Flash AS3教程:动态文本滚动条

学as3几个星期了，发一个我的小练习：动态文本滚动条
功能说明：
本版滚动条除了继续保持体积小（小于2k），界面容易修改，资源占用率小的优势外，主要有以下几点改进：

使用as3编写。 宽高动态指定。 增加滚动条背景点击事件。 消除了鼠标滚轮无法同时准确控制多个文本框的重大bug。

源文件下载
使用方法见源文件
为了方便懒人，直接帖一下代码：
package com.qoolu.component
{
import flash.events.mouseevent;
import flash.events.event;
import flash.display.simplebutton;
import flash.text.textfield;
import flash.display.sprite;
import flash.utils.gettimer;
import flash.geom.rectangle;
/**
* @author 寂寞火山:[url]http://www.huoshan.org[/url]
* @version v5 [08.3.15]
* 动态文本滚动条
*/
public class scrollbar extends sprite {
//=============本类属性==============
////接口元件
private var scrolltext : textfield;
private var scrollbar_sprite : sprite;
private var up_btn : simplebutton;
private var down_btn : simplebutton;
private var pole_sprite : sprite;
private var bg_sprite : sprite;
////初始数据
private var polestartheight : number;
private var polestarty : number;
private var totalpixels : number;
private var isselect : boolean;
////上下滚动按钮按钮下时间
private var puttime : number;
/**
* @param scrolltext_fc:被滚动的文本框
* @param scrollbarmc_fc：舞台上与本类所代理的滚动条元件
* @param height_fc：滚动条高
* @param width_fc：滚动条宽
*/
public function scrollbar(scrolltext_fc : textfield, scrollbarmc_fc : sprite, height_fc : uint = 0,width_fc : uint = 0) {
//——————滚动条_sprite，滚动条按钮和滑块mc，被滚动的文本域初始化
scrolltext = scrolltext_fc;
scrollbar_sprite = scrollbarmc_fc;
up_btn = simplebutton(scrollbar_sprite.getchildbyname("up_btn"));
down_btn = simplebutton(scrollbar_sprite.getchildbyname("down_btn"));
pole_sprite = sprite(scrollbar_sprite.getchildbyname("pole_mc"));
bg_sprite = sprite(scrollbar_sprite.getchildbyname("bg_mc"));

//——————可用性控制
pole_sprite.visible = false;
up_btn.enabled = false;
down_btn.enabled = false;

//——————其他属性初始化
bg_sprite.usehandcursor = false;
isselect = scrolltext.selectable;
if(height_fc == 0) {
bg_sprite.height = scrolltext.height;
}else {
bg_sprite.height = height_fc;
}
if(width_fc != 0) {
bg_sprite.width = width_fc 2;
pole_sprite.width = width_fc;
up_btn.width = up_btn.height = down_btn.width = down_btn .height = width_fc;
}
down_btn.y = bg_sprite.y bg_sprite.height - down_btn.height - 1;
polestartheight = math.floor(down_btn.y - up_btn.y - up_btn.height);
polestarty = pole_sprite.y = math.floor(up_btn.y up_btn.height);

