Stuff I'm working on at the moment

Clear iPhone simulator cache (out-dated files being loaded)

Mar15
2010 Leave a Comment Written by edlong

Quick post that might help someone.

I had an XML file that I had changed in Dashcode and for some reason the older XML content was being read into my app. I ‘re-touched’ it in XCode and even though the right XML showed up within the project the wrong XML was being loaded up in the simulator.

A little perplexed by this I checked what file was being loaded by stepping through code and saw that the XML was being loaded up from a path that looked something like “/Users//Library/Application Support/iPhone Simulator/User/Applications/xxx”. This location obviously contained the old version of the XML file and not the new one I had in XCode. To solve this problem I cleaned the project and performed a full re-build and low-and-behold the correct XML was loaded. I suspect cleaning the project deletes the app and all associated data from the simulator cache.

Posted in iPhone, Objective C

Create a class from a string

Mar15
2010 Leave a Comment Written by edlong

I found myself in the position that I had a string that came in from XML and wanted to create an appropriate class from this string. After some searching I found the neat little function NSClassFromString. So given a string I could allocate a class by doing

id newClass = [[NSClassFromString(string) alloc] init];

I also needed to go back the other way, get the name of the class as a string. Again there is a similar function definition

NSString* name = NSStringFromClass([self class]);

This above shows how to get the class from self using [self class].

Posted in Objective C

Selectors with multiple arguments

Mar15
2010 Leave a Comment Written by edlong

I’ve needed to figure out if a certain function exists for a class before instantiating a new class. However the init function takes two parameters and all code samples I’ve seen use selectors with just a single parameter. Below is the code that checks if a selector with two parameters is present.

if([NSClassFromString(classType) instancesRespondToSelector: @selector(initWithTwoParameters: withSecondParameter:)])
{
}
Posted in Objective C

Posting code in wordpress blogs

Mar15
2010 Leave a Comment Written by edlong

Hi,
I’ve regularly needed to post code in blogs and there are many plugins out there that do this job. However as I upgrade WordPress they regularly break which is highly annoying. At the moment I’m using SyntaxHighlighter. It works with the latest WordPress 2.9.2 and seems fairly easy to use.

Syntax Highlighter

The usage is quite straight-forward

 …Your Code Here

The list of valid code-aliases are shown here (the middle column):

Brushes

Posted in Wordpress - Tagged

New site content

Dec15
2009 Leave a Comment Written by Eddie Long

Hi all,

I’ve just uploaded two new two new projects to the site.

The first is a little physics simulation I did last week.

The second is an application framework for DirectX that provides a basic scene along with camera setup and manipulation, logging, mesh loading and rendering support and direct input support.

You can get them in my downloads section of the site.

Cheers,
Eddie

Posted in C/C++

Really annoying ActionScript error

Dec12
2009 Leave a Comment Written by Eddie Long

Hi,

I’ve been working with ActionScript for the first time and created a really simple class with a couple of getters and setters and wanted to instantiate the class and use a few setters.

So the original class was: 

package MyPackage
{
	import mx.core.UIComponent;

	public class AClass extends UIComponent
	{
		public function AClass()
		{
			super();
		}

		public function get AValue():Number
		{
			return _aValue;
		}

		public function set AValue(_newAValue:Number):void
		{
			_aValue = _newAValue;
		}

		private var _aValue:Number;
	}
}

That looks fine right?

So in my class I call
import MyPackage.AClass at the top of the file.

Next in another class I called

var myClass:AClass = new AClass();

myClass.AValue(20.0);

I figured that this looked fine, you want to call the function AValue with the value 20.0 passed in. However I was getting the cryptic error:

1195: Attempted access of inaccessible method AValue through a reference with static type MyPackage:AClass

Took me a while to figure this one out I thought I had defined the functions incorrectly or wasn’t importing the class right. However the solution is a simple one. When you use get and set you are essentially saying that you can use the assignment operator but for some weird reason you can’t call the functions directly.
So the solution was to do:

var myClass:AClass = new AClass();

myClass.AValue = 20.0;

Use the assignment operator instead of calling the set function directly.

Posted in Flex

Site update

Nov25
2009 Leave a Comment Written by Eddie Long

Hello all,

Well I’ve spent the last few days updating my site, hopefully all the downloads now work with Visual Studio 2005 and the most recent DirectX.

I’ve not got a chance to actually clean up the code yet so don’t expect miracles!

Please let me know if you find anything broken!

Cheers,
Eddie

Posted in Uncategorized

Setting up a basic OpenGL project on Mac OS Leopard and XCode

Oct11
2009 2 Comments Written by edlong

I’ve recently setup a basic OpenGL project in XCode to have a black window.

