graphics: Remove 'Resume'

graphicscontext.go

@@ -16,6 +16,7 @@ package ebiten
 
 import (
 	"github.com/hajimehoshi/ebiten/internal/graphics"
+	"github.com/hajimehoshi/ebiten/internal/graphics/opengl"
 	"github.com/hajimehoshi/ebiten/internal/ui"
 )
 
@@ -54,6 +55,16 @@ func (c *graphicsContext) SetSize(screenWidth, screenHeight, screenScale int) er
 	return nil
 }
 
+func (c *graphicsContext) needsRestoring(context *opengl.Context) (bool, error) {
+	imageM.Lock()
+	defer imageM.Unlock()
+	// FlushCommands is required because c.screen.impl might not have an actual texture.
+	if err := graphics.FlushCommands(ui.GLContext()); err != nil {
+		return false, err
+	}
+	return c.screen.impl.isInvalidated(context), nil
+}
+
 func (c *graphicsContext) Update() error {
 	if !c.initialized {
 		if err := graphics.Initialize(ui.GLContext()); err != nil {
@@ -61,6 +72,15 @@ func (c *graphicsContext) Update() error {
 		}
 		c.initialized = true
 	}
+	r, err := c.needsRestoring(ui.GLContext())
+	if err != nil {
+		return err
+	}
+	if r {
+		if err := c.restore(); err != nil {
+			return err
+		}
+	}
 	if err := c.screen.Clear(); err != nil {
 		return err
 	}
@@ -104,7 +124,7 @@ func (c *graphicsContext) flush() error {
 	return nil
 }
 
-func (c *graphicsContext) Resume() error {
+func (c *graphicsContext) restore() error {
 	imageM.Lock()
 	defer imageM.Unlock()
 	ui.GLContext().Resume()

image.go

@@ -347,6 +347,10 @@ func (i *imageImpl) ReplacePixels(p []uint8) error {
 	return i.image.ReplacePixels(p)
 }
 
+func (i *imageImpl) isInvalidated(context *opengl.Context) bool {
+	return i.image.IsInvalidated(context)
+}
+
 // A DrawImageOptions represents options to render an image on an image.
 type DrawImageOptions struct {
 	ImageParts    ImageParts

internal/graphics/image.go

@@ -107,3 +107,7 @@ func (i *Image) ReplacePixels(p []uint8) error {
 	theCommandQueue.Enqueue(c)
 	return nil
 }
+
+func (i *Image) IsInvalidated(context *opengl.Context) bool {
+	return !context.IsTexture(i.texture.native)
+}

internal/graphics/opengl/context_desktop.go

@@ -195,6 +195,15 @@ func (c *Context) DeleteTexture(t Texture) {
 	})
 }
 
+func (c *Context) IsTexture(t Texture) bool {
+	r := false
+	c.RunOnContextThread(func() error {
+		r = gl.IsTexture(uint32(t))
+		return nil
+	})
+	return r
+}
+
 func (c *Context) TexSubImage2D(p []uint8, width, height int) {
 	c.RunOnContextThread(func() error {
 		gl.TexSubImage2D(gl.TEXTURE_2D, 0, 0, 0, int32(width), int32(height), gl.RGBA, gl.UNSIGNED_BYTE, gl.Ptr(p))

internal/graphics/opengl/context_js.go

@@ -196,6 +196,11 @@ func (c *Context) DeleteTexture(t Texture) {
 	gl.DeleteTexture(t.Object)
 }
 
+func (c *Context) IsTexture(t Texture) bool {
+	gl := c.gl
+	return gl.IsTexture(t.Object)
+}
+
 func (c *Context) TexSubImage2D(p []uint8, width, height int) {
 	gl := c.gl
 	// void texSubImage2D(GLenum target, GLint level, GLint xoffset, GLint yoffset,

internal/graphics/opengl/context_mobile.go

@@ -162,6 +162,11 @@ func (c *Context) DeleteTexture(t Texture) {
 	gl.DeleteTexture(mgl.Texture(t))
 }
 
