first commit

README.txt

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+UIImage+Editor: useful category for quickly manipulating UIImages as in a simple image editor
+Some hints, ideas and code was taken from StackOverflow and random web sites
+The Alpha, Rounded Corner and Resize categories were written by Trevor Harmon.
+Licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. I am not responsible for any damage related to the use of the software. There is no warranty at all.
+

UIImage+Alpha.h

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+// UIImage+Alpha.h
+// Created by Trevor Harmon on 9/20/09.
+// Free for personal or commercial use, with or without modification.
+// No warranty is expressed or implied.
+
+// Helper methods for adding an alpha layer to an image
+
+#import <CoreGraphics/CoreGraphics.h>
+#import <UIKit/UIKit.h>
+
+@interface UIImage (Alpha)
+- (BOOL)hasAlpha;
+- (UIImage *)imageWithAlpha;
+- (UIImage *)transparentBorderImage:(NSUInteger)borderSize;
+@end
+

UIImage+Alpha.m

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+// UIImage+Alpha.m
+// Created by Trevor Harmon on 9/20/09.
+// Free for personal or commercial use, with or without modification.
+// No warranty is expressed or implied.
+
+#import "UIImage+Alpha.h"
+
+// Private helper methods
+@interface UIImage ()
+- (CGImageRef)newBorderMask:(NSUInteger)borderSize size:(CGSize)size;
+@end
+
+@implementation UIImage (Alpha)
+
+// Returns true if the image has an alpha layer
+- (BOOL)hasAlpha {
+    CGImageAlphaInfo alpha = CGImageGetAlphaInfo(self.CGImage);
+    return (alpha == kCGImageAlphaFirst ||
+            alpha == kCGImageAlphaLast ||
+            alpha == kCGImageAlphaPremultipliedFirst ||
+            alpha == kCGImageAlphaPremultipliedLast);
+}
+
+// Returns a copy of the given image, adding an alpha channel if it doesn't already have one
+- (UIImage *)imageWithAlpha {
+    if ([self hasAlpha]) {
+        return self;
+    }
+
+    CGImageRef imageRef = self.CGImage;
+    size_t width = CGImageGetWidth(imageRef);
+    size_t height = CGImageGetHeight(imageRef);
+
+    // The bitsPerComponent and bitmapInfo values are hard-coded to prevent an "unsupported parameter combination" error
+    CGContextRef offscreenContext = CGBitmapContextCreate(NULL,
+                                                          width,
+                                                          height,
+                                                          8,
+                                                          0,
+                                                          CGImageGetColorSpace(imageRef),
+                                                          kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedFirst);
+
+    // Draw the image into the context and retrieve the new image, which will now have an alpha layer
+    CGContextDrawImage(offscreenContext, CGRectMake(0, 0, width, height), imageRef);
+    CGImageRef imageRefWithAlpha = CGBitmapContextCreateImage(offscreenContext);
+    UIImage *imageWithAlpha = [UIImage imageWithCGImage:imageRefWithAlpha];
+
+    // Clean up
+    CGContextRelease(offscreenContext);
+    CGImageRelease(imageRefWithAlpha);
+
+    return imageWithAlpha;
+}
+
+// Returns a copy of the image with a transparent border of the given size added around its edges.
+// If the image has no alpha layer, one will be added to it.
+- (UIImage *)transparentBorderImage:(NSUInteger)borderSize {
+    // If the image does not have an alpha layer, add one
+    UIImage *image = [self imageWithAlpha];
+
+    CGRect newRect = CGRectMake(0, 0, image.size.width + borderSize * 2, image.size.height + borderSize * 2);
+
+    // Build a context that's the same dimensions as the new size
+    CGContextRef bitmap = CGBitmapContextCreate(NULL,
+                                                newRect.size.width,
+                                                newRect.size.height,
+                                                CGImageGetBitsPerComponent(self.CGImage),
+                                                0,
+                                                CGImageGetColorSpace(self.CGImage),
+                                                CGImageGetBitmapInfo(self.CGImage));
+
+    // Draw the image in the center of the context, leaving a gap around the edges
+    CGRect imageLocation = CGRectMake(borderSize, borderSize, image.size.width, image.size.height);
+    CGContextDrawImage(bitmap, imageLocation, self.CGImage);
+    CGImageRef borderImageRef = CGBitmapContextCreateImage(bitmap);
+
+    // Create a mask to make the border transparent, and combine it with the image
+    CGImageRef maskImageRef = [self newBorderMask:borderSize size:newRect.size];
+    CGImageRef transparentBorderImageRef = CGImageCreateWithMask(borderImageRef, maskImageRef);
+    UIImage *transparentBorderImage = [UIImage imageWithCGImage:transparentBorderImageRef];
+
+    // Clean up
+    CGContextRelease(bitmap);
+    CGImageRelease(borderImageRef);
+    CGImageRelease(maskImageRef);
+    CGImageRelease(transparentBorderImageRef);
+
+    return transparentBorderImage;
+}
+
+#pragma mark -
+#pragma mark Private helper methods
+
+// Creates a mask that makes the outer edges transparent and everything else opaque
+// The size must include the entire mask (opaque part + transparent border)
+// The caller is responsible for releasing the returned reference by calling CGImageRelease
+- (CGImageRef)newBorderMask:(NSUInteger)borderSize size:(CGSize)size {
+    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();
+
+    // Build a context that's the same dimensions as the new size
+    CGContextRef maskContext = CGBitmapContextCreate(NULL,
+                                                     size.width,
+                                                     size.height,
+                                                     8, // 8-bit grayscale
+                                                     0,
+                                                     colorSpace,
+                                                     kCGBitmapByteOrderDefault | kCGImageAlphaNone);
+
+    // Start with a mask that's entirely transparent
+    CGContextSetFillColorWithColor(maskContext, [UIColor blackColor].CGColor);
+    CGContextFillRect(maskContext, CGRectMake(0, 0, size.width, size.height));
+
+    // Make the inner part (within the border) opaque
+    CGContextSetFillColorWithColor(maskContext, [UIColor whiteColor].CGColor);
+    CGContextFillRect(maskContext, CGRectMake(borderSize, borderSize, size.width - borderSize * 2, size.height - borderSize * 2));
+
+    // Get an image of the context
+    CGImageRef maskImageRef = CGBitmapContextCreateImage(maskContext);
+
+    // Clean up
+    CGContextRelease(maskContext);
+    CGColorSpaceRelease(colorSpace);
+
+    return maskImageRef;
+}
+
+@end

UIImage+Editor.h

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+//
+// UIImage+Editor.h
+// Originally created for MyFile
+//
+// UIImage+Editor is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License.
+// As attribution, I just require that you mention my name in conjunction
+// with this library, and that your application can reproduce this legal notice.
+// For details, see: http://creativecommons.org/licenses/
+//
+// Although this library was written in the hope that it will be useful,
+// THIS SOFTWARE IS PROVIDED BY THE AUTHOR 'AS IS', THUS
+// THERE IS NO WARRANTY AT ALL, NEITHER EXPRESSED OR IMPLIED, NOT EVEN
+// FOR MERCHANTABILITY OR FITTNESS FOR A PARTICUALR PURPOSE. I (THE AUTHOR) AM NOT RESPONSIBLE
+// FOR ANY DAMAGE, DATA LOSS OR ANY OTHER TYPES OF UNEXPECTED AND/OR BAD RESULTS
+// IN CONNECTION OF THIS SOFTWARE.
+//
+// Created by Árpád Goretity, 2011.
+//
+
+#import <CoreGraphics/CoreGraphics.h>
+#import <UIKit/UIKit.h>
+#import "UIImage+Resize.h"
+#import "UIImage+RoundedCorner.h"
+#import "UIImage+Alpha.h"
+
+CGFloat degreesToRadians (CGFloat degrees);
+CGFloat radiansToDegrees (CGFloat radians);
+
+@interface UIImage (Editor)
+
+// resize to a specified (width, height) size. Can be used for stretching.
+- (UIImage *) resizedToSize: (CGSize) size;
+// resize to a specified ratio (ratio must not be 0)
+- (UIImage *) resizedByRatio: (CGFloat) ratio;
+// crop a specified rect from the middle of the image
+- (UIImage *) croppedToRect: (CGRect) rect;
+// generate a rounded corner image by adjusting the corner arcs' alpha
+- (UIImage *) withBorderRadius: (CGFloat) radius;
+// draw a string to the specified string at a given point, with a given font and color
+- (UIImage *) addText: (NSString *) str atPoint: (CGPoint) point withFont: (UIFont *) font ofColor: (UIColor *) color;
+// return a grayscale copy of the image
+- (UIImage *) grayscaled;
+// return a transparent copy of the image
+- (UIImage *) withAlpha: (CGFloat) alpha;
+// return a rotated copy of the image. Specify rotation angle in degrees. Use radiansToDegrees() to convert radians to degrees.
+- (UIImage *) rotatedByDegrees: (CGFloat) degrees;
+@end
+