name string) (legal bool) {
+	legal = strings.ContainsAny(name, "/\\|:.%")
+	return
+}

config/xdg.go

@@ -0,0 +1,54 @@
+package config
+
+import "os"
+import "strings"
+import "path/filepath"
+
+var homeDirectory string
+var configHome    string
+var configDirs    []string
+var dataHome      string
+var cacheHome     string
+
+func init () {
+	var err error
+	homeDirectory, err = os.UserHomeDir()
+	if err != nil {
+		panic("could not get user home directory: " + err.Error())
+	}
+
+	configHome = os.Getenv("XDG_CONFIG_HOME")
+	if configHome == "" {
+		configHome = filepath.Join(homeDirectory, "/.config/")
+	}
+	
+	configDirsString := os.Getenv("XDG_CONFIG_DIRS")
+	if configDirsString == "" {
+		configDirsString = "/etc/xdg/"
+	}
+
+	configDirs = append(strings.Split(configDirsString, ":"), configHome)
+
+	dataHome = os.Getenv("XDG_DATA_HOME")
+	if dataHome == "" {
+		dataHome = filepath.Join(homeDirectory, "/.local/share/")
+	}
+
+	cacheHome = os.Getenv("XDG_CACHE_HOME")
+	if cacheHome == "" {
+		cacheHome = filepath.Join(homeDirectory, "/.cache/")
+	}
+}
+
+// DataHome returns the path to the directory where user data should be stored.
+func DataHome (name string) (home string) {
+	home = filepath.Join(dataHome, name)
+	return
+}
+
+// CacheHome returns the path to the directory where cache files should be
+// stored.
+func CacheHome (name string) (home string) {
+	home = filepath.Join(cacheHome, name)
+	return
+}

event.go

@@ -2,7 +2,7 @@ package stone
 
 type CallbackManager struct {
 	onQuit      func ()
-	onPress     func (button Button)
+	onPress     func (button Button, modifiers Modifiers)
 	onRelease   func (button Button)
 	onResize    func ()
 	onMouseMove func (x, y int)
@@ -15,9 +15,9 @@ func (manager *CallbackManager) RunQuit () {
 	manager.onQuit()
 }
 
-func (manager *CallbackManager) RunPress (button Button) {
+func (manager *CallbackManager) RunPress (button Button, modifiers Modifiers) {
 	if manager.onPress == nil { return }
-	manager.onPress(button)
+	manager.onPress(button, modifiers)
 }
 
 func (manager *CallbackManager) RunRelease (button Button) {

examples/color/main.go

@@ -58,7 +58,7 @@ func redraw () {
 	application.SetRune(0, height - 1, '+')
 
 	for x := 0; x < width; x ++ {
-		application.SetColor(x, height / 2, stone.Color(x % 6 + 2))
+		application.SetColor(x, height / 2, stone.Color(x % 5 + 3))
 	}
 	
