Fix child boxes rendering on top of borders

Closes #4

go.mod

@@ -3,7 +3,7 @@ module git.tebibyte.media/tomo/backend
 go 1.20
 
 require (
-	git.tebibyte.media/tomo/tomo v0.45.0
+	git.tebibyte.media/tomo/tomo v0.46.1
 	git.tebibyte.media/tomo/typeset v0.7.1
 	git.tebibyte.media/tomo/xgbkb v1.0.1
 	github.com/jezek/xgb v1.1.1

go.sum

@@ -1,6 +1,6 @@
 git.tebibyte.media/sashakoshka/xgbkb v1.0.0/go.mod h1:pNcE6TRO93vHd6q42SdwLSTTj25L0Yzggz7yLe0JV6Q=
-git.tebibyte.media/tomo/tomo v0.45.0 h1:fQH0WIPidW275hOq9dE6R7p064xG1RGx2QU68Avlr84=
-git.tebibyte.media/tomo/tomo v0.45.0/go.mod h1:WrtilgKB1y8O2Yu7X4mYcRiqOlPR8NuUnoA/ynkQWrs=
+git.tebibyte.media/tomo/tomo v0.46.1 h1:/8fT6I9l4TK529zokrThbNDHGRvUsNgif1Zs++0PBSQ=
+git.tebibyte.media/tomo/tomo v0.46.1/go.mod h1:WrtilgKB1y8O2Yu7X4mYcRiqOlPR8NuUnoA/ynkQWrs=
 git.tebibyte.media/tomo/typeset v0.7.1 h1:aZrsHwCG5ZB4f5CruRFsxLv5ezJUCFUFsQJJso2sXQ8=
 git.tebibyte.media/tomo/typeset v0.7.1/go.mod h1:PwDpSdBF3l/EzoIsa2ME7QffVVajnTHZN6l3MHEGe1g=
 git.tebibyte.media/tomo/xgbkb v1.0.1 h1:b3HDUopjdQp1MZrb5Vpil4bOtk3NnNXtfQW27Blw2kE=

internal/system/box.go

@@ -75,7 +75,8 @@ func (this *System) newBox (outer anyBox) *box {
 		if box.parent == nil { return nil }
 		parentCanvas := box.parent.getCanvas()
 		if parentCanvas == nil { return nil }
-		return parentCanvas.SubCanvas(box.bounds)
+		drawableArea := box.bounds.Intersect(box.parent.getInnerClippingBounds())
+		return parentCanvas.SubCanvas(drawableArea)
 	})
 	if outer == nil {
 		box.drawer = box
@@ -130,11 +131,15 @@ func (this *box) Tag (tag string) bool {
 }
 
 func (this *box) SetTag (tag string, on bool) {
+	wasOn := this.tags.Has(tag)
 	if on {
 		this.tags.Add(tag)
 	} else {
 		delete(this.tags, tag)
 	}
+	if wasOn != on {
+		this.invalidateStyle()
+	}
 }
 
 func (this *box) SetAttr (attr tomo.Attr) {
@@ -255,6 +260,24 @@ func (this *box) unsetAttr (kind tomo.AttrKind, user bool) {
 	}
 }
 
+func (this *box) unsetAllAttrs (user bool) {
+	// keep this in sync with tomo.AttrKind!
+	this.outer.unsetAttr(tomo.AttrKindColor, user)
+	this.outer.unsetAttr(tomo.AttrKindTexture, user)
+	this.outer.unsetAttr(tomo.AttrKindTextureMode, user)
+	this.outer.unsetAttr(tomo.AttrKindBorder, user)
+	this.outer.unsetAttr(tomo.AttrKindMinimumSize, user)
+	this.outer.unsetAttr(tomo.AttrKindPadding, user)
+	this.outer.unsetAttr(tomo.AttrKindGap, user)
+	this.outer.unsetAttr(tomo.AttrKindTextColor, user)
+	this.outer.unsetAttr(tomo.AttrKindDotColor, user)
+	this.outer.unsetAttr(tomo.AttrKindFace, user)
+	this.outer.unsetAttr(tomo.AttrKindWrap, user)
+	this.outer.unsetAttr(tomo.AttrKindAlign, user)
+	this.outer.unsetAttr(tomo.AttrKindOverflow, user)
+	this.outer.unsetAttr(tomo.AttrKindLayout, user)
+}
+
 func (this *box) setBounds (bounds image.Rectangle) {
 	if this.bounds == bounds { return }
 	this.bounds = bounds
@@ -620,6 +643,7 @@ func (this *box) recursiveReApply () {
 		// applicator for every box, it's so style applicators can cache
 		// information about the boxes they're linked to (like all rules
 		// with a matching role).
+		this.unsetAllAttrs(false)
 		this.lastStyleNonce = hierarchyStyleNonce
 		this.styleApplicator = hierarchy.newStyleApplicator()
 		this.invalidateStyle()

