add golang bmp pkg

vendor/golang.org/x/image/bmp/reader.go

@@ -0,0 +1,199 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package bmp implements a BMP image decoder and encoder.
+//
+// The BMP specification is at http://www.digicamsoft.com/bmp/bmp.html.
+package bmp // import "golang.org/x/image/bmp"
+
+import (
+	"errors"
+	"image"
+	"image/color"
+	"io"
+)
+
+// ErrUnsupported means that the input BMP image uses a valid but unsupported
+// feature.
+var ErrUnsupported = errors.New("bmp: unsupported BMP image")
+
+func readUint16(b []byte) uint16 {
+	return uint16(b[0]) | uint16(b[1])<<8
+}
+
+func readUint32(b []byte) uint32 {
+	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+// decodePaletted reads an 8 bit-per-pixel BMP image from r.
+// If topDown is false, the image rows will be read bottom-up.
+func decodePaletted(r io.Reader, c image.Config, topDown bool) (image.Image, error) {
+	paletted := image.NewPaletted(image.Rect(0, 0, c.Width, c.Height), c.ColorModel.(color.Palette))
+	if c.Width == 0 || c.Height == 0 {
+		return paletted, nil
+	}
+	var tmp [4]byte
+	y0, y1, yDelta := c.Height-1, -1, -1
+	if topDown {
+		y0, y1, yDelta = 0, c.Height, +1
+	}
+	for y := y0; y != y1; y += yDelta {
+		p := paletted.Pix[y*paletted.Stride : y*paletted.Stride+c.Width]
+		if _, err := io.ReadFull(r, p); err != nil {
+			return nil, err
+		}
+		// Each row is 4-byte aligned.
+		if c.Width%4 != 0 {
+			_, err := io.ReadFull(r, tmp[:4-c.Width%4])
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+	return paletted, nil
+}
+
+// decodeRGB reads a 24 bit-per-pixel BMP image from r.
+// If topDown is false, the image rows will be read bottom-up.
+func decodeRGB(r io.Reader, c image.Config, topDown bool) (image.Image, error) {
+	rgba := image.NewRGBA(image.Rect(0, 0, c.Width, c.Height))
+	if c.Width == 0 || c.Height == 0 {
+		return rgba, nil
+	}
+	// There are 3 bytes per pixel, and each row is 4-byte aligned.
+	b := make([]byte, (3*c.Width+3)&^3)
+	y0, y1, yDelta := c.Height-1, -1, -1
+	if topDown {
+		y0, y1, yDelta = 0, c.Height, +1
+	}
+	for y := y0; y != y1; y += yDelta {
+		if _, err := io.ReadFull(r, b); err != nil {
+			return nil, err
+		}
+		p := rgba.Pix[y*rgba.Stride : y*rgba.Stride+c.Width*4]
+		for i, j := 0, 0; i < len(p); i, j = i+4, j+3 {
+			// BMP images are stored in BGR order rather than RGB order.
+			p[i+0] = b[j+2]
+			p[i+1] = b[j+1]
+			p[i+2] = b[j+0]
+			p[i+3] = 0xFF
+		}
+	}
+	return rgba, nil
+}
+
+// decodeNRGBA reads a 32 bit-per-pixel BMP image from r.
+// If topDown is false, the image rows will be read bottom-up.
+func decodeNRGBA(r io.Reader, c image.Config, topDown bool) (image.Image, error) {
+	rgba := image.NewNRGBA(image.Rect(0, 0, c.Width, c.Height))
+	if c.Width == 0 || c.Height == 0 {
+		return rgba, nil
+	}
+	y0, y1, yDelta := c.Height-1, -1, -1
+	if topDown {
+		y0, y1, yDelta = 0, c.Height, +1
+	}
+	for y := y0; y != y1; y += yDelta {
+		p := rgba.Pix[y*rgba.Stride : y*rgba.Stride+c.Width*4]
+		if _, err := io.ReadFull(r, p); err != nil {
+			return nil, err
+		}
+		for i := 0; i < len(p); i += 4 {
