如何在 iPhone 中裁剪图像

Question

我想做同样的事情

Answer 1

您可以创建具有任何属性的新图像。这是我的功能，女巫执行此操作。您只需要使用自己的新图像参数即可。就我而言，图像没有被裁剪，我只是做了一些效果，将像素从原始位置移动到另一个位置。但是，如果您使用另一个高度和宽度初始化新图像，则可以将所需的旧图像的任何像素范围复制到新图像：

-(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);