unity 加载BMP格式图片数据流

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创建BMPLoader.cs

此方法是用来将数据流解析成texture，BMP数据流不同于其他图片数据，所以需要特殊处理

#region License and Information
/*****
*
* BMPLoader.cs
* 
* This is a simple implementation of a BMP file loader for Unity3D.
* Formats it should support are:
*  - 1 bit monochrome indexed
*  - 2-8 bit indexed
*  - 16 / 24 / 32 bit color (including "BI_BITFIELDS")
*  - RLE-4 and RLE-8 support has been added.
* 
* Unless the type is "BI_ALPHABITFIELDS" the loader does not interpret alpha
* values by default, however you can set the "ReadPaletteAlpha" setting to
* true to interpret the 4th (usually "00") value as alpha for indexed images.
* You can also set "ForceAlphaReadWhenPossible" to true so it will interpret
* the "left over" bits as alpha if there are any. It will also force to read
* alpha from a palette if it's an indexed image, just like "ReadPaletteAlpha".
* 
* It's not tested well to the bone, so there might be some errors somewhere.
* However I tested it with 4 different images created with MS Paint
* (1bit, 4bit, 8bit, 24bit) as those are the only formats supported.
* 
* 2017.02.05 - first version 
* 2017.03.06 - Added RLE4 / RLE8 support
* 2021.01.21 - Fixed RLE4 bug; Fixed wrongly reading bit masks for indexed images.
* 2021.01.22 - Addes support for negative heights (top-down images) The actual
*              flipping happens once at the Texture2D conversion.
* 
* Copyright (c) 2017 Markus Göbel (Bunny83)
* 
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
* 
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* 
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
* 
*****/
#endregion License and Information
using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System;namespace B83.Image.BMP
{public enum BMPComressionMode : int{BI_RGB = 0x00,BI_RLE8 = 0x01,BI_RLE4 = 0x02,BI_BITFIELDS = 0x03,BI_JPEG = 0x04,BI_PNG = 0x05,BI_ALPHABITFIELDS = 0x06,BI_CMYK = 0x0B,BI_CMYKRLE8 = 0x0C,BI_CMYKRLE4 = 0x0D,}public struct BMPFileHeader{public ushort magic; // "BM"public uint filesize;public uint reserved;public uint offset;}public struct BitmapInfoHeader{public uint size;public int width;public int height;public ushort nColorPlanes; // always 1public ushort nBitsPerPixel; // [1,4,8,16,24,32]public BMPComressionMode compressionMethod;public uint rawImageSize; // can be "0"public int xPPM;public int yPPM;public uint nPaletteColors;public uint nImportantColors;public int absWidth { get { return Mathf.Abs(width); } }public int absHeight { get { return Mathf.Abs(height); } }}public class BMPImage{public BMPFileHeader header;public BitmapInfoHeader info;public uint rMask = 0x00FF0000;public uint gMask = 0x0000FF00;public uint bMask = 0x000000FF;public uint aMask = 0x00000000;public List<Color32> palette;public Color32[] imageData;public Texture2D ToTexture2D(){var tex = new Texture2D(info.absWidth, info.absHeight);if (info.height < 0)FlipImage();tex.SetPixels32(imageData);tex.Apply();return tex;}// flip image if height is negativeinternal void FlipImage(){if (info.height > 0)return;int w = info.absWidth;int h = info.absHeight;int h2 = h / 2;for (int y = 0; y < h2; y++){for (int x = 0, o1 = y * w, o2 = (h - y - 1) * w; x < w; x++, o1++, o2++){var tmp = imageData[o1];imageData[o1] = imageData[o2];imageData[o2] = tmp;}}info.height = h;}public void ReplaceColor(Color32 aColorToSearch, Color32 aReplacementColor){var s = aColorToSearch;for (int i = 0; i < imageData.Length; i++){var c = imageData[i];if (c.r == s.r && c.g == s.g && c.b == s.b && c.a == s.a)imageData[i] = aReplacementColor;}}public void ReplaceFirstPixelColor(Color32 aReplacementColor){ReplaceColor(imageData[0], aReplacementColor);}public void ReplaceFirstPixelColorWithTransparency(){ReplaceFirstPixelColor(new Color32(0, 0, 0, 0));}}public class BMPLoader{const ushort MAGIC = 0x4D42; // "BM" little endianpublic bool ReadPaletteAlpha = false;public bool ForceAlphaReadWhenPossible = false;public BMPImage LoadBMP(string aFileName){using (var file = File.OpenRead(aFileName))return LoadBMP(file);}public BMPImage LoadBMP(byte[] aData){using (var stream = new MemoryStream(aData))return LoadBMP(stream);}public BMPImage LoadBMP(Stream aData){using (var reader = new BinaryReader(aData))return LoadBMP(reader);}public BMPImage LoadBMP(BinaryReader aReader){BMPImage bmp = new BMPImage();if (!ReadFileHeader(aReader, ref bmp.header)){Debug.LogError("Not a BMP file");return null;}if (!ReadInfoHeader(aReader, ref bmp.info)){Debug.LogError("Unsupported header format");return null;}if (bmp.info.compressionMethod != BMPComressionMode.BI_RGB&& bmp.info.compressionMethod != BMPComressionMode.BI_BITFIELDS&& bmp.info.compressionMethod != BMPComressionMode.BI_ALPHABITFIELDS&& bmp.info.compressionMethod != BMPComressionMode.BI_RLE4&& bmp.info.compressionMethod != BMPComressionMode.BI_RLE8){Debug.LogError("Unsupported image format: " + bmp.info.compressionMethod);return null;}long offset = 14 + bmp.info.size;aReader.BaseStream.Seek(offset, SeekOrigin.Begin);if (bmp.info.nBitsPerPixel < 24){bmp.rMask = 0x00007C00;bmp.gMask = 0x000003E0;bmp.bMask = 0x0000001F;}if (bmp.info.nBitsPerPixel > 8 && (bmp.info.compressionMethod == BMPComressionMode.BI_BITFIELDS || bmp.info.compressionMethod == BMPComressionMode.BI_ALPHABITFIELDS)){bmp.rMask = aReader.ReadUInt32();bmp.gMask = aReader.ReadUInt32();bmp.bMask = aReader.ReadUInt32();}if (ForceAlphaReadWhenPossible)bmp.aMask = GetMask(bmp.info.nBitsPerPixel) ^ (bmp.rMask | bmp.gMask | bmp.bMask);if (bmp.info.compressionMethod == BMPComressionMode.BI_ALPHABITFIELDS)bmp.aMask = aReader.ReadUInt32();if (bmp.info.nPaletteColors > 0 || bmp.info.nBitsPerPixel <= 8)bmp.palette = ReadPalette(aReader, bmp, ReadPaletteAlpha || ForceAlphaReadWhenPossible);aReader.BaseStream.Seek(bmp.header.offset, SeekOrigin.Begin);bool uncompressed = bmp.info.compressionMethod == BMPComressionMode.BI_RGB ||bmp.info.compressionMethod == BMPComressionMode.BI_BITFIELDS ||bmp.info.compressionMethod == BMPComressionMode.BI_ALPHABITFIELDS;if (bmp.info.nBitsPerPixel == 32 && uncompressed)Read32BitImage(aReader, bmp);else if (bmp.info.nBitsPerPixel == 24 && uncompressed)Read24BitImage(aReader, bmp);else if (bmp.info.nBitsPerPixel == 16 && uncompressed)Read16BitImage(aReader, bmp);else if (bmp.info.compressionMethod == BMPComressionMode.BI_RLE4 && bmp.info.nBitsPerPixel == 4 && bmp.palette != null)ReadIndexedImageRLE4(aReader, bmp);else if (bmp.info.compressionMethod == BMPComressionMode.BI_RLE8 && bmp.info.nBitsPerPixel == 8 && bmp.palette != null)ReadIndexedImageRLE8(aReader, bmp);else if (uncompressed && bmp.info.nBitsPerPixel <= 8 && bmp.palette != null)ReadIndexedImage(aReader, bmp);else{Debug.LogError("Unsupported file format: " + bmp.info.compressionMethod + " BPP: " + bmp.info.nBitsPerPixel);return null;}return bmp;}private static void Read32BitImage(BinaryReader aReader, BMPImage bmp){int w = Mathf.Abs(bmp.info.width);int h = Mathf.Abs(bmp.info.height);Color32[] data = bmp.imageData = new Color32[w * h];if (aReader.BaseStream.Position + w * h * 4 > aReader.BaseStream.Length){Debug.LogError("Unexpected end of file.");return;}int shiftR = GetShiftCount(bmp.rMask);int shiftG = GetShiftCount(bmp.gMask);int shiftB = GetShiftCount(bmp.bMask);int shiftA = GetShiftCount(bmp.aMask);byte a = 255;for (int i = 0; i < data.Length; i++){uint v = aReader.ReadUInt32();byte r = (byte)((v & bmp.rMask) >> shiftR);byte g = (byte)((v & bmp.gMask) >> shiftG);byte b = (byte)((v & bmp.bMask) >> shiftB);if (bmp.bMask != 0)a = (byte)((v & bmp.aMask) >> shiftA);data[i] = new Color32(r, g, b, a);}}private static void Read24BitImage(BinaryReader aReader, BMPImage bmp){int w = Mathf.Abs(bmp.info.width);int h = Mathf.Abs(bmp.info.height);int rowLength = ((24 * w + 31) / 32) * 4;int count = rowLength * h;int pad = rowLength - w * 3;Color32[] data = bmp.imageData = new Color32[w * h];if (aReader.BaseStream.Position + count > aReader.BaseStream.Length){Debug.LogError("Unexpected end of file. (Have " + (aReader.BaseStream.Position + count) + " bytes, expected " + aReader.BaseStream.Length + " bytes)");return;}int shiftR = GetShiftCount(bmp.rMask);int shiftG = GetShiftCount(bmp.gMask);int shiftB = GetShiftCount(bmp.bMask);for (int y = 0; y < h; y++){for (int x = 0; x < w; x++){uint v = aReader.ReadByte() | ((uint)aReader.ReadByte() << 8) | ((uint)aReader.ReadByte() << 16);byte r = (byte)((v & bmp.rMask) >> shiftR);byte g = (byte)((v & bmp.gMask) >> shiftG);byte b = (byte)((v & bmp.bMask) >> shiftB);data[x + y * w] = new Color32(r, g, b, 255);}for (int i = 0; i < pad; i++)aReader.ReadByte();}}private static void Read16BitImage(BinaryReader aReader, BMPImage bmp){int w = Mathf.Abs(bmp.info.width);int h = Mathf.Abs(bmp.info.height);int rowLength = ((16 * w + 31) / 32) * 4;int count = rowLength * h;int pad = rowLength - w * 2;Color32[] data = bmp.imageData = new Color32[w * h];if (aReader.BaseStream.Position + count > aReader.BaseStream.Length){Debug.LogError("Unexpected end of file. (Have " + (aReader.BaseStream.Position + count) + " bytes, expected " + aReader.BaseStream.Length + " bytes)");return;}int shiftR = GetShiftCount(bmp.rMask);int shiftG = GetShiftCount(bmp.gMask);int shiftB = GetShiftCount(bmp.bMask);int shiftA = GetShiftCount(bmp.aMask);byte a = 255;for (int y = 0; y < h; y++){for (int x = 0; x < w; x++){uint v = aReader.ReadByte() | ((uint)aReader.ReadByte() << 8);byte r = (byte)((v & bmp.rMask) >> shiftR);byte g = (byte)((v & bmp.gMask) >> shiftG);byte b = (byte)((v & bmp.bMask) >> shiftB);if (bmp.aMask != 0)a = (byte)((v & bmp.aMask) >> shiftA);data[x + y * w] = new Color32(r, g, b, a);}for (int i = 0; i < pad; i++)aReader.ReadByte();}}private static void ReadIndexedImage(BinaryReader aReader, BMPImage bmp){int w = Mathf.Abs(bmp.info.width);int h = Mathf.Abs(bmp.info.height);int bitCount = bmp.info.nBitsPerPixel;int rowLength = ((bitCount * w + 31) / 32) * 4;int count = rowLength * h;int pad = rowLength - (w * bitCount + 7) / 8;Color32[] data = bmp.imageData = new Color32[w * h];if (aReader.BaseStream.Position + count > aReader.BaseStream.Length){Debug.LogError("Unexpected end of file. (Have " + (aReader.BaseStream.Position + count) + " bytes, expected " + aReader.BaseStream.Length + " bytes)");return;}BitStreamReader bitReader = new BitStreamReader(aReader);for (int y = 0; y < h; y++){for (int x = 0; x < w; x++){int v = (int)bitReader.ReadBits(bitCount);if (v >= bmp.palette.Count){Debug.LogError("Indexed bitmap has indices greater than it's color palette");return;}data[x + y * w] = bmp.palette[v];}bitReader.Flush();for (int i = 0; i < pad; i++)aReader.ReadByte();}}private static void ReadIndexedImageRLE4(BinaryReader aReader, BMPImage bmp){int w = Mathf.Abs(bmp.info.width);int h = Mathf.Abs(bmp.info.height);Color32[] data = bmp.imageData = new Color32[w * h];int x = 0;int y = 0;int yOffset = 0;while (aReader.BaseStream.Position < aReader.BaseStream.Length - 1){int count = (int)aReader.ReadByte();byte d = aReader.ReadByte();if (count > 0){for (int i = (count / 2); i > 0; i--){data[x++ + yOffset] = bmp.palette[(d >> 4) & 0x0F];data[x++ + yOffset] = bmp.palette[d & 0x0F];}if ((count & 0x01) > 0){data[x++ + yOffset] = bmp.palette[(d >> 4) & 0x0F];}}else{if (d == 0){x = 0;y += 1;yOffset = y * w;}else if (d == 