读取位图文件到结构 [英] read bitmap file into structure

问题描述

我想读一个位图文件到一个struct和manuplate它喜欢做镜面效果等，但我不明白哪种结构的，我应该为了读进去要创建。

I would like to read a bitmap file into a struct and manuplate it like make a mirror effect etc. but I cannot understand which kind of struct should i be creating in order to read into it.

感谢您的帮助。

推荐答案

»你这是怎么maually加载一个bmp文件

»This is how you maually load a bmp file

的位图文件格式：
位图文件头
位图信息头
调色板数据
位图达达

The bitmap file format: Bitmap file header Bitmap info header palette data Bitmap Dada

等都与code的一部分，这是我们的结构，我们需要创建举行位图文件头

so on with the code part, this is our struct we need to create to hold the bitmap file header

#pragma pack(push, 1)

typedef struct tagBITMAPFILEHEADER
{
    WORD bfType;  //specifies the file type
    DWORD bfSize;  //specifies the size in bytes of the bitmap file
    WORD bfReserved1;  //reserved; must be 0
    WORD bfReserved2;  //reserved; must be 0
    DWORD bOffBits;  //species the offset in bytes from the bitmapfileheader to the bitmap bits
}BITMAPFILEHEADER;

#pragma pack(pop)

在bftype现场检查，看，如果你是逸岸加载bmp文件，如果你是该领域应覆盖0x4D42。

the bftype field checks to see if you are infact loading a bmp file, and if you are the field should be 0x4D42.

现在，我们需要建立我们BITMAPINFOHEADER结构。这个拥有我们的位图（个体经营explainitory）信息。

Now we need to create our bitmapinfoheader struct. This holds info about our bitmap(self explainitory).

#pragma pack(push, 1)

typedef struct tagBITMAPINFOHEADER
{
    DWORD biSize;  //specifies the number of bytes required by the struct
    LONG biWidth;  //specifies width in pixels
    LONG biHeight;  //species height in pixels
    WORD biPlanes; //specifies the number of color planes, must be 1
    WORD biBitCount; //specifies the number of bit per pixel
    DWORD biCompression;//spcifies the type of compression
    DWORD biSizeImage;  //size of image in bytes
    LONG biXPelsPerMeter;  //number of pixels per meter in x axis
    LONG biYPelsPerMeter;  //number of pixels per meter in y axis
    DWORD biClrUsed;  //number of colors used by th ebitmap
    DWORD biClrImportant;  //number of colors that are important
}BITMAPINFOHEADER;

#pragma pack(pop)

现在到我们的装载位图

unsigned char *LoadBitmapFile(char *filename, BITMAPINFOHEADER *bitmapInfoHeader)
{
    FILE *filePtr; //our file pointer
    BITMAPFILEHEADER bitmapFileHeader; //our bitmap file header
    unsigned char *bitmapImage;  //store image data
    int imageIdx=0;  //image index counter
    unsigned char tempRGB;  //our swap variable

    //open filename in read binary mode
    filePtr = fopen(filename,"rb");
    if (filePtr == NULL)
        return NULL;

    //read the bitmap file header
    fread(&bitmapFileHeader, sizeof(BITMAPFILEHEADER),1,filePtr);

    //verify that this is a bmp file by check bitmap id
    if (bitmapFileHeader.bfType !=0x4D42)
    {
        fclose(filePtr);
        return NULL;
    }

    //read the bitmap info header
    fread(bitmapInfoHeader, sizeof(BITMAPINFOHEADER),1,filePtr); // small edit. forgot to add the closing bracket at sizeof

    //move file point to the begging of bitmap data
    fseek(filePtr, bitmapFileHeader.bfOffBits, SEEK_SET);

    //allocate enough memory for the bitmap image data
    bitmapImage = (unsigned char*)malloc(bitmapInfoHeader->biSizeImage);

    //verify memory allocation
    if (!bitmapImage)
    {
        free(bitmapImage);
        fclose(filePtr);
        return NULL;
    }

    //read in the bitmap image data
    fread(bitmapImage,bitmapInfoHeader->biSizeImage,filePtr);

    //make sure bitmap image data was read
    if (bitmapImage == NULL)
    {
        fclose(filePtr);
        return NULL;
    }

    //swap the r and b values to get RGB (bitmap is BGR)
    for (imageIdx = 0,imageIdx < bitmapInfoHeader->biSizeImage;imageIdx+=3)
    {
        tempRGB = bitmapImage[imageIdx];
        bitmapImage[imageIdx] = bitmapImage[imageIdx + 2];
        bitmapImage[imageIdx + 2] = tempRGB;
    }

    //close file and return bitmap iamge data
    fclose(filePtr);
    return bitmapImage;
}

现在利用了这一切：

BITMAPINFOHEADER bitmapInfoHeader;
unsigned char *bitmapData;
...
bitmapData = LoadBitmapFile("mypic.bmp",&bitmapInfoHeader);
//now do what you want with it, later on i will show you how to display it in a normal window

后来生病挂上写为BMP以及如何加载一个TARGA文件，以及如何显示它们。«

Later on ill put up Writing a to bmp and how to load a targa file and how to display them.«

的引自：<一href=\"http://www.vbforums.com/showthread.php?261522-C-C-Loading-Bitmap-Files-%28Manually%29\">http://www.vbforums.com/showthread.php?261522-C-C-Loading-Bitmap-Files-%28Manually%29 （网友：BeholderOf）。 （做了一些小的修改）的

Quoted from: http://www.vbforums.com/showthread.php?261522-C-C-Loading-Bitmap-Files-%28Manually%29 (User: BeholderOf). (Some minor corrections done)

这篇关于读取位图文件到结构的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！