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path: root/vendor/golang.org/x/image/bmp/writer.go
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Diffstat (limited to 'vendor/golang.org/x/image/bmp/writer.go')
-rw-r--r--vendor/golang.org/x/image/bmp/writer.go166
1 files changed, 166 insertions, 0 deletions
diff --git a/vendor/golang.org/x/image/bmp/writer.go b/vendor/golang.org/x/image/bmp/writer.go
new file mode 100644
index 0000000..6947968
--- /dev/null
+++ b/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)
+}