Add support for AttrIcon

internal/system/box.go

@@ -27,12 +27,15 @@ type box struct {
 	focusQueued *bool
 
 	attrColor       attrHierarchy[tomo.AttrColor]
+	attrIcon        attrHierarchy[tomo.AttrIcon]
 	attrTexture     attrHierarchy[tomo.AttrTexture]
 	attrTextureMode attrHierarchy[tomo.AttrTextureMode]
 	attrBorder      attrHierarchy[tomo.AttrBorder]
 	attrMinimumSize attrHierarchy[tomo.AttrMinimumSize]
 	attrPadding     attrHierarchy[tomo.AttrPadding]
 
+	icon canvas.Texture
+
 	dndData   data.Data
 	dndAccept []data.Mime
 	focusable bool
@@ -192,6 +195,11 @@ func (this *box) setAttr (attr tomo.Attr, user bool) {
 			this.invalidateDraw()
 		}
 		
+	case tomo.AttrIcon:
+		if this.attrIcon.Set(attr, user) {
+			this.handleIconChange()
+		}
+		
 	case tomo.AttrTexture:
 		if this.attrTexture.Set(attr, user) {
 			this.invalidateDraw()
@@ -227,6 +235,11 @@ func (this *box) unsetAttr (kind tomo.AttrKind, user bool) {
 			this.invalidateDraw()
 		}
 		
+	case tomo.AttrKindIcon:
+		if this.attrIcon.Unset(user) {
+			this.handleIconChange()
+		}
+		
 	case tomo.AttrKindTexture:
 		if this.attrTexture.Unset(user) {
 			this.invalidateDraw()
@@ -423,20 +436,31 @@ func (this *box) Draw (can canvas.Canvas) {
 
 	// centered texture
 	if textureMode == tomo.TextureModeCenter && texture != nil {
-		textureBounds := texture.Bounds()
-		textureOrigin :=
-			bounds.Min.
-			Add(image.Pt (
-				bounds.Dx() / 2,
-				bounds.Dy() / 2)).
-			Sub(image.Pt (
-				textureBounds.Dx() / 2,
-				textureBounds.Dy() / 2))
-	
-		pen.Fill(color.Transparent)
-		pen.Texture(texture)
-		pen.Rectangle(textureBounds.Sub(textureBounds.Min).Add(textureOrigin))
+		this.centeredTexture(can, texture)
 	}
+
+	// centered icon
+	if this.icon != nil {
+		this.centeredTexture(can, this.icon)
+	}
+}
+
+func (this *box) centeredTexture (can canvas.Canvas, texture canvas.Texture) {
+	pen           := can.Pen()
+	bounds        := this.Bounds()
+	textureBounds := texture.Bounds()
+	textureOrigin :=
+		bounds.Min.
+		Add(image.Pt (
+			bounds.Dx() / 2,
+			bounds.Dy() / 2)).
+		Sub(image.Pt (
+			textureBounds.Dx() / 2,
+			textureBounds.Dy() / 2))
+
+	pen.Fill(color.Transparent)
+	pen.Texture(texture)
+	pen.Rectangle(textureBounds.Sub(textureBounds.Min).Add(textureOrigin))
 }
 
 func (this *box) drawBorders (can canvas.Canvas) {
@@ -576,6 +600,15 @@ func (this *box) handleBorderChange (previousBorderSum tomo.Inset, different boo
 	}
 }
 
+func (this *box) handleIconChange () {
+	this.icon = nil
+	hierarchy := this.getHierarchy()
+	if hierarchy == nil { return }	
+	icon := this.attrIcon.Value()
+	if icon.Icon == tomo.IconUnknown { return }
+	this.icon = hierarchy.getIconSet().Icon(icon.Icon, icon.Size)
+}
+
 func (this *box) invalidateStyle () {
 	hierarchy := this.getHierarchy()
 	if hierarchy == nil { return }