J2ME游戏开发中使用层的概念[3]

        // Right
        if ((keyStates & RIGHT_PRESSED) != 0)
            if (currentX + 5 < width)
            {
                currentX = Math.min(width, currentX + 1);
                playerSprite.setFrame(3);
            }

        // Up
        if ((keyStates & UP_PRESSED) != 0)
        {
            currentY = Math.max(0, currentY - 1);
            playerSprite.setFrame(2);
        }

        // Down
        if ((keyStates & DOWN_PRESSED) != 0)
            if (currentY + 10 < height)
            {
                currentY = Math.min(height, currentY + 1);
                playerSprite.setFrame(4);
            }
    }

    // Method to Display Graphics
    private void drawScreen(Graphics g)
    {
        g.setColor(0xffffff);
        g.fillRect(0, 0, getWidth(), getHeight());
        g.setColor(0x0000ff);

        // updating player sprite position
        playerSprite.setPosition(currentX, currentY);

        layerManager.setViewWindow(55, 20, 140, 140);
        layerManager.paint(g, 20, 20);

        flushGraphics();
    }

}