如何获得触摸的像素颜色？
我知道这是一个常见的问题，这个问题有很多答案。 我用过这个。 虽然其中许多是相同的。 可悲的是我没有一个人为我工作。 以下代码我使用到现在。
-(void)getRGBAsFromImage:(UIImage*)image atX:(int)xx andY:(int)yy { // 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. int byteIndex = (bytesPerRow * yy) + xx * bytesPerPixel; 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; NSLog(@"the vale of the rbg of red is %f",red); demoColor.tintColor = [UIColor colorWithRed:red green:green blue:blue alpha:alpha]; free(rawData); } 这是我用过的另一种方法 –
- (CGContextRef) createARGBBitmapContextFromImage:(CGImageRef) inImage { CGContextRef context = NULL; CGColorSpaceRef colorSpace; void * bitmapData; int bitmapByteCount; int bitmapBytesPerRow; // Get image width, height. We'll use the entire image. size_t pixelsWide = CGImageGetWidth(inImage); size_t pixelsHigh = CGImageGetHeight(inImage); // Declare the number of bytes per row. Each pixel in the bitmap in this // example is represented by 4 bytes; 8 bits each of red, green, blue, and // alpha. bitmapBytesPerRow = (pixelsWide * 4); bitmapByteCount = (bitmapBytesPerRow * pixelsHigh); // Use the generic RGB color space. //colorSpace = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB); colorSpace = CGColorSpaceCreateDeviceRGB(); if (colorSpace == NULL) { fprintf(stderr, "Error allocating color space\n"); return NULL; } // Allocate memory for image data. This is the destination in memory // where any drawing to the bitmap context will be rendered. bitmapData = malloc( bitmapByteCount ); if (bitmapData == NULL) { fprintf (stderr, "Memory not allocated!"); CGColorSpaceRelease( colorSpace ); return NULL; } // Create the bitmap context. We want pre-multiplied ARGB, 8-bits // per component. Regardless of what the source image format is // (CMYK, Grayscale, and so on) it will be converted over to the format // specified here by CGBitmapContextCreate. context = CGBitmapContextCreate (bitmapData, pixelsWide, pixelsHigh, 8, // bits per component bitmapBytesPerRow, colorSpace, kCGImageAlphaPremultipliedFirst); if (context == NULL) { free (bitmapData); fprintf (stderr, "Context not created!"); } // Make sure and release colorspace before returning CGColorSpaceRelease( colorSpace ); return context; } - (UIColor*) getPixelColorAtLocation:(CGPoint)point { UIColor* color = nil; //CGImageRef inImage = self.image.CGImage; CGImageRef inImage = [AppDelegate getInstance].capturedImage.CGImage; // Create off screen bitmap context to draw the image into. Format ARGB is 4 bytes for each pixel: Alpa, Red, Green, Blue CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage]; if (cgctx == NULL) { return nil; /* error */ } size_t w = CGImageGetWidth(inImage); size_t h = CGImageGetHeight(inImage); CGRect rect = {{0,0},{w,h}}; // Draw the image to the bitmap context. Once we draw, the memory // allocated for the context for rendering will then contain the // raw image data in the specified color space. CGContextDrawImage(cgctx, rect, inImage); // Now we can get a pointer to the image data associated with the bitmap // context. unsigned char* data = CGBitmapContextGetData (cgctx); if (data != NULL) { //offset locates the pixel in the data from x,y. //4 for 4 bytes of data per pixel, w is width of one row of data. int offset = 4*((w*round(point.y))+round(point.x)); int alpha = data[offset]; int red = data[offset+1]; int green = data[offset+2]; int blue = data[offset+3]; NSLog(@"offset: %i colors: RGB A %i %i %i %i",offset,red,green,blue,alpha); color = [UIColor colorWithRed:(red/255.0f) green:(green/255.0f) blue:(blue/255.0f) alpha:(alpha/255.0f)]; } // When finished, release the context CGContextRelease(cgctx); // Free image data memory for the context if (data) { free(data); } return color; }
但是这些都没有为我工作。 请帮我解决这个问题。 有什么我失踪？
我有2 UIImageView在我的用户界面。 在后面的那个包含我需要select被触摸的像素的颜色的图像。 另一个UIImageView是用拾取的颜色在后面的图像上绘制。
请帮忙。 任何帮助将非常感激。
这是我用过的，看起来比你试过的方法简单。
在我的自定义视图类中，我有这样的：
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [[event allTouches] anyObject]; CGPoint loc = [touch locationInView:self]; self.pickedColor = [self colorOfPoint:loc]; }