1){break;}else if (d == 2){x += aReader.ReadByte();y += aReader.ReadByte();yOffset = y * w;}else{for (int i = (d / 2); i > 0; i--){byte d2 = aReader.ReadByte();data[x++ + yOffset] = bmp.palette[(d2 >> 4) & 0x0F];if (x + 1 < w)data[x++ + yOffset] = bmp.palette[d2 & 0x0F];}if ((d & 0x01) > 0){data[x++ + yOffset] = bmp.palette[(aReader.ReadByte() >> 4) & 0x0F];}if ((((d - 1) / 2) & 1) == 0){aReader.ReadByte(); // padding (word alignment)}}}}}private static void ReadIndexedImageRLE8(BinaryReader aReader, BMPImage bmp){int w = Mathf.Abs(bmp.info.width);int h = Mathf.Abs(bmp.info.height);Color32[] data = bmp.imageData = new Color32[w * h];int x = 0;int y = 0;int yOffset = 0;while (aReader.BaseStream.Position < aReader.BaseStream.Length - 1){int count = (int)aReader.ReadByte();byte d = aReader.ReadByte();if (count > 0){for (int i = count; i > 0; i--){data[x++ + yOffset] = bmp.palette[d];}}else{if (d == 0){x = 0;y += 1;yOffset = y * w;}else if (d == 1){break;}else if (d == 2){x += aReader.ReadByte();y += aReader.ReadByte();yOffset = y * w;}else{for (int i = d; i > 0; i--){data[x++ + yOffset] = bmp.palette[aReader.ReadByte()];}if ((d & 0x01) > 0){aReader.ReadByte(); // padding (word alignment)}}}}}private static int GetShiftCount(uint mask){for (int i = 0; i < 32; i++){if ((mask & 0x01) > 0)return i;mask >>= 1;}return -1;}private static uint GetMask(int bitCount){uint mask = 0;for (int i = 0; i < bitCount; i++){mask <<= 1;mask |= 0x01;}return mask;}private static bool ReadFileHeader(BinaryReader aReader, ref BMPFileHeader aFileHeader){aFileHeader.magic = aReader.ReadUInt16();if (aFileHeader.magic != MAGIC)return false;aFileHeader.filesize = aReader.ReadUInt32();aFileHeader.reserved = aReader.ReadUInt32();aFileHeader.offset = aReader.ReadUInt32();return true;}private static bool ReadInfoHeader(BinaryReader aReader, ref BitmapInfoHeader aHeader){aHeader.size = aReader.ReadUInt32();if (aHeader.size < 40)return false;aHeader.width = aReader.ReadInt32();aHeader.height = aReader.ReadInt32();aHeader.nColorPlanes = aReader.ReadUInt16();aHeader.nBitsPerPixel = aReader.ReadUInt16();aHeader.compressionMethod = (BMPComressionMode)aReader.ReadInt32();aHeader.rawImageSize = aReader.ReadUInt32();aHeader.xPPM = aReader.ReadInt32();aHeader.yPPM = aReader.ReadInt32();aHeader.nPaletteColors = aReader.ReadUInt32();aHeader.nImportantColors = aReader.ReadUInt32();int pad = (int)aHeader.size - 40;if (pad > 0)aReader.ReadBytes(pad);return true;}public static List<Color32> ReadPalette(BinaryReader aReader, BMPImage aBmp, bool aReadAlpha){uint count = aBmp.info.nPaletteColors;if (count == 0u)count = 1u << aBmp.info.nBitsPerPixel;var palette = new List<Color32>((int)count);for (int i = 0; i < count; i++){byte b = aReader.ReadByte();byte g = aReader.ReadByte();byte r = aReader.ReadByte();byte a = aReader.ReadByte();if (!aReadAlpha)a = 255;palette.Add(new Color32(r, g, b, a));}return palette;}}public class BitStreamReader{BinaryReader m_Reader;byte m_Data = 0;int m_Bits = 0;public BitStreamReader(BinaryReader aReader){m_Reader = aReader;}public BitStreamReader(Stream aStream) : this(new BinaryReader(aStream)) { }public byte ReadBit(){if (m_Bits <= 0){m_Data = m_Reader.ReadByte();m_Bits = 8;}return (byte)((m_Data >> --m_Bits) & 1);}public ulong ReadBits(int aCount){ulong val = 0UL;if (aCount <= 0 || aCount > 32)throw new System.ArgumentOutOfRangeException("aCount", "aCount must be between 1 and 32 inclusive");for (int i = aCount - 1; i >= 0; i--)val |= ((ulong)ReadBit() << i);return val;}public void Flush(){m_Data = 0;m_Bits = 0;}}
}

调用方法

BMPLoader bmpLoader = new BMPLoader();
//imagebytes为bmp数据流
BMPImage bmpimage = bmpLoader.LoadBMP(imagebytes);
Raw.texture = bmpimage.ToTexture2D();

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