Fixed a bug with the transparency not being preserved when converting between UIImage and the RGBA format.

Added some test code using c++ (changed app delegate to use .mm instead of m for obj-c++ support)
Wrapped image code in a function to add it to the window to support multiple images
Added a GraphicsCommon file, which contains C++ code to convert from RGBA8 to a 4 float structure.
Added a transparent image to test

Author: PaulSolt

GraphicsCommon.h

@@ -0,0 +1,119 @@
+//
+//  GraphicsCommon.h
+//  ImageConversion
+//
+//  Created by Paul Solt on 8/24/11.
+//  Copyright 2011 Paul Solt. All rights reserved.
+//
+
+//#import <Foundation/Foundation.h>
+//
+//@interface GraphicsCommon : NSObject
+//
+//
+//@end
+
+#include <iostream>
+#include <sstream>
+
+static const int NUMBER_COLORS = 4;	
+
+/** The Color3D structure is used for storing the Red, Green, Blue, and Alpha components. */
+struct Color3D {
+    
+    Color3D() : red(0.0f), green(0.0f), blue(0.0f), alpha(1.0f) {}
+    
+    float red;
+    float green;
+    float blue;
+    float alpha;
+}; // Color3D;
+
+/** Prints out a Color3D structure */
+static std::ostream &operator<<(std::ostream &os, const Color3D &c) {
+    os << "Color: (" << c.red << ", " << c.green << ", " << c.blue << ", " << c.alpha << ")";
+    return os;
+}
+
+static std::string toString(const Color3D &c) {
+    std::ostringstream os;
+    os << "Color: (" << c.red << ", " << c.green << ", " << c.blue << ", " << c.alpha << ")";
+    std::string str(os.str());
+    return str;
+}
+
+/** Converts a single color value from floating point space (0.0-1.0) to unsigned char (RGBA8) format.
+ Red,green,blue,alpha in 0.0-1.0 space
+ color will be in range 0-255
+ Requires 4 component (RGBA) (unsigned char *) to be already allocated
+ */
+static inline void color3dToRGBA8(Color3D *colorIn, unsigned char *colorOut) {
+    
+    // Clamp the negative colors to black, it's undefined behavior otherwise. 
+    Color3D newColor = *colorIn;
+    if(newColor.red < 0) {
+        newColor.red = 0;
+    }
+    if(newColor.green < 0) {
+        newColor.green = 0;
+    }
+    if(newColor.blue < 0) {
+        newColor.blue = 0;
+    }
+    
+    colorOut[0] = static_cast<unsigned char>(newColor.red * 255);
+    colorOut[1] = static_cast<unsigned char>(newColor.green * 255);
+    colorOut[2] = static_cast<unsigned char>(newColor.blue * 255);
+    colorOut[3] = static_cast<unsigned char>(newColor.alpha * 255);
+}
+
+static inline void RGBA8ToColor3d(unsigned char *colorIn, Color3D *colorOut) {
+    colorOut->red = static_cast<float>(colorIn[0]) / 255.0f;
+    colorOut->green = static_cast<float>(colorIn[1]) / 255.0f;
+    colorOut->blue = static_cast<float>(colorIn[2]) / 255.0f;
+    colorOut->alpha = static_cast<float>(colorIn[3]) / 255.0f;
+}
+
+/** Converts a single color value from the colors Red, Green, Blue, Alpha in RGBA8 format to floating
+ point format in (0.0-1.0) range.
+ Requires the memory to be allocated for the colorOut parameter.
+ @param red - the red component
+ @param green - the green component
+ @param blue - the blue component
+ @param alpha - the alpha component
+ @param colorOut - the floating point Color3D structure to store the conversion
+ */
+static inline void RGBA8ToColor3d(unsigned char red, unsigned char green, unsigned char blue,
+                                  unsigned char alpha, Color3D *colorOut) {
+    colorOut->red = static_cast<float>(red) / 255.0f;
+    colorOut->green = static_cast<float>(green) / 255.0f;
+    colorOut->blue = static_cast<float>(blue) / 255.0f;
+    colorOut->alpha = static_cast<float>(alpha) / 255.0f;
+}
+
+/** Converts a Color3D image to RGBA8 (unsigned char *) given the image dimensions. The function
+ assumes the number of bytes per pixel color is 4. The memory should be allocated before calling this 
+ method. It simply copies data from one type to the other. ImageOut should be width*height*4
+ @param imageIn - the image that should be converted
+ @param imageOut - the image that should be used for output
+ @param width - the number of pixels wide
+ @param height - the number of pixels high.
+ */
+static inline void ConvertImageColor3dToRGBA8(Color3D *imageIn, unsigned char *imageOut, int width, int height) {
+    int length = width * height;
+    
+    // Need to increment unsigned char pointer by the number of colors each loop
+    for(int i = 0, j = 0; i < length; ++i, j+=NUMBER_COLORS) {
+        color3dToRGBA8(&imageIn[i], &imageOut[j]);
+    }
+    
+}
+
+static inline void ConvertImageRGBA8ToColor3d(unsigned char *imageIn, Color3D *imageOut, int width, int height) {
+    int length = width * height;
+    
+    // Need to increment unsigned char pointer by the number of colors each loop
+    for(int i = 0, j = 0; i < length; ++i, j+=NUMBER_COLORS) {
+        RGBA8ToColor3d(&imageIn[j], &imageOut[i]);
+    }
+}

