Layout recommended size takes in layout hints and boxes

Remedy #6

backend.go

@@ -33,6 +33,17 @@ type Backend interface {
 	// must reject any canvas that was not made by it.
 	NewCanvas (image.Rectangle) canvas.CanvasCloser
 
+	// SetStyle sets the style that will be used on objects. The backend is
+	// in charge of applying the style to objects. When this method is
+	// called, it must propagate a StyleChange event to all boxes it is
+	// keeping track of.
+	SetStyle (Style)
+
+	// SetIcons sets the icon set that icons will be pulled from. When this
+	// method is called, it must propagate an IconChange event to all boxes
+	// it is keeping track of.
+	SetIcons (Icons)
+
 	// Run runs the event loop until Stop() is called, or the backend
 	// experiences a fatal error.
 	Run () error

icon.go

@@ -382,12 +382,44 @@ const (
 
 // Texture returns a texture of the corresponding icon ID.
 func (id Icon) Texture (size IconSize) canvas.Texture {
-	if theme == nil { return nil }
-	return theme.Icon(id, size)
+	if icons == nil { return nil }
+	return icons.Icon(id, size)
 }
 
 // MimeIcon returns an icon corresponding to a MIME type.
 func MimeIcon (mime data.Mime, size IconSize) canvas.Texture {
-	if theme == nil { return nil }
-	return theme.MimeIcon(mime, size)
+	if icons == nil { return nil }
+	return icons.MimeIcon(mime, size)
+}
+
+// Icons holds a set of icon textures.
+type Icons interface {
+	// A word on textures:
+	//
+	// Because textures can be linked to some resource that is outside of
+	// the control of Go's garbage collector, methods of Icons must not
+	// allocate new copies of a texture each time they are called. It is
+	// fine to lazily load textures and save them for later use, but the
+	// same texture must never be allocated multiple times as this could
+	// cause a memory leak.
+	//
+	// As such, textures returned by these methods must be protected.
+	
+	// Icon returns a texture of the corresponding icon ID. If there is no
+	// suitable option, it should return nil.
+	Icon (Icon, IconSize) canvas.Texture
+
+	// MimeIcon returns a texture of an icon corresponding to a MIME type.
+	// If there is no suitable specific option, it should return a more
+	// generic icon or a plain file icon.
+	MimeIcon (data.Mime, IconSize) canvas.Texture
+}
+
+var icons Icons
+
+// SetIcons sets the icon set.
+func SetIcons (icns Icons) {
+	assertBackend()
+	icons = icns
+	backend.SetIcons(icns)
 }

object.go

@@ -9,98 +9,6 @@ import "git.tebibyte.media/tomo/tomo/event"
 import "git.tebibyte.media/tomo/tomo/input"
 import "git.tebibyte.media/tomo/tomo/canvas"
 
-// Side represents one side of a rectangle.
-type Side int; const (
-	SideTop Side = iota
-	SideRight
-	SideBottom
-	SideLeft
-)
-
-// Inset represents a rectangle inset that can have a different value for each
-// side.
-type Inset [4]int
-
-// I allows you to create an inset in a CSS-ish way:
-//
-//   - One argument: all sides are set to this value
-//   - Two arguments: the top and bottom sides are set to the first value, and
-//     the left and right sides are set to the second value.
-//   - Three arguments: the top side is set by the first value, the left and
-//     right sides are set by the second vaue, and the bottom side is set by the
-//     third value.
-//   - Four arguments: each value corresponds to a side.
-//
-// This function will panic if an argument count that isn't one of these is
-// given.
-func I (sides ...int) Inset {
-	switch len(sides) {
-	case 1: return Inset { sides[0], sides[0], sides[0], sides[0] }
-	case 2: return Inset { sides[0], sides[1], sides[0], sides[1] }
-	case 3: return Inset { sides[0], sides[1], sides[2], sides[1] }
-	case 4: return Inset { sides[0], sides[1], sides[2], sides[3] }
-	default: panic("I: illegal argument count.")
-	}
-}
-
-// Apply returns the given rectangle, shrunk on all four sides by the given
-// inset. If a measurment of the inset is negative, that side will instead be
-// expanded outward. If the rectangle's dimensions cannot be reduced any
-// further, an empty rectangle near its center will be returned.
-func (inset Inset) Apply (bigger image.Rectangle) (smaller image.Rectangle) {
-	smaller = bigger
-	if smaller.Dx() < inset[3] + inset[1] {
-		smaller.Min.X = (smaller.Min.X + smaller.Max.X) / 2
-		smaller.Max.X = smaller.Min.X
-	} else {
-		smaller.Min.X += inset[3]
-		smaller.Max.X -= inset[1]
-	}
-
-	if smaller.Dy() < inset[0] + inset[2] {
-		smaller.Min.Y = (smaller.Min.Y + smaller.Max.Y) / 2
-		smaller.Max.Y = smaller.Min.Y
-	} else {
-		smaller.Min.Y += inset[0]
-		smaller.Max.Y -= inset[2]
-	}
-	return
-}
-
-// Inverse returns a negated version of the inset.
-func (inset Inset) Inverse () (prime Inset) {
-	return Inset {
-		inset[0] * -1,
-		inset[1] * -1,
-		inset[2] * -1,
-		inset[3] * -1,
-	}
-}
-
-// Horizontal returns the sum of SideRight and SideLeft.
-func (inset Inset) Horizontal () int {
-	return inset[SideRight] + inset[SideLeft]
-}
-
-// Vertical returns the sum of SideTop and SideBottom.
-func (inset Inset) Vertical () int {
-	return inset[SideTop] + inset[SideBottom]
-}
-
-// Border represents a single border of a box.
-type Border struct {
-	Width Inset
-	Color [4]color.Color
-}
-
-// Align lists basic alignment types.
-type Align int; const (
-	AlignStart Align = iota // similar to left-aligned text
-	AlignMiddle             // similar to center-aligned text
-	AlignEnd                // similar to right-aligned text
-	AlignEven               // similar to justified text
-)
-
 // Object is any onscreen object that is linked to a box (or is that box).
 // Unlike the Box interface and associated interfaces, Object implementations
 // may originate from anywhere.
@@ -216,6 +124,8 @@ type Box interface {
 	OnScroll      (func (deltaX, deltaY float64)) event.Cookie
 	OnKeyDown     (func (key input.Key, numberPad bool)) event.Cookie
 	OnKeyUp       (func (key input.Key, numberPad bool)) event.Cookie
+	OnStyleChange (func ()) event.Cookie
+	OnIconsChange (func ()) event.Cookie
 }
 