 	for x := 1; x < width - 1; x ++ {

examples/confview/confview.go

@@ -0,0 +1,106 @@
+package main
+
+import "os"
+import "image"
+import "image/color"
+import _ "image/png"
+import "git.tebibyte.media/sashakoshka/stone"
+import "git.tebibyte.media/sashakoshka/stone/config"
+import _ "git.tebibyte.media/sashakoshka/stone/backends/x"
+
+var application = &stone.Application { }
+var inputState struct {
+	x int
+	y int
+}
+var globalConfig config.Config
+
+func main () {
+	application.SetTitle("configuration viewer")
+	application.SetSize(32, 16)
+
+	iconFile16, err := os.Open("assets/scaffold16.png")
+	if err != nil { panic(err) }
+	icon16, _, err := image.Decode(iconFile16)
+	if err != nil { panic(err) }
+	iconFile16.Close()
+	iconFile32, err := os.Open("assets/scaffold32.png")
+	if err != nil { panic(err) }
+	icon32, _, err := image.Decode(iconFile32)
+	if err != nil { panic(err) }
+	iconFile16.Close()
+	
+	application.SetIcon([]image.Image { icon16, icon32 })
+	
+	application.OnPress(onPress)
+	application.OnRelease(onRelease)
+	application.OnMouseMove(onMouseMove)
+	application.OnStart(onStart)
+	application.OnResize(redraw)
+	
+	err = application.Run()
+	if err != nil { panic(err) }
+}
+
+func onStart () {
+	// this is just copy pasted from config.go
+	globalConfig = config.Config {
+		LegalParameters: map[string] config.Type {
+			"fontNormal":      config.TypeString,
+			"fontSize":        config.TypeInteger,
+			"padding":         config.TypeInteger,
+			"center":          config.TypeBoolean,
+			"colorBackground": config.TypeColor,
+			"colorForeground": config.TypeColor,
+			"colorDim":        config.TypeColor,
+			"colorRed":        config.TypeColor,
+			"colorYellow":     config.TypeColor,
+			"colorGreen":      config.TypeColor,
+			"colorBlue":       config.TypeColor,
+			"colorPurple":     config.TypeColor,
+		},
+		
+		Parameters: map[string] any {
+			"fontNormal": "",
+			"fontSize":   11,
+			"padding":    2,
+			"center":     false,
+			"colorBackground":
+				color.RGBA { R: 0, G: 0, B: 0, A: 0 },
+			"colorForeground":
+				color.RGBA { R: 0xFF, G: 0xFF, B: 0xFF, A: 0xFF },
+			"colorDim":
+				color.RGBA { R: 0x80, G: 0x80, B: 0x80, A: 0xFF },
+			"colorRed":
+				color.RGBA { R: 0xFF, G: 0x00, B: 0x00, A: 0xFF },
+			"colorYellow":
+				color.RGBA { R: 0xFF, G: 0xFF, B: 0x00, A: 0xFF },
+			"colorGreen":
+				color.RGBA { R: 0x00, G: 0xFF, B: 0x00, A: 0xFF },
+			"colorBlue":
+				color.RGBA { R: 0x00, G: 0x80, B: 0xFF, A: 0xFF },
+			"colorPurple":
+				color.RGBA { R: 0x80, G: 0x40, B: 0xFF, A: 0xFF },
+		},
+	}
+	globalConfig.Load("stone")
+	redraw()
+}
+
+func redraw () {
+	// i fucking love go interfaces
+	application.Clear()
+	application.SetDot(0, 0)
+	globalConfig.SaveTo(application)
+}
+
+func onPress (button stone.Button, modifiers stone.Modifiers) {
+}
+
+func onRelease (button stone.Button) {
+}
+
+func onMouseMove (x, y int) {
+	inputState.x = x
+	inputState.y = y
+}

examples/draw/main.go

@@ -34,7 +34,7 @@ func main () {
 	if err != nil { panic(err) }
 }
 
-func onPress (button stone.Button) {
+func onPress (button stone.Button, modifiers stone.Modifiers) {
 	if button == stone.MouseButtonLeft {
 		mousePressed = true
 		application.SetRune(0, 0, '+')
@@ -50,7 +50,8 @@ func onRelease (button stone.Button) {
 	}
 }
 
-func onMouseMove (x, y int) {	if mousePressed {
+func onMouseMove (x, y int) {
+	if mousePressed {
 		application.SetRune(x, y, '#')
 		application.Draw()
 	}