internal/system/containerbox.go

@@ -298,6 +298,10 @@ func (this *containerBox) getCanvas () canvas.Canvas {
 	return this.canvas.Value()
 }
 
+func (this *containerBox) getInnerClippingBounds () image.Rectangle {
+	return this.innerClippingBounds
+}
+
 func (this *containerBox) notifyMinimumSizeChange (child anyBox) {
 	this.invalidateMinimum()
 	size   := child.minimumSize()

internal/system/hierarchy.go

@@ -193,6 +193,10 @@ func (this *Hierarchy) getCanvas () canvas.Canvas {
 	return this.canvas
 }
 
+func (this *Hierarchy) getInnerClippingBounds () image.Rectangle {
+	return this.canvas.Bounds()
+}
+
 func (this *Hierarchy) getModifiers () input.Modifiers {
 	return this.modifiers
 }

internal/system/internal-iface.go

@@ -12,6 +12,9 @@ type parent interface {
 	getHierarchy            () *Hierarchy
 	// canvas returns the canvas held by the parent.
 	getCanvas               () canvas.Canvas
+	// getInnerClippingBounds returns the area of the canvas that children
+	// can draw to.
+	getInnerClippingBounds  () image.Rectangle
 	// notifyMinimumSizeChange informs the parent that the minimum size of
 	// one of its children has changed.
 	notifyMinimumSizeChange (anyBox)

internal/system/style.go

@@ -4,9 +4,10 @@ import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/backend/style"
 
 type styleApplicator struct {
-	style *style.Style
-	role  tomo.Role
-	rules []style.Rule
+	style      *style.Style
+	role       tomo.Role
+	rules      []style.Rule
+	currentSet style.AttrSet
 }
 
 func (this *styleApplicator) apply (box anyBox) {
@@ -41,7 +42,18 @@ func (this *styleApplicator) apply (box anyBox) {
 		}
 	}
 
+	// reset an attribute if it is no longer specified
+	if this.currentSet != nil {
+		for kind := range this.currentSet {
+			_, exists := attrs[kind]
+			if !exists {
+				box.unsetAttr(kind, false)
+			}
+		}
+	}
+
 	// apply that list of attributes
+	this.currentSet = attrs
 	for _, attr := range attrs {
 		box.setAttr(attr, false)
 	}

x/canvas/canvas.go

@@ -132,3 +132,32 @@ func convertColor (c color.Color) xgraphics.BGRA {
 		A: uint8(a >> 8),
 	}
 }
+
+// For some reason, xgraphics.BGRA does not specify whether or not it uses
+// premultiplied alpha, and information regarding this is contradictory.
+// Basically:
+//   - BGRAModel just takes the result of c.RGBA and bit shifts it, without
+//     un-doing the aplha premultiplication that is required by Color.RGBA,
+//     suggesting that xgraphics.BGRA stores alpha-premultiplied color.
+//   - xgraphics.BlendBGRA lerps between dest and src using only the alpha of
+//     src (temporarily converting the colors to fucking floats for some reason)
+//     which seems to suggest that xgraphics.BGRA *does not* store alpha-
+//     premultiplied color.
+// There is no issues page on xgbutil so we may never get an answer to this
+// question. However, in this package we just use xgraphics.BGRA to store alpha-
+// premultiplied color anyway because its way faster, and I would sooner eat
+// spaghetti with a spoon than convert to and from float64 to blend pixels.
+func blendPremultipliedBGRA (dst, src xgraphics.BGRA) xgraphics.BGRA {
+	// https://en.wikipedia.org/wiki/Alpha_compositing
+	return xgraphics.BGRA {
+		B: blendPremultipliedChannel(dst.B, src.B, src.A),
+		G: blendPremultipliedChannel(dst.G, src.G, src.A),
+		R: blendPremultipliedChannel(dst.R, src.R, src.A),
+		A: blendPremultipliedChannel(dst.A, src.A, src.A),
+	}
+}
+
+func blendPremultipliedChannel (dst, src, a uint8) uint8 {
+	dst16, src16, a16 := uint16(dst), uint16(src), uint16(a)
+	return uint8(src16 + ((dst16 * (255 - a16)) >> 8))
+}