+			// BMP images are stored in BGRA order rather than RGBA order.
+			p[i+0], p[i+2] = p[i+2], p[i+0]
+		}
+	}
+	return rgba, nil
+}
+
+// Decode reads a BMP image from r and returns it as an image.Image.
+// Limitation: The file must be 8, 24 or 32 bits per pixel.
+func Decode(r io.Reader) (image.Image, error) {
+	c, bpp, topDown, err := decodeConfig(r)
+	if err != nil {
+		return nil, err
+	}
+	switch bpp {
+	case 8:
+		return decodePaletted(r, c, topDown)
+	case 24:
+		return decodeRGB(r, c, topDown)
+	case 32:
+		return decodeNRGBA(r, c, topDown)
+	}
+	panic("unreachable")
+}
+
+// DecodeConfig returns the color model and dimensions of a BMP image without
+// decoding the entire image.
+// Limitation: The file must be 8, 24 or 32 bits per pixel.
+func DecodeConfig(r io.Reader) (image.Config, error) {
+	config, _, _, err := decodeConfig(r)
+	return config, err
+}
+
+func decodeConfig(r io.Reader) (config image.Config, bitsPerPixel int, topDown bool, err error) {
+	// We only support those BMP images that are a BITMAPFILEHEADER
+	// immediately followed by a BITMAPINFOHEADER.
+	const (
+		fileHeaderLen = 14
+		infoHeaderLen = 40
+	)
+	var b [1024]byte
+	if _, err := io.ReadFull(r, b[:fileHeaderLen+infoHeaderLen]); err != nil {
+		return image.Config{}, 0, false, err
+	}
+	if string(b[:2]) != "BM" {
+		return image.Config{}, 0, false, errors.New("bmp: invalid format")
+	}
+	offset := readUint32(b[10:14])
+	if readUint32(b[14:18]) != infoHeaderLen {
+		return image.Config{}, 0, false, ErrUnsupported
+	}
+	width := int(int32(readUint32(b[18:22])))
+	height := int(int32(readUint32(b[22:26])))
+	if height < 0 {
+		height, topDown = -height, true
+	}
+	if width < 0 || height < 0 {
+		return image.Config{}, 0, false, ErrUnsupported
+	}
+	// We only support 1 plane, 8 or 24 bits per pixel and no compression.
+	planes, bpp, compression := readUint16(b[26:28]), readUint16(b[28:30]), readUint32(b[30:34])
+	if planes != 1 || compression != 0 {
+		return image.Config{}, 0, false, ErrUnsupported
+	}
+	switch bpp {
+	case 8:
+		if offset != fileHeaderLen+infoHeaderLen+256*4 {
+			return image.Config{}, 0, false, ErrUnsupported
+		}
+		_, err = io.ReadFull(r, b[:256*4])
+		if err != nil {
+			return image.Config{}, 0, false, err
+		}
+		pcm := make(color.Palette, 256)
+		for i := range pcm {
+			// BMP images are stored in BGR order rather than RGB order.
+			// Every 4th byte is padding.
+			pcm[i] = color.RGBA{b[4*i+2], b[4*i+1], b[4*i+0], 0xFF}
+		}
+		return image.Config{ColorModel: pcm, Width: width, Height: height}, 8, topDown, nil
+	case 24:
+		if offset != fileHeaderLen+infoHeaderLen {
+			return image.Config{}, 0, false, ErrUnsupported
+		}
+		return image.Config{ColorModel: color.RGBAModel, Width: width, Height: height}, 24, topDown, nil
+	case 32:
+		if offset != fileHeaderLen+infoHeaderLen {
+			return image.Config{}, 0, false, ErrUnsupported
+		}
+		return image.Config{ColorModel: color.RGBAModel, Width: width, Height: height}, 32, topDown, nil
+	}
+	return image.Config{}, 0, false, ErrUnsupported
+}
+
+func init() {
+	image.RegisterFormat("bmp", "BM????\x00\x00\x00\x00", Decode, DecodeConfig)
+}

