Fix centered texture rendering

box.go

@@ -339,10 +339,14 @@ func (this *box) Draw (can canvas.Canvas) {
 	// centered texture
 	if this.textureMode == textureModeCenter {
 		textureBounds := this.texture.Bounds()
-		textureOrigin := image.Pt (
-			textureBounds.Dx() / -2,
-			textureBounds.Dy() / -2).
-			Add(bounds.Min)
+		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(this.texture)

examples/blank/main.go

@@ -0,0 +1,18 @@
+package main
+
+import "image"
+import "git.tebibyte.media/tomo/x"
+import "git.tebibyte.media/tomo/tomo"
+
+func main () {
+	tomo.Register(0, x.NewBackend)
+	err := tomo.Run(run)
+	if err != nil { panic(err) }
+}
+
+func run () {
+	window, err := tomo.NewWindow(image.Rect(0, 0, 200, 300))
+	if err != nil { panic(err) }
+	window.OnClose(tomo.Stop)
+	window.SetVisible(true)
+}

examples/text/main.go

@@ -0,0 +1,29 @@
+package main
+
+import "image"
+import "image/color"
+import "git.tebibyte.media/tomo/x"
+import "git.tebibyte.media/tomo/tomo"
+import "golang.org/x/image/font/basicfont"
+
+func main () {
+	tomo.Register(0, x.NewBackend)
+	err := tomo.Run(run)
+	if err != nil { panic(err) }
+}
+
+func run () {
+	window, err := tomo.NewWindow(image.Rectangle { })
+	if err != nil { panic(err) }
+
+	text := tomo.NewTextBox()
+	text.SetText("hello, world!")
+	text.SetTextColor(color.White)
+	text.SetColor(color.Black)
+	text.SetFace(basicfont.Face7x13)
+	text.SetPadding(tomo.I(8))
+	window.SetRoot(text)
+	
+	window.OnClose(tomo.Stop)
+	window.SetVisible(true)
+}

examples/texture/main.go

@@ -0,0 +1,83 @@
+package main
+
+import "math"
+import "image"
+import "math/rand"
+import "image/color"
+import "git.tebibyte.media/tomo/x"
+import "git.tebibyte.media/tomo/tomo"
+
+func main () {
+	tomo.Register(0, x.NewBackend)
+	err := tomo.Run(run)
+	if err != nil { panic(err) }
+}
+
+func run () {
+	window, err := tomo.NewWindow(image.Rect(0, 0, 256, 256))
+	if err != nil { panic(err) }
+	
+	texture := tomo.NewTexture(coolTexture())
+	
+	box := tomo.NewBox()
+	box.SetColor(color.Black)
+	box.SetTextureCenter(texture)
+	box.SetBorder (
+		tomo.Border {
+			Color: [4] color.Color {
+				color.Black, color.Black,
+				color.Black, color.Black },
+			Width: tomo.I(2),
+		},
+		tomo.Border {
+			Color: [4] color.Color {
+			color.White, color.White,
+			color.White, color.White },
+			Width: tomo.I(2),
+		})
+	
+	window.SetRoot(box)
+	window.OnClose(tomo.Stop)
+	window.SetVisible(true)
+}
+
+func coolTexture () image.Image {
+	// this picture IS COOL because i spent AN HOUR on it when i could have
+	// been FIXING BUGS!
+	speedX := 0.015
+	speedY := 0.035
+	bitmap := image.NewRGBA (image.Rect(0, 0, 200, 200))
+	for y := bitmap.Bounds().Min.Y; y < bitmap.Bounds().Max.Y; y++ {
+	for x := bitmap.Bounds().Min.X; x < bitmap.Bounds().Max.X; x++ {
+		value := ((
+			math.Sin(float64(y) * speedY) +
+			math.Cos(float64(x) * speedX)) + 2) / 4
+		value *= 0.7
+
+		r := value * 0.7 + 0.3
+		g := math.Sin(value * 7) * 0.7
+		b := (1 - value) * 0.7
+
+		noise := math.Mod(rand.Float64(), 1)
+		noise = math.Pow(noise, 2) + noise * 0.5
+		noise *= 0.05
+		
+		channel := func (f float64) uint8 {
+			contrast := 1.4
+			f = f * (contrast) - ((contrast - 1) / 2)
+			
+			if f < 0 { f = 0 }
+			if f > 1 { f = 1 }
+			
+			return uint8(f * 255)
+		}
+		
+		bitmap.Set(x, y, color.RGBA {
+			R: channel(r + noise),
+			G: channel(g + noise),
+			B: channel(b + noise),
+			A: 255,
+		})
+	}}
+	return bitmap
+}

system.go

@@ -241,7 +241,9 @@ func (window *window) afterEvent () {
 		// set child bounds
 		childBounds := window.metrics.bounds
 		childBounds = childBounds.Sub(childBounds.Min)
-		window.root.SetBounds(childBounds)
+		if window.root != nil {
+			window.root.SetBounds(childBounds)	
+		}
 
 		// full relayout/redraw
 		if window.root != nil {