图片缩放转换bpp 图片合并

图片缩放

缩放原理：
原图和缩放图内点的位置，在图片中的相对位置不变。

缩放图中每个点的都可以根据图中公式计算出在原图中的位置，然后把原图颜色赋给缩放图。可以用两个for循环复制数据。
函数原型：int PicZoom(PT_PixelDatas ptOriginPic, PT_PixelDatas ptZoomPic)
图片的象素数据结构体PixelDatas，用缩放后的数据更改该结构体内容。
优化：
1.每行的Sy坐标不变，所以在第一个for循环里计算y坐标。
2.Sx每行都要重新计算，但是对整个图来说每行的Sx参数是一样的，可以先计算出来保存在数组里。

int PicZoom(PT_PixelDatas ptOriginPic, PT_PixelDatas ptZoomPic){unsigned long dwDstWidth = ptZoomPic->iWidth;unsigned long* pdwSrcXTable;unsigned long dwSrcY;unsigned long dwPixelBytes = ptOriginPic->iBpp/8;if (ptOriginPic->iBpp != ptZoomPic->iBpp){return -1;}pdwSrcXTable = malloc(sizeof(unsigned long) * dwDstWidth);if (NULL == pdwSrcXTable){DBG_PRINTF("malloc error!\n");return -1;}for (unsigned long x = 0; x < dwDstWidth; x++)        //生成表 pdwSrcXTable    pdwSrcXTable[x]=(x*ptOriginPic->iWidth/ptZoomPic->iWidth);for (unsigned long y = 0; y < ptZoomPic->iHeight; y++) {            dwSrcY = (y * ptOriginPic->iHeight / ptZoomPic->iHeight);unsigned char *pucDest = ptZoomPic->aucPixelDatas + y*ptZoomPic->iLineBytes;unsigned char *pucSrc  = ptOriginPic->aucPixelDatas + dwSrcY*ptOriginPic->iLineBytes;for (x = 0; x <dwDstWidth; x++)/* 原图座标: pdwSrcXTable[x]，srcy* 缩放座标: x, y*/        //从原图拷贝到缩放图，长度为bppmemcpy(pucDest+x*dwPixelBytes, pucSrc+pdwSrcXTable[x]*dwPixelBytes, dwPixelBytes);}    free(pdwSrcXTable);return 0;
}

转换bpp

函数原型CovertOneLine(iWidth, iBMPBpp, ptPixelDatas->iBpp, pucSrc, pucDest);
宽度源bpp 目的bpp 源数据地址目的数据地址
从源数据地址，逐个像素处理，若是24位直接复制，若不是，则取出蓝绿红三个字节进行颜色转换，赋给目的地址。

static int CovertOneLine(int iWidth, int iSrcBpp, int iDstBpp, unsigned char *pudSrcDatas, unsigned char *pudDstDatas){unsigned int dwRed,dwGreen,dwBlue;unsigned int dwColor;unsigned short *pwDstDatas16bpp = (unsigned short *)pudDstDatas;  //16位bpp，2字节unsigned int   *pwDstDatas32bpp = (unsigned int *)pudDstDatas;      //32位bpp，4字节if (iDstBpp == 24)     //源24bpp，目的的bpp相同，直接复制    memcpy(pudDstDatas, pudSrcDatas, iWidth*3);else{for (int i = 0; i < iWidth; i++){dwBlue  = pudSrcDatas[pos++]; //取出蓝绿红数据，3字节dwGreen = pudSrcDatas[pos++];dwRed   = pudSrcDatas[pos++];if (iDstBpp == 32){       //算出32位的bpp，红绿蓝  dwColor = (dwRed << 16) | (dwGreen << 8) | dwBlue;*pwDstDatas32bpp = dwColor;pwDstDatas32bpp++;}else if (iDstBpp == 16){  //算出16位的bpp，红绿蓝565       /* 565 */dwRed   = dwRed >> 3;dwGreen = dwGreen >> 2;dwBlue  = dwBlue >> 3;dwColor = (dwRed << 11) | (dwGreen << 5) | (dwBlue);*pwDstDatas16bpp = dwColor;pwDstDatas16bpp++;}}}return 0;
}

图片合并

函数原型int PicMerge(int iX, int iY, PT_PixelDatas ptSmallPic, PT_PixelDatas ptBigPic)
将小图片合并到大图片的(x,y)处，参数为8.3.2中自定义的图片描述结构体指针PT_PixelDatas。将小图片内容memcpy复制到大图片对应位置处。

把小图片合并入大图片里

int PicMerge(int iX, int iY, PT_PixelDatas ptSmallPic, PT_PixelDatas ptBigPic){if ((ptSmallPic->iWidth > ptBigPic->iWidth)  ||(ptSmallPic->iHeight > ptBigPic->iHeight) ||(ptSmallPic->iBpp != ptBigPic->iBpp)){return -1;}unsigned char *pucSrc = ptSmallPic->aucPixelDatas;unsigned char *pucDst = ptBigPic->aucPixelDatas + iY * ptBigPic->iLineBytes + iX * ptBigPic->iBpp / 8;for (int i = 0; i < ptSmallPic->iHeight; i++){memcpy(pucDst, pucSrc, ptSmallPic->iLineBytes);pucSrc += ptSmallPic->iLineBytes;pucDst += ptBigPic->iLineBytes;}return 0;
}

把新图片的某部分, 合并入老图片的指定区域

int PicMergeRegion(int iStartXofNewPic, int iStartYofNewPic, int iStartXofOldPic, int iStartYofOldPic, int iWidth, int iHeight, PT_PixelDatas ptNewPic, PT_PixelDatas ptOldPic){int iLineBytesCpy = iWidth * ptNewPic->iBpp / 8;if ((iStartXofNewPic < 0 || iStartXofNewPic >= ptNewPic->iWidth) || \(iStartYofNewPic < 0 || iStartYofNewPic >= ptNewPic->iHeight) || \(iStartXofOldPic < 0 || iStartXofOldPic >= ptOldPic->iWidth) || \(iStartYofOldPic < 0 || iStartYofOldPic >= ptOldPic->iHeight)){return -1;}unsigned char *pucSrc = ptNewPic->aucPixelDatas + iStartYofNewPic * ptNewPic->iLineBytes + iStartXofNewPic * ptNewPic->iBpp / 8;unsigned char *pucDst = ptOldPic->aucPixelDatas + iStartYofOldPic * ptOldPic->iLineBytes + iStartXofOldPic * ptOldPic->iBpp / 8;for (int i = 0; i < iHeight; i++){memcpy(pucDst, pucSrc, iLineBytesCpy);pucSrc += ptNewPic->iLineBytes;pucDst += ptOldPic->iLineBytes;}return 0;
}