From 0967df7f5e3b7dca264f326d90bae3e675347e23 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sun, 5 Feb 2017 04:24:07 +0900
Subject: [PATCH] graphics: Fix TestImagePixels to check out-of-range pixels

---
 image_test.go                | 8 ++++++--
 internal/restorable/image.go | 8 ++++++--
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/image_test.go b/image_test.go
index 825a7ac22..d5022761e 100644
--- a/image_test.go
+++ b/image_test.go
@@ -25,6 +25,7 @@ import (
 	"testing"
 
 	. "github.com/hajimehoshi/ebiten"
+	"github.com/hajimehoshi/ebiten/internal/graphics"
 )
 
 func TestMain(m *testing.M) {
@@ -87,8 +88,11 @@ func TestImagePixels(t *testing.T) {
 		t.Fatalf("img size: got %d; want %d", got, img.Bounds().Size())
 	}
 
-	for j := 0; j < img0.Bounds().Size().Y; j++ {
-		for i := 0; i < img0.Bounds().Size().X; i++ {
+	w, h := img0.Bounds().Size().X, img0.Bounds().Size().Y
+	// Check out of range part
+	w2, h2 := graphics.NextPowerOf2Int(w), graphics.NextPowerOf2Int(h)
+	for j := -100; j < h2+100; j++ {
+		for i := -100; i < w2+100; i++ {
 			got := img0.At(i, j)
 			want := color.RGBAModel.Convert(img.At(i, j))
 			if got != want {
diff --git a/internal/restorable/image.go b/internal/restorable/image.go
index 4dc6ab19b..3d4bf6af2 100644
--- a/internal/restorable/image.go
+++ b/internal/restorable/image.go
@@ -170,13 +170,17 @@ func (p *Image) appendDrawImageHistory(image *Image, vertices []float32, colorm
 // Note that this must not be called until context is available.
 // This means Pixels members must match with acutal state in VRAM.
 func (p *Image) At(x, y int, context *opengl.Context) (color.RGBA, error) {
-	w, _ := p.image.Size()
+	w, h := p.image.Size()
+	w2, h2 := graphics.NextPowerOf2Int(w), graphics.NextPowerOf2Int(h)
+	if x < 0 || y < 0 || w2 <= x || h2 <= y {
+		return color.RGBA{}, nil
+	}
 	if p.basePixels == nil || p.drawImageHistory != nil || p.stale {
 		if err := p.readPixelsFromVRAM(p.image, context); err != nil {
 			return color.RGBA{}, err
 		}
 	}
-	idx := 4*x + 4*y*graphics.NextPowerOf2Int(w)
+	idx := 4*x + 4*y*w2
 	r, g, b, a := p.basePixels[idx], p.basePixels[idx+1], p.basePixels[idx+2], p.basePixels[idx+3]
 	return color.RGBA{r, g, b, a}, nil
 }