论取任意图片上任意点的颜色值

Posted 2020-08-19

原来，我们可爱的产品汪有个需求，就是显示访客啊，或者企业头像啊，外圈呢默认不加边框，这样显得更文艺，头像和背景酷炫的图片完美融合，但是背景图都是浅色调，如果遇到用户头像是白色背景，或者室外蓝天白云的，就会模糊不清，分不清头像和背景图，然后就有了一个需求，取头像最外圈的色值，如果是浅色调，那给它加上浅蓝色边框，如果是深色不做处理，然后就有了这个demo，参考过别人代码，自己做过修正，无内存泄漏。话不多说，贴代码。

 

//

//  ViewController.m

//  获取图片某一点颜色值

//

//  Created by Minge on 16/11/15.

//  Copyright ? 2016年 guoxin. All rights reserved.

//

 

#import "ViewController.h"

#import <CoreImage/CoreImage.h>

#import <CoreGraphics/CoreGraphics.h>

 

@interface ViewController ()

 

@property (nonatomic, strong) UIImageView *imageView;

 

@property (nonatomic, strong) UIView *showView;

@end

 

@implementation ViewController

 

- (void)viewDidLoad {

    [super viewDidLoad];

    

    UILabel *label = [[UILabel alloc] init];

    label.text = @"取色板";

    [self.view addSubview:label];

    

    UILabel *label1 = [[UILabel alloc] init];

    label1.text = @"显色板";

    [self.view addSubview:label1];

    

    //239 × 168 pixels

    UIImageView *imageView = [[UIImageView alloc] init];

    imageView.frame = CGRectMake((self.view.frame.size.width - 240) * 0.5, 150, 240, 168);

    imageView.image = [UIImage imageNamed:@"colors.jpg"];

    imageView.userInteractionEnabled = NO;

    imageView.backgroundColor = [UIColor redColor];

    self.imageView = imageView;

    [self.view addSubview:imageView];

    

    label.frame = CGRectMake((self.view.frame.size.width - 240) * 0.5, 120, 100, 20);

    

    UIView *showView = [[UIView alloc] init];

    showView.backgroundColor = [UIColor blackColor];

    self.showView = showView;

    showView.frame = CGRectMake((self.view.frame.size.width - 240) * 0.5, 350, 50, 50);

    [self.view addSubview:showView];

    

    label1.frame = CGRectMake((self.view.frame.size.width - 240) * 0.5, 320, 100, 20);

}

 

 

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {

 

    NSSet *allTouches = [event allTouches];

    

    UITouch *touch = [allTouches anyObject];

    

    CGPoint touchPoint = [touch locationInView:self.imageView];

    

    int x = touchPoint.x;

    int y = touchPoint.y;

    NSLog(@"touch (x, y) is (%d, %d) in (%f, %f)", x, y,self.imageView.frame.size.width,self.imageView.frame.size.height);

    

    if (touchPoint.x > self.imageView.frame.size.width || touchPoint.y > self.imageView.frame.size.height) {

        NSLog(@"超出图片范围,无法识别");

        return;

        

    } else {

    

        UIColor *color = [self getPixelColorAtLocation:touchPoint inImage:[UIImage imageNamed:@"colors.jpg"]];

        self.showView.backgroundColor = color;

    }

    

}

 

 

 

- (UIColor*) getPixelColorAtLocation:(CGPoint)point inImage:(UIImage *)image

{

    

    UIColor* color = nil;

    CGImageRef inImage = image.CGImage;

    CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage];

    

    if (cgctx == NULL) {

        return nil;

    }

    size_t w = CGImageGetWidth(inImage);

    size_t h = CGImageGetHeight(inImage);

    CGRect rect = {{0,0},{w,h}};

    

    CGContextDrawImage(cgctx, rect, inImage);

    unsigned char* data = CGBitmapContextGetData (cgctx);

    if (data != NULL) {

        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];

        color = [UIColor colorWithRed:(red/255.0f) green:(green/255.0f) blue:

                 (blue/255.0f) alpha:(alpha/255.0f)];

    }

    CGContextRelease(cgctx);

    if (data) {

        free(data);

    }

    return color;

}

 

- (CGContextRef)createARGBBitmapContextFromImage:(CGImageRef)inImage

{

    CGContextRef context = NULL;

    CGColorSpaceRef colorSpace;

    void *bitmapData;

    int bitmapByteCount;

    int bitmapBytesPerRow;

    

    size_t pixelsWide = CGImageGetWidth(inImage);

    size_t pixelsHigh = CGImageGetHeight(inImage);

    

    bitmapBytesPerRow   = (int)(pixelsWide * 4);

    bitmapByteCount     = (int)(bitmapBytesPerRow * pixelsHigh);

    

    colorSpace = CGColorSpaceCreateDeviceRGB();

    

    if (colorSpace == NULL)

    {

        fprintf(stderr,"Error allocating color space\\n");

        return NULL;

    }

    

    bitmapData = malloc(bitmapByteCount);

    if (bitmapData == NULL)

    {

        fprintf(stderr,"Memory not allocated!");

        CGColorSpaceRelease(colorSpace);

        return NULL;

    }

 

    context = CGBitmapContextCreate(bitmapData,

                                    pixelsWide,

                                    pixelsHigh,

                                    8,

                                    bitmapBytesPerRow,

                                    colorSpace,

                                    kCGImageAlphaPremultipliedFirst);

    if (context == NULL)

    {

        free(bitmapData);

        fprintf(stderr,"Context not created!");

    }

    

    CGColorSpaceRelease(colorSpace);

    

    return context;

}

@end

中间有两张我测试用的图片，随便给一个就好了，放上效果图。

通过这个demo就可以轻松完成产品汪的需求了，取图片上几个点的色值，拿出来让ui给个浅色的参考标准，判断一下就可以了。