driver: Add Graphics.NeedsRestoring

internal/driver/graphics.go

@@ -31,6 +31,7 @@ type Graphics interface {
 	Draw(indexLen int, indexOffset int, mode graphics.CompositeMode, colorM *affine.ColorM, filter graphics.Filter, address graphics.Address) error
 	SetVsyncEnabled(enabled bool)
 	VDirection() VDirection
+	NeedsRestoring() bool
 	IsGL() bool
 }
 

internal/graphicscommand/command.go

@@ -28,6 +28,10 @@ func SetGraphicsDriver(driver driver.Graphics) {
 	theGraphicsDriver = driver
 }
 
+func NeedsRestoring() bool {
+	return theGraphicsDriver.NeedsRestoring()
+}
+
 // command represents a drawing command.
 //
 // A command for drawing that is created when Image functions are called like DrawTriangles,

internal/graphicsdriver/metal/driver.go

@@ -707,6 +707,10 @@ func (d *Driver) VDirection() driver.VDirection {
 	return driver.VUpward
 }
 
+func (d *Driver) NeedsRestoring() bool {
+	return false
+}
+
 func (d *Driver) IsGL() bool {
 	return false
 }

internal/graphicsdriver/opengl/context_desktop.go

@@ -500,3 +500,7 @@ func (c *context) flush() {
 		return nil
 	})
 }
+
+func (c *context) needsRestoring() bool {
+	return false
+}

internal/graphicsdriver/opengl/context_js.go

@@ -22,6 +22,7 @@ import (
 	"syscall/js"
 
 	"github.com/hajimehoshi/ebiten/internal/graphics"
+	"github.com/hajimehoshi/ebiten/internal/web"
 )
 
 type (
@@ -459,3 +460,7 @@ func (c *context) flush() {
 	gl := c.gl
 	gl.Call("flush")
 }
+
+func (c *context) needsRestoring() bool {
+	return !web.IsMobileBrowser()
+}

internal/graphicsdriver/opengl/context_mobile.go

@@ -378,3 +378,7 @@ func (c *context) flush() {
 	gl := c.gl
 	gl.Flush()
 }
+
+func (c *context) needsRestoring() bool {
+	return true
+}

internal/graphicsdriver/opengl/driver.go

@@ -126,6 +126,10 @@ func (d *Driver) VDirection() driver.VDirection {
 	return driver.VDownward
 }
 
+func (d *Driver) NeedsRestoring() bool {
+	return d.context.needsRestoring()
+}
+
 func (d *Driver) IsGL() bool {
 	return true
 }

internal/restorable/enabled_desktop.go

@@ -1,26 +0,0 @@
-// Copyright 2017 The Ebiten Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// +build darwin freebsd linux windows
-// +build !js
-// +build !android
-// +build !ios
-
-package restorable
-
-func init() {
-	// OpenGL (not ES) never causes context lost,
-	// so restorable feature is not needed.
-	restoringEnabled = false
-}

internal/restorable/enabled_js.go

@@ -1,27 +0,0 @@
-// Copyright 2017 The Ebiten Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// +build js
-
-package restorable
-
-import (
-	"github.com/hajimehoshi/ebiten/internal/web"
-)
-
-func init() {
-	if web.IsMobileBrowser() {
-		restoringEnabled = false
-	}
-}

internal/restorable/image.go

@@ -301,7 +301,7 @@ func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
 	}
 	i.image.ReplacePixels(pixels, x, y, width, height)
 
-	if !IsRestoringEnabled() {
+	if !NeedsRestoring() {
 		i.makeStale()
 		return
 	}
@@ -362,7 +362,7 @@ func (i *Image) DrawTriangles(img *Image, vertices []float32, indices []uint16,
 	}
 	theImages.makeStaleIfDependingOn(i)
 
-	if img.stale || img.volatile || i.screen || !IsRestoringEnabled() || i.volatile {
+	if img.stale || img.volatile || i.screen || !NeedsRestoring() || i.volatile {
 		i.makeStale()
 	} else {
 		i.appendDrawTrianglesHistory(img, vertices, indices, colorm, mode, filter, address)
@@ -447,7 +447,7 @@ func (i *Image) readPixelsFromGPU() {
 
 // resolveStale resolves the image's 'stale' state.
 func (i *Image) resolveStale() {
-	if !IsRestoringEnabled() {
+	if !NeedsRestoring() {
 		return
 	}
 
@@ -557,7 +557,7 @@ func (i *Image) Dispose() {
 func (i *Image) IsInvalidated() (bool, error) {
 	// FlushCommands is required because c.offscreen.impl might not have an actual texture.
 	graphicscommand.FlushCommands()
-	if !IsRestoringEnabled() {
+	if !NeedsRestoring() {
 		return false, nil
 	}
 

internal/restorable/images.go

@@ -20,22 +20,20 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/graphicscommand"
 )
 
-// restoringEnabled indicates if restoring happens or not.
+// forceRestoring reports whether restoring forcely happens or not.
-//
+var forceRestoring = true
-// This value is overridden at enabled_*.go.
-var restoringEnabled = true
 
-// IsRestoringEnabled returns a boolean value indicating whether
+// NeedsRestoring reports whether restoring process works or not.
-// restoring process works or not.
+func NeedsRestoring() bool {
-func IsRestoringEnabled() bool {
+	if forceRestoring {
-	// This value is updated only at init or EnableRestoringForTesting.
+		return true
-	// No need to lock here.
+	}
-	return restoringEnabled
+	return graphicscommand.NeedsRestoring()
 }
 
 // EnableRestoringForTesting forces to enable restoring for testing.
 func EnableRestoringForTesting() {
-	restoringEnabled = true
+	forceRestoring = true
 }
 
 // images is a set of Image objects.
@@ -55,7 +53,7 @@ var theImages = &images{
 // ResolveStaleImages is intended to be called at the end of a frame.
 func ResolveStaleImages() {
 	graphicscommand.FlushCommands()
-	if !restoringEnabled {
+	if !NeedsRestoring() {
 		return
 	}
 	theImages.resolveStaleImages()
@@ -146,7 +144,7 @@ func (i *images) makeStaleIfDependingOnImpl(target *Image) {
 //
 // Restoring means to make all *graphicscommand.Image objects have their textures and framebuffers.
 func (i *images) restore() error {
-	if !IsRestoringEnabled() {
+	if !NeedsRestoring() {
 		panic("restorable: restore cannot be called when restoring is disabled")
 	}
 

internal/shareable/shareable.go

@@ -508,9 +508,9 @@ func ResolveStaleImages() {
 	restorable.ResolveStaleImages()
 }
 
-func IsRestoringEnabled() bool {
+func NeedsRestoring() bool {
-	// As IsRestoringEnabled is an immutable state, no need to lock here.
+	// As NeedsRestoring is an immutable state, no need to lock here.
-	return restorable.IsRestoringEnabled()
+	return restorable.NeedsRestoring()
 }
 
 func Restore() error {

uicontext.go

@@ -151,7 +151,7 @@ func (c *uiContext) needsRestoring() (bool, error) {
 }
 
 func (c *uiContext) restoreIfNeeded() error {
-	if !shareable.IsRestoringEnabled() {
+	if !shareable.NeedsRestoring() {
 		return nil
 	}
 	r, err := c.needsRestoring()