gpu: rename method GPU.Frame to BeginFrame and drop redundant argument

The viewport size was already specified in the call to Collect.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/headless/headless.go

@@ -91,7 +91,7 @@ func (w *Window) Release() {
 func (w *Window) Frame(frame *op.Ops) {
 	contextDo(w.ctx, func() error {
 		w.gpu.Collect(w.size, frame)
-		w.gpu.Frame(w.size)
+		w.gpu.BeginFrame()
 		w.gpu.EndFrame()
 		return nil
 	})

app/loop.go

@@ -83,7 +83,7 @@ func (l *renderLoop) renderLoop(glctx window.Context) error {
 				g.Collect(frame.viewport, frame.ops)
 				// Signal that we're done with the frame ops.
 				l.ack <- struct{}{}
-				g.Frame(frame.viewport)
+				g.BeginFrame()
 				var res frameResult
 				res.err = glctx.Present()
 				g.EndFrame()

gpu/gpu.go

@@ -260,6 +260,8 @@ func (g *GPU) Release() {
 }
 
 func (g *GPU) Collect(viewport image.Point, frameOps *op.Ops) {
+	g.renderer.blitter.viewport = viewport
+	g.renderer.pather.viewport = viewport
 	g.drawOps.reset(g.cache, viewport)
 	g.drawOps.collect(g.cache, frameOps, viewport)
 	g.frameStart = time.Now()
@@ -279,9 +281,8 @@ func (g *GPU) Collect(viewport image.Point, frameOps *op.Ops) {
 	}
 }
 
-func (g *GPU) Frame(viewport image.Point) {
-	g.renderer.blitter.viewport = viewport
-	g.renderer.pather.viewport = viewport
+func (g *GPU) BeginFrame() {
+	viewport := g.renderer.blitter.viewport
 	for _, img := range g.drawOps.imageOps {
 		expandPathOp(img.path, img.clip)
 	}