From 6b906bb8135a0f61e40ea084bd31ab9cb5a8ece2 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Tue, 13 Sep 2022 06:53:30 -0700
Subject: [PATCH] internal/restorable: extend the staleRegion when the image is
 already stale on WritePixels

This is a kind of refactoring. There seems no case that this condition
change is really needed, but this is more logical.
---
 internal/restorable/image.go | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/internal/restorable/image.go b/internal/restorable/image.go
index 9e44bfb4a..d75fc0bd5 100644
--- a/internal/restorable/image.go
+++ b/internal/restorable/image.go
@@ -314,7 +314,8 @@ func (i *Image) WritePixels(pixels []byte, x, y, width, height int) {
 		i.image.WritePixels(make([]byte, 4*width*height), x, y, width, height)
 	}
 
-	if !needsRestoring() || !i.needsRestoring() {
+	// Even if the image is already stale, call makeStale to extend the stale region.
+	if !needsRestoring() || !i.needsRestoring() || i.stale {
 		i.makeStale(image.Rect(x, y, x+width, y+height))
 		return
 	}
@@ -341,11 +342,6 @@ func (i *Image) WritePixels(pixels []byte, x, y, width, height int) {
 		return
 	}
 
-	if i.stale {
-		// TODO: panic here?
-		return
-	}
-
 	if pixels != nil {
 		// pixels can point to a shared region.
 		// This function is responsible to copy this.