iphone - iPhoneで画像を切り抜く方法

Question

私はこの質問で尋ねられたのと同じことをしたいです。私のアプリでは、FaceBookでの画像のトリミングと同じように画像をトリミングしたいのですが、優れたチュートリアルのリンクやサンプルコードを使ってガイドしてくれます。私が提供したリンクは私の要件を完全に説明します。

Answer 1

任意のプロパティで新しい画像を作成できます。これが私の機能です、魔女はそれをします。新しい画像の独自のパラメータを使用する必要があります。私の場合、画像はトリミングされません。ピクセルを元の場所から別の場所に移動して、何らかの効果を出すだけです。ただし、新しい画像を別の高さと幅で初期化すると、必要な古い画像の任意の範囲のピクセルから新しい画像にコピーできます。

-(UIImage *)Color:(UIImage *)img
{
    int R;
    float m_width = img.size.width;
    float m_height = img.size.height;
    if (m_width>m_height) R = m_height*0.9;
    else R = m_width*0.9;
    int m_wint = (int)m_width;      //later,  we will need this parameters in float and int. you may just use "(int)" and "(float)" before variables later, and do not implement another ones
    int m_hint = (int)m_height;

    CGRect imageRect;
    //cheking image orientation. we will work with image pixel-by-pixel, so we need to make top side at the top.
    if(img.imageOrientation==UIImageOrientationUp 
       || img.imageOrientation==UIImageOrientationDown) 
    {
        imageRect = CGRectMake(0, 0, m_wint, m_hint); 
    }
    else 
    {
        imageRect = CGRectMake(0, 0, m_hint, m_wint); 
    }
    uint32_t *rgbImage = (uint32_t *) malloc(m_wint * m_hint * sizeof(uint32_t));
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef context = CGBitmapContextCreate(rgbImage, m_wint, m_hint, 8, m_wint *sizeof(uint32_t), colorSpace,   kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast);
    CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
    CGContextSetShouldAntialias(context, NO);
    CGContextTranslateCTM(context, 0, m_hint);
    CGContextScaleCTM(context, 1.0, -1.0);
    switch (img.imageOrientation) {
        case UIImageOrientationRight:
        {
            CGContextRotateCTM(context, M_PI / 2);
            CGContextTranslateCTM(context, 0, -m_wint);            
        }break;
        case UIImageOrientationLeft:
        {
            CGContextRotateCTM(context, - M_PI / 2);
            CGContextTranslateCTM(context, -m_hint, 0);            
        }break;
        case UIImageOrientationUp:
        {
            CGContextTranslateCTM(context, m_wint, m_hint);
            CGContextRotateCTM(context, M_PI);
        }
        default:
            break;
    }

    CGContextDrawImage(context, imageRect, img.CGImage);
    CGContextRelease(context);
    CGColorSpaceRelease(colorSpace);

    //here is new image. you can change m_wint and m_hint as you whant
    uint8_t *result = (uint8_t *) calloc(m_wint * m_hint * sizeof(uint32_t), 1);
    for(int y = 0; y < m_hint; y++) //new m_hint here
    {
        float fy=y;
        double yy =    (m_height*(  asinf(m_height/(2*R))-asin(((m_height/2)-fy)/R)   )) /
        (2*asin(m_height/(2*R))); // (xx, yy) - coordinates of pixel of OLD image
        for(int x =  0; x < m_wint; x++) //new m_wint here
        {
            float fx=x;
            double xx =    (m_width*(  asin(m_width/(2*R))-asin(((m_width/2)-fx)/R)   )) /
            (2*asin(m_width/(2*R)));
            uint32_t rgbPixel=rgbImage[(int)yy * m_wint + (int)xx];
            int intRedSource = (rgbPixel>>24)&255;
            int intGreenSource = (rgbPixel>>16)&255;
            int intBlueSource = (rgbPixel>>8)&255;
            result[(y * (int)m_wint + x) * 4] = 0;
            result[(y * (int)m_wint + x) * 4 + 1] = intBlueSource;
            result[(y * (int)m_wint + x) * 4 + 2] = intGreenSource;
            result[(y * (int)m_wint + x) * 4 + 3] = intRedSource;

        }
    }

    free(rgbImage);

    colorSpace = CGColorSpaceCreateDeviceRGB();
    context = CGBitmapContextCreate(result, m_wint, m_hint, 8, m_wint * sizeof(uint32_t), colorSpace,   kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast  ); //new m_wint and m_hint as well


    CGImageRef image1 = CGBitmapContextCreateImage(context);
    CGContextRelease(context);
    CGColorSpaceRelease(colorSpace);
    UIImage *resultUIImage = [UIImage imageWithCGImage:image1];
    CGImageRelease(image1);


    @try {
        free(result);
    }
    @catch (NSException * e) {
        NSLog(@"proc. Exception: %@", e);
    }

    return resultUIImage;
}

Answer 2

CGRect rectImage = CGRectMake（p1.x、p1.y、p2.x-p1.x、p4.y-p1.y）;

//Create bitmap image from original image data,
//using rectangle to specify desired crop area

CGImageRef imageRef = CGImageCreateWithImageInRect([imageForCropping CGImage], rectImage); 
UIImage *croppedImage = [UIImage imageWithCGImage:imageRef]; 
imageView1 = [[UIImageView alloc] initWithFrame:CGRectMake(p1.x, p1.y,p2.x-p1.x p4.y-p1.y)];
imageView1.image = croppedImage;
[self.view addSubview:imageView1];
CGImageRelease(imageRef);