iOS颜色摄合器，获取图片某点的颜色值
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1.新建一个继承于UIImageView的类-YWColorByImageView
2.重写set方法，并通过上下图文创建实际对应像素的image
/**
重设image
@param image image
*/
- (void)setImage:(UIImage *)image {
UIImage *temp = [self imageForResizeWithImage:image resize:CGSizeMake(self.frame.size.width, self.frame.size.width)];
[super setImage:temp];
}
/**
通过上下图文创建self对应像素的image
@param picture 要加载的图片
@param resize 实际self的大小
@return 返回self对应像素的大小的image
*/
- (UIImage *)imageForResizeWithImage:(UIImage *)picture resize:(CGSize)resize {
CGSize imageSize = resize; //CGSizeMake(25, 25)
/**
UIGraphicsBeginImageContextWithOptions(CGSize size, BOOL opaque, CGFloat scale);
1.参数size为新创建的位图上下文的大小
2.opaque—透明开关，如果图形完全不用透明，设置为YES以优化位图的存储
3.scale—–缩放因子 iPhone 4是2.0，其他是1.0;实际上设为0后，系统就会自动设置正确的比例了。
*/
UIGraphicsBeginImageContextWithOptions(imageSize, NO,0.0);
CGRect imageRect = CGRectMake(0.0, 0.0, imageSize.width, imageSize.height);
[picture drawInRect:imageRect];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
return image;
}
- 通过触摸点，判断该点是否在范围内，然后获取某点的颜色值
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event {
UITouch *touch = [touches anyObject];
CGPoint location_point = [touch locationInView:self];
if ([YWDistanceTool getlayer:location_point withRadius:self.bounds.size.width/2]) {
UIColor *color = [UIColor colorAtPixel:location_point withImage:self.image];
if (self.pointColorBlock) {
self.pointColorBlock(color);
}
if ([self.delegate respondsToSelector:@selector(getCurrentColor:)]) {
[self.delegate getCurrentColor:color];
}
}
}
- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event {
UITouch *touch = [touches anyObject];
CGPoint location_point = [touch locationInView:self];
if ([YWDistanceTool getlayer:location_point withRadius:self.bounds.size.width/2]) {
UIColor *color = [UIColor colorAtPixel:location_point withImage:self.image];
if (self.pointColorBlock) {
self.pointColorBlock(color);
}
if ([self.delegate respondsToSelector:@selector(getCurrentColor:)]) {
[self.delegate getCurrentColor:color];
}
}
}
- (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event {
UITouch *touch = [touches anyObject];
CGPoint location_point = [touch locationInView:self];
if ([YWDistanceTool getlayer:location_point withRadius:self.bounds.size.width/2]) {
UIColor *color = [UIColor colorAtPixel:location_point withImage:self.image];
if (self.pointColorBlock) {
self.pointColorBlock(color);
}
if ([self.delegate respondsToSelector:@selector(getCurrentColor:)]) {
[self.delegate getCurrentColor:color];
}
}
}
/**
获取图片某一点的颜色
@param point 点击图片的某一点
@param image 图片
@return 图片某点的颜色值
*/
+ (UIColor *)colorAtPixel:(CGPoint)point withImage:(UIImage *)image {
// 判断给定的点是否被一个CGRect包含
if (!CGRectContainsPoint(CGRectMake(0.0f, 0.0f, image.size.width, image.size.height), point)) {
return nil;
}
// trunc（n1,n2），n1表示被截断的数字，n2表示要截断到那一位。n2可以是负数，表示截断小数点前。注意，TRUNC截断不是四舍五入。
// TRUNC(15.79)---15
// trunc(15.79,1)--15.7
NSInteger pointX = trunc(point.x);
NSInteger pointY = trunc(point.y);
CGImageRef cgImage = image.CGImage;
NSUInteger width = image.size.width;
NSUInteger height = image.size.height;
// 创建色彩标准
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
int bytesPerPixel = 4;
int bytesPerRow = bytesPerPixel * 1;
NSUInteger bitsPerComponent = 8;
unsigned char pixelData[4] = { 0, 0, 0, 0 };
CGContextRef context = CGBitmapContextCreate(pixelData,
1,
1,
bitsPerComponent,
bytesPerRow,
colorSpace,
kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
CGContextSetBlendMode(context, kCGBlendModeCopy);
CGContextTranslateCTM(context, -pointX, pointY-(CGFloat)height);
CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, (CGFloat)width, (CGFloat)height), cgImage);
CGContextRelease(context);
CGFloat red = (CGFloat)pixelData[0] / 255.0f;
CGFloat green = (CGFloat)pixelData[1] / 255.0f;
CGFloat blue = (CGFloat)pixelData[2] / 255.0f;
CGFloat alpha = (CGFloat)pixelData[3] / 255.0f;
return [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
}
