Question

我有一个UIImage，我想通过设置RGBA来改变一些像素颜色。我有需要更改的所有像素的CGPoints。如何通过设置RGBA值来更改颜色？

如果无法更改UIImage像素的颜色，可以在包含图像的UIImageView上绘图，但我需要它才能很好地执行，因为我要多次执行此操作。

我该怎么做？

修改

我找到了解决问题的方法。这为CGPoint红色着色：

-(void)pixelate:(CGPoint)point
{
    CGImageRef inImage = self.drawImage.image.CGImage;
    CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage];
    if (cgctx == nil) { NSAssert(NO,@"Context shouldn't be nil!"); }

    size_t w = CGImageGetWidth(inImage);
    size_t h = CGImageGetHeight(inImage);
    CGRect rect = {{0,0},{w,h}}; 

    CGContextDrawImage(cgctx, rect, inImage); 

    unsigned char* data = CGBitmapContextGetData(cgctx);
    if (data != nil)
    {
        int offset = 4*((w*round(point.y))+round(point.x));
        data[offset] = 255; //alpha
        data[offset+1] = 255; //red
        data[offset+2] = 0; //green
        data[offset+3] = 0; //blue
    }

    CGImageRef img = CGBitmapContextCreateImage(cgctx);
    UIGraphicsEndImageContext();

    CGContextRelease(cgctx);

    if (data) { free(data); }

    self.drawImage.image = [UIImage imageWithCGImage:img];
}

Answer 1

第一个Imaport关注文件.. ＆gt;＆gt;＆gt;＆gt;编辑....

#import <QuartzCore/QuartzCore.h> CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGContextRef bitmContext = CGBitmapContextCreate(NULL, width, height, 8,bytesPerRow, colorSpace, kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedFirst); CGColorSpaceRelease(colorSpace); CGContextDrawImage(bitmContext, (CGRect){.origin.x = 0.0f, .origin.y = 0.0f, .size.width = originalWidth, .size.height = originalHeight}, cgImage);

获取对基础像素的引用：

UInt8* data = (UInt8*)CGBitmapContextGetData(bitmContext);

像素操作：

const size_t bitmapByteCount = bytesPerRow * originalHeight; for (size_t i = 0; i < bitmapByteCount; i += 4) { UInt8 a = data[i]; UInt8 r = data[i + 1]; UInt8 g = data[i + 2]; UInt8 b = data[i + 3]; data[i] = (UInt8)newAlpha data[i + 1] = (UInt8)newRed; data[i + 2] = (UInt8)newGreen; data[i + 3] = (UInt8)newBlue; } CGImageRef newImage = CGBitmapContextCreateImage(bitmContext);

或使用此Refrence ......

http://www.markj.net/iphone-uiimage-pixel-color/

希望，这会帮助你......享受

Answer 2

我找到了解决问题的方法。这为CGPoint红色着色：

-(void)pixelate:(CGPoint)point
{
    CGImageRef inImage = self.drawImage.image.CGImage;
    CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage];
    if (cgctx == nil) { NSAssert(NO,@"Context shouldn't be nil!"); }

    size_t w = CGImageGetWidth(inImage);
    size_t h = CGImageGetHeight(inImage);
    CGRect rect = {{0,0},{w,h}}; 

    CGContextDrawImage(cgctx, rect, inImage); 

    unsigned char* data = CGBitmapContextGetData(cgctx);
    if (data != nil)
    {
        int offset = 4*((w*round(point.y))+round(point.x));
        data[offset] = 255; //alpha
        data[offset+1] = 255; //red
        data[offset+2] = 0; //green
        data[offset+3] = 0; //blue
    }

    CGImageRef img = CGBitmapContextCreateImage(cgctx);
    UIGraphicsEndImageContext();

    CGContextRelease(cgctx);

    if (data) { free(data); }

    self.drawImage.image = [UIImage imageWithCGImage:img];
}

着色UIImage的CGPoint

2 个答案: