ui: Remove opengl dependency from ui package (desktop)

internal/graphicscommand/command.go

@@ -198,6 +198,13 @@ func (q *commandQueue) Flush() {
 	q.nindices = 0
 	q.tmpNumIndices = 0
 	q.nextIndex = 0
+
+	// The bound framebuffer must be the original screen framebuffer before swapping buffers.
+	// Note that swapping might not happen after this function. BeforeSwapping should not be
+	// harmful in any cases.
+	//
+	// TODO: Confirm which machine requires this. Probably BungBungame Photon 2?
+	opengl.GetContext().BeforeSwapping()
 }
 
 // Error returns an OpenGL error for the last command.

internal/opengl/context_js.go

@@ -506,3 +506,7 @@ func (c *Context) RestoreContext() {
 		c.loseContext.Call("restoreContext")
 	}
 }
+
+func (c *Context) BeforeSwapping() {
+	// Do nothing
+}

internal/opengl/context_mobile.go

@@ -400,3 +400,7 @@ func (c *Context) Flush() {
 	gl := c.gl
 	gl.Flush()
 }
+
+func (c *Context) BeforeSwapping() {
+	// Do nothing
+}

internal/ui/ui_glfw.go

@@ -32,7 +32,6 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/hooks"
 	"github.com/hajimehoshi/ebiten/internal/input"
 	"github.com/hajimehoshi/ebiten/internal/mainthread"
-	"github.com/hajimehoshi/ebiten/internal/opengl"
 )
 
 type userInterface struct {
@@ -649,10 +648,6 @@ func (u *userInterface) loop(g GraphicsContext) error {
 		vsync := u.vsync
 		u.m.Unlock()
 
-		// The bound framebuffer must be the original screen framebuffer
-		// before swapping buffers.
-		opengl.GetContext().BeforeSwapping()
-
 		_ = mainthread.Run(func() error {
 			if !vsync {
 				u.swapBuffers()