編輯:關於Android編程
如圖:點擊或者根據圖中黑點滑動獲取圖片色值及黑點坐標。ColorImageView是繼承UIImageView的封裝,用起來很方便。
下面我們先講demo的ViewController布局:
1,引進ColorImageView.h ;
#import "ColorImageView.h"
2, 聲明了兩個label用於顯示rag值 及黑點位置;
@interface ViewController () @property (nonatomic,strong)UILabel *rgbLabel;//rgba @property (nonatomic,strong)UILabel *locationLabel;//黑點位置 @end
3, 就是把聲明的label在 viewDidLoad 中進行添加:
_rgbLabel = [[UILabel alloc] init]; _rgbLabel.frame=CGRectMake(10,60, self.view.frame.size.width-20, 23); _rgbLabel.backgroundColor = [UIColor clearColor]; _rgbLabel.font = [UIFont systemFontOfSize:13 ]; _rgbLabel.textAlignment = NSTextAlignmentCenter; _rgbLabel.textColor = [UIColor blackColor]; _rgbLabel.text = @"點擊或移動下面的彩色圖片,獲取色值!"; [self.view addSubview:_rgbLabel]; _locationLabel = [[UILabel alloc] init]; _locationLabel.frame=CGRectMake(10,90, self.view.frame.size.width-20, 23); _locationLabel.backgroundColor = [UIColor clearColor]; _locationLabel.font = [UIFont systemFontOfSize:13 ]; _locationLabel.textAlignment = NSTextAlignmentCenter; _locationLabel.textColor = [UIColor whiteColor]; [self.view addSubview:_locationLabel];
4,把封裝的ColorImageView也添加在viewDidLoad中,關於ColorImageView值傳出我用的是一個block,如果對block不理解,就自己上網查咯!
ColorImageView *colorImageView = [[ColorImageView alloc] initWithFrame:CGRectMake((self.view.frame.size.width-248)/2,130, 248, 248)]; colorImageView.backgroundColor = [UIColor clearColor]; colorImageView.userInteractionEnabled = YES; colorImageView.image = [UIImage imageNamed:@"color_s"]; //避免循序引用 弱化 __weak typeof(self) weakSelf = self; colorImageView.block =^ (NSString *rgbaString,NSString *locationString,UIColor *color){ weakSelf.rgbLabel.text = rgbaString; weakSelf.rgbLabel.textColor = color; weakSelf.locationLabel.text = locationString; }; [self.view addSubview:colorImageView];
上面ViewController的介紹完了,下面就是(重頭戲)ColorImageView的封裝介紹:
1,開始就是控件的添加 ,有注釋 ;不用多說直接粘代碼:
// //ColorImageVIew.m // TableView_choose // // Created by Simon on 16/6/15. // Copyright ? 2016年 Simon. All rights reserved. // #import "ColorImageView.h" #define radiusColor 120 //圖片半徑值 @interface ColorImageView () @property (nonatomic,strong)UIImageView *selectColorIamge;//黑點 @property (nonatomic,copy)NSString *rgbaString;//rgb字符串 @property (nonatomic,copy)NSString *locationString;//黑點位置字符串 @end @implementation ColorImageView - (id)initWithFrame:(CGRect)frame { self = [super initWithFrame:frame]; if (self) { // Initialization code _selectColorIamge = [[UIImageView alloc] init]; _selectColorIamge.backgroundColor = [UIColor blackColor]; _selectColorIamge.frame=CGRectMake((frame.size.width-16)/2, (frame.size.height-16)/2, 16, 16); _selectColorIamge.layer.cornerRadius = 8; _selectColorIamge.layer.masksToBounds = YES; [self addSubview:_selectColorIamge]; } return self; }
2,用系統自帶touchesBegan touchesMoved touchesEnded方法實現我們的點擊,移動;在移動中要限制黑點不能逃出色值圖片的范圍,就有了一個關於高中數學的運算,挺有意思的(不妨看看,是不是很多人都忘了)!這裡block的傳值就是這一句_block(_rgbaString,_locationString,color);
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { UITouch* touch = [touches anyObject]; CGPoint point = [touch locationInView:self]; //where image was tapped CGPoint center = CGPointMake(self.frame.size.width/2, self.frame.size.height/2); float distance = [self distanceFromPointX:center distanceToPointY:point]; if(distance
3,上面看到(distanceFromPointX:distanceToPointY:)一直都有調用,他是干什麼的呢;其實很簡單,就是把黑點限制在牢裡用的(不逃出色值圖片范圍):
//計算圓點所在位置 -(float)distanceFromPointX:(CGPoint)start distanceToPointY:(CGPoint)end{ float distance; //下面就是高中的數學,不詳細解釋了 CGFloat xDist = (end.x - start.x); CGFloat yDist = (end.y - start.y); distance = sqrt((xDist * xDist) + (yDist * yDist)); return distance; }
4,(getPixelColorAtLocation:)和(createARGBBitmapContextFromImage:)這兩個方法呢,就是關鍵所在了,把在色值圖片上黑點的位置轉化成我們想要的值。。不明白的多看看,實在不行就找度娘!
#pragma mark private - (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); if(rect.size.width==480){ point.x = point.x*2; point.y = point.y*2; } // Now we can get a pointer to the image data associated with the bitmap // context. unsigned char* data = CGBitmapContextGetData (cgctx); if (data != NULL) { //讀取RGB顏色值 //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]; unsigned int red = data[offset+1]; unsigned int green = data[offset+2]; unsigned int blue = data[offset+3]; color = [UIColor colorWithRed:(red/255.0f) green:(green/255.0f) blue:(blue/255.0f) alpha:(alpha/255.0f)]; _rgbaString = [NSString stringWithFormat:@"RGBA值: red:%d green:%d blue:%d alpha:%d",red,green,blue,alpha]; _locationString =[NSString stringWithFormat:@"黑點位置point: %.2f %.2f",point.x,point.y]; } // 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; long bitmapByteCount; long 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; }
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