app: avoid relocking contexts every frame

Signed-off-by: Joe Julian <me@joejulian.name>

app/window.go

@@ -154,6 +154,10 @@ func (w *Window) validateAndProcess(size image.Point, sync bool, frame *op.Ops,
 				sync = true
 			}
 		}
+		if err := w.lockContext(); err != nil {
+			w.destroyGPU()
+			return err
+		}
 		if sync && w.ctx != nil {
 			if err := w.ctx.Refresh(); err != nil {
 				if errors.Is(err, errOutOfDate) {
@@ -167,14 +171,11 @@ func (w *Window) validateAndProcess(size image.Point, sync bool, frame *op.Ops,
 				}
 				return err
 			}
-			w.ctxNeedsLock = true
-		}
-		if w.ctx != nil && w.ctxNeedsLock {
-			if err := w.ctx.Lock(); err != nil {
+			w.unlockContext()
+			if err := w.lockContext(); err != nil {
 				w.destroyGPU()
 				return err
 			}
-			w.ctxNeedsLock = false
 		}
 		if w.gpu == nil && !w.nocontext {
 			gpu, err := gpu.New(w.ctx.API())
@@ -509,6 +510,17 @@ func (c *callbacks) ActionAt(p f32.Point) (system.Action, bool) {
 	return c.w.queue.ActionAt(p)
 }
 
+func (w *Window) lockContext() error {
+	if w.ctx == nil || !w.ctxNeedsLock {
+		return nil
+	}
+	if err := w.ctx.Lock(); err != nil {
+		return err
+	}
+	w.ctxNeedsLock = false
+	return nil
+}
+
 func (w *Window) unlockContext() {
 	if w.ctx == nil || w.ctxNeedsLock {
 		return
@@ -519,9 +531,9 @@ func (w *Window) unlockContext() {
 
 func (w *Window) destroyGPU() {
 	if w.gpu != nil {
-		if err := w.ctx.Lock(); err == nil {
+		if err := w.lockContext(); err == nil {
 			w.gpu.Release()
-			w.ctx.Unlock()
+			w.unlockContext()
 		}
 		w.gpu = nil
 	}
@@ -671,12 +683,11 @@ func (w *Window) processEvent(e event.Event) bool {
 		w.coalesced.destroy = &e2
 	case ViewEvent:
 		if !e2.Valid() && w.gpu != nil {
-			if err := w.ctx.Lock(); err == nil {
+			if err := w.lockContext(); err == nil {
 				w.gpu.Release()
-				w.ctx.Unlock()
+				w.unlockContext()
 			}
 			w.gpu = nil
-			w.ctxNeedsLock = true
 		}
 		w.coalesced.view = &e2
 	case ConfigEvent: