Added simple white areas trimming

README.md

@@ -19,4 +19,11 @@ Additionally, if you merely desire to know the `UIEdgeInsets` of the transparenc
 
 `[yourImage transparencyInsetsRequiringFullOpacity:YES];`
 
-This call works based on the same principles as the "advanced" trim method, with the boolean dictating whether non-opaque pixels should be considered transparent.
+This call works based on the same principles as the "advanced" trim method, with the boolean dictating whether non-opaque pixels should be considered transparent.
+
+
+This fork adds support for trimming white area around image with given tolerance
+
+`[yourImage imageByTrimmingWhitePixelsWithOpacity:VALUE];`
+
+where 0 - cut only white, 255 - remove everything

Transparency Trim Demo/Transparency Trim Demo.xcodeproj/project.pbxproj

@@ -21,6 +21,10 @@
 		6B06373E177B30D900B55AC5 /* UIImage+Trim.m in Sources */ = {isa = PBXBuildFile; fileRef = 6B06373D177B30D900B55AC5 /* UIImage+Trim.m */; };
 		6B063741177B33B900B55AC5 /* demo_image.png in Resources */ = {isa = PBXBuildFile; fileRef = 6B06373F177B33B900B55AC5 /* demo_image.png */; };
 		6B063742177B33B900B55AC5 /* demo_image@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = 6B063740177B33B900B55AC5 /* demo_image@2x.png */; };
+		9F31271D18C1239E008CD497 /* demo_white_image.png in Resources */ = {isa = PBXBuildFile; fileRef = 9F31271B18C1239E008CD497 /* demo_white_image.png */; };
+		9F31271E18C1239E008CD497 /* demo_white_image@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = 9F31271C18C1239E008CD497 /* demo_white_image@2x.png */; };
+		9F31272118C123D5008CD497 /* ELCWhiteViewController.m in Sources */ = {isa = PBXBuildFile; fileRef = 9F31272018C123D5008CD497 /* ELCWhiteViewController.m */; };
+		9F31272418C123DE008CD497 /* ELCWhiteViewController.xib in Resources */ = {isa = PBXBuildFile; fileRef = 9F31272218C123DE008CD497 /* ELCWhiteViewController.xib */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
@@ -44,6 +48,11 @@
 		6B06373D177B30D900B55AC5 /* UIImage+Trim.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "UIImage+Trim.m"; sourceTree = "<group>"; };
 		6B06373F177B33B900B55AC5 /* demo_image.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = demo_image.png; sourceTree = "<group>"; };
 		6B063740177B33B900B55AC5 /* demo_image@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "demo_image@2x.png"; sourceTree = "<group>"; };
+		9F31271B18C1239E008CD497 /* demo_white_image.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = demo_white_image.png; sourceTree = "<group>"; };
+		9F31271C18C1239E008CD497 /* demo_white_image@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "demo_white_image@2x.png"; sourceTree = "<group>"; };
+		9F31271F18C123D5008CD497 /* ELCWhiteViewController.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ELCWhiteViewController.h; sourceTree = "<group>"; };
+		9F31272018C123D5008CD497 /* ELCWhiteViewController.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ELCWhiteViewController.m; sourceTree = "<group>"; };
+		9F31272318C123DE008CD497 /* en */ = {isa = PBXFileReference; lastKnownFileType = file.xib; name = en; path = en.lproj/ELCWhiteViewController.xib; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -97,6 +106,9 @@
 				6B063731177B30C400B55AC5 /* ELCViewController.h */,
 				6B063732177B30C400B55AC5 /* ELCViewController.m */,
 				6B063734177B30C400B55AC5 /* ELCViewController.xib */,
+				9F31271F18C123D5008CD497 /* ELCWhiteViewController.h */,
+				9F31272018C123D5008CD497 /* ELCWhiteViewController.m */,
+				9F31272218C123DE008CD497 /* ELCWhiteViewController.xib */,
 				6B063720177B30C400B55AC5 /* Supporting Files */,
 			);
 			path = "Transparency Trim Demo";
@@ -107,6 +119,8 @@
 			children = (
 				6B06373F177B33B900B55AC5 /* demo_image.png */,
 				6B063740177B33B900B55AC5 /* demo_image@2x.png */,
+				9F31271B18C1239E008CD497 /* demo_white_image.png */,
+				9F31271C18C1239E008CD497 /* demo_white_image@2x.png */,
 				6B063721177B30C400B55AC5 /* Transparency Trim Demo-Info.plist */,
 				6B063722177B30C400B55AC5 /* InfoPlist.strings */,
 				6B063725177B30C400B55AC5 /* main.m */,
@@ -171,11 +185,14 @@
 			buildActionMask = 2147483647;
 			files = (
 				6B063724177B30C400B55AC5 /* InfoPlist.strings in Resources */,
+				9F31271E18C1239E008CD497 /* demo_white_image@2x.png in Resources */,
 				6B06372C177B30C400B55AC5 /* Default.png in Resources */,
 				6B06372E177B30C400B55AC5 /* Default@2x.png in Resources */,
 				6B063730177B30C400B55AC5 /* Default-568h@2x.png in Resources */,
+				9F31272418C123DE008CD497 /* ELCWhiteViewController.xib in Resources */,
 				6B063736177B30C400B55AC5 /* ELCViewController.xib in Resources */,
 				6B063741177B33B900B55AC5 /* demo_image.png in Resources */,
+				9F31271D18C1239E008CD497 /* demo_white_image.png in Resources */,
 				6B063742177B33B900B55AC5 /* demo_image@2x.png in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -190,6 +207,7 @@
 				6B063726177B30C400B55AC5 /* main.m in Sources */,
 				6B06372A177B30C400B55AC5 /* ELCAppDelegate.m in Sources */,
 				6B063733177B30C400B55AC5 /* ELCViewController.m in Sources */,
+				9F31272118C123D5008CD497 /* ELCWhiteViewController.m in Sources */,
 				6B06373E177B30D900B55AC5 /* UIImage+Trim.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -213,6 +231,14 @@
 			name = ELCViewController.xib;
 			sourceTree = "<group>";
 		};
+		9F31272218C123DE008CD497 /* ELCWhiteViewController.xib */ = {
+			isa = PBXVariantGroup;
+			children = (
+				9F31272318C123DE008CD497 /* en */,
+			);
+			name = ELCWhiteViewController.xib;
+			sourceTree = "<group>";
+		};
 /* End PBXVariantGroup section */
 
