Get UIImageView CGPoints - objective-c

Question

i want to get all the points in my UIImageVeiw , so i can change "some" points colors without the need of UITouch .. is it possible?
What i am thinking about is:
get all points in uiimageview
get color of each point.
if the previous color= some specific color, then change the color.
i googled this a lot but i found that all the tutorials depends on UITouch like this http://www.markj.net/iphone-uiimage-pixel-color/
my main goal now is how to get all points ?!
any help is appreciated

Answer 1

i found a solution .. hope it will help anyone one day.
this method returns array of pixels in some image.
-(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;}
you can call it like this:
NSArray*arrayOfPixels= [self getRGBAsFromImage:_patternFirstImage.image atX:_patternFirstImage.frame.origin.x andY:_patternFirstImage.frame.origin.y count:_patternFirstImage.frame.size.width*_patternFirstImage.frame.size.height];
NSLog(#"arrayOfPixels = %zd",[arrayOfPixels count]);
you can loop through all pixels to get its color like the following :
for(int i=0;i<[arrayOfPixels count];i++){
NSLog(#"objects = ---%#----",[arrayOfPixels objectAtIndex:i]);
if([self color:[arrayOfPixels objectAtIndex:i] isEqualToColor:UIColorFromRGB(0xE0E0E0) withTolerance:0.2]){
NSLog(#"index = %zd",i);
}
}
thanx a lot for the answer here:
https://stackoverflow.com/a/1262893/2168496