是否可以通过编程方式更改图像的颜色？ [英] Is that possible to change the color for an image programmatically?

问题描述

我正在使用一个具有不同主题颜色的应用程序，但我不想在项目中有太多图像资源（基本上不想让项目大小太大），是否可以使用一个图像，但不同的颜色？

I am working an app which has different theme color, but i don't want to have too much image assets in the project (basically don't want to make the project size too big), is that possible to use one image but different colors?

谢谢！

推荐答案

我同意马特，您应该检查CIFilter以便将来修改图像。但如果你正在寻找一个快速的代码示例，我就是这样做的。对我来说工作得很好，只需要像这样调用：

I agree with Matt, you should check CIFilter for future image modification. but if you are looking for a quick code sample, here is how i did it. works pretty fine for me, simply need to call like this :

 [self useColor:[UIColor redColor] forImage:WHATEVER_IMAGE];

 - (UIImage *)useColor:(UIColor *)color forImage:(UIImage *)image
 {
     if(!color)
         return image;

     NSUInteger width = CGImageGetWidth([image CGImage]);
     NSUInteger height = CGImageGetHeight([image CGImage]);
     CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

     NSUInteger bytesPerPixel = 4;
     NSUInteger bytesPerRow = bytesPerPixel * width;
     NSUInteger bitsPerComponent = 8;
     NSUInteger bitmapByteCount = bytesPerRow * height;

     unsigned char *rawData = (unsigned char*) calloc(bitmapByteCount, sizeof(unsigned char));

     CGContextRef context = CGBitmapContextCreate(rawData, width, height,
                                             bitsPerComponent, bytesPerRow, colorSpace,
                                             kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
     CGColorSpaceRelease(colorSpace);

     CGContextDrawImage(context, CGRectMake(0, 0, width, height), [image CGImage]);

     CGColorRef cgColor = [color CGColor];
     const CGFloat *components = CGColorGetComponents(cgColor);
     float r = components[0] * 255.0;
     float g = components[1] * 255.0;
     float b = components[2] * 255.0;
     //float a = components[3]; // not needed

     int byteIndex = 0;

     while (byteIndex < bitmapByteCount)
     {
         int oldR = rawData[byteIndex];
         int oldG = rawData[byteIndex + 1];
         int oldB = rawData[byteIndex + 2];
         int oldA = rawData[byteIndex + 3];
         if(oldR != 0 || oldG != 0 || oldB != 0 || oldA != 0)
         {
             rawData[byteIndex] = r;
             rawData[byteIndex + 1] = g;
             rawData[byteIndex + 2] = b;
         }

         byteIndex += 4;
     }

     UIImage *result = [UIImage imageWithCGImage:CGBitmapContextCreateImage(context) scale:image.scale orientation:image.imageOrientation];

     CGContextRelease(context);
     free(rawData);

     return result;
 }

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