examples/printbuttons/main.go

@@ -0,0 +1,51 @@
+package main
+
+import "os"
+import "fmt"
+import "image"
+import _ "image/png"
+import "git.tebibyte.media/sashakoshka/stone"
+import _ "git.tebibyte.media/sashakoshka/stone/backends/x"
+
+var application = &stone.Application { }
+
+func main () {
+	application.SetTitle("press any key")
+	application.SetSize(8, 1)
+
+	iconFile16, err := os.Open("assets/scaffold16.png")
+	if err != nil { panic(err) }
+	icon16, _, err := image.Decode(iconFile16)
+	if err != nil { panic(err) }
+	iconFile16.Close()
+	iconFile32, err := os.Open("assets/scaffold32.png")
+	if err != nil { panic(err) }
+	icon32, _, err := image.Decode(iconFile32)
+	if err != nil { panic(err) }
+	iconFile16.Close()
+	
+	application.SetIcon([]image.Image { icon16, icon32 })
+	
+	application.OnPress(onPress)
+	application.OnRelease(onRelease)
+	
+	err = application.Run()
+	if err != nil { panic(err) }
+}
+
+func onPress (button stone.Button, modifiers stone.Modifiers) {
+	fmt.Printf (
+		"=>>\t0x%X\tsh: %t\tctrl: %t\talt: %t\tm: %t\ts: %t \th: %t\tnumpad: %t\n",
+		button,
+		modifiers.Shift,
+		modifiers.Control,
+		modifiers.Alt,
+		modifiers.Meta,
+		modifiers.Super,
+		modifiers.Hyper,
+		modifiers.NumberPad)
+}
+
+func onRelease (button stone.Button) {
+	fmt.Printf("<--\t0x%X\n", button)
+}

examples/style/main.go

@@ -0,0 +1,77 @@
+package main
+
+import "os"
+import "fmt"
+import "image"
+import "math/rand"
+import _ "image/png"
+import "git.tebibyte.media/sashakoshka/stone"
+import _ "git.tebibyte.media/sashakoshka/stone/backends/x"
+
+var application = &stone.Application { }
+
+func main () {
+	application.SetTitle("style demo")
+	application.SetSize(11, 8)
+
+	iconFile16, err := os.Open("assets/scaffold16.png")
+	if err != nil { panic(err) }
+	icon16, _, err := image.Decode(iconFile16)
+	if err != nil { panic(err) }
+	iconFile16.Close()
+	iconFile32, err := os.Open("assets/scaffold32.png")
+	if err != nil { panic(err) }
+	icon32, _, err := image.Decode(iconFile32)
+	if err != nil { panic(err) }
+	iconFile16.Close()
+	
+	application.SetIcon([]image.Image { icon16, icon32 })
+	
+	application.OnStart(redraw)
+	application.OnResize(redraw)
+	application.OnPress(onPress)
+	
+	err = application.Run()
+	if err != nil { panic(err) }
+}
+
+func onPress (button stone.Button, modifiers stone.Modifiers) {
+	redraw()
+	application.Draw()
+}
+
+func redraw () {
+	width, _ := application.Size()
+	application.SetDot(0, 0)
+	fmt.Fprint (
+		application,
+		"normal\n",
+		"bold\n",
+		"italic\n",
+		"underline\n",
+		"all 3\n",
+		"highlighted\n",
+		"all 4\n",
+		"highlight?")
+	fillStyle(0, width, stone.StyleNormal)
+	fillStyle(1, width, stone.StyleBold)
+	fillStyle(2, width, stone.StyleItalic)
+	fillStyle(3, width, stone.StyleUnderline)
+	fillStyle(4, width, stone.StyleBoldItalic | stone.StyleUnderline)
+	fillStyle(5, width, stone.StyleHighlight)
+	fillStyle(6, width, stone.StyleBoldItalic | stone.StyleUnderline |
+		stone.StyleHighlight)
+
+	if rand.Int() % 2 == 0 {
+		fillStyle(7, width, stone.StyleNormal)
+	} else {
+		fillStyle(7, width, stone.StyleHighlight)
+	}
+}
+
+func fillStyle (yOffset, width int, style stone.Style) {
+	for x := 0; x < width; x ++ {
+		application.SetStyle(x, yOffset, style)
+		application.SetColor(x, yOffset, stone.Color(x % 7 + 1))
+	}
+}

examples/type/main.go

@@ -1,17 +1,20 @@
 package main
 
 import "os"
+import "fmt"
 import "image"
 import _ "image/png"
 import "git.tebibyte.media/sashakoshka/stone"
 import _ "git.tebibyte.media/sashakoshka/stone/backends/x"
 
 var application = &stone.Application { }
-var caret = 0
+var caretX = 0
+var caretY = 2
+var page = 1
 
 func main () {
 	application.SetTitle("hellorld")
-	application.SetSize(32, 16)
+	application.SetSize(32, 28)
 
 	iconFile16, err := os.Open("assets/scaffold16.png")
 	if err != nil { panic(err) }
@@ -25,32 +28,57 @@ func main () {
 	iconFile16.Close()
 	
 	application.SetIcon([]image.Image { icon16, icon32 })
+	application.OnStart(redraw)
+	application.OnPress(onPress)
+	application.OnResize(redraw)
 	