GraphicsCommon.m

@@ -0,0 +1,26 @@
+//
+//  GraphicsCommon.m
+//  ImageConversion
+//
+//  Created by Paul Solt on 8/24/11.
+//  Copyright 2011 Paul Solt. All rights reserved.
+//
+
+#import "GraphicsCommon.h"
+
+@implementation GraphicsCommon
+
+- (id)init
+{
+    self = [super init];
+    if (self) {
+        // Initialization code here.
+    }
+    
+    return self;
+}
+
+
+
+
+@end

ImageConversion.xcodeproj/project.pbxproj

@@ -3,7 +3,7 @@
 	archiveVersion = 1;
 	classes = {
 	};
-	objectVersion = 45;
+	objectVersion = 46;
 	objects = {
 
 /* Begin PBXBuildFile section */
@@ -12,12 +12,13 @@
 		1DF5F4E00D08C38300B7A737 /* UIKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 1DF5F4DF0D08C38300B7A737 /* UIKit.framework */; };
 		2860E328111B887F00E27156 /* AppDelegate_iPhone.m in Sources */ = {isa = PBXBuildFile; fileRef = 2860E326111B887F00E27156 /* AppDelegate_iPhone.m */; };
 		2860E329111B887F00E27156 /* MainWindow_iPhone.xib in Resources */ = {isa = PBXBuildFile; fileRef = 2860E327111B887F00E27156 /* MainWindow_iPhone.xib */; };
-		2860E32E111B888700E27156 /* AppDelegate_iPad.m in Sources */ = {isa = PBXBuildFile; fileRef = 2860E32C111B888700E27156 /* AppDelegate_iPad.m */; };
+		2860E32E111B888700E27156 /* AppDelegate_iPad.mm in Sources */ = {isa = PBXBuildFile; fileRef = 2860E32C111B888700E27156 /* AppDelegate_iPad.mm */; };
 		2860E32F111B888700E27156 /* MainWindow_iPad.xib in Resources */ = {isa = PBXBuildFile; fileRef = 2860E32D111B888700E27156 /* MainWindow_iPad.xib */; };
 		288765FD0DF74451002DB57D /* CoreGraphics.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 288765FC0DF74451002DB57D /* CoreGraphics.framework */; };
 		BD12AFAF134E31C40052742A /* MITLicense.txt in Resources */ = {isa = PBXBuildFile; fileRef = BD12AFAE134E31C40052742A /* MITLicense.txt */; };
 		BD3F462C124A7A5D00959DE5 /* ImageHelper.m in Sources */ = {isa = PBXBuildFile; fileRef = BD3F462B124A7A5D00959DE5 /* ImageHelper.m */; };
 		BD3F4650124A852600959DE5 /* Icon4.png in Resources */ = {isa = PBXBuildFile; fileRef = BD3F464F124A852600959DE5 /* Icon4.png */; };
+		BD93538F14054F72009660CC /* ShareArrow.png in Resources */ = {isa = PBXBuildFile; fileRef = BD93538E14054F72009660CC /* ShareArrow.png */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
@@ -28,7 +29,7 @@
 		2860E326111B887F00E27156 /* AppDelegate_iPhone.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = AppDelegate_iPhone.m; sourceTree = "<group>"; };
 		2860E327111B887F00E27156 /* MainWindow_iPhone.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = MainWindow_iPhone.xib; sourceTree = "<group>"; };
 		2860E32B111B888700E27156 /* AppDelegate_iPad.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = AppDelegate_iPad.h; sourceTree = "<group>"; };
-		2860E32C111B888700E27156 /* AppDelegate_iPad.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = AppDelegate_iPad.m; sourceTree = "<group>"; };
+		2860E32C111B888700E27156 /* AppDelegate_iPad.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = AppDelegate_iPad.mm; sourceTree = "<group>"; };
 		2860E32D111B888700E27156 /* MainWindow_iPad.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = MainWindow_iPad.xib; sourceTree = "<group>"; };
 		288765FC0DF74451002DB57D /* CoreGraphics.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = CoreGraphics.framework; path = System/Library/Frameworks/CoreGraphics.framework; sourceTree = SDKROOT; };
 		29B97316FDCFA39411CA2CEA /* main.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; name = main.m; path = Shared/main.m; sourceTree = "<group>"; };
@@ -38,6 +39,8 @@
 		BD3F462A124A7A5D00959DE5 /* ImageHelper.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ImageHelper.h; sourceTree = "<group>"; };
