使用c#，合并多個bitMap圖像

當只需要兩個圖像合并的時候，可以簡單的使用gdi+，把兩個圖像畫到一個畫布上面實現合并bitmap.

當需要將許多bitmap合并時，由于bitmap類限制，長度或寬度太大時會報異常，前面這種方法就行不通了。

由于bitmapp屬于位圖格式，了解圖像格式后，發現，bitmap文件的第3-8位存儲了文件大小信息，第19-22位存儲了高度信息，第23-26位存儲了寬度信息。文件頭后面都是像素的argb，并無其它信息。于是，試想一下，如果把第二張圖像的像素argb放到第一張后面，并修改第一張的文件頭信息，是不是就可以實現文件合并了呢。事實證明：yes。

下面就看看代碼：

//設置文件頭里面文件大小信息

public void SetBitmapFileSizeInfo(string filePath){FileInfo fileInfo = new FileInfo(filePath); long le = fileInfo.Length; string hexSize = le.ToString("X").PadLeft(8, '0'); int size1 = Convert.ToInt32(hexSize.Substring(0, 2), 16); int size2 = Convert.ToInt32(hexSize.Substring(2, 2), 16); int size3 = Convert.ToInt32(hexSize.Substring(4, 2), 16); int size4 = Convert.ToInt32(hexSize.Substring(6, 2), 16); byte[] sizeBytes = new byte[] { (byte)size4, (byte)size3, (byte)size2, (byte)size1 }; using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Write)){ using (BinaryWriter r = new BinaryWriter(fs)){r.Seek(2, 0);r.Write(sizeBytes, 0, sizeBytes.Length);}}}

設置文件頭里面文件長度和寬度信息

public void SetBitmapSizeInfo(string filePath,int width=0,int height=0){ if (height != 0){ string hexHeight = height.ToString("X").PadLeft(8, '0'); int h1 = Convert.ToInt32(hexHeight.Substring(0, 2), 16); int h2 = Convert.ToInt32(hexHeight.Substring(2, 2), 16); int h3 = Convert.ToInt32(hexHeight.Substring(4, 2), 16); int h4 = Convert.ToInt32(hexHeight.Substring(6, 2), 16); byte[] sizeHeight = new byte[] { (byte)h4, (byte)h3, (byte)h2, (byte)h1 }; using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.ReadWrite)){ using (BinaryWriter r = new BinaryWriter(fs)){r.Seek(22, 0);//高度保存位置r.Write(sizeHeight, 0, sizeHeight.Length);}}} if (width != 0){ string hexWidth = height.ToString("X").PadLeft(8, '0'); int w1 = Convert.ToInt32(hexWidth.Substring(0, 2), 16); int w2 = Convert.ToInt32(hexWidth.Substring(2, 2), 16); int w3 = Convert.ToInt32(hexWidth.Substring(4, 2), 16); int w4 = Convert.ToInt32(hexWidth.Substring(6, 2), 16); byte[] sizeWidth = new byte[] { (byte)w4, (byte)w3, (byte)w2, (byte)w1 }; using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.ReadWrite)){ using (BinaryWriter r = new BinaryWriter(fs)){r.Seek(18, 0);//高度保存位置r.Write(sizeWidth, 0, sizeWidth.Length);}}}}

合并多個bitmap文件,并生成一個最終文件

private void CreateBitMap(string tempPath,string imagePath){ string[] files = Directory.GetFiles(tempPath, "*.png");Bitmap bmp; int height=0; for (int i = files.Length-1; i >0; i--){ string fileName = files[i];bmp = new Bitmap(fileName); if (i == files.Length - 1){bmp.Save(imagePath, ImageFormat.Bmp);height += bmp.Height;bmp.Dispose(); continue;} else{ byte[] bytes = GetImageRasterBytes(bmp, PixelFormat.Format32bppRgb); using (FileStream fs = new FileStream(imagePath, FileMode.Open, FileAccess.Write)){fs.Seek(fs.Length, 0);fs.Write(bytes, 0, bytes.Length);}height += bmp.Height;bmp.Dispose();}}SetBitmapFileSizeInfo(imagePath);SetBitmapSizeInfo(imagePath, height: height); //MessageBox.Show("合并成功");} private static byte[] GetImageRasterBytes(Bitmap bmp, PixelFormat format){Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height); byte[] bits = null; try{ // Lock the managed memoryBitmapData bmpdata = bmp.LockBits(rect, ImageLockMode.ReadWrite, format); // Declare an array to hold the bytes of the bitmap.bits = new byte[bmpdata.Stride * bmpdata.Height]; // Copy the values into the array.System.Runtime.InteropServices.Marshal.Copy(bmpdata.Scan0, bits, 0, bits.Length); // Release managed memorybmp.UnlockBits(bmpdata);} catch{ return null;} return bits;}

完成嘍。

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