//——————注册侦听器
//文本滚动与鼠标滚轮
scrolltext.addeventlistener(event.scroll, textscroll);
scrolltext.addeventlistener(mouseevent.mouse_wheel, mousewheel);
//上滚动按钮
up_btn.addeventlistener(mouseevent.mouse_down, upbtn);
up_btn.stage.addeventlistener(mouseevent.mouse_up, upbtnup);
//下滚动按钮
down_btn.addeventlistener(mouseevent.mouse_down, downbtn);
down_btn.stage.addeventlistener(mouseevent.mouse_up, downbtnup);
//滑块
pole_sprite.addeventlistener(mouseevent.mouse_down, polesprite);
pole_sprite.stage.addeventlistener(mouseevent.mouse_up, poleup);
//滑块背景点击
bg_sprite.addeventlistener(mouseevent.mouse_down, bgdown);
}
/**
* 文本滚动事件
*/
private function textscroll(event : event) : void {
//判断滑块儿是否显示，并根据文本内容多少定义滑块高度
if(scrolltext.maxscrollv != 1) {
pole_sprite.visible = true;
up_btn.enabled = true;
down_btn.enabled = true;
//定义一个高度因子，此因子随加载文本的增多，将无限趋向于1
var heightvar : number = 1 - (scrolltext.maxscrollv - 1) / scrolltext.maxscrollv;
//根据高度因子初始化滑块的高度
pole_sprite.height = math.floor(polestartheight * math.pow(heightvar, 1 / 3));
totalpixels = math.floor(down_btn.y - up_btn.y - up_btn.height - pole_sprite.height);
pole_sprite.y = math.floor(polestarty totalpixels * (scrolltext.scrollv - 1) / (scrolltext.maxscrollv - 1));
}else {
pole_sprite.visible = false;
up_btn.enabled = false;
down_btn.enabled = false;
}
}
/**
* 滑块滚动
*/
private function polesprite(event : mouseevent) : void {
//首先取消文本框滚动侦听，因为文本滚动的时候会设置滑块的位置，而此时是通过滑块调整文本的位置，所以会产生冲突
scrolltext.removeeventlistener(event.scroll, textscroll);
//监听舞台，这样可以保证拖动滑竿的时候，鼠标在舞台的任意位置松手，都会停止拖动
scrollbar_sprite.stage.addeventlistener(mouseevent.mouse_up, poleup);
//限定拖动范围
var dragrect : rectangle = new rectangle(pole_sprite.x, polestarty, 0, totalpixels);
pole_sprite.startdrag(false, dragrect);
scrollbar_sprite.addeventlistener(event.enter_frame, poledown);
}
private function poledown(event : event) : void {
//在滚动过程中及时获得滑块所处位置
var nowposition : number = math.floor(pole_sprite.y);
//使文本随滚动条滚动,这里为什么要加1，可见scroll属性值应该是取正的，也就是说它会删除小数部分，而非采用四舍五入制？
scrolltext.scrollv = (scrolltext.maxscrollv - 1) * (nowposition - polestarty) / totalpixels 2;
//误差校正
var unitpixels : number = totalpixels / (scrolltext.maxscrollv - 1);
if((nowposition - polestarty) < unitpixels) {
scrolltext.scrollv = (scrolltext.maxscrollv - 1) * (nowposition - polestarty) / totalpixels;
}
}
private function poleup(event : mouseevent) : void {
pole_sprite.stopdrag();
scrollbar_sprite.removeeventlistener(event.enter_frame, poledown);
scrollbar_sprite.stage.removeeventlistener(mouseevent.mouse_up, poleup);
scrolltext.addeventlistener(event.scroll, textscroll);
}
/**
* 滑块背景点击
*/
private function bgdown(event : mouseevent) : void {
var nowposition : number;
if((scrollbar_sprite.mousey - up_btn.y) < (pole_sprite.height / 2)) {
nowposition = math.floor(up_btn.y up_btn.height);
}else if((down_btn.y - scrollbar_sprite.mousey) < pole_sprite.height / 2) {
nowposition = math.floor(down_btn.y - pole_sprite.height);
}else {
nowposition = scrollbar_sprite.mousey - pole_sprite.height / 2;
}
pole_sprite.y = nowposition;
scrolltext.scrollv = (scrolltext.maxscrollv - 1) * (nowposition - polestarty) / totalpixels 2;
var unitpixels : number = totalpixels / (scrolltext.maxscrollv - 1);
if((nowposition - polestarty) < unitpixels) {
scrolltext.scrollv = (scrolltext.maxscrollv - 1) * (nowposition - polestarty) / totalpixels 1;
}
}
/**
* 下滚动按钮
*/
private function downbtn(event : mouseevent) : void {
scrolltext.scrollv ;
pole_sprite.y = math.floor(polestarty totalpixels * (scrolltext.scrollv - 1) / (scrolltext.maxscrollv - 1));
//当鼠标在按钮上按下的时间大于设定时间时，连续滚动
puttime = gettimer();
scrollbar_sprite.addeventlistener(event.enter_frame, downbtndown);
}
private function downbtndown(event : event) : void {
if(gettimer() - puttime > 500) {
scrolltext.scrollv ;
pole_sprite.y = math.floor(polestarty totalpixels * (scrolltext.scrollv - 1) / (scrolltext.maxscrollv - 1));
}
}
private function downbtnup(event : mouseevent) : void {
scrollbar_sprite.removeeventlistener(event.enter_frame, downbtndown);
}
/**
* 上滚动按钮
*/
private function upbtn(event : mouseevent) : void {
scrolltext.scrollv--;
pole_sprite.y = math.floor(polestarty totalpixels * (scrolltext.scrollv - 1) / (scrolltext.maxscrollv - 1));
//当鼠标在按钮上按下的时间大于设定时间时，连续滚动
puttime = gettimer();
scrollbar_sprite.addeventlistener(event.enter_frame, upbtndown);
}
private function upbtndown(event : event) : void {
if(gettimer() - puttime > 500) {
scrolltext.scrollv--;
pole_sprite.y = math.floor(polestarty totalpixels * (scrolltext.scrollv - 1) / (scrolltext.maxscrollv - 1));
}
}
private function upbtnup(event : mouseevent) : void {
scrollbar_sprite.removeeventlistener(event.enter_frame, upbtndown);
}
/**
* 鼠标滚轮事件
*/
private function mousewheel(event : mouseevent) : void {
if(isselect == false) {
scrolltext.scrollv -= math.floor(event.delta / 2);
}else if(isselect == true) {
event.delta = 1;
}
pole_sprite.y = math.floor(polestarty totalpixels * (scrolltext.scrollv - 1) / (scrolltext.maxscrollv - 1));
}
}
}