Motorola C450, C550, C370 Using Sprites, Defining View Windows, PlayField Constructor

8

Gaming API and Sound

calling setAnimatedTileImage(-2, 2);, cells (0,0) and (0,1) will then be drawn with the image of static Tile 2.

Using Sprites

In addition to being a grid of cells, a Playfield can have a set of associated Sprites (see 0 item). When the PlayField is drawn, the grid is considered to have depth 0. Therefore, Sprites below the grid (Sprites with Sprite.getDepth() < 0) are drawn first. Then all cells in the grid are drawn. Then all the Sprites above the grid (Sprite.getDepth() >= 0) are drawn. The Sprites are drawn according to their location and visibility status as defined in the Sprite class. The location of Sprites is relative to the top-left corner of the PlayField.

Defining View Windows

A view window onto the PlayField can be defined using the method setViewWindow(). This defines the area of the PlayField that will be drawn by the draw() method. The default viewing window onto a PlayField (at construction time) is the entire area of the PlayField.

PlayField Constructor

The PlayField class defines the following constructors:

PlayField (int columns, int rows, Image img, int tWidth, int tHeight) throws NullPointerException, IllegalArgumentException - Creates a new PlayField with a tile set. The parameter are the following:

−columns - width of the PlayField in number of cells;

−rows - height of the PlayField in number of cells;

−img - Image to use for creating tiles;

−tWidth - width, in pixels, of the individual tiles;

−tHeight - height, in pixels, of the individual tiles.

It creates a new PlayField, rows cells high and columns cells wide. The static tile set for the PlayField will be created from subsections of the image passed in. The PlayField grid is initially filled with empty cells (tile 0 - a reserved tile and represents an empty square) and laying out tiles must be accomplished through the use of other methods in the class. The creation of the static tile set follows these standards:

Tiles must be equally sized, all being of the tile width (tWidth) and height

(tHeight) defined in the constructor parameters. They may be laid out in the image horizontally, vertically, or as a grid. The width of the source image must be an integer

49