vendor/golang.org/x/image/bmp/reader_test.go

@@ -0,0 +1,75 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package bmp
+
+import (
+	"fmt"
+	"image"
+	"os"
+	"testing"
+
+	_ "image/png"
+)
+
+const testdataDir = "../testdata/"
+
+func compare(t *testing.T, img0, img1 image.Image) error {
+	b := img1.Bounds()
+	if !b.Eq(img0.Bounds()) {
+		return fmt.Errorf("wrong image size: want %s, got %s", img0.Bounds(), b)
+	}
+	for y := b.Min.Y; y < b.Max.Y; y++ {
+		for x := b.Min.X; x < b.Max.X; x++ {
+			c0 := img0.At(x, y)
+			c1 := img1.At(x, y)
+			r0, g0, b0, a0 := c0.RGBA()
+			r1, g1, b1, a1 := c1.RGBA()
+			if r0 != r1 || g0 != g1 || b0 != b1 || a0 != a1 {
+				return fmt.Errorf("pixel at (%d, %d) has wrong color: want %v, got %v", x, y, c0, c1)
+			}
+		}
+	}
+	return nil
+}
+
+// TestDecode tests that decoding a PNG image and a BMP image result in the
+// same pixel data.
+func TestDecode(t *testing.T) {
+	testCases := []string{
+		"video-001",
+		"yellow_rose-small",
+	}
+
+	for _, tc := range testCases {
+		f0, err := os.Open(testdataDir + tc + ".png")
+		if err != nil {
+			t.Errorf("%s: Open PNG: %v", tc, err)
+			continue
+		}
+		defer f0.Close()
+		img0, _, err := image.Decode(f0)
+		if err != nil {
+			t.Errorf("%s: Decode PNG: %v", tc, err)
+			continue
+		}
+
+		f1, err := os.Open(testdataDir + tc + ".bmp")
+		if err != nil {
+			t.Errorf("%s: Open BMP: %v", tc, err)
+			continue
+		}
+		defer f1.Close()
+		img1, _, err := image.Decode(f1)
+		if err != nil {
+			t.Errorf("%s: Decode BMP: %v", tc, err)
+			continue
+		}
+
+		if err := compare(t, img0, img1); err != nil {
+			t.Errorf("%s: %v", tc, err)
+			continue
+		}
+	}
+}

vendor/golang.org/x/image/bmp/writer.go

@@ -0,0 +1,166 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package bmp
+
+import (
+	"encoding/binary"
+	"errors"
+	"image"
+	"io"
+)
+
+type header struct {
+	sigBM           [2]byte
+	fileSize        uint32
+	resverved       [2]uint16
+	pixOffset       uint32
+	dibHeaderSize   uint32
+	width           uint32
+	height          uint32
+	colorPlane      uint16
+	bpp             uint16
+	compression     uint32
+	imageSize       uint32
+	xPixelsPerMeter uint32
+	yPixelsPerMeter uint32
+	colorUse        uint32
+	colorImportant  uint32
+}
+
+func encodePaletted(w io.Writer, pix []uint8, dx, dy, stride, step int) error {
+	var padding []byte
+	if dx < step {
+		padding = make([]byte, step-dx)
+	}
+	for y := dy - 1; y >= 0; y-- {
+		min := y*stride + 0
+		max := y*stride + dx
+		if _, err := w.Write(pix[min:max]); err != nil {
+			return err
+		}
+		if padding != nil {
+			if _, err := w.Write(padding); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+func encodeRGBA(w io.Writer, pix []uint8, dx, dy, stride, step int) error {
+	buf := make([]byte, step)
+	for y := dy - 1; y >= 0; y-- {
+		min := y*stride + 0
+		max := y*stride + dx*4
+		off := 0
+		for i := min; i < max; i += 4 {
+			buf[off+2] = pix[i+0]
+			buf[off+1] = pix[i+1]
+			buf[off+0] = pix[i+2]
+			off += 3
+		}
+		if _, err := w.Write(buf); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func encode(w io.Writer, m image.Image, step int) error {
+	b := m.Bounds()
+	buf := make([]byte, step)
+	for y := b.Max.Y - 1; y >= b.Min.Y; y-- {
+		off := 0
+		for x := b.Min.X; x < b.Max.X; x++ {
+			r, g, b, _ := m.At(x, y).RGBA()
+			buf[off+2] = byte(r >> 8)
+			buf[off+1] = byte(g >> 8)
+			buf[off+0] = byte(b >> 8)
+			off += 3
+		}
+		if _, err := w.Write(buf); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Encode writes the image m to w in BMP format.
+func Encode(w io.Writer, m image.Image) error {
+	d := m.Bounds().Size()
+	if d.X < 0 || d.Y < 0 {
+		return errors.New("bmp: negative bounds")
+	}
+	h := &header{
+		sigBM:         [2]byte{'B', 'M'},
+		fileSize:      14 + 40,
+		pixOffset:     14 + 40,
+		dibHeaderSize: 40,
+		width:         uint32(d.X),
+		height:        uint32(d.Y),
+		colorPlane:    1,
+	}
+
+	var step int
+	var palette []byte
+	switch m := m.(type) {
+	case *image.Gray:
+		step = (d.X + 3) &^ 3
+		palette = make([]byte, 1024)
+		for i := 0; i < 256; i++ {
+			palette[i*4+0] = uint8(i)
+			palette[i*4+1] = uint8(i)
+			palette[i*4+2] = uint8(i)
+			palette[i*4+3] = 0xFF
+		}
+		h.imageSize = uint32(d.Y * step)
+		h.fileSize += uint32(len(palette)) + h.imageSize
+		h.pixOffset += uint32(len(palette))
+		h.bpp = 8
+
+	case *image.Paletted:
+		step = (d.X + 3) &^ 3
+		palette = make([]byte, 1024)
+		for i := 0; i < len(m.Palette) && i < 256; i++ {
+			r, g, b, _ := m.Palette[i].RGBA()
+			palette[i*4+0] = uint8(b >> 8)
+			palette[i*4+1] = uint8(g >> 8)
+			palette[i*4+2] = uint8(r >> 8)
+			palette[i*4+3] = 0xFF
+		}
+		h.imageSize = uint32(d.Y * step)
+		h.fileSize += uint32(len(palette)) + h.imageSize
+		h.pixOffset += uint32(len(palette))
+		h.bpp = 8
+	default:
+		step = (3*d.X + 3) &^ 3
+		h.imageSize = uint32(d.Y * step)
+		h.fileSize += h.imageSize
+		h.bpp = 24
+	}
+
+	if err := binary.Write(w, binary.LittleEndian, h); err != nil {
+		return err
+	}
+	if palette != nil {
+		if err := binary.Write(w, binary.LittleEndian, palette); err != nil {
+			return err
+		}
+	}
+
+	if d.X == 0 || d.Y == 0 {
+		return nil
+	}
+
+	switch m := m.(type) {
+	case *image.Gray:
+		return encodePaletted(w, m.Pix, d.X, d.Y, m.Stride, step)
+	case *image.Paletted:
+		return encodePaletted(w, m.Pix, d.X, d.Y, m.Stride, step)
+	case *image.RGBA:
+		return encodeRGBA(w, m.Pix, d.X, d.Y, m.Stride, step)
+	}
+	return encode(w, m, step)
+}

