iOS—常用圖片處理技術

========== (one) UIImage 映像 等比例縮放==================================

PicAfterZoomWidth:縮放後圖片寬 PicAfterZoomHeight:縮放後圖片高 (預定義)

#define PicAfterZoomWidth 320#define PicAfterZoomHeight 480+ (UIImage *)getPicZoomImage:(UIImage *)image {    UIImage *img = image;    int h = img.size.height;    int w = img.size.width;    if(h <= PicAfterZoomWidth && w <= PicAfterZoomHeight)    {        image = img;    }    else     {        float b = (float)PicAfterZoomWidth/w < (float)PicAfterZoomHeight/h ? (float)PicAfterZoomWidth/w : (float)PicAfterZoomHeight/h;        CGSize itemSize = CGSizeMake(b*w, b*h);       UIGraphicsBeginImageContext(itemSize);        CGRect imageRect = CGRectMake(0, 0, b*w, b*h);        [img drawInRect:imageRect];        img = UIGraphicsGetImageFromCurrentImageContext();        UIGraphicsEndImageContext();    }    return img;}

=============== ( two )把圖片 圓角 化==================================

static void addRoundedRectToPath(CGContextRef context, CGRect rect, float ovalWidth,                                 float ovalHeight){    float fw, fh;    if (ovalWidth == 0 || ovalHeight == 0) {        CGContextAddRect(context, rect);        return;    }    CGContextSaveGState(context);    CGContextTranslateCTM(context, CGRectGetMinX(rect), CGRectGetMinY(rect));    CGContextScaleCTM(context, ovalWidth, ovalHeight);    fw = CGRectGetWidth(rect) / ovalWidth;    fh = CGRectGetHeight(rect) / ovalHeight;    CGContextMoveToPoint(context, fw, fh/2);  // Start at lower right corner    CGContextAddArcToPoint(context, fw, fh, fw/2, fh, 1);  // Top right corner    CGContextAddArcToPoint(context, 0, fh, 0, fh/2, 1); // Top left corner    CGContextAddArcToPoint(context, 0, 0, fw/2, 0, 1); // Lower left corner    CGContextAddArcToPoint(context, fw, 0, fw, fh/2, 1); // Back to lower right    CGContextClosePath(context);    CGContextRestoreGState(context);}+ (id) createRoundedRectImage:(UIImage*)image size:(CGSize)size{    // the size of CGContextRef    int w = size.width;    int h = size.height;    UIImage *img = image;    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();    CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace,kCGImageAlphaPremultipliedFirst);    CGRect rect = CGRectMake(0, 0, w, h);    CGContextBeginPath(context);    addRoundedRectToPath(context, rect, 10, 10);    CGContextClosePath(context);    CGContextClip(context);    CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage);    CGImageRef imageMasked = CGBitmapContextCreateImage(context);    CGContextRelease(context);    CGColorSpaceRelease(colorSpace);    return [UIImage imageWithCGImage:imageMasked];}