我有這樣的代碼,我發現在這裏,它找到一個像素的顏色的圖像:「<Error>:CGContextDrawImage:無效的情況下爲0x0」
+ (NSArray*)getRGBAsFromImage:(UIImage*)image atX:(int)xx andY:(int)yy 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 = malloc(height * width * 4);
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.
int byteIndex = (bytesPerRow * yy) + xx * bytesPerPixel;
for (int ii = 0 ; ii < count ; ++ii)
{
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 += 4;
UIColor *acolor = [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
[result addObject:acolor];
}
free(rawData);
return result;
}
但在該行CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
它給出了一個錯誤在NSLog的<Error>: CGContextDrawImage: invalid context 0x0
。它不會崩潰應用程序,但顯然我不希望在那裏發生錯誤。
對此有何建議?
kCGBitmapByteOrder32Big?你在哪裏看到?我沒跟着你。 – RyeMAC3
等一下,找出它....看下面。 – RyeMAC3
對我來說,在某些情況下,不支持的組合將零寬度和/或高度傳遞給CGBitmapContextCreate。必須添加一個檢查來跳過這些。 –