j2me实现动态绘制滚动条,页面滚动操作.
1.计算相关参数
//元素总个数
musicCount = musicArray.length;
//滚动总高==屏幕高度-开始Y坐标-底部按钮高-动态move_top.
scrollHeight = screenHeight -
musicY - getImageHeight(Resources.button)
-
move_top;
//屏幕可显示元素个数==屏幕高度 / 每行高度
musicShowCount = scrollHeight /
contentHeight;
if (musicCount
<= musicShowCount) { //元素总个数 小于
屏幕可显示元素个数不会出滚动条
musicShowCount
= musicCount;
displayWidth
= screenWidth - musicX;
} else {
//**** 滚动条高度******
scroll_bar_height
= (musicShowCount * scrollHeight) / musicCount;
//***** 滚动条每次移动距离 *****
moveHeight =
scrollHeight / musicCount;
//***** 滚动条宽度 == 起始X坐标 - 滚动条宽
displayWidth
= screenWidth - musicX - scroll_bar_width;
}
1.计算相关参数