Jak uzyskać kolor piksela na dotyku?
Wiem, że jest to częste pytanie i jest na nie wiele odpowiedzi. Użyłem trochę tego. Chociaż wiele z nich jest takich samych. Ale smutne jest to, że żaden z nich nie pracował dla mnie. Poniższe kody używałem do tej pory.
-(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);
}
Oto inne podejście, które zastosowałem -
- (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;
}
/ Align = "left" / Proszę, pomóż mi z tym. Czy coś mi umyka ?
Mam 2 UIImageView w moim interfejsie. Ten, który jest w powrót zawiera obraz, z którego muszę wybrać kolor piksela, który jest dotykany. A drugi UIImageView jest malowanie na tylnym obrazie wybranym kolorem.
Proszę o pomoc. Każda pomoc będzie bardzo mile widziana.4 answers
To jest ten, którego użyłem, i wygląda prościej niż metody, których próbowałeś.
W mojej klasie custom view mam to:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [[event allTouches] anyObject];
CGPoint loc = [touch locationInView:self];
self.pickedColor = [self colorOfPoint:loc];
}
ColorOfPoint jest metodą w kategorii na UIView, o tym kodzie:
#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;
}
Nie zapomnij zaimportować kategorii do niestandardowej klasy widoku i dodać framework QuartzCore.
Trywialna uwaga na rok 2013: Wrzuć ten ostatni argument jako (CGBitmapInfo), aby uniknąć niejawnego ostrzeżenia o konwersji: przykład tutaj. Hope it pomaga.
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2017-05-23 11:54:53
Dziękuję za wstawienie powyższego kodu przez @ Aggressor
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 w wersji 8.2 (8C38) oraz Swift 4 , Xcode Wersja 9.1 (9B55)
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)
var color: UIColor? = nil
if let context = context {
context.translateBy(x: -point.x, y: -point.y)
sourceView.layer.render(in: context)
color = 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
}
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2017-11-25 02:18:32
Świetna odpowiedź rdelmar to bardzo mi pomogło!
Oto jak zrobiłem powyższe w Swift:
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
}
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2015-01-02 18:34:49
Swift 4, Xcode 9-z rozszerzeniem UIImageView
Jest to kombinacja wszystkich powyższych odpowiedzi, ale w rozszerzeniu
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
}
}
Jak używać
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)
}
}
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2017-11-28 14:33:55