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image/gif: allow encoding a single-frame image whose top-left corner 

isn't (0, 0).

Also fix a s/b.Min.X/b.Max.X/ typo in bounds checking.

Fixes #10676

Change-Id: Ie5ff7ec20ca30367a8e65d32061959a2d8e089e9
Reviewed-on: https://go-review.googlesource.com/9712
Reviewed-by: Rob Pike <r@golang.org>
This commit is contained in:
Nigel Tao 2015-05-05 17:39:09 +10:00
parent 96dad7ff3e
commit 8ae44af2bb
2 changed files with 37 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
src/image/gif/writer.go
View File

@ -190,7 +190,7 @@ func (e *encoder) writeImageBlock(pm *image.Paletted, delay int, disposal byte)
}
b := pm.Bounds()
if b.Dx() >= 1<<16 || b.Dy() >= 1<<16 || b.Min.X < 0 || b.Min.X >= 1<<16 || b.Min.Y < 0 || b.Min.Y >= 1<<16 {
if b.Min.X < 0 || b.Max.X >= 1<<16 || b.Min.Y < 0 || b.Max.Y >= 1<<16 {
e.err = errors.New("gif: image block is too large to encode")
return
}
@ -365,6 +365,15 @@ func Encode(w io.Writer, m image.Image, o *Options) error {
opts.Drawer.Draw(pm, b, m, image.ZP)
}
// When calling Encode instead of EncodeAll, the single-frame image is
// translated such that its top-left corner is (0, 0), so that the single
// frame completely fills the overall GIF's bounds.
if pm.Rect.Min != (image.Point{}) {
dup := *pm
dup.Rect = dup.Rect.Sub(dup.Rect.Min)
pm = &dup
}
return EncodeAll(w, &GIF{
Image: []*image.Paletted{pm},
Delay: []int{0},

28
src/image/gif/writer_test.go
View File

@ -297,7 +297,7 @@ func TestEncodeZeroGIF(t *testing.T) {
}
}
func TestEncodeFrameOutOfBounds(t *testing.T) {
func TestEncodeAllFramesOutOfBounds(t *testing.T) {
images := []*image.Paletted{
image.NewPaletted(image.Rect(0, 0, 5, 5), palette.Plan9),
image.NewPaletted(image.Rect(2, 2, 8, 8), palette.Plan9),
@ -326,6 +326,32 @@ func TestEncodeFrameOutOfBounds(t *testing.T) {
}
}
func TestEncodeNonZeroMinPoint(t *testing.T) {
points := []image.Point{
image.Point{-8, -9},
image.Point{-4, -4},
image.Point{-3, +3},
image.Point{+0, +0},
image.Point{+2, +2},
}
for _, p := range points {
src := image.NewPaletted(image.Rectangle{Min: p, Max: p.Add(image.Point{6, 6})}, palette.Plan9)
var buf bytes.Buffer
if err := Encode(&buf, src, nil); err != nil {
t.Errorf("p=%v: Encode: %v", p, err)
continue
}
m, err := Decode(&buf)
if err != nil {
t.Errorf("p=%v: Decode: %v", p, err)
continue
}
if got, want := m.Bounds(), image.Rect(0, 0, 6, 6); got != want {
t.Errorf("p=%v: got %v, want %v", p, got, want)
}
}
}
func TestEncodeImplicitConfigSize(t *testing.T) {
// For backwards compatibility for Go 1.4 and earlier code, the Config
// field is optional, and if zero, the width and height is implied by the