 // CanvasBox is a box that can be drawn to.
@@ -275,6 +185,14 @@ type ContentBox interface {
 	// ContentBounds returns the bounds of the inner content of the Box
 	// relative to the Box's InnerBounds.
 	ContentBounds () image.Rectangle
+	// RecommendedHeight returns the recommended height for a given width,
+	// if supported by the current content or layout. Otherwise, it should
+	// just return the minimum height.
+	RecommendedHeight (width int) int
+	// RecommendedWidth returns the recommended width for a given height, if
+	// supported by the current content or layout. Otherwise, it should just
+	// return the minimum width.
+	RecommendedWidth (height int) int
 	// ScrollTo shifts the origin of the Box's content to the origin of the
 	// Box's InnerBounds, offset by the given point.
 	ScrollTo (image.Point)
@@ -371,9 +289,21 @@ type Layout interface {
 	MinimumSize (LayoutHints, []Box) image.Point
 	// Arrange arranges child boxes according to the given LayoutHints.
 	Arrange (LayoutHints, []Box)
+	// RecommendedHeight returns the recommended height for a given width,
+	// if supported. Otherwise, it should just return the minimum height.
+	// The result of this behavior may or may not be respected, depending on
+	// the situation.
+	RecommendedHeight (LayoutHints, []Box, int) int
+	// RecommendedWidth returns the recommended width for a given height, if
+	// supported. Otherwise, it should just return the minimum width. The
+	// result of this behavior may or may not be respected, depending on the
+	// situation.
+	RecommendedWidth (LayoutHints, []Box, int) int
 }
 
-// Window is an operating system window. It can contain one object.
+// Window is an operating system window. It can contain one object. Windows
+// themselves are completely transparent, and become opaque once an opaque
+// object is added as their root.
 type Window interface {
 	// SetRoot sets the root child of the window. There can only be one at
 	// a time, and setting it will remove the current child if there is one.
@@ -383,6 +313,13 @@ type Window interface {
 	// SetIcon sets the icon of the window. When multiple icon sizes are
 	// provided, the best fitting one is chosen for display.
 	SetIcon (... canvas.Texture)
+	// SetResizable sets whether the window can be resized by the user in
+	// the X and Y directions. If one or both axes are false, the ones that
+	// are will be shrunk to the window's minimum size.
+	SetResizable (x, y bool)
+	// SetBounds sets this window's bounds. This may or may not have any
+	// effect on the window's position on screen depending on the platform.
+	SetBounds (image.Rectangle)
 	// Widget returns a window representing a smaller iconified form of this
 	// window. How exactly this window is used depends on the platform.
 	// Subsequent calls to this method on the same window will return the

style.go

@@ -1,9 +1,7 @@
 package tomo
 
 import "fmt"
-import "git.tebibyte.media/tomo/tomo/data"
 import "git.tebibyte.media/tomo/tomo/event"
-import "git.tebibyte.media/tomo/tomo/canvas"
 
 // Role describes the role of an object.
 type Role struct {
@@ -60,23 +58,12 @@ func (c Color) String () string {
 
 // RGBA satisfies the color.Color interface.
 func (id Color) RGBA () (r, g, b, a uint32) {
-	if theme == nil { return }
-	return theme.RGBA(id)
+	if style == nil { return }
+	return style.RGBA(id)
 }
 