 /* Begin XCBuildConfiguration section */
@@ -345,6 +371,7 @@
 				6B06373B177B30C400B55AC5 /* Release */,
 			);
 			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
 		};
 /* End XCConfigurationList section */
 	};

Transparency Trim Demo/Transparency Trim Demo/ELCAppDelegate.h

@@ -8,12 +8,12 @@
 
 #import <UIKit/UIKit.h>
 
-@class ELCViewController;
+@class UIViewController;
 
 @interface ELCAppDelegate : UIResponder <UIApplicationDelegate>
 
 @property (strong, nonatomic) UIWindow *window;
 
-@property (strong, nonatomic) ELCViewController *viewController;
+@property (strong, nonatomic) UIViewController *viewController;
 
 @end

Transparency Trim Demo/Transparency Trim Demo/ELCAppDelegate.m

@@ -8,15 +8,15 @@
 
 #import "ELCAppDelegate.h"
 
-#import "ELCViewController.h"
+#import "ELCWhiteViewController.h"
 
 @implementation ELCAppDelegate
 
 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
 {
     self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
     // Override point for customization after application launch.
-	self.viewController = [[ELCViewController alloc] initWithNibName:@"ELCViewController" bundle:nil];
+	self.viewController = [[ELCWhiteViewController alloc] initWithNibName:@"ELCWhiteViewController" bundle:nil];
 	self.window.rootViewController = self.viewController;
     [self.window makeKeyAndVisible];
 

