src/ios/UIImage+CropScaleOrientation.m

/*
 Licensed to the Apache Software Foundation (ASF) under one
 or more contributor license agreements.  See the NOTICE file
 distributed with this work for additional information
 regarding copyright ownership.  The ASF licenses this file
 to you under the Apache License, Version 2.0 (the
 "License"); you may not use this file except in compliance
 with the License.  You may obtain a copy of the License at
 
 http://www.apache.org/licenses/LICENSE-2.0
 
 Unless required by applicable law or agreed to in writing,
 software distributed under the License is distributed on an
 "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 KIND, either express or implied.  See the License for the
 specific language governing permissions and limitations
 under the License.
 */

#import "UIImage+CropScaleOrientation.h"

@implementation UIImage (CropScaleOrientation)

- (UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize
{
    UIImage* sourceImage = self;
    UIImage* newImage = nil;
    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;
    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;
    CGFloat scaleFactor = 0.0;
    CGFloat scaledWidth = targetWidth;
    CGFloat scaledHeight = targetHeight;
    CGPoint thumbnailPoint = CGPointMake(0.0, 0.0);
    
    if (CGSizeEqualToSize(imageSize, targetSize) == NO) {
        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;
        
        if (widthFactor > heightFactor) {
            scaleFactor = widthFactor; // scale to fit height
        } else {
            scaleFactor = heightFactor; // scale to fit width
        }
        scaledWidth = width * scaleFactor;
        scaledHeight = height * scaleFactor;
        
        // center the image
        if (widthFactor > heightFactor) {
            thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
        } else if (widthFactor < heightFactor) {
            thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
        }
    }
    
    UIGraphicsBeginImageContext(targetSize); // this will crop
    
    CGRect thumbnailRect = CGRectZero;
    thumbnailRect.origin = thumbnailPoint;
    thumbnailRect.size.width = scaledWidth;
    thumbnailRect.size.height = scaledHeight;
    
    [sourceImage drawInRect:thumbnailRect];
    
    newImage = UIGraphicsGetImageFromCurrentImageContext();
    if (newImage == nil) {
        NSLog(@"could not scale image");
    }
    
    // pop the context to get back to the default
    UIGraphicsEndImageContext();
    return newImage;
}

- (UIImage*)imageCorrectedForCaptureOrientation:(UIImageOrientation)imageOrientation
{
    float rotation_radians = 0;
    bool perpendicular = false;
    
    switch (imageOrientation) {
        case UIImageOrientationUp :
            rotation_radians = 0.0;
            break;
            
        case UIImageOrientationDown:
            rotation_radians = M_PI; // don't be scared of radians, if you're reading this, you're good at math
            break;
            
        case UIImageOrientationRight:
            rotation_radians = M_PI_2;
            perpendicular = true;
            break;
            
        case UIImageOrientationLeft:
            rotation_radians = -M_PI_2;
            perpendicular = true;
            break;
            
        default:
            break;
    }
    
    UIGraphicsBeginImageContext(CGSizeMake(self.size.width, self.size.height));
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    // Rotate around the center point
    CGContextTranslateCTM(context, self.size.width / 2, self.size.height / 2);
    CGContextRotateCTM(context, rotation_radians);
    
    CGContextScaleCTM(context, 1.0, -1.0);
    float width = perpendicular ? self.size.height : self.size.width;
    float height = perpendicular ? self.size.width : self.size.height;
    CGContextDrawImage(context, CGRectMake(-width / 2, -height / 2, width, height), [self CGImage]);
    
    // Move the origin back since the rotation might've change it (if its 90 degrees)
    if (perpendicular) {
        CGContextTranslateCTM(context, -self.size.height / 2, -self.size.width / 2);
    }
    
    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

- (UIImage*)imageCorrectedForCaptureOrientation
{
    return [self imageCorrectedForCaptureOrientation:[self imageOrientation]];
}

- (UIImage*)imageByScalingNotCroppingForSize:(CGSize)targetSize
{
    UIImage* sourceImage = self;
    UIImage* newImage = nil;
    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;
    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;
    CGFloat scaleFactor = 0.0;
    CGSize scaledSize = targetSize;
    
    if (CGSizeEqualToSize(imageSize, targetSize) == NO) {
        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;
        
        // opposite comparison to imageByScalingAndCroppingForSize in order to contain the image within the given bounds
        if (widthFactor > heightFactor) {
            scaleFactor = heightFactor; // scale to fit height
        } else {
            scaleFactor = widthFactor; // scale to fit width
        }
        scaledSize = CGSizeMake(MIN(width * scaleFactor, targetWidth), MIN(height * scaleFactor, targetHeight));
    }
    
    // If the pixels are floats, it causes a white line in iOS8 and probably other versions too
    scaledSize.width = (int)scaledSize.width;
    scaledSize.height = (int)scaledSize.height;
    
    UIGraphicsBeginImageContext(scaledSize); // this will resize
    
    [sourceImage drawInRect:CGRectMake(0, 0, scaledSize.width, scaledSize.height)];
    
    newImage = UIGraphicsGetImageFromCurrentImageContext();
    if (newImage == nil) {
        NSLog(@"could not scale image");
    }
    
    // pop the context to get back to the default
    UIGraphicsEndImageContext();
    return newImage;
}

@end