OS实现智能背景

// 1.此处缩放图片，缩小图片大小，提升计算速度

    CGFloat scale = [UIScreen mainScreen].scale;

    CGSize thumbSize = CGSizeMake(kImgW, image.size.height/image.size.width*kImgW);

    UIGraphicsBeginImageContextWithOptions(thumbSize, NO, scale);

    [image drawInRect:CGRectMake(0, 0, thumbSize.width, thumbSize.height)];

    image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

      // 2.将图片通过颜色空间转换为二进制数据。

    int bitmapInfo = kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedLast;

    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);

    unsigned char* data = CGBitmapContextGetData (context);

    if (data == NULL) return nil;

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];

            // 过滤掉白色

            if (red!=255 & green!=255 & blue!=255) {

                NSArray *clr = @[@(red),@(green),@(blue),@(alpha)];

                // 当前颜色数量超过限制后，不再加入cls集合，如果需要计算最多颜色数量，则需要加入每一个大于LimitCount的颜色

                if ([cls containsObject:clr] >= LimitCount)continue;

                [cls addObject:clr];

            }

        }

    }

    NSArray *curColor = nil;

    NSUInteger tempcount = 0;

    NSEnumerator *enumerator = [cls objectEnumerator];

    // 4.1除去重复颜色，获取单一颜色数组

    while ((curColor = [enumerator nextObject]) != nil ){

        if ([moreCls containsObject:curColor] > 0) continue;

        tempcount = [cls countForObject:curColor];

        if (tempcount < LimitCount) continue;

        [moreCls addObject:curColor];

    }

// 4.2除去相近颜色算法。

    NSArray *currentH = nil;

    enumerator = [moreCls objectEnumerator];

    while ((curColor = [enumerator nextObject]) != nil ){

        int red = [curColor[0] intValue];

        int green = [curColor[1] intValue];

        int blue = [curColor[2] intValue];

    //        int alpha =  [curColor[3] intValue];

        // RGB转HSV算法

        CGFloat max = MAX(MAX(red, blue), green);

        CGFloat min = MIN(MIN(red, blue), green);

        CGFloat hue = 0,s,value;

        value = max;

        s     = (max-min)/max;

        if (red == max) hue = (green-blue)/(max-min)* 60;

        if (green == max) hue = 120+(blue-red)/(max-min)* 60;

        if (blue == max) hue = 240 +(red-green)/(max-min)* 60;

        if (hue < 0) hue = hue + 360;

        NSEnumerator *moreenur = [huarr objectEnumerator];

        BOOL isAdd = YES;

        // HSV模型可参考https://baike.baidu.com/item/HSV/547122?fr=aladdin

        while ((currentH = [moreenur nextObject]) != nil ){

            // 抛弃灰白色，和暗黑色颜色，可参考HSV模型

            if (s > 0.2 && value > 0.3*255) {

                if (value < 0.5*255) { // 根据value大小抛弃范围不同

                    // 抛弃某一个颜色周围的相近颜色

                    if (fabs(hue-[currentH[0] floatValue]) < 180 && fabs(s-[currentH[1] floatValue])*255 < 125 && fabs(value-[currentH[2] floatValue]) < 0.5*255) {

                        isAdd = NO;

                        break;

                    }

                }else{

                    // 抛弃某一个颜色周围的相近颜色

                    if (fabs(hue-[currentH[0] floatValue]) < 20 && fabs(s-[currentH[1] floatValue])*255 < 25 && fabs(value-[currentH[2] floatValue]) < 25) {

                        isAdd = NO;

                        break;

                    }

                }

            }else{

                isAdd = NO;

            }

        }

        if (isAdd) {

            // 确认的颜色HSV转RGB算法。注意，直接用RGB颜色部分颜色会出问题，建议还是再转换一次。

            [huarr addObject:@[@(hue),@(s),@(value)]];

            if (s == 0)

            red = green = blue = value;

            else{

            hue /= 60;

            int i = hue;

            CGFloat f = hue - i;

            CGFloat a = value * ( 1 - s );

            CGFloat b = value * ( 1 - s * f );

            CGFloat c = value * ( 1 - s * (1 - f ) );

                switch (i) {

                    case 0: red = value; green = c; blue = a;

                        break;

                    case 1: red = b; green = value; blue = a;

                        break;

                    case 2: red = a; green = value; blue = c;

                        break;

                    case 3: red = a; green = b; blue = value;

                        break;

                    case 4: red = c; green = a; blue = value;

                        break;

                        case 5: red = value; green = a; blue = b;

                    default:

                        break;

                }

            }

            UIColor *c = [UIColor colorWithRed:(red/255.0f) green:(green/255.0f) blue:(blue/255.0f) alpha:([curColor[3] intValue]/255.0f)];

            [colorArr addObject:c];

        }

    }