Transparency Trim Demo/Transparency Trim Demo/ELCWhiteViewController.h

@@ -0,0 +1,17 @@
+//
+//  ELCWhiteViewController.h
+//  Transparency Trim Demo
+//
+//  Created by Blazej Stanek on 28.02.2014.
+//  Copyright (c) 2013 Chris Stroud. All rights reserved.
+//
+
+#import <UIKit/UIKit.h>
+
+@interface ELCWhiteViewController : UIViewController
+
+@property (weak, nonatomic) IBOutlet UIImageView *semiTransparentImageView;
+@property (weak, nonatomic) IBOutlet UIImageView *originalImageView;
+@property (weak, nonatomic) IBOutlet UIImageView *fullyOpaqueImageView;
+
+@end

Transparency Trim Demo/Transparency Trim Demo/ELCWhiteViewController.m

@@ -0,0 +1,27 @@
+//
+//  ELCWhiteViewController.m
+//  Transparency Trim Demo
+//
+//  Created by Blazej Stanek on 28.02.2014.
+//  Copyright (c) 2013 Chris Stroud. All rights reserved.
+//
+
+#import "ELCWhiteViewController.h"
+#import "UIImage+Trim.h"
+
+@implementation ELCWhiteViewController
+
+- (void)viewDidLoad
+{
+    [super viewDidLoad];
+
+	UIImage *originalImage = [UIImage imageNamed:@"demo_white_image"];
+	UIImage *semiTransparentCrop = [originalImage imageByTrimmingWhitePixelsWithOpacity:24];
+	UIImage *fullOpacityCrop = [originalImage imageByTrimmingWhitePixelsWithOpacity:64];
+
+	[self.originalImageView setImage:originalImage];
+	[self.semiTransparentImageView setImage:semiTransparentCrop];
+	[self.fullyOpaqueImageView setImage:fullOpacityCrop];
+}
+
+@end

Transparency Trim Demo/Transparency Trim Demo/UIImage+Trim.h

@@ -14,5 +14,6 @@
 - (UIEdgeInsets)transparencyInsetsRequiringFullOpacity:(BOOL)fullyOpaque;
 - (UIImage *)imageByTrimmingTransparentPixels;
 - (UIImage *)imageByTrimmingTransparentPixelsRequiringFullOpacity:(BOOL)fullyOpaque;
+- (UIImage *)imageByTrimmingWhitePixelsWithOpacity:(UInt8)tolerance;
 
 @end

Transparency Trim Demo/Transparency Trim Demo/UIImage+Trim.m

@@ -28,7 +28,7 @@ - (UIEdgeInsets)transparencyInsetsRequiringFullOpacity:(BOOL)fullyOpaque
 	uint8_t * bitmapData = calloc((size_t)(width * height), sizeof(uint8_t));
 
 	// Create alpha-only bitmap context
-	CGContextRef contextRef = CGBitmapContextCreate(bitmapData, (NSUInteger)width, (NSUInteger)height, 8, (NSUInteger)bytesPerRow, NULL, kCGImageAlphaOnly);
+	CGContextRef contextRef = CGBitmapContextCreate(bitmapData, (NSUInteger)width, (NSUInteger)height, 8, (NSUInteger)bytesPerRow, NULL, (kCGBitmapAlphaInfoMask & kCGImageAlphaOnly));
 
 	CGImageRef cgImage = self.CGImage;
 	CGRect rect = CGRectMake(0, 0, width, height);
@@ -172,4 +172,139 @@ - (UIImage *)imageByTrimmingTransparentPixelsRequiringFullOpacity:(BOOL)fullyOpa
     return img;
 }
 
