Changed Buffer.Render signature.

Added BufferControl on top of Buffer.

ui/buffer.go

@@ -2,31 +2,60 @@ package ui
 
 import "opslag.de/schobers/geom"
 
+type RenderBufferFn func(ctx Context, size geom.PointF32)
+
 type Buffer struct {
-	im Image
+	im   Image
+	size geom.PointF32
 }
 
 func (b *Buffer) Update(ctx Context, size geom.PointF32) error {
 	if b.im != nil {
-		if b.im.Width() == size.X && b.im.Height() == size.Y {
+		if size == b.size {
 			return nil
 		}
 		b.im.Destroy()
 		b.im = nil
+		b.size = geom.ZeroPtF32
 	}
 	im, err := ctx.Renderer().CreateImageSize(size.X, size.Y)
 	if err != nil {
 		return err
 	}
 	b.im = im
+	b.size = size
 	return nil
 }
 
-func (b *Buffer) Render(ctx Context, pos geom.PointF32, render func()) {
+func (b *Buffer) Render(ctx Context, pos geom.PointF32, fn RenderBufferFn) {
+	if b.im == nil {
+		return
+	}
 	renderer := ctx.Renderer()
 	currTarget := renderer.Target()
 	renderer.RenderTo(b.im)
-	render()
+	fn(ctx, b.size)
 	renderer.RenderTo(currTarget)
 	renderer.DrawImage(b.im, pos)
 }
+
+type BufferControl struct {
+	ControlBase
+
+	buffer Buffer
+}
+
+func (c *BufferControl) Arrange(ctx Context, bounds geom.RectangleF32, offset geom.PointF32) {
+	c.ControlBase.Arrange(ctx, bounds, offset)
+	c.buffer.Update(ctx, bounds.Size())
+}
+
+func (c *BufferControl) Render(ctx Context) {
+	c.RenderFn(ctx, c.RenderBuffer)
+}
+
+func (c *BufferControl) RenderFn(ctx Context, render RenderBufferFn) {
+	c.buffer.Render(ctx, c.bounds.Min, render)
+}
+
+func (c *BufferControl) RenderBuffer(ctx Context, size geom.PointF32) {}

ui/overflow.go

@@ -128,7 +128,7 @@ func (o *overflow) Render(ctx Context) {
 	if err != nil {
 		panic(err)
 	}
-	o.content.Render(ctx, o.bounds.Min, func() {
+	o.content.Render(ctx, o.bounds.Min, func(Context, geom.PointF32) {
 		renderer.Clear(color.Transparent)
 		o.Content.Render(ctx)
 	})