From 6ba6cdc721c31fcd05898ae05ada5d4f076d17ad Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Fri, 16 Aug 2019 00:36:54 +0900
Subject: [PATCH] restorable: Bug fix: Dispose all the image before start
 restoring

A current texture ID and a new texture ID can be duplicated.
Disposing part of textures and creating textures at the same time
can make contradicted situation.
---
 internal/restorable/image.go  | 16 ++++++----------
 internal/restorable/images.go | 14 +++++++++++++-
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/internal/restorable/image.go b/internal/restorable/image.go
index d9aaa2908..c20f6addb 100644
--- a/internal/restorable/image.go
+++ b/internal/restorable/image.go
@@ -472,24 +472,20 @@ func (i *Image) hasDependency() bool {
 }
 
 // Restore restores *graphicscommand.Image from the pixels using its state.
-func (i *Image) restore() {
-	w, h := i.Size()
-
-	// Dispose the internal image after getting its size for safety.
-	i.image.Dispose()
-	i.image = nil
+func (i *Image) restore(width, height int) {
+	// Do not dispose the image here. The image should be already disposed.
 
 	if i.screen {
 		// The screen image should also be recreated because framebuffer might
 		// be changed.
-		i.image = graphicscommand.NewScreenFramebufferImage(w, h)
+		i.image = graphicscommand.NewScreenFramebufferImage(width, height)
 		i.basePixels = Pixels{}
 		i.drawTrianglesHistory = nil
 		i.stale = false
 		return
 	}
 	if i.volatile {
-		i.image = graphicscommand.NewImage(w, h)
+		i.image = graphicscommand.NewImage(width, height)
 		i.clear()
 		return
 	}
@@ -497,7 +493,7 @@ func (i *Image) restore() {
 		panic("restorable: pixels must not be stale when restoring")
 	}
 
-	gimg := graphicscommand.NewImage(w, h)
+	gimg := graphicscommand.NewImage(width, height)
 	// Clear the image explicitly.
 	if i != emptyImage {
 		// As clearImage uses emptyImage, clearImage cannot be called on emptyImage.
@@ -515,7 +511,7 @@ func (i *Image) restore() {
 
 	if len(i.drawTrianglesHistory) > 0 {
 		i.basePixels = Pixels{}
-		i.basePixels.AddOrReplace(gimg.Pixels(), 0, 0, w, h)
+		i.basePixels.AddOrReplace(gimg.Pixels(), 0, 0, width, height)
 	}
 
 	i.image = gimg
diff --git a/internal/restorable/images.go b/internal/restorable/images.go
index 8a23de1ad..f29408572 100644
--- a/internal/restorable/images.go
+++ b/internal/restorable/images.go
@@ -152,6 +152,17 @@ func (i *images) restore() {
 		panic("restorable: restore cannot be called when restoring is disabled")
 	}
 
+	// Dispose all the images ahead of restoring. A current texture ID and a new texture ID can be duplicated.
+	// TODO: Write a test to confirm that ID duplication never happens.
+	sizes := map[*Image]struct{ w, h int }{}
+	for i := range i.images {
+		// Keep the size before disposing i.image.
+		w, h := i.Size()
+		sizes[i] = struct{ w, h int }{w, h}
+		i.image.Dispose()
+		i.image = nil
+	}
+
 	// Let's do topological sort based on dependencies of drawing history.
 	// It is assured that there are not loops since cyclic drawing makes images stale.
 	type edge struct {
@@ -204,7 +215,8 @@ func (i *images) restore() {
 	}
 
 	for _, img := range sorted {
-		img.restore()
+		s := sizes[img]
+		img.restore(s.w, s.h)
 	}
 }