[IOS 開發] UIImage改變像素值

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[IOS 開發] UIImage改變像素值

- (UIImage*) imageBlackToTransparent:(UIImage*) image{    // 分配記憶體    const int imageWidth = image.size.width;    const int imageHeight = image.size.height;    size_t      bytesPerRow = imageWidth * 4;    uint32_t* rgbImageBuf = (uint32_t*)malloc(bytesPerRow * imageHeight);        // 建立context    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();    CGContextRef context = CGBitmapContextCreate(rgbImageBuf, imageWidth, imageHeight, 8, bytesPerRow, colorSpace,kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast);    CGContextDrawImage(context, CGRectMake(0, 0, imageWidth, imageHeight), image.CGImage);        // 遍曆像素    int pixelNum = imageWidth * imageHeight;    uint32_t* pCurPtr = rgbImageBuf;        for (int i = 0; i < pixelNum; i++, pCurPtr++)    {        if ((*pCurPtr & 0xFFFFFF00) == 0)    // 將黑色變成透明        {            uint8_t* ptr = (uint8_t*)pCurPtr;                        ptr[0] = 0;            ptr[1] = 0;            ptr[2] = 0;            ptr[3] = 0;        }    }        // 將記憶體轉成image    CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, rgbImageBuf, bytesPerRow * imageHeight,ProviderReleaseData);    CGImageRef imageRef = CGImageCreate(imageWidth, imageHeight, 8, 32, bytesPerRow, colorSpace,kCGImageAlphaLast | kCGBitmapByteOrder32Little, dataProvider,NULL, true, kCGRenderingIntentDefault);        CGDataProviderRelease(dataProvider);        UIImage* resultUIImage = [UIImage imageWithCGImage:imageRef];        // 釋放    CGImageRelease(imageRef);    CGContextRelease(context);    CGColorSpaceRelease(colorSpace);        // free(rgbImageBuf) 建立dataProvider時已提供釋放函數,這裡不用free    return resultUIImage;}/** 顏色變化 */void ProviderReleaseData (void *info, const void *data, size_t size){    free((void*)data);}

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