colorOfPoint是UIView类别中的一个方法，使用下面的代码：
#import "UIView+ColorOfPoint.h" #import <QuartzCore/QuartzCore.h> @implementation UIView (ColorOfPoint) -(UIColor *) colorOfPoint:(CGPoint)point { unsigned char pixel[4] = {0}; CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGContextRef context = CGBitmapContextCreate(pixel, 1, 1, 8, 4, colorSpace, (CGBitmapInfo)kCGImageAlphaPremultipliedLast); CGContextTranslateCTM(context, -point.x, -point.y); [self.layer renderInContext:context]; CGContextRelease(context); CGColorSpaceRelease(colorSpace); UIColor *color = [UIColor colorWithRed:pixel[0]/255.0 green:pixel[1]/255.0 blue:pixel[2]/255.0 alpha:pixel[3]/255.0]; return color; }
不要忘记将类别导入到自定义视图类中，并添加QuartzCore框架。
2013年的简单说明：将最后一个参数强制转换为（CGBitmapInfo）以避免隐式转换警告： 此处为示例。 希望它有帮助。
感谢@ Aggressor发布了上面的代码
Swift 2.1
func getPixelColorAtPoint(point:CGPoint) -> UIColor{ let pixel = UnsafeMutablePointer<CUnsignedChar>.alloc(4) let colorSpace = CGColorSpaceCreateDeviceRGB() let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.PremultipliedLast.rawValue) let context = CGBitmapContextCreate(pixel, 1, 1, 8, 4, colorSpace, bitmapInfo.rawValue) CGContextTranslateCTM(context, -point.x, -point.y) view.layer.renderInContext(context!) let color:UIColor = UIColor(red: CGFloat(pixel[0])/255.0, green: CGFloat(pixel[1])/255.0, blue: CGFloat(pixel[2])/255.0, alpha: CGFloat(pixel[3])/255.0) pixel.dealloc(4) return color }
Swift 3 ，Xcode版本8.2（8C38）
func getPixelColorAtPoint(point:CGPoint, sourceView: UIView) -> UIColor{ let pixel = UnsafeMutablePointer<CUnsignedChar>.allocate(capacity: 4) let colorSpace = CGColorSpaceCreateDeviceRGB() let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedLast.rawValue) let context = CGContext(data: pixel, width: 1, height: 1, bitsPerComponent: 8, bytesPerRow: 4, space: colorSpace, bitmapInfo: bitmapInfo.rawValue) context!.translateBy(x: -point.x, y: -point.y) sourceView.layer.render(in: context!) let color:UIColor = UIColor(red: CGFloat(pixel[0])/255.0, green: CGFloat(pixel[1])/255.0, blue: CGFloat(pixel[2])/255.0, alpha: CGFloat(pixel[3])/255.0) pixel.deallocate(capacity: 4) return color }
伟大的回答rdelmar这帮了我很多！
下面是我在Swift中如何做到的：
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) { var touch:UITouch = event.allTouches()!.anyObject() as UITouch var loc = touch.locationInView(self) var color:UIColor = getPixelColorAtPoint(loc) println(color) } //returns the color data of the pixel at the currently selected point func getPixelColorAtPoint(point:CGPoint)->UIColor { let pixel = UnsafeMutablePointer<CUnsignedChar>.alloc(4) var colorSpace = CGColorSpaceCreateDeviceRGB() let bitmapInfo = CGBitmapInfo(CGImageAlphaInfo.PremultipliedLast.rawValue) let context = CGBitmapContextCreate(pixel, 1, 1, 8, 4, colorSpace, bitmapInfo) CGContextTranslateCTM(context, -point.x, -point.y) layer.renderInContext(context) var color:UIColor = UIColor(red: CGFloat(pixel[0])/255.0, green: CGFloat(pixel[1])/255.0, blue: CGFloat(pixel[2])/255.0, alpha: CGFloat(pixel[3])/255.0) pixel.dealloc(4) return color }
Swift 3，Xcode 8.3 – 使用UIImageView扩展
这是以上所有答案的组合，但是是一个扩展
extension UIImageView { func getPixelColorAt(point:CGPoint) -> UIColor{ let pixel = UnsafeMutablePointer<CUnsignedChar>.allocate(capacity: 4) let colorSpace = CGColorSpaceCreateDeviceRGB() let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedLast.rawValue) let context = CGContext(data: pixel, width: 1, height: 1, bitsPerComponent: 8, bytesPerRow: 4, space: colorSpace, bitmapInfo: bitmapInfo.rawValue) context!.translateBy(x: -point.x, y: -point.y) layer.render(in: context!) let color:UIColor = UIColor(red: CGFloat(pixel[0])/255.0, green: CGFloat(pixel[1])/255.0, blue: CGFloat(pixel[2])/255.0, alpha: CGFloat(pixel[3])/255.0) pixel.deallocate(capacity: 4) return color } }
如何使用
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) { let touch = touches.first if let point = touch?.location(in: view) { let color = myUIImageView.getPixelColorAt(point: point) print(color) } }