vendor/golang.org/x/image/bmp/writer_test.go

@@ -0,0 +1,91 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package bmp
+
+import (
+	"bytes"
+	"fmt"
+	"image"
+	"io/ioutil"
+	"os"
+	"testing"
+	"time"
+)
+
+func openImage(filename string) (image.Image, error) {
+	f, err := os.Open(testdataDir + filename)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	return Decode(f)
+}
+
+func TestEncode(t *testing.T) {
+	img0, err := openImage("video-001.bmp")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	buf := new(bytes.Buffer)
+	err = Encode(buf, img0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	img1, err := Decode(buf)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	compare(t, img0, img1)
+}
+
+// TestZeroWidthVeryLargeHeight tests that encoding and decoding a degenerate
+// image with zero width but over one billion pixels in height is faster than
+// naively calling an io.Reader or io.Writer method once per row.
+func TestZeroWidthVeryLargeHeight(t *testing.T) {
+	c := make(chan error, 1)
+	go func() {
+		b := image.Rect(0, 0, 0, 0x3fffffff)
+		var buf bytes.Buffer
+		if err := Encode(&buf, image.NewRGBA(b)); err != nil {
+			c <- err
+			return
+		}
+		m, err := Decode(&buf)
+		if err != nil {
+			c <- err
+			return
+		}
+		if got := m.Bounds(); got != b {
+			c <- fmt.Errorf("bounds: got %v, want %v", got, b)
+			return
+		}
+		c <- nil
+	}()
+	select {
+	case err := <-c:
+		if err != nil {
+			t.Fatal(err)
+		}
+	case <-time.After(3 * time.Second):
+		t.Fatalf("timed out")
+	}
+}
+
+// BenchmarkEncode benchmarks the encoding of an image.
+func BenchmarkEncode(b *testing.B) {
+	img, err := openImage("video-001.bmp")
+	if err != nil {
+		b.Fatal(err)
+	}
+	s := img.Bounds().Size()
+	b.SetBytes(int64(s.X * s.Y * 4))
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		Encode(ioutil.Discard, img)
+	}
+}