+/*
+ * Calculates the insets of white area around all sides of the image
+ *
+ * @param tolerance
+ *        Maximal difference from white
+ */
+- (UIEdgeInsets)transparencyInsetsByCuttingWhitespace:(UInt8)tolerance
+{
+	// Draw our image on that context
+	NSInteger width  = (NSInteger)CGImageGetWidth([self CGImage]);
+	NSInteger height = (NSInteger)CGImageGetHeight([self CGImage]);
+	NSInteger bytesPerRow = width * (NSInteger)sizeof(uint8_t);
+
+	// Allocate array to hold alpha channel
+	uint8_t * bitmapData = calloc((size_t)(width * height), sizeof(uint8_t));
+
+	// Create grayscale image
+    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();
+	CGContextRef contextRef = CGBitmapContextCreate(bitmapData, (NSUInteger)width, (NSUInteger)height, 8, (NSUInteger)bytesPerRow, colorSpace, (kCGBitmapAlphaInfoMask & kCGImageAlphaNone));
+
+	CGImageRef cgImage = self.CGImage;
+	CGRect rect = CGRectMake(0, 0, width, height);
+	CGContextDrawImage(contextRef, rect, cgImage);
+
+	// Sum all non-transparent pixels in every row and every column
+	uint16_t * rowSum = calloc((size_t)height, sizeof(uint16_t));
+	uint16_t * colSum = calloc((size_t)width,  sizeof(uint16_t));
+
+	// Enumerate through all pixels
+	for (NSInteger row = 0; row < height; row++) {
+
+		for (NSInteger col = 0; col < width; col++) {
+
+            // Found darker pixel
+            if (bitmapData[row*bytesPerRow + col] <= UINT8_MAX - tolerance) {
+
+                rowSum[row]++;
+                colSum[col]++;
+
+            }
+		}
+	}
+
+	// Initialize crop insets and enumerate cols/rows arrays until we find non-empty columns or row
+	UIEdgeInsets crop = UIEdgeInsetsZero;
+
+    // Top
+	for (NSInteger i = 0; i < height; i++) {
+
+		if (rowSum[i] > 0) {
+
+			crop.top = i;
+            break;
+
+		}
+
+	}
+
+    // Bottom
+	for (NSInteger i = height - 1; i >= 0; i--) {
+
+		if (rowSum[i] > 0) {
+			crop.bottom = MAX(0, height - i - 1);
+            break;
+		}
+
+	}
+
+    // Left
+	for (NSInteger i = 0; i < width; i++) {
+
+		if (colSum[i] > 0) {
+			crop.left = i;
+            break;
+		}
+
+	}
+
+    // Right
+	for (NSInteger i = width - 1; i >= 0; i--) {
+
+		if (colSum[i] > 0) {
+
+			crop.right = MAX(0, width - i - 1);
+            break;
+
+		}
+	}
+
+	free(bitmapData);
+	free(colSum);
+	free(rowSum);
+
+    CGContextRelease(contextRef);
+
+	return crop;
+}
+
+- (UIImage *)imageByTrimmingWhitePixelsWithOpacity:(UInt8)tolerance
+{
+	if (self.size.height < 2 || self.size.width < 2) {
+
+		return self;
+
+	}
+
+	CGRect rect = CGRectMake(0, 0, self.size.width * self.scale, self.size.height * self.scale);
+	UIEdgeInsets crop = [self transparencyInsetsByCuttingWhitespace:tolerance];
+
+    UIImage *img = self;
+
+	if (crop.top == 0 && crop.bottom == 0 && crop.left == 0 && crop.right == 0) {
+
+		// No cropping needed
+
+	} else {
+
+		// Calculate new crop bounds
+		rect.origin.x += crop.left;
+		rect.origin.y += crop.top;
+		rect.size.width -= crop.left + crop.right;
+		rect.size.height -= crop.top + crop.bottom;
+
+		// Crop it
+		CGImageRef newImage = CGImageCreateWithImageInRect([self CGImage], rect);
+
+		// Convert back to UIImage
+        img = [UIImage imageWithCGImage:newImage scale:self.scale orientation:self.imageOrientation];
+
+        CGImageRelease(newImage);
+	}
+
+    return img;
+}
+
 @end