jixin_new/shiku_im/videoRecorder/UIImage-Extensions.m

//
//  UIImage-Extensions.m
//  CutPicetureDemo
//
//  Created by yang kong on 12-6-27.
//  Copyright 2012 __MyCompanyName__. All rights reserved.
//

#import "UIImage-Extensions.h"


CGFloat DegreesToRadians(CGFloat degrees) {return degrees * M_PI / 180;};
CGFloat RadiansToDegrees(CGFloat radians) {return radians * 180/M_PI;};

@implementation UIImage (CS_Extensions)

-(UIImage *)imageAtRect:(CGRect)rect
{
	
	CGImageRef imageRef = CGImageCreateWithImageInRect([self CGImage], rect);
	UIImage* subImage = [UIImage imageWithCGImage: imageRef];
	CGImageRelease(imageRef);
	
	return subImage;
	
}

- (UIImage *)imageByScalingProportionallyToMinimumSize:(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;
		else
			scaleFactor = heightFactor;
		
		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;
		}
	}
	
	
	// this is actually the interesting part:
	
	UIGraphicsBeginImageContext(targetSize);
	
	CGRect thumbnailRect = CGRectZero;
	thumbnailRect.origin = thumbnailPoint;
	thumbnailRect.size.width  = scaledWidth;
	thumbnailRect.size.height = scaledHeight;
	
	[sourceImage drawInRect:thumbnailRect];
	
	newImage = UIGraphicsGetImageFromCurrentImageContext();
	UIGraphicsEndImageContext();
	
	if(newImage == nil) NSLog(@"could not scale image");
	
	
	return newImage ;
}


- (UIImage *)imageByScalingProportionallyToSize:(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;
		else
			scaleFactor = heightFactor;
		
		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;
		}
	}
	
	
	// this is actually the interesting part:
	
	UIGraphicsBeginImageContext(targetSize);
	
	CGRect thumbnailRect = CGRectZero;
	thumbnailRect.origin = thumbnailPoint;
	thumbnailRect.size.width  = scaledWidth;
	thumbnailRect.size.height = scaledHeight;
	
	[sourceImage drawInRect:thumbnailRect];
	
	newImage = UIGraphicsGetImageFromCurrentImageContext();
	UIGraphicsEndImageContext();
	
	if(newImage == nil) NSLog(@"could not scale image");
	
	
	return newImage ;
}


- (UIImage *)imageByScalingToSize:(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);
	
	// this is actually the interesting part:
	
	UIGraphicsBeginImageContext(targetSize);
	
	CGRect thumbnailRect = CGRectZero;
	thumbnailRect.origin = thumbnailPoint;
	thumbnailRect.size.width  = scaledWidth;
	thumbnailRect.size.height = scaledHeight;
	
	[sourceImage drawInRect:thumbnailRect];
	
	newImage = UIGraphicsGetImageFromCurrentImageContext();
	UIGraphicsEndImageContext();
	
	if(newImage == nil) NSLog(@"could not scale image");
	
	
	return newImage ;
}

- (UIImage *)imageByScalingToScale:(CGFloat)toScale{
    UIImage *sourceImage = self;
    CGSize targetSize = CGSizeMake(self.size.width*toScale, self.size.height*toScale);
    
    UIGraphicsBeginImageContext(targetSize);
    [sourceImage drawInRect:CGRectMake(0, 0, targetSize.width, targetSize.height)];
    UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    if (scaledImage == nil) {
        NSLog(@"could not scale image");
    }
    
    return scaledImage;
}

- (UIImage *)cutImageBy:(CGSize)oSize{
    CGSize newSize;
    CGImageRef imageRef = nil;
    
    if ((self.size.width / self.size.height) < (oSize.width / oSize.height)) {
        newSize.width = self.size.width;
        newSize.height = self.size.width * oSize.height / oSize.width;
        
        imageRef = CGImageCreateWithImageInRect([self CGImage], CGRectMake(0, fabs(self.size.height - newSize.height) / 2, newSize.width, newSize.height));
    } else {
        newSize.height = self.size.height;
        newSize.width = self.size.height * oSize.width / oSize.height;
        
        imageRef = CGImageCreateWithImageInRect([self CGImage], CGRectMake(fabs(self.size.width - newSize.width) / 2, 0, newSize.width, newSize.height));
    }
    
    return [UIImage imageWithCGImage:imageRef];
}

- (UIImage *)imageRotatedByRadians:(CGFloat)radians
{
	return [self imageRotatedByDegrees:RadiansToDegrees(radians)];
}

- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees 
{   
	// calculate the size of the rotated view's containing box for our drawing space
	UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0,self.size.width, self.size.height)];
	CGAffineTransform t = CGAffineTransformMakeRotation(DegreesToRadians(degrees));
	rotatedViewBox.transform = t;
	CGSize rotatedSize = rotatedViewBox.frame.size;
//	[rotatedViewBox release];
	
	// Create the bitmap context
	UIGraphicsBeginImageContext(rotatedSize);
	CGContextRef bitmap = UIGraphicsGetCurrentContext();
	
	// Move the origin to the middle of the image so we will rotate and scale around the center.
	CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);
	
	//   // Rotate the image context
	CGContextRotateCTM(bitmap, DegreesToRadians(degrees));
	
	// Now, draw the rotated/scaled image into the context
	CGContextScaleCTM(bitmap, 1.0, -1.0);
	CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2, self.size.width, self.size.height), [self CGImage]);
	
	UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
	UIGraphicsEndImageContext();
	return newImage;
	
}

@end;