app: avoid relocking contexts every frame

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

app/window_test.go

@@ -11,18 +11,40 @@ import (
 	"gioui.org/op"
 )
 
-func TestValidateAndProcessLocksBeforeRefresh(t *testing.T) {
+func TestValidateAndProcessRelocksAfterRefresh(t *testing.T) {
 	ctx := &testContext{}
 	w := &Window{
-		ctx: ctx,
-		gpu: &testGPU{},
+		ctx:          ctx,
+		gpu:          &testGPU{},
+		ctxNeedsLock: false,
 	}
 
 	if err := w.validateAndProcess(image.Pt(320, 240), true, new(op.Ops), nil); err != nil {
 		t.Fatalf("validateAndProcess returned error: %v", err)
 	}
 
-	want := []string{"lock", "refresh", "render-target", "present", "unlock"}
+	want := []string{"refresh", "lock", "render-target", "present"}
+	if got := ctx.ops; !equalStringSlices(got, want) {
+		t.Fatalf("unexpected call order:\n got  %v\n want %v", got, want)
+	}
+	if w.ctxNeedsLock {
+		t.Fatalf("context should remain current after a successful frame")
+	}
+}
+
+func TestValidateAndProcessSkipsRedundantRelock(t *testing.T) {
+	ctx := &testContext{}
+	w := &Window{
+		ctx:          ctx,
+		gpu:          &testGPU{},
+		ctxNeedsLock: false,
+	}
+
+	if err := w.validateAndProcess(image.Pt(320, 240), false, new(op.Ops), nil); err != nil {
+		t.Fatalf("validateAndProcess returned error: %v", err)
+	}
+
+	want := []string{"render-target", "present"}
 	if got := ctx.ops; !equalStringSlices(got, want) {
 		t.Fatalf("unexpected call order:\n got  %v\n want %v", got, want)
 	}