ebiten/internal/restorable/images.go

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// 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.
package restorable
import (
"github.com/hajimehoshi/ebiten/internal/graphics"
)
// restoringEnabled indicates if restoring happens or not.
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//
// This value is overridden at enabled_*.go.
var restoringEnabled = true
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// IsRestoringEnabled returns a boolean value indicating whether
// restoring process works or not.
func IsRestoringEnabled() bool {
// This value is updated only at init or EnableRestoringForTesting.
// No need to lock here.
return restoringEnabled
}
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// EnableRestoringForTesting forces to enable restoring for testing.
func EnableRestoringForTesting() {
restoringEnabled = true
}
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// images is a set of Image objects.
type images struct {
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images map[*Image]struct{}
lastTarget *Image
}
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// theImages represents the images for the current process.
var theImages = &images{
images: map[*Image]struct{}{},
}
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// ResolveStaleImages flushes the queued draw commands and resolves
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// all stale images.
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//
// ResolveStaleImages is intended to be called at the end of a frame.
func ResolveStaleImages() error {
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if err := graphics.FlushCommands(); err != nil {
return err
}
if !restoringEnabled {
return nil
}
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return theImages.resolveStaleImages()
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}
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// Restore restores the images.
//
// Restoring means to make all *graphics.Image objects have their textures and framebuffers.
func Restore() error {
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if err := graphics.ResetGLState(); err != nil {
return err
}
return theImages.restore()
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}
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// add adds img to the images.
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func (i *images) add(img *Image) {
i.images[img] = struct{}{}
}
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// remove removes img from the images.
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func (i *images) remove(img *Image) {
i.makeStaleIfDependingOnImpl(img)
delete(i.images, img)
}
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// resolveStaleImages resolves stale images.
func (i *images) resolveStaleImages() error {
i.lastTarget = nil
for img := range i.images {
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if err := img.resolveStale(); err != nil {
return err
}
}
return nil
}
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// makeStaleIfDependingOn makes all the images stale that depend on target.
//
// When target is changed, all images depending on target can't be restored with target.
// makeStaleIfDependingOn is called in such situation.
func (i *images) makeStaleIfDependingOn(target *Image) {
// Avoid defer for performance
i.makeStaleIfDependingOnImpl(target)
}
func (i *images) makeStaleIfDependingOnImpl(target *Image) {
if target == nil {
panic("not reached")
}
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if i.lastTarget == target {
return
}
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i.lastTarget = target
for img := range i.images {
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img.makeStaleIfDependingOn(target)
}
}
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// restore restores the images.
//
// Restoring means to make all *graphics.Image objects have their textures and framebuffers.
func (i *images) restore() error {
if !IsRestoringEnabled() {
panic("not reached")
}
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// Dispose image explicitly
for img := range i.images {
img.image.Dispose()
// img.image can't be set nil here, or Size() panics when restoring.
}
// Let's do topological sort based on dependencies of drawing history.
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// It is assured that there are not loops since cyclic drawing makes images stale.
type edge struct {
source *Image
target *Image
}
images := map[*Image]struct{}{}
for i := range i.images {
images[i] = struct{}{}
}
edges := map[edge]struct{}{}
for t := range images {
for s := range t.dependingImages() {
edges[edge{source: s, target: t}] = struct{}{}
}
}
sorted := []*Image{}
for len(images) > 0 {
// current repesents images that have no incoming edges.
current := map[*Image]struct{}{}
for i := range images {
current[i] = struct{}{}
}
for e := range edges {
if _, ok := current[e.target]; ok {
delete(current, e.target)
}
}
for i := range current {
delete(images, i)
sorted = append(sorted, i)
}
removed := []edge{}
for e := range edges {
if _, ok := current[e.source]; ok {
removed = append(removed, e)
}
}
for _, e := range removed {
delete(edges, e)
}
}
for _, img := range sorted {
if err := img.restore(); err != nil {
return err
}
}
return nil
}
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// InitializeGLState initializes the GL state.
func InitializeGLState() error {
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return graphics.ResetGLState()
}