Question

而不是使用[UIColor colorWithPatternImage:[UIImage imageNamed:@"my_image.png"]];从图像设置视图的背景颜色，下次我只想使用检索到的RGB值来设置视图的背景颜色。

Answer 1

希望您正在寻找我从其他来源复制的内容。

+ (NSArray*)getRGBAsFromImage:(UIImage*)image atX:(int)x andY:(int)y count:(int)count{
NSMutableArray *result = [NSMutableArray arrayWithCapacity:count];

// First get the image into your data buffer
CGImageRef imageRef = [image CGImage];
NSUInteger width = CGImageGetWidth(imageRef);
NSUInteger height = CGImageGetHeight(imageRef);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
unsigned char *rawData = (unsigned char*) calloc(height * width * 4, sizeof(unsigned char));
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
CGContextRef context = CGBitmapContextCreate(rawData, width, height,
                bitsPerComponent, bytesPerRow, colorSpace,
                kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);

CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
CGContextRelease(context);

// Now your rawData contains the image data in the RGBA8888 pixel format.
NSUInteger byteIndex = (bytesPerRow * y) + x * bytesPerPixel;
for (int i = 0 ; i < count ; ++i)
{
    CGFloat red   = (rawData[byteIndex]     * 1.0) / 255.0;
    CGFloat green = (rawData[byteIndex + 1] * 1.0) / 255.0;
    CGFloat blue  = (rawData[byteIndex + 2] * 1.0) / 255.0;
    CGFloat alpha = (rawData[byteIndex + 3] * 1.0) / 255.0;
    byteIndex += bytesPerPixel;

    UIColor *acolor = [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
    [result addObject:acolor];
}free(rawData);return result;}'

如何提取图像的RGB值？

1 个答案: