From 0f8233000910c0ed76963a5509f2637b711c275b Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sun, 29 Jul 2018 23:54:46 +0900
Subject: [PATCH] graphics: Bug fix: mipmap images should be volatile when the
 base image is volatile

---
 image.go                        |  9 ++++++++-
 internal/restorable/image.go    |  4 ++++
 internal/shareable/shareable.go | 10 ++++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/image.go b/image.go
index 5981efe73..e5d0047ec 100644
--- a/image.go
+++ b/image.go
@@ -45,6 +45,8 @@ type Image struct {
 	// See strings.Builder for similar examples.
 	addr *Image
 
+	// shareableImages is a set of shareable.Image sorted by the order of mipmap level.
+	// The level 0 image is a regular image and higher-level images are used for mipmap.
 	shareableImages []*shareable.Image
 
 	filter Filter
@@ -282,7 +284,12 @@ func (i *Image) DrawImage(img *Image, options *DrawImageOptions) error {
 		if w2 == 0 || h2 == 0 {
 			break
 		}
-		s := shareable.NewImage(w2, h2)
+		var s *shareable.Image
+		if img.shareableImages[0].IsVolatile() {
+			s = shareable.NewVolatileImage(w2, h2)
+		} else {
+			s = shareable.NewImage(w2, h2)
+		}
 		vs := src.QuadVertices(0, 0, w, h, 0.5, 0, 0, 0.5, 0, 0, nil)
 		is := graphicsutil.QuadIndices()
 		s.DrawImage(src, vs, is, opengl.CompositeModeCopy, graphics.FilterLinear)
diff --git a/internal/restorable/image.go b/internal/restorable/image.go
index a2625dd28..917b1a519 100644
--- a/internal/restorable/image.go
+++ b/internal/restorable/image.go
@@ -99,6 +99,10 @@ func NewScreenFramebufferImage(width, height int) *Image {
 	return i
 }
 
+func (i *Image) IsVolatile() bool {
+	return i.volatile
+}
+
 // BasePixelsForTesting returns the image's basePixels for testing.
 func (i *Image) BasePixelsForTesting() []byte {
 	return i.basePixels
diff --git a/internal/shareable/shareable.go b/internal/shareable/shareable.go
index 8e8ba13b2..21788106a 100644
--- a/internal/shareable/shareable.go
+++ b/internal/shareable/shareable.go
@@ -323,6 +323,16 @@ func (i *Image) dispose(markDisposed bool) {
 	theBackends = append(theBackends[:index], theBackends[index+1:]...)
 }
 
+func (i *Image) IsVolatile() bool {
+	backendsM.Lock()
+	defer backendsM.Unlock()
+	if i.backend == nil {
+		// Not allocated yet. Only non-volatile images can do lazy allocation so far.
+		return false
+	}
+	return i.backend.restorable.IsVolatile()
+}
+
 func (i *Image) IsInvalidated() (bool, error) {
 	backendsM.Lock()
 	defer backendsM.Unlock()