【发布时间】：2013-06-17 06:19:41
【问题描述】：
我的 .m ImageView 类文件中有这个函数
- (UIColor*) getPixelColorAtLocation:(CGPoint)point {
如何从视图控制器调用此函数？我试过了`
- (void)viewDidLoad
{
CGPoint point = CGPointMake(100, 100);
UIColor* color = [ImageView getPixelColorAtLocation:point];
}`
但这给了我一个警告：“没有已知的扇区方法'getPixelColorAtLocation：'（我确实将ImageView类文件导入到视图控制器）
我在 ImageView 中的 .h 文件
#import <Foundation/Foundation.h>
@interface ImageView : UIImageView {
UIColor* lastColor;
//id pickedColorDelegate;
}
@property (nonatomic, retain) UIColor* lastColor;
//@property (nonatomic, retain) id pickedColorDelegate;
- (UIColor*) getPixelColorAtLocation:(CGPoint)point;
- (CGContextRef) createARGBBitmapContextFromImage:(CGImageRef)inImage;
@end
我在 ImageView 中的 .m 文件
#import "ImageView.h"
#import "ViewController.h"
#import <CoreGraphics/CoreGraphics.h>
#import <QuartzCore/CoreAnimation.h>
@implementation ImageView
@synthesize lastColor;
//@synthesize pickedColorDelegate;
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
}
- (void) touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event {
if (self.hidden==YES) {
//color wheel is hidden, so don't handle this as a color wheel event.
[[self nextResponder] touchesEnded:touches withEvent:event];
return;
}
UITouch* touch = [touches anyObject];
// ColorPickerAppDelegate *mainDelegate = (ColorPickerAppDelegate *)[[UIApplication sharedApplication] delegate];
CGPoint point = [touch locationInView:self]; //where image was tapped
self.lastColor = [self getPixelColorAtLocation:point];
NSLog(@"color %@",lastColor);
//[pickedColorDelegate pickedColor:(UIColor*)self.lastColor];
}
- (UIColor*) getPixelColorAtLocation:(CGPoint)point {
UIColor* color = nil;
CGImageRef inImage = self.image.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;
}
- (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 = 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;
}
【问题讨论】：
-
这个你的类名 ImageView 或 ivar name.....应该是 ivar name.
-
ImageView* imageView = [[ImageView alloc] init]; UIColor* color = [imageView getPixelColorAtLocation:CGPointMake(100, 100)];
-
取决于 getPixelColorAtLocation: 声明的位置。从外观上看，它应该属于 UIImage 而不是 UIImageView 的类别，并将该文件导入您的视图控制器中。并调用 [ImageView.image getPixelColorAtLocation:point]
-
显示此方法getPixelColorAtLocation的代码？
标签： iphone ios xcode uiviewcontroller uiimageview