Progress Update

Time for a quick update on the huge progress I have made in the past few days.

Virtual Keyboard Parser

Thanks to Vicent's great work implementing the XMLParser base class this was a relatively simple task. There was a lot of error handling code to write, and I added a couple of new features to the base class. Apart from that it didn't take me long at all to have a parser that was parsing the file format that I had earlier settled upon.

Keyboard's main loop

This involved writing the event loop that would be run while the virtual keyboard was visible. It involved catching all the mouse click events, and passing them to the processClick() method. I also had to ensure the screen was being updated (so that the mouse cursor continued to move) and that EVENT_QUIT events were handled properly (so that closing the window had an effect).

Displaying the keyboard

The main challenge here was implementing keycolor transparency for the keyboard bitmap. To do this I created a subclass of Surface, SurfaceKeyColored, that provided a blit() method. This method would be passed a source Surface and a transparency color, and any pixels in the source Surface that was not the same color as the transparency color, would be copied into the Surface. Once I had this class, I could grab the overlay into an instance of SurfaceKeyColored, then blit the keyboard bitmap's Surface into it, before copying the SurfaceKeyColored's pixels back into the overlay. Below are some images demonstrating it in action:

Imagemap testing

After I had the bitmap's being displayed and the event loop implemented, I could test my image map code that I had written last week. The processClick() method of my VirtualKeyboard class simply had to pass the mouse co-ordinates to the corresponding ImageMap class and it would return the ID string (ie. the target attribute) of the matching area. I created a few image map areas for some keys of my test image in GIMP (making sure to use rectangle and polygon areas), then used the exported HTML in my keyboard pack XML file. After a couple of bugfixes I got the ImageMap working perfectly, proving that my Polygon::contains() method was correct.

Delivery of virtual events

I had written the VirtualKeyboard class to save all the key presses it created into a queue. But, once it was no longer visible it had to insert these key press events into the main event queue. I decided that the VirtualKeyboard should have a pollEvent() method, that would return an event if the keyboard was closed and there was a key press in the queue. Then all I had to do was modify the DefaultEventManager to first poll the VirtualKeyboard, and then poll the backend, but only if the VirtualKeyboard did not return an event. The DefaultEventManager class was also made responsible for showing the virtual keyboard when a special button press was made. While writing this code, it was decided that the VirtualKeyboard class should be instantiated from within the DefaultEventManager class, because they were very closely related.

Next...

Tomorrow I will try to create a complete keyboard pack, with multiple modes and resolutions, together with complete image maps, and event specifications. This will allow me to fully test my current code, as well as test the little bits of code that I am still to write.