Motorola C370, C550, C450 technical manual Animation Frames, Sprite Drawing, Sprite Constructor

Animation Frames

An animated sprite is created from an image divided into sections as described in the constructor Sprite(Image, int, int). The individual sections of the image are considered the raw frames of the Sprite. The method getNumRawFrames returns the number of raw frames.

Sprite Drawing

Sprites can be drawn at anytime using the draw(Graphics) method. The sprite will be drawn on the Graphics object, according to the current state information maintained by the Sprite (i.e. position, frame, visibility). Some potential uses of Sprites include:

•Arbitrarily draw the Sprite on a GameScreen.

•A Sprite can be added to a PlayField. Then PlayField.draw(Graphics, int, int) will automatically draw all the Sprites associated with the PlayField.

•draw(Graphics) could be called from the paint() method in a subclass of

Canvas.

•draw(Graphics) could be called at any time to draw the Sprite on a MIDP mutable image. This is virtually identical to the first bullet, drawing on a GameScreen.

Only in the case where a set of Sprites are a part of a container object (i.e. where the Sprite is associated with a PlayField) is the depth information automatically handled by the system. In other situations, managing the drawing order is the responsibility of the developer.

Sprite Constructor

The Sprite class defines the following constructors:

•public Sprite(Image img) – Creates a new non-animated Sprite from an Image object. All animation operations on a non-animated Sprite behave as if there is a single raw frame. At construction time, the Sprite's position will be set to (0,0), the depth will be set to 0, and the Sprite will be visible. The Sprite shall behave as if the image used in creation were cached. If a mutable image is used to create the Sprite, the Sprite's appearance should not reflect changes to mutable source image.

•public Sprite(Image img, int fWidth, int fHeight) –

Creates a new animated Sprite from an Image. The constructor parameters are the following:

−img - Image to use for Sprite;

−fWidth - width, in pixels, of the individual raw frames;

−fHeight - height, in pixels, of the individual raw frames.