From 64fa922ec013079f8f0c90fc9e93c56db3611d30 Mon Sep 17 00:00:00 2001 From: Tulir Asokan Date: Sun, 22 Apr 2018 21:25:06 +0300 Subject: Switch to dep --- vendor/golang.org/x/image/bmp/reader.go | 199 ++++++++++++++++++++++++++++++++ 1 file changed, 199 insertions(+) create mode 100644 vendor/golang.org/x/image/bmp/reader.go (limited to 'vendor/golang.org/x/image/bmp/reader.go') diff --git a/vendor/golang.org/x/image/bmp/reader.go b/vendor/golang.org/x/image/bmp/reader.go new file mode 100644 index 0000000..a0f2715 --- /dev/null +++ b/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) +} -- cgit v1.2.3