x/canvas/draw.go

@@ -46,7 +46,7 @@ func (this *pen) textureRectangleTransparent (bounds image.Rectangle) {
 		srcPos := pos.Add(offset)
 		dstIndex := this.image.PixOffset(pos.X, pos.Y)
 		srcIndex := this.texture.PixOffset(srcPos.X, srcPos.Y)
-		pixel := xgraphics.BlendBGRA(xgraphics.BGRA {
+		pixel := blendPremultipliedBGRA(xgraphics.BGRA {
 			B: dst[dstIndex + 0],
 			G: dst[dstIndex + 1],
 			R: dst[dstIndex + 2],
@@ -93,7 +93,7 @@ func (this *pen) fillRectangleTransparent (c xgraphics.BGRA, bounds image.Rectan
 	for pos.Y = bounds.Min.Y; pos.Y < bounds.Max.Y; pos.Y ++ {
 	for pos.X = bounds.Min.X; pos.X < bounds.Max.X; pos.X ++ {
 		index := this.image.PixOffset(pos.X, pos.Y)
-		pixel := xgraphics.BlendBGRA(xgraphics.BGRA {
+		pixel := blendPremultipliedBGRA(xgraphics.BGRA {
 			B: this.image.Pix[index + 0],
 			G: this.image.Pix[index + 1],
 			R: this.image.Pix[index + 2],
@@ -256,7 +256,7 @@ func (context *fillingContext) fillPolygonHotTransparent () {
 			// fill pixels in between
 			for x := left; x < right; x ++ {
 				index := context.image.PixOffset(x, context.y)
-				pixel := xgraphics.BlendBGRA(xgraphics.BGRA {
+				pixel := blendPremultipliedBGRA(xgraphics.BGRA {
 					B: context.image.Pix[index + 0],
 					G: context.image.Pix[index + 1],
 					R: context.image.Pix[index + 2],

x/canvas/plot.go

@@ -32,7 +32,7 @@ func (context plottingContext) plot (center image.Point) {
 		for y := square.Min.Y; y < square.Max.Y; y ++ {
 		for x := square.Min.X; x < square.Max.X; x ++ {
 			index := context.image.PixOffset(x, y)
-			pixel := xgraphics.BlendBGRA(xgraphics.BGRA {
+			pixel := blendPremultipliedBGRA(xgraphics.BGRA {
 				B: context.image.Pix[index + 0],
 				G: context.image.Pix[index + 1],
 				R: context.image.Pix[index + 2],

x/event.go

@@ -145,12 +145,15 @@ func (window *window) updateBounds () {
 	// need to sum up all their positions.
 	decorGeometry, _ := window.xWindow.DecorGeometry()
 	windowGeometry, _ := window.xWindow.Geometry()
-	origin := image.Pt(
-		windowGeometry.X() + decorGeometry.X(),
-		windowGeometry.Y() + decorGeometry.Y())
-	window.metrics.bounds = image.Rectangle {
-		Min: origin,
-		Max: origin.Add(image.Pt(windowGeometry.Width(), windowGeometry.Height())),
+	origin := image.Pt (
+		decorGeometry.X(),
+		decorGeometry.Y())
+	innerOrigin := origin.Add(image.Pt (
+		windowGeometry.X(),
+		windowGeometry.Y()))
+	window.metrics.innerBounds = image.Rectangle {
+		Min: innerOrigin,
+		Max: innerOrigin.Add(image.Pt(windowGeometry.Width(), windowGeometry.Height())),
 	}
 }
 
@@ -161,9 +164,9 @@ func (window *window) handleConfigureNotify (
 	configureEvent := *event.ConfigureNotifyEvent
 	configureEvent = window.compressConfigureNotify(configureEvent)
 	
