iOS获取图片的区域主色

2017-03-20 19:30:56来源:CSDN作者:pengf_wuxiaowu人点击

之前的项目有这样的需求,有一个页面可以检索一块区域内图片的主色。效果图如图所示
这里写图片描述
下面是如何获取区域主色的实现思路:
首先,我们需要从相册,或者相机去获取图片;
其次,得到图片需要截取区域图片;
然后,获取截取图片的主色。
理想中是这样的,但是有很多阻碍,得到的图片需要自适应imageView(imageView的宽高是固定的),截图的得到的区域不是自己想要的区域。这里需要将图片等比例缩放,按照ImageView的宽高。

那现在就直接上代码吧!

首先我们需要等比例缩放Image:

/** *  缩放图片 * *  @param img  image *  @param size 缩放后的大小 * *  @return image */+ (UIImage *)scaleToSize:(UIImage *)img size:(CGSize)size{    // 创建一个bitmap的context    CGFloat width = CGImageGetWidth(img.CGImage);    CGFloat height = CGImageGetHeight(img.CGImage);    CGFloat max = width >= height ? width:height;    CGSize originSize;    if (max <= 0) {        return nil;    }    if (width >= height) {        originSize = CGSizeMake(size.width, (size.width * height)/width);    }else{        originSize = CGSizeMake((size.height * width)/height, size.height);    }    // 并把它设置成为当前正在使用的context    UIGraphicsBeginImageContext(size);    // 绘制改变大小的图片    [img drawInRect:CGRectMake((size.width - originSize.width)/2, (size.height - originSize.height)/2, originSize.width, originSize.height)];    // 从当前context中创建一个改变大小后的图片    UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();    // 使当前的context出堆栈    UIGraphicsEndImageContext();    // 返回新的改变大小后的图片    return scaledImage;}

之后就是截取区域图片,这理解去10*10的方块:

// 裁剪图片+ (UIImage *)imageFromImage:(UIImage *)image inRect:(CGRect)rect {    CGImageRef sourceImageRef = [image CGImage];    CGImageRef newImageRef = CGImageCreateWithImageInRect(sourceImageRef, rect);    UIImage *newImage = [UIImage imageWithCGImage:newImageRef];    CGImageRelease(newImageRef);    return newImage;}

然后获取图片的主色:

/** *  获取图片的主色 * *  @param image image *  @param scale 精准度0.1~1 * *  @return 图片的主要颜色 */+ (NSDictionary *)mostColor:(UIImage *)image scale:(CGFloat)scale{#if __IPHONE_OS_VERSION_MAX_ALLOWED > __IPHONE_6_1    int bitmapInfo = kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedLast;#else    int bitmapInfo = kCGImageAlphaPremultipliedLast;#endif    if (scale <= 0.1) {        scale = 0.1;    }else if(scale >= 1){        scale = 1;    }    //第一步 先把图片缩小 加快计算速度. 但越小结果误差可能越大        CGSize thumbSize=CGSizeMake([image size].width * scale, [image size].height * scale);    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();    CGContextRef context = CGBitmapContextCreate(NULL,                                                 thumbSize.width,                                                 thumbSize.height,                                                 8,//bits per component                                                 thumbSize.width*4,                                                 colorSpace,                                                 bitmapInfo);    CGRect drawRect = CGRectMake(0, 0, thumbSize.width, thumbSize.height);    CGContextDrawImage(context, drawRect, image.CGImage);    CGColorSpaceRelease(colorSpace);    //第二步 取每个点的像素值    unsigned char* data = CGBitmapContextGetData (context);    if (data == NULL){        CGContextRelease(context);        return nil;    }    NSCountedSet *cls=[NSCountedSet setWithCapacity:thumbSize.width*thumbSize.height];    for (int x=0; x<thumbSize.width; x++) {        for (int y=0; y<thumbSize.height; y++) {            int offset = 4*(x*y);            int red = data[offset];            int green = data[offset+1];            int blue = data[offset+2];            int alpha =  data[offset+3];            NSArray *clr=@[@(red),@(green),@(blue),@(alpha)];            [cls addObject:clr];        }    }    CGContextRelease(context);    //第三步 找到出现次数最多的那个颜色    NSEnumerator *enumerator = [cls objectEnumerator];    NSArray *curColor = nil;    NSArray *MaxColor=nil;    NSUInteger MaxCount=0;    while ( (curColor = [enumerator nextObject]) != nil )    {        NSUInteger tmpCount = [cls countForObject:curColor];        if ( tmpCount < MaxCount ) continue;        MaxCount=tmpCount;        MaxColor=curColor;    }    //返回三原色色值    NSMutableDictionary *dic = [[NSMutableDictionary alloc] initWithCapacity:0];    [dic setValue:@([MaxColor[0] intValue]/255.0f) forKey:@"red"];    [dic setValue:@([MaxColor[1] intValue]/255.0f) forKey:@"green"];    [dic setValue:@([MaxColor[2] intValue]/255.0f) forKey:@"blue"];    return dic;}

其实获取图片区域的主要颜色就是这么简单,线面附上获取单点的颜色:

/** *  获取图片上一个点的颜色 * *  @param point 点击的点的位置 *  @param image image * *  @return 返回点击点的颜色 */+ (UIColor *)colorAtPixel:(CGPoint)point UIImage:(UIImage *)image CGRect:(CGRect)rect{    // Cancel if point is outside image coordinates    if (!CGRectContainsPoint(CGRectMake(0.0f, 0.0f,rect.size.width, rect.size.height), point)) {        return nil;    }    NSInteger pointX = trunc(point.x);    NSInteger pointY = trunc(point.y);    CGImageRef cgImage = image.CGImage;    NSUInteger width = image.size.width;    NSUInteger height = image.size.height;    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();    int bytesPerPixel = 4;    int bytesPerRow = bytesPerPixel * 1;    NSUInteger bitsPerComponent = 8;    unsigned char pixelData[4] = { 0, 0, 0, 0 };    CGContextRef context = CGBitmapContextCreate(pixelData,                                                 1,                                                 1,                                                 bitsPerComponent,                                                 bytesPerRow,                                                 colorSpace,                                                 kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);    CGColorSpaceRelease(colorSpace);    CGContextSetBlendMode(context, kCGBlendModeCopy);    // Draw the pixel we are interested in onto the bitmap context    CGContextTranslateCTM(context, -pointX, pointY-(CGFloat)height);    CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, (CGFloat)width, (CGFloat)height), cgImage);    CGContextRelease(context);    // Convert color values [0..255] to floats [0.0..1.0]    CGFloat red   = (CGFloat)pixelData[0] / 255.0f;    CGFloat green = (CGFloat)pixelData[1] / 255.0f;    CGFloat blue  = (CGFloat)pixelData[2] / 255.0f;    CGFloat alpha = (CGFloat)pixelData[3] / 255.0f;    return [UIColor colorWithRed:red green:green blue:blue alpha:alpha];}

最终就实现如上图的想过,页面丑了点,但是效果是实现了,又不真确的地方,请留言。

项目源码:https://github.com/pengjinfeng/ColorPicker.git

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