J2ME下实现滚动文字效果

J2ME下实现滚动文字也很简单,就是基于剪裁区的应用

看一下效果:

来看一下代码:

private int tipStringPos = SCREEN_WIDTH; //当前字符串左边的位置
private int tipStringSpeed = 2; //字符串移动速度
private static final int TIPSTR_LEFT = 5 - 5; //左边消失绘制坐标
private static final int TIPSTR_RIGHT = 123 + 5; //右边出现绘制坐标

private static final int FONT_HEIGHT = 11; //字体高度 font.getHeight() 不准确

/**
 * @param Graphics g - 画刷
 * @param String str - 所画字符串
 * @param int height - 字符串高度
 * @param int rectX - 剪裁区顶点X坐标
 * @param int rectY - 剪裁区顶点Y坐标
 * @param int rectWidth - 剪裁区宽度
 * @param int rectHeight - 剪裁区高度
 */

private void drawTipString(Graphics g, String str, int height, 
			int rectX, int rectY, int rectWidth, int rectHeight) {
	int strWidth = g.getFont().stringWidth(str);
	int strHeight = FONT_HEIGHT;
	
	tipStringPos -= tipStringSpeed;
	if (tipStringPos + strWidth < TIPSTR_LEFT) {
		tipStringPos = TIPSTR_RIGHT;
	}

	//裁减区
	int oldClipX = g.getClipX();
	int oldClipY = g.getClipY();
	int oldClipWidth = g.getClipWidth();
	int oldClipHeight = g.getClipHeight();

	g.setClip(rectX, rectY, rectWidth, rectHeight);

	g.drawString(str, tipStringPos, height - strHeight / 2,
				 Graphics.LEFT | Graphics.TOP);
	g.setClip(oldClipX, oldClipY, oldClipWidth, oldClipHeight);
}

原理是很简单的,我感觉算法还是比较幼稚的,呵呵,你的算法呢?