-	oldBounds := window.metrics.bounds
+	oldBounds := window.metrics.innerBounds
 	window.updateBounds()
-	newBounds := window.metrics.bounds
+	newBounds := window.metrics.innerBounds
 
 	sizeChanged :=
 		oldBounds.Dx() != newBounds.Dx() ||

x/window.go

@@ -37,7 +37,8 @@ type window struct {
 	resizeY     bool
 
 	metrics struct {
-		bounds image.Rectangle
+		bounds      image.Rectangle // bounds, including frame
+		innerBounds image.Rectangle // bounds of the drawable area
 	}
 
 	onClose event.FuncBroadcaster
@@ -156,7 +157,7 @@ func (this *Backend) newWindow (
 	// xevent.SelectionRequestFun(window.handleSelectionRequest).
 		// Connect(this.x, window.xWindow.Id)
 	
-	window.metrics.bounds = bounds
+	window.metrics.innerBounds = bounds
 	window.doMinimumSize()
 
 	this.windows[window.xWindow.Id] = window
@@ -165,6 +166,14 @@ func (this *Backend) newWindow (
 	return
 }
 
+func (this *window) Bounds () image.Rectangle {
+	return this.metrics.bounds.Sub(this.metrics.innerBounds.Min)
+}
+
+func (this *window) InnerBounds () image.Rectangle {
+	return this.metrics.innerBounds.Sub(this.metrics.innerBounds.Min)
+}
+
 func (this *window) SetRoot (root tomo.Object) {
 	if root == nil {
 		this.hierarchy.SetRoot(nil)
@@ -242,7 +251,7 @@ func (this *window) NewChild (bounds image.Rectangle) (tomo.Window, error) {
 	leader := this.leader
 	
 	child, err := this.backend.newWindow (
-		bounds.Add(this.metrics.bounds.Min), false)
+		bounds.Add(this.metrics.innerBounds.Min), false)
 	child.leader = leader
 	if err != nil { return nil, err }
 	
@@ -260,7 +269,7 @@ func (this *window) NewChild (bounds image.Rectangle) (tomo.Window, error) {
 
 func (this *window) NewMenu (bounds image.Rectangle) (tomo.Window, error) {
 	menu, err := this.backend.newWindow (
-		bounds.Add(this.metrics.bounds.Min), true)
+		bounds.Add(this.metrics.innerBounds.Min), true)
 	menu.shy = true
 	icccm.WmTransientForSet (
 		this.backend.x,
@@ -273,7 +282,7 @@ func (this *window) NewMenu (bounds image.Rectangle) (tomo.Window, error) {
 
 func (this *window) NewModal (bounds image.Rectangle) (tomo.Window, error) {
 	modal, err := this.backend.newWindow (
-		bounds.Add(this.metrics.bounds.Min), false)
+		bounds.Add(this.metrics.innerBounds.Min), false)
 	icccm.WmTransientForSet (
 		this.backend.x,
 		modal.xWindow.Id,
@@ -382,8 +391,8 @@ func (this *window) reallocateCanvas () {
 		previousHeight = this.xCanvas.Bounds().Dy()
 	}
 	
-	newWidth  := this.metrics.bounds.Dx()
-	newHeight := this.metrics.bounds.Dy()
+	newWidth  := this.metrics.innerBounds.Dx()
+	newHeight := this.metrics.innerBounds.Dy()
 	larger    := newWidth > previousWidth || newHeight > previousHeight
 	smaller   := newWidth < previousWidth / 2 || newHeight < previousHeight / 2
 
@@ -403,7 +412,7 @@ func (this *window) reallocateCanvas () {
 	}
 
 	this.hierarchy.SetCanvas(this.xCanvas.SubCanvas (
-		this.metrics.bounds.Sub(this.metrics.bounds.Min)))
+		this.metrics.innerBounds.Sub(this.metrics.innerBounds.Min)))
 }
 
 func (this *window) pushAll () {
@@ -458,12 +467,12 @@ func (this *window) doMinimumSize () {
 		this.backend.x,
 		this.xWindow.Id,
 		&hints)
-	newWidth  := this.metrics.bounds.Dx()
-	newHeight := this.metrics.bounds.Dy()
+	newWidth  := this.metrics.innerBounds.Dx()
+	newHeight := this.metrics.innerBounds.Dy()
 	if newWidth  < size.X { newWidth  = size.X }
 	if newHeight < size.Y { newHeight = size.Y }
-	if newWidth != this.metrics.bounds.Dx() ||
-		newHeight != this.metrics.bounds.Dy() {
+	if newWidth != this.metrics.innerBounds.Dx() ||
+		newHeight != this.metrics.innerBounds.Dy() {
 		this.xWindow.Resize(newWidth, newHeight)
 	}
 }