+func (c *Context) IsTexture(t Texture) bool {
+	gl := c.gl
+	return gl.IsTexture(mgl.Texture(t))
+}
+
 func (c *Context) TexSubImage2D(p []uint8, width, height int) {
 	gl := c.gl
 	gl.TexSubImage2D(mgl.TEXTURE_2D, 0, 0, 0, width, height, mgl.RGBA, mgl.UNSIGNED_BYTE, p)

internal/loop/run.go

@@ -96,7 +96,6 @@ func (c *runContext) setRunningSlowly(isRunningSlowly bool) {
 type GraphicsContext interface {
 	SetSize(width, height, scale int) error
 	Update() error
-	Resume() error
 }
 
 func Run(g GraphicsContext, width, height, scale int, title string, fps int) error {
@@ -165,11 +164,6 @@ func Run(g GraphicsContext, width, height, scale int, title string, fps int) err
 				frames = 0
 			}
 			e.Done <- struct{}{}
-		case ui.ResumeEvent:
-			if err := g.Resume(); err != nil {
-				return err
-			}
-			e.Done <- struct{}{}
 		default:
 			panic("not reach")
 		}

internal/ui/event.go

@@ -27,11 +27,3 @@ type ScreenSizeEvent struct {
 type RenderEvent struct {
 	Done chan struct{}
 }
-
-type PauseEvent struct {
-	Done chan struct{}
-}
-
-type ResumeEvent struct {
-	Done chan struct{}
-}

internal/ui/ui_mobile.go

@@ -37,11 +37,6 @@ func Render(chError <-chan error) error {
 	}
 	// TODO: Check this is called on the rendering thread
 	select {
-	case <-chResumeStart:
-		if err := doGLWorks(chError, chResumeEnd); err != nil {
-			return err
-		}
-		return nil
 	case chRender <- struct{}{}:
 		return doGLWorks(chError, chRenderEnd)
 	case <-time.After(500 * time.Millisecond):
@@ -79,12 +74,9 @@ type userInterface struct {
 }
 
 var (
-	chRender      = make(chan struct{})
-	chRenderEnd   = make(chan struct{})
-	chResume      = make(chan struct{})
-	chResumeStart = make(chan struct{})
-	chResumeEnd   = make(chan struct{})
-	currentUI     = &userInterface{
+	chRender    = make(chan struct{})
+	chRenderEnd = make(chan struct{})
+	currentUI   = &userInterface{
 		sizeChanged: true,
 	}
 )
@@ -117,13 +109,8 @@ func (u *userInterface) Update() (interface{}, error) {
 		}
 		return e, nil
 	}
-	select {
-	case <-chRender:
-		return RenderEvent{chRenderEnd}, nil
-	case <-chResume:
-		chResumeStart <- struct{}{}
-		return ResumeEvent{chResumeEnd}, nil
-	}
+	<-chRender
+	return RenderEvent{chRenderEnd}, nil
 }
 
 func (u *userInterface) SwapBuffers() error {
@@ -148,16 +135,6 @@ func (u *userInterface) actualScreenScale() int {
 	return u.scale
 }
 
-// TODO: Remove Resume() and do resuming in Update instead.
-// In Update, we'd be able to detect GL context lost by glIsTexture or something,
-// and we can do resuming when detecting it.
-
-func Resume() error {
-	chResume <- struct{}{}
-	// Don't have to wait for resumeing done.
-	return nil
-}
-
 func UpdateTouches(touches []Touch) {
 	currentInput.updateTouches(touches)
 }

mobile/run.go

@@ -29,7 +29,6 @@ type EventDispatcher interface {
 	SetScreenSize(width, height int)
 	SetScreenScale(scale int)
 	Render() error
-	Resume()
 	TouchDown(id int, x, y int)
 	TouchMove(id int, x, y int)
 	TouchUp(id int)
@@ -69,10 +68,6 @@ func (e *eventDispatcher) Render() error {
 	return ui.Render(chError)
 }
 
-func (e *eventDispatcher) Resume() {
-	ui.Resume()
-}
-
 // touch implements ui.Touch.
 type touch struct {
 	id       int