-// Theme can apply a visual style to different objects.
-type Theme interface {
-	// A word on textures:
-	//
-	// Because textures can be linked to some resource that is outside of
-	// the control of Go's garbage collector, methods of Theme must not
-	// allocate new copies of a texture each time they are called. It is
-	// fine to lazily load textures and save them for later use, but the
-	// same texture must never be allocated multiple times as this could
-	// cause a memory leak.
-	//
-	// As such, textures returned by these methods must be protected.
-	
+// Style can apply a visual style to different objects.
+type Style interface {
 	// Apply applies the theme to the given object, according to its role.
 	// This may register event listeners with the given object; closing the
 	// returned cookie must remove them.
@@ -84,28 +71,13 @@ type Theme interface {
 
 	// RGBA returns the RGBA values of the corresponding color ID.
 	RGBA (Color) (r, g, b, a uint32)
-
-	// Icon returns a texture of the corresponding icon ID. If there is no
-	// suitable option, it should return nil.
-	Icon (Icon, IconSize) canvas.Texture
-
-	// MimeIcon returns a texture of an icon corresponding to a MIME type.
-	// If there is no suitable specific option, it should return a more
-	// generic icon or a plain file icon.
-	MimeIcon (data.Mime, IconSize) canvas.Texture
 }
 
-var theme Theme
+var style Style
 
-// SetTheme sets the theme.
-func SetTheme (them Theme) {
-	theme = them
-}
-
-// Apply applies the current theme to the given object, according its role. This
-// may register event listeners with the given object; closing the returned
-// cookie will remove them.
-func Apply (object Object) event.Cookie {
-	if theme == nil { return event.NoCookie { } }
-	return theme.Apply(object)
+// SetStyle sets the style.
+func SetStyle (sty Style) {
+	assertBackend()
+	style = sty
+	backend.SetStyle(sty)
 }

unit.go

@@ -0,0 +1,96 @@
+package tomo
+
+import "image"
+import "image/color"
+
+// Side represents one side of a rectangle.
+type Side int; const (
+	SideTop Side = iota
+	SideRight
+	SideBottom
+	SideLeft
+)
+
+// Inset represents a rectangle inset that can have a different value for each
+// side.
+type Inset [4]int
+
+// I allows you to create an inset in a CSS-ish way:
+//
+//   - One argument: all sides are set to this value
+//   - Two arguments: the top and bottom sides are set to the first value, and
+//     the left and right sides are set to the second value.
+//   - Three arguments: the top side is set by the first value, the left and
+//     right sides are set by the second vaue, and the bottom side is set by the
+//     third value.
+//   - Four arguments: each value corresponds to a side.
+//
+// This function will panic if an argument count that isn't one of these is
+// given.
+func I (sides ...int) Inset {
+	switch len(sides) {
+	case 1: return Inset { sides[0], sides[0], sides[0], sides[0] }
+	case 2: return Inset { sides[0], sides[1], sides[0], sides[1] }
+	case 3: return Inset { sides[0], sides[1], sides[2], sides[1] }
+	case 4: return Inset { sides[0], sides[1], sides[2], sides[3] }
+	default: panic("I: illegal argument count.")
+	}
+}
+
+// Apply returns the given rectangle, shrunk on all four sides by the given
+// inset. If a measurment of the inset is negative, that side will instead be
+// expanded outward. If the rectangle's dimensions cannot be reduced any
+// further, an empty rectangle near its center will be returned.
+func (inset Inset) Apply (bigger image.Rectangle) (smaller image.Rectangle) {
+	smaller = bigger
+	if smaller.Dx() < inset[3] + inset[1] {
+		smaller.Min.X = (smaller.Min.X + smaller.Max.X) / 2
+		smaller.Max.X = smaller.Min.X
+	} else {
+		smaller.Min.X += inset[3]
+		smaller.Max.X -= inset[1]
+	}
+
+	if smaller.Dy() < inset[0] + inset[2] {
+		smaller.Min.Y = (smaller.Min.Y + smaller.Max.Y) / 2
+		smaller.Max.Y = smaller.Min.Y
+	} else {
+		smaller.Min.Y += inset[0]
+		smaller.Max.Y -= inset[2]
+	}
+	return
+}
+
+// Inverse returns a negated version of the inset.
+func (inset Inset) Inverse () (prime Inset) {
+	return Inset {
+		inset[0] * -1,
+		inset[1] * -1,
+		inset[2] * -1,
+		inset[3] * -1,
+	}
+}
+
+// Horizontal returns the sum of SideRight and SideLeft.
+func (inset Inset) Horizontal () int {
+	return inset[SideRight] + inset[SideLeft]
+}
+
+// Vertical returns the sum of SideTop and SideBottom.
+func (inset Inset) Vertical () int {
+	return inset[SideTop] + inset[SideBottom]
+}
+
+// Border represents a single border of a box.
+type Border struct {
+	Width Inset
+	Color [4]color.Color
+}
+
+// Align lists basic alignment types.
+type Align int; const (
+	AlignStart Align = iota // similar to left-aligned text
+	AlignMiddle             // similar to center-aligned text
+	AlignEnd                // similar to right-aligned text
+	AlignEven               // similar to justified text
+)