 		BD3F462B124A7A5D00959DE5 /* ImageHelper.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ImageHelper.m; sourceTree = "<group>"; };
 		BD3F464F124A852600959DE5 /* Icon4.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = Icon4.png; sourceTree = "<group>"; };
+		BD93538E14054F72009660CC /* ShareArrow.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = ShareArrow.png; sourceTree = "<group>"; };
+		BD9353BB140554F7009660CC /* GraphicsCommon.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = GraphicsCommon.h; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -75,9 +78,10 @@
 		2860E32A111B888700E27156 /* iPad */ = {
 			isa = PBXGroup;
 			children = (
+				BD93538E14054F72009660CC /* ShareArrow.png */,
 				BD3F464F124A852600959DE5 /* Icon4.png */,
 				2860E32B111B888700E27156 /* AppDelegate_iPad.h */,
-				2860E32C111B888700E27156 /* AppDelegate_iPad.m */,
+				2860E32C111B888700E27156 /* AppDelegate_iPad.mm */,
 				2860E32D111B888700E27156 /* MainWindow_iPad.xib */,
 			);
 			path = iPad;
@@ -89,6 +93,7 @@
 				8D1107310486CEB800E47090 /* ImageConversion-Info.plist */,
 				BD3F462A124A7A5D00959DE5 /* ImageHelper.h */,
 				BD3F462B124A7A5D00959DE5 /* ImageHelper.m */,
+				BD9353BB140554F7009660CC /* GraphicsCommon.h */,
 			);
 			name = Shared;
 			sourceTree = "<group>";
@@ -152,10 +157,11 @@
 		29B97313FDCFA39411CA2CEA /* Project object */ = {
 			isa = PBXProject;
 			attributes = {
+				LastUpgradeCheck = 0410;
 				ORGANIZATIONNAME = "Paul Solt";
 			};
 			buildConfigurationList = C01FCF4E08A954540054247B /* Build configuration list for PBXProject "ImageConversion" */;
-			compatibilityVersion = "Xcode 3.1";
+			compatibilityVersion = "Xcode 3.2";
 			developmentRegion = English;
 			hasScannedForEncodings = 1;
 			knownRegions = (
@@ -182,6 +188,7 @@
 				2860E32F111B888700E27156 /* MainWindow_iPad.xib in Resources */,
 				BD3F4650124A852600959DE5 /* Icon4.png in Resources */,
 				BD12AFAF134E31C40052742A /* MITLicense.txt in Resources */,
+				BD93538F14054F72009660CC /* ShareArrow.png in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -194,7 +201,7 @@
 			files = (
 				1D60589B0D05DD56006BFB54 /* main.m in Sources */,
 				2860E328111B887F00E27156 /* AppDelegate_iPhone.m in Sources */,
-				2860E32E111B888700E27156 /* AppDelegate_iPad.m in Sources */,
+				2860E32E111B888700E27156 /* AppDelegate_iPad.mm in Sources */,
 				BD3F462C124A7A5D00959DE5 /* ImageHelper.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -211,7 +218,7 @@
 				GCC_OPTIMIZATION_LEVEL = 0;
 				GCC_PRECOMPILE_PREFIX_HEADER = YES;
 				GCC_PREFIX_HEADER = ImageConversion_Prefix.pch;
-				GCC_VERSION = 4.2;
+				GCC_VERSION = com.apple.compilers.llvmgcc42;
 				INFOPLIST_FILE = "ImageConversion-Info.plist";
 				IPHONEOS_DEPLOYMENT_TARGET = 3.2;
 				PRODUCT_NAME = ImageConversion;
@@ -225,7 +232,7 @@
 				COPY_PHASE_STRIP = YES;
 				GCC_PRECOMPILE_PREFIX_HEADER = YES;
 				GCC_PREFIX_HEADER = ImageConversion_Prefix.pch;
-				GCC_VERSION = 4.2;
+				GCC_VERSION = com.apple.compilers.llvmgcc42;
 				INFOPLIST_FILE = "ImageConversion-Info.plist";
 				IPHONEOS_DEPLOYMENT_TARGET = 3.2;
 				PRODUCT_NAME = ImageConversion;
@@ -242,7 +249,6 @@
 				GCC_WARN_ABOUT_RETURN_TYPE = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
 				IPHONEOS_DEPLOYMENT_TARGET = 3.2;
-				PREBINDING = NO;
 				SDKROOT = iphoneos;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
@@ -259,7 +265,6 @@
 				GCC_WARN_UNUSED_VARIABLE = YES;
 				IPHONEOS_DEPLOYMENT_TARGET = 3.2;
 				OTHER_CFLAGS = "-DNS_BLOCK_ASSERTIONS=1";
-				PREBINDING = NO;
 				PROVISIONING_PROFILE = "";
 				SDKROOT = iphoneos;
 				TARGETED_DEVICE_FAMILY = "1,2";

