[英]Unable to change the colour of pixel in UIImage
我已經通過使用其他代碼解決了我的問題。 我只想知道下一個是什么問題?
我想使用位圖數據更改UIImage
中每個像素的顏色。 我的代碼如下:
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
UIImage *image = self.imageViewMain.image;
CGImageRef imageRef = image.CGImage;
NSData *data = (NSData *)CFBridgingRelease(CGDataProviderCopyData(CGImageGetDataProvider(imageRef)));
char *pixels = (char *)[data bytes];
// this is where we manipulate the individual pixels
for(int i = 1; i < [data length]; i += 3)
{
int r = i;
int g = i+1;
int b = i+2;
int a = i+3;
pixels[r] = 0; // eg. remove red
pixels[g] = pixels[g];
pixels[b] = pixels[b];
pixels[a] = pixels[a];
}
// create a new image from the modified pixel data
size_t width = CGImageGetWidth(imageRef);
size_t height = CGImageGetHeight(imageRef);
size_t bitsPerComponent = CGImageGetBitsPerComponent(imageRef);
size_t bitsPerPixel = CGImageGetBitsPerPixel(imageRef);
size_t bytesPerRow = CGImageGetBytesPerRow(imageRef);
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, pixels, [data length], NULL);
CGImageRef newImageRef = CGImageCreate (
width,
height,
bitsPerComponent,
bitsPerPixel,
bytesPerRow,
colorspace,
bitmapInfo,
provider,
NULL,
false,
kCGRenderingIntentDefault
);
// the modified image
UIImage *newImage = [UIImage imageWithCGImage:newImageRef];
// cleanup
free(pixels);
CGImageRelease(imageRef);
CGColorSpaceRelease(colorspace);
CGDataProviderRelease(provider);
CGImageRelease(newImageRef);
}
但是當此代碼運行時-我得到EXC_BAD_ACCESS
錯誤 ,如下圖所示:
這是調試的更多信息:
我想念或做錯了什么?
嘗試為像素數組分配內存,例如以下代碼
char *pixels = (char *)malloc(data.length);
memcpy(pixels, [data bytes], data.length);
當不需要像素時,通過調用free(pixels)
釋放此內存
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