In XCode select File->New Project. Select an Empty Project and name it whatever you want, screenie below:




newproject




Within XCode select Project->New Target again. Select Cocoa on the left then Application and name it whatever you’d like.




targetapp




You will now see a window with a whole bunch of settings. In the General tab press the + button in Linked Libraries. Add OpenGL.Framework and Glut.framework from the list of frameworks in the dialog that appears.




generalwindow




Next select Build in the tabs along the top and clear the bottom field GCC_PREFIX_HEADER so that its blank.




targetsettings




In the Groups and Files explorer right click on the top level project and select Add->New File. Choose C and C++ and select C file. Again choose whatever name you wish.




candc_





Paste the following code into the C file:

#include stdlib.h
#include GLUT/glut.h

void myCustomDisplay(void)
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glutSwapBuffers();
}

void myCustomReshape(int width, int height)
{
    glViewport(0, 0, width, height);
}

void doSomethingWhenIdle(void)
{
    glutPostRedisplay();
}

int main(int argc, char** argv)
{
    glutInit(&argc, argv);

    glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
    glutInitWindowSize(800, 600);

    glutCreateWindow("My First Window");

    glutDisplayFunc(myCustomDisplay);
    glutReshapeFunc(myCustomReshape);
    glutIdleFunc(doSomethingWhenIdle);

    glutMainLoop();
    return EXIT_SUCCESS;
}

Next Build the application using ‘Build and Go’ and you’ll be presented with a 800×600 empty window with the title ‘My First Window’, easy! I won’t go into the explanation of the different functions, there are plenty of sites out there for that!

Posted in C/C++

Display correct text colour on a background colour

Sep10
2009 Leave a Comment Written by edlong

Hi,

I haven’t posted for a bit, back to some handy C++. I’ve been working with a lot of text being displayed on a background which can be various colours. Not knowing the background colour is in advance is problematic as if you specify the text colour to be always white and the background colour changes to white then the text is unreadable. Likewise for black and there are a range of colours in between that suffer with the same problem, light grey or dark purple for example.

I needed a way of determining correct text colour based on a given background colour. After doing a little bit of digging I came across this article on CodeProject which almost gives the solution I was looking for. However I want to just display white or black text depending on the background colour. So here is the code I used to do so, it works remarkably well. I’ve pseudo coded it up a bit to remove various bits and pieces that may not be important but you can just replace bits of it with proper objects. Also ignore the magic numbers, they’re there just to show the numbers that worked for me. This algorithm can potentially be used in any language, I’m using C++ here as it is what I’m currently using.

COLOUR GetTextColourFromBackground(COLOUR BackgroundColour)
{
	uint32 uDarkLightColourThreshold(105);
	float fRedThresholdValue(0.299);
	float fGreenThresholdValue(0.587);
	float fBlueThresholdValue(0.114);

	uint8 bgDelta = static_cast((BackgroundColour.GetRed() * fRedThresholdValue) + (BackgroundColour.GetGreen() * fGreenThresholdValue) +
		(BackgroundColour.GetBlue() * fBlueThresholdValue));

	COLOUR TextColour(GetColour(White));
	if((255 - bgDelta) < uDarkLightColourThreshold)
	{
		TextColour = GetColour(Black);
	}

	return TextColour;
}

So on a white background the text colour returned will be black and on a black background the text colour will be white. Also on a light grey background the colour returned will be black and so on.
The formula used above originally comes from the W3C http://www.w3.org/TR/AERT#color-contrast.

Posted in C/C++

Quieten XCode’s output to the console

Aug06
2009 Leave a Comment Written by Eddie Long

Hi,

During some iPhone dev i noticed that the console on my macbook had many entries like:

Xcode(19838,0xb0103000) malloc: free_garbage: garbage ptr = 0x319a380, has non-zero refcount = 1
Xcode(19838,0xb0103000) malloc: free_garbage: garbage ptr = 0x31bf6e0, has non-zero refcount = 1
Xcode(19838,0xb0103000) malloc: free_garbage: garbage ptr = 0x3263da0, has non-zero refcount = 1
Xcode(19838,0xb0103000) malloc: free_garbage: garbage ptr = 0x3274eb0, has non-zero refcount = 1
Xcode(19838,0xb0103000) malloc: free_garbage: garbage ptr = 0x319a380, has non-zero refcount = 1
Xcode(19838,0xb0103000) malloc: free_garbage: garbage ptr = 0x31bf6e0, has non-zero refcount = 1

These messages I found out are not actually anything to do with my program, I thought I was doing something wrong and not freeing up resources. It is actually the internal workings of XCode which is automatically freeing up resources. Knowing this, I decided to turn off these annoying console outputs and found this XCode project which basically gobbles up output from XCode in the same mould as above.

Just compile the project and it will install the QuietXCode plugin to ~/Library/Application Support/Developer/Shared/Xcode/Plug-ins. Restart Xcode and fire up the console and you’ll see an inital output of:

06/08/2009 19:34:32 Xcode[5147] <QuietXcode> loaded successfully

You should no longer see the annoying output!

Posted in C/C++
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