app/internal/window: move context refresh to window

Instead of calling from the low level context into the window
for its surface and dimensions, add a Context.MakeCurrent method
that does it directly.

The result is simpler and clearer logic. For example, synchronization
is obviously no longer needed. It wasn't necessary before, but the
reason was unclear.

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

app/internal/window/egl_android.go

@@ -14,20 +14,38 @@ import (
 	"gioui.org/app/internal/gl"
 )
 
-func (w *window) EGLDestroy() {
-}
-
-func (w *window) EGLDisplay() egl.NativeDisplayType {
-	return nil
-}
-
-func (w *window) EGLWindow(visID int) (egl.NativeWindowType, int, int, error) {
-	win, width, height := w.nativeWindow(visID)
-	return egl.NativeWindowType(unsafe.Pointer(win)), width, height, nil
+type context struct {
+	win *window
+	*egl.Context
 }
 
 func (w *window) NewContext() (gl.Context, error) {
-	return egl.NewContext(w)
+	ctx, err := egl.NewContext(nil)
+	if err != nil {
+		return nil, err
+	}
+	return &context{win: w, Context: ctx}, nil
 }
 
-func (w *window) NeedVSync() bool { return false }
+func (c *context) Release() {
+	if c.Context != nil {
+		c.Context.Release()
+		c.Context = nil
+	}
+}
+
+func (c *context) MakeCurrent() error {
+	c.Context.ReleaseSurface()
+	win, width, height := c.win.nativeWindow(c.Context.VisualID())
+	if win == nil {
+		return nil
+	}
+	eglSurf := egl.NativeWindowType(unsafe.Pointer(win))
+	if err := c.Context.CreateSurface(eglSurf, width, height); err != nil {
+		return err
+	}
+	if err := c.Context.MakeCurrent(); err != nil {
+		return err
+	}
+	return nil
+}