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));
                }
        }
}