ImageHelper.m

@@ -109,14 +109,13 @@ + (CGContextRef) newBitmapRGBA8ContextFromImage:(CGImageRef) image {
 	}
 
 	//Create bitmap context
-	
 	context = CGBitmapContextCreate(bitmapData, 
 									width, 
 									height, 
 									bitsPerComponent, 
 									bytesPerRow, 
 									colorSpace, 
-									kCGImageAlphaPremultipliedLast);	// RGBA
+                                    kCGImageAlphaPremultipliedLast);	// RGBA
 
 	if(!context) {
 		free(bitmapData);
@@ -145,8 +144,7 @@ + (UIImage *) convertBitmapRGBA8ToUIImage:(unsigned char *) buffer
 		CGDataProviderRelease(provider);
 		return nil;
 	}
-	
-	CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
+	CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedLast;
 	CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;
 
 	CGImageRef iref = CGImageCreate(width, 
@@ -177,7 +175,7 @@ + (UIImage *) convertBitmapRGBA8ToUIImage:(unsigned char *) buffer
 												 bitsPerComponent, 
 												 bytesPerRow, 
 												 colorSpaceRef,
-												 kCGImageAlphaPremultipliedLast); 
+                                                 bitmapInfo);
 
 	if(context == NULL) {
 		NSLog(@"Error context not created");

iPad/AppDelegate_iPad.h

@@ -14,5 +14,9 @@
 
 @property (nonatomic, retain) IBOutlet UIWindow *window;
 
+
+// Adds an image to an imageview on the window
+- (void)addImage:(NSString *)theFilename atPosition:(CGPoint)thePosition;
+
 @end