1. Interface
2. Concrete Command
3. Receiver
4. Client
5. Invoker

Command Pattern Structure

In this post I will touch upon Interface element of the command pattern. The command interface defines the execute() method, which is responsible for executing the requested operation. Also multiple command types can be implemented using the same interface. The command interface provides a programmatic approach to manage the objects which have disparate modes of operation.

//General interface implementation
package com.thepixelcode.sampleCPExample.commands {

  public interface ICommand {
     function execute():void;
  }

}

The above snippet can be further extended to support the redo/undo functionality, and in order to implement, we would need to create two command interfaces, one for redo and another for undo which shall extend the ICommand.

//Interface for undo
package com.thepixelcode.sampleCPExample.commands {

  public interface IUndoCommand extends ICommand {
     function undo():void;
  }
}

//Interface for redo
package com.thepixelcode.sampleCPExample.commands {

  public interface IRedoCommand extends ICommand {
     function redo():void;
  }
}

I didn’t want to write a long post over the weekend, also neither i wanted to loose on my writing spirit. Shall continue on other elements and a demo app in next post. Till then have a great weekend.

The simple principle behind the AR is that in the live video feed, a Marker needs to be placed in the live video feed and the application then does the image processing (breaks the video into BitMapData) to determine the Marker and match it with the pre stored marker pattern, which can be created using Adobe Photoshop.  After determining the position of the marker in the video, the AR toolkit augments the 3D object.

I think to understand more about augment reality one needs to experience it, so kindly find a live demo here created using Flex 3, FLARToolkit and PaperVision3D. As I told earlier you will need a marker, so kindly print the  following PDF which can be used as a marker with the live demo.

Simple AR Cube Demo Source Code

To try out, lets look at embedding few fonts which I wish to use in Flex project for styling the label text. Open Flash CS3, and follow the steps to create an SWC in which fonts are embedded.

1. Embed a font by going to the library, and in the top right corner drop down, select “New Font…”. In the dialogue box, select the font that you want to embed, and give it a library name.
2. Then, in the library, right click the font, and select “Linkage…”.
3. Select “Export for ActionScript”, and give the font a class name, I gave here as com.thepixelcode.fonts.EmbedSensation.
4. While exporting make sure that the option Export SWC is selected, you can name at this point the SWC as FontsLibrary.swc.

Fire up your Flex Builder 3 and follow this steps :

1. Create a Flex project called SampleFontTest and click Next.
2. Let the output folder be bin-debug and click Next.
3. In the Main Application Field, I usually prefer to name it as index.mxml, this is because when hosting on servers, its easy to deploy through scripts (don’t need t change name or do a mapping).
4. Now in the Navigator you should find your flex project, and in the libs folder add the FontsLibrary.swc.
5. Look at the code below for  index.mxml where during the project initialization the fonts are registered and can be used as fontNames for labels or text.

import com.thepixelcode.fonts.*;

//Registering fonts embedded in FontsLibrary.swc during initialization

public function init():void {

Font.registerFont(com.thepixelcode.fonts.EmbedGoudyTwenty);
Font.registerFont(com.thepixelcode.fonts.EmbedKomika);
Font.registerFont(com.thepixelcode.fonts.EmbedMothproof);
Font.registerFont(com.thepixelcode.fonts.EmbedSensation);

}

You can find the source code below to try and test, there are other ways to register the font, but would simply increase code or add would need to add CSS definitions for styles.

SampleTestFont Source Zip