-	channel, err := application.Run()
+	err = application.Run()
 	if err != nil { panic(err) }
 	
 	application.Draw()
-
-	for {
-		event := <- channel
-		switch event.(type) {
-		case stone.EventQuit:
-			os.Exit(0)
-
-		case stone.EventPress:
-			button := event.(stone.EventPress).Button
-			if button.Printable() {
-				application.SetRune(caret, 0, rune(button))
-				caret ++
-				width, _ := application.Size()
-				if caret >= width {
-					caret = 0
-				}
-				application.Draw()
-			}
-
-		case stone.EventResize:
-			application.Draw()
-		}
-	}
+}
+
+func redraw () {
+	application.Clear()
+	_, height := application.Size()
+	application.SetDot(0, 0)
+	fmt.Fprint(application, "type some text below:")
+	caretX = 0
+	caretY = 2
+	application.SetDot(0, height - 1)
+	fmt.Fprintf(application, "page %d", page)
+	drawCaret()
+}
+
+func drawCaret () {
+	application.SetRune(caretX, caretY, '+')
+	application.SetColor(caretX, caretY, stone.ColorDim)
+}
+
+func onPress (button stone.Button, modifiers stone.Modifiers) {
+	width, height := application.Size()
+	
+	if button == stone.KeyEnter {
+		application.SetRune(caretX, caretY, 0)
+		caretX = 0
+		caretY ++
+			
+	} else if button.Printable() {
+		application.SetRune(caretX, caretY, rune(button))
+		application.SetColor(caretX, caretY, stone.ColorForeground)
+		caretX ++
+		
+		if caretX >= width {
+			caretX = 0
+			caretY ++
+		}
+	}
+
+	if caretY >= height - 2 {
+		page ++
+		redraw()
+	}
+		
+	drawCaret()
+	application.Draw()
 }

input.go

@@ -35,8 +35,12 @@ const (
 	KeyRightControl Button = 23
 	KeyLeftAlt      Button = 24
 	KeyRightAlt     Button = 25
-	KeyLeftSuper    Button = 26
-	KeyRightSuper   Button = 27
+	KeyLeftMeta     Button = 26
+	KeyRightMeta    Button = 27	
+	KeyLeftSuper    Button = 28
+	KeyRightSuper   Button = 29
+	KeyLeftHyper    Button = 30
+	KeyRightHyper   Button = 31
 	
 	KeyDelete       Button = 127
 	
@@ -67,6 +71,8 @@ const (
 	KeyF10 Button = 153
 	KeyF11 Button = 154
 	KeyF12 Button = 155
+	
+	KeyDead Button = 156
 )
 
 // Printable returns whether or not the character could show up on screen. If
@@ -76,3 +82,22 @@ func (button Button) Printable () (printable bool) {
 	printable = unicode.IsPrint(rune(button))
 	return
 }
+
+// Modifiers lists what modifier keys are being pressed. This is used in
+// conjunction with a button code in a button press event. These should be used
+// instead of attempting to track the state of the modifier keys, because there
+// is no guarantee that one press event will be coupled with one release event.
+type Modifiers struct {
+	Shift   bool
+	Control bool
+	Alt     bool
+	Meta    bool
+	Super   bool
+	Hyper   bool
+
+	// NumberPad does not represent a key, but it behaves like one. If it is
+	// set to true, the button was pressed on the number pad. It is treated
+	// as a modifier key because if you don't care whether a key was pressed
+	// on the number pad or not, you can just ignore this value.
+	NumberPad bool
+}