如何在 C# 中从 byte[] 创建 bmp 文件

问题描述

我在 TCP 客户端接收到一个 byte[] 数组.该数组包含一个 24 位 RGB 位图文件.如何创建具有给定宽度、高度和数据的位图文件?

I have a byte[] array received in TCP Client.The array contains a 24-bit RGB Bitmap file.How to create that bitmap file with given Width ,Height and data?

在 C++ 中我使用这个

In C++ I use this

int WriteBitmapFile(const char *filename, int width, int height, unsigned char *imageData)
{
FILE             *filePtr;        // file pointer
BITMAPFILEHEADER bitmapFileHeader;    // bitmap file header
BITMAPINFOHEADER bitmapInfoHeader;    // bitmap info header
DWORD                 imageIdx;    // used for swapping RGB->BGR
unsigned char     tempRGB;            // used for swapping

// open file for writing binary mode
filePtr = fopen(filename, "wb");
if (!filePtr)
    return 0;

// define the bitmap file header
bitmapFileHeader.bfSize = sizeof(BITMAPFILEHEADER);
bitmapFileHeader.bfType = 0x4D42;
bitmapFileHeader.bfReserved1 = 0;
bitmapFileHeader.bfReserved2 = 0;
bitmapFileHeader.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);

// define the bitmap information header
bitmapInfoHeader.biSize = sizeof(BITMAPINFOHEADER);
bitmapInfoHeader.biPlanes = 1;
bitmapInfoHeader.biBitCount = 32;                        // 24-bit
bitmapInfoHeader.biCompression = BI_RGB;                // no compression
bitmapInfoHeader.biSizeImage = width * abs(height) * 4;    // width * height * (RGB bytes)
bitmapInfoHeader.biXPelsPerMeter = 0;
bitmapInfoHeader.biYPelsPerMeter = 0;
bitmapInfoHeader.biClrUsed = 0;
bitmapInfoHeader.biClrImportant = 0;
bitmapInfoHeader.biWidth = width;                        // bitmap width
bitmapInfoHeader.biHeight = height;                    // bitmap height

// switch the image data from RGB to BGR
for(imageIdx = 0; imageIdx < bitmapInfoHeader.biSizeImage; imageIdx+=4)
{
    tempRGB = imageData[imageIdx];
    imageData[imageIdx] = imageData[imageIdx + 2];
    imageData[imageIdx + 2] = tempRGB;
}

// write the bitmap file header
fwrite(&bitmapFileHeader, 1, sizeof(BITMAPFILEHEADER), filePtr);

// write the bitmap info header
fwrite(&bitmapInfoHeader, 1, sizeof(BITMAPINFOHEADER), filePtr);

// write the image data
fwrite(imageData, 1, bitmapInfoHeader.biSizeImage, filePtr);

// close our file
fclose(filePtr);

// Success
return 1;
}

我怎么能在 C# 中做到这一点?

How could I do that in C#?

推荐答案

如果数组实际上包含一个位图文件，那么您可以将字节保存为文件:

If the array actually contains a bitmap file, then you can just save the bytes as a file:

File.WriteAllBytes(fileName, imageData);

如果数组只包含原始像素数据，您可以使用该数据创建一个 Bitmap 对象:

If the array contains only raw pixel data, you can create a Bitmap object using the data:

unsafe {
   fixed (byte* ptr = imageData) {
      using (Bitmap image = new Bitmap(width, height, stride, PixelFormat.Format24bppRgb, new IntPtr(ptr))) {
         image.Save(fileName);
      }
   }
}

stride 值是扫描线之间的字节数.如果扫描线之间没有填充，则为 24bpp 格式的 width * 3.

The stride value is the number of bytes between the scan lines. If there is no padding between the scan lines, it's width * 3 for a 24bpp format.

此方法使用数组中的数据，而无需在内存中创建整个图像的另一个副本(这就是它需要步幅值的原因).

This method uses the data in the array without creating another copy of the entire image in memory (which is why it needs the stride value).

如果位图数据倒置存放在数组中，stride的值应该是负的，指针应该是内存中最后一个扫描行的开始(ptr + stride* (高度 - 1)).

If the bitmap data is stored upside down in the array, the stride value should be negative, and the pointer should be the start of the last scan line in memory (ptr + stride * (height - 1)).

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