iOS 关于UIImage的处理总结
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void ProviderReleaseData (void *info, const void *data, size_t size){ free((void*)data);}#pragma mark - 去掉最常见颜色为透明颜色- (UIImage*)imageBlackToTransparent:(UIImage*)image weight:(NSInteger)weight{ // 分配内存 const int imageWidth = image.size.width; const int imageHeight = image.size.height; size_t bytesPerRow = imageWidth * 4; uint32_t* rgbImageBuf = (uint32_t*)malloc(bytesPerRow * imageHeight); // 创建context CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGContextRef context = CGBitmapContextCreate(rgbImageBuf, imageWidth, imageHeight, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast); CGContextDrawImage(context, CGRectMake(0, 0, imageWidth, imageHeight), image.CGImage); // 遍历像素 int pixelNum = imageWidth * imageHeight; uint32_t* pCurPtr = rgbImageBuf; NSDictionary *dictColor = [self mostColorFromImage:image]; CGFloat mostR = [dictColor[@"red"] floatValue]; CGFloat mostG = [dictColor[@"green"] floatValue]; CGFloat mostB = [dictColor[@"blue"] floatValue]; for (int i = 0; i < pixelNum; i++, pCurPtr++){ CGFloat r = (float)((*pCurPtr & 0xFF0000) >> 16); CGFloat g = (float)((*pCurPtr & 0xFF00) >> 8); CGFloat b = (float)(*pCurPtr & 0xFF); //NSLog(@"r:%f g:%f b:%f",r,g,b); if ((mostR-weight)<=r&&r<=(mostR+weight)&&(mostG-weight)<=g&&g<=(mostG+weight)&&(mostB-weight)<=b&&b<=(mostB+weight)) { uint8_t* ptr = (uint8_t*)pCurPtr; // 将白色变成透明 ptr[0] = 0; } // // else // // { // // // 改成下面的代码，会将图片转成想要的颜色 // // uint8_t* ptr = (uint8_t*)pCurPtr; // // ptr[3] = 0; //0~255 // // ptr[2] = 0; // // ptr[1] = 0; // // // } } // 将内存转成image CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, rgbImageBuf, bytesPerRow * imageHeight, ProviderReleaseData); CGImageRef imageRef = CGImageCreate(imageWidth, imageHeight, 8, 32, bytesPerRow, colorSpace, kCGImageAlphaLast | kCGBitmapByteOrder32Little, dataProvider, NULL, true, kCGRenderingIntentDefault); CGDataProviderRelease(dataProvider); UIImage* resultUIImage = [UIImage imageWithCGImage:imageRef]; // 释放 CGImageRelease(imageRef); CGContextRelease(context); CGColorSpaceRelease(colorSpace); // free(rgbImageBuf) 创建dataProvider时已提供释放函数，这里不用free return resultUIImage; }#pragma mark - 获取图片中出现次数最多的RGB-(NSDictionary*)mostColorFromImage:(UIImage *)image{ #if __IPHONE_OS_VERSION_MAX_ALLOWED > __IPHONE_6_1 int bitmapInfo = kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedLast;#else int bitmapInfo = kCGImageAlphaPremultipliedLast;#endif //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 50 50 CGSize thumbSize=CGSizeMake(150, 150); 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) 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; } CGFloat mostR = [MaxColor[1] intValue]; CGFloat mostG = [MaxColor[2] intValue]; CGFloat mostB = [MaxColor[3] intValue]; NSLog(@"mostR:%f mostG:%f mostB:%f",mostR,mostG,mostB); NSDictionary *dictColor = @{@"red":[NSNumber numberWithFloat:[MaxColor[0] intValue]],@"green":[NSNumber numberWithFloat:[MaxColor[1] intValue]],@"blue":[NSNumber numberWithFloat:[MaxColor[2] intValue]],@"alpha":[NSNumber numberWithFloat:[MaxColor[3] intValue]]}; return dictColor; //return [UIColor colorWithRed:([MaxColor[0] intValue]/255.0f) green:([MaxColor[1] intValue]/255.0f) blue:([MaxColor[2] intValue]/255.0f) alpha:([MaxColor[3] intValue]/255.0f)];}#pragma mark - 设置图片透明度
- (UIImage *)imageByApplyingAlpha:(CGFloat)alpha image:(UIImage*)image{ UIGraphicsBeginImageContextWithOptions(image.size, NO, 0.0f); CGContextRef ctx = UIGraphicsGetCurrentContext(); CGRect area = CGRectMake(0, 0, image.size.width, image.size.height); CGContextScaleCTM(ctx, 1, -1); CGContextTranslateCTM(ctx, 0, -area.size.height); CGContextSetBlendMode(ctx, kCGBlendModeMultiply); CGContextSetAlpha(ctx, alpha); CGContextDrawImage(ctx, area, image.CGImage); UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return newImage; }#pragma mark - 合并2张图片
- (UIImage *)addImage:(UIImage *)image1 toImage:(UIImage *)image2 { UIGraphicsBeginImageContext(image1.size); // Draw image1 [image1 drawInRect:CGRectMake(0, 0, image1.size.width, image1.size.height)]; NSLog(@"image1:%@",NSStringFromCGRect(CGRectMake(0, 0, image1.size.width, image1.size.height))); // Draw image2 [image2 drawInRect:CGRectMake(0, 0, image2.size.width, image2.size.height)]; NSLog(@"image2:%@",NSStringFromCGRect(CGRectMake(0, 0, image2.size.width, image2.size.height))); UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext(); NSLog(@"imageRes:%@",NSStringFromCGRect(CGRectMake(0, 0, resultingImage.size.width, resultingImage.size.height))); UIGraphicsEndImageContext(); return resultingImage; }#pragma mark - 将UIImage缩放到指定大小尺寸
- (UIImage *)scaleToSize:(UIImage *)img size:(CGSize)size{ // 创建一个bitmap的context // 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(0, 0, size.width, size.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; }#pragma mark - 根据图片的大小等比例压缩返回图片
-(UIImage *)fitSmallImage:(UIImage *)image size:(CGSize)size{ if (nil == image) { return nil; } if (image.size.width&&image.size.height){ return image; } UIGraphicsBeginImageContext(size); CGRect rect = CGRectMake(0, 0, size.width, size.height); [image drawInRect:rect]; UIImage *newing = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return newing; }#pragma mark - 获取图片点对应的颜色
+ (UIColor*) getPixelColorAtLocation:(CGPoint)point inImage:(UIImage *)image { UIColor* color = nil; CGImageRef inImage = image.CGImage; CGContextRef cgctx = [ViewController createARGBBitmapContextFromImage: inImage]; if (cgctx == NULL) { return nil; /* error */ } 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]; NSLog(@"offset: %i colors: RGB A %i %i %i %i",offset,red,green, blue,alpha); NSLog(@"x:%f y:%f", point.x, point.y); 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 = (pixelsWide * 4); bitmapByteCount = (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; }参考文章
http://blog.sina.com.cn/s/blog_64cfe8f00101pm3x.html
http://blog.csdn.net/ssanonymity/article/details/7643236
http://www.cocoachina.com/bbs/read.php?tid=181490
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