From e42cff071c36b54db2998405672726afc3736f1e Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sat, 16 Nov 2019 02:10:51 +0900
Subject: [PATCH] restorable: Merge two 'copy' into one

Fixes #983
---
 internal/graphicscommand/image.go |  4 +---
 internal/restorable/image.go      | 13 ++++++++++---
 internal/restorable/rect.go       | 11 ++++-------
 3 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/internal/graphicscommand/image.go b/internal/graphicscommand/image.go
index 94f29e3c1..ef6f89f55 100644
--- a/internal/graphicscommand/image.go
+++ b/internal/graphicscommand/image.go
@@ -155,15 +155,13 @@ func (i *Image) Pixels() []byte {
 	return c.result
 }
 
-func (i *Image) ReplacePixels(p []byte, x, y, width, height int) {
+func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
 	// ReplacePixels for a part might invalidate the current image that are drawn by DrawTriangles (#593, #738).
 	if i.lastCommand == lastCommandDrawTriangles {
 		if x != 0 || y != 0 || i.width != width || i.height != height {
 			panic("graphicscommand: ReplacePixels for a part after DrawTriangles is forbidden")
 		}
 	}
-	pixels := make([]byte, len(p))
-	copy(pixels, p)
 	c := &replacePixelsCommand{
 		dst:    i,
 		pixels: pixels,
diff --git a/internal/restorable/image.go b/internal/restorable/image.go
index bebd978ff..e037bdd24 100644
--- a/internal/restorable/image.go
+++ b/internal/restorable/image.go
@@ -328,8 +328,15 @@ func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
 	// For this purpuse, images should remember which part of that is used for DrawTriangles.
 	theImages.makeStaleIfDependingOn(i)
 
+	// TODO: Avoid copying if possible (#983)
+	var copiedPixels []byte
 	if pixels != nil {
-		i.image.ReplacePixels(pixels, x, y, width, height)
+		copiedPixels = make([]byte, len(pixels))
+		copy(copiedPixels, pixels)
+	}
+
+	if pixels != nil {
+		i.image.ReplacePixels(copiedPixels, x, y, width, height)
 	} else {
 		// TODO: When pixels == nil, we don't have to care the pixel state there. In such cases, the image
 		// accepts only ReplacePixels and not Fill or DrawTriangles.
@@ -339,7 +346,7 @@ func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
 
 	if x == 0 && y == 0 && width == w && height == h {
 		if pixels != nil {
-			i.basePixels.AddOrReplace(pixels, 0, 0, w, h)
+			i.basePixels.AddOrReplace(copiedPixels, 0, 0, w, h)
 		} else {
 			i.basePixels.Remove(0, 0, w, h)
 		}
@@ -361,7 +368,7 @@ func (i *Image) ReplacePixels(pixels []byte, x, y, width, height int) {
 	}
 
 	if pixels != nil {
-		i.basePixels.AddOrReplace(pixels, x, y, width, height)
+		i.basePixels.AddOrReplace(copiedPixels, x, y, width, height)
 	} else {
 		i.basePixels.Remove(x, y, width, height)
 	}
diff --git a/internal/restorable/rect.go b/internal/restorable/rect.go
index 842d43e8c..54088d7c4 100644
--- a/internal/restorable/rect.go
+++ b/internal/restorable/rect.go
@@ -37,16 +37,13 @@ func (rtp *rectToPixels) addOrReplace(pixels []byte, x, y, width, height int) {
 		rtp.m = map[image.Rectangle][]byte{}
 	}
 
-	copied := make([]byte, len(pixels))
-	copy(copied, pixels)
-
 	newr := image.Rect(x, y, x+width, y+height)
 	for r := range rtp.m {
 		if r == newr {
 			// Replace the region.
-			rtp.m[r] = copied
+			rtp.m[r] = pixels
 			if r == rtp.lastR {
-				rtp.lastPix = copied
+				rtp.lastPix = pixels
 			}
 			return
 		}
@@ -56,9 +53,9 @@ func (rtp *rectToPixels) addOrReplace(pixels []byte, x, y, width, height int) {
 	}
 
 	// Add the region.
-	rtp.m[newr] = copied
+	rtp.m[newr] = pixels
 	if newr == rtp.lastR {
-		rtp.lastPix = copied
+		rtp.lastPix = pixels
 	}
 }