如何拖动图像平滑地移动它在屏幕上，使用ActionScript？拖动、平滑、它在、图像
我在想这是个简单的任务，但是我错了。
我用了一个精灵来显示图像，而当用户拖动它（MOUSE_DOWN和MOUSE_MOVE），我得到的位置 MOUSE_MOVE 和计算的偏移量：
无功电流：点=新的点（event.localX，event.localY）;
sprite.x = current.x - start.x;
sprite.y = current.y - start.y;
它的工作原理，但并不顺利。有没有更好的解决办法？
更新
调试了一天之后，我终于找到了原因。
更大的 FPS 可以让它流畅，但它不是对这个问题的关键所在。
关键是我应该使用期来听 MOUSE_MOVE ，而不是图像本身。并获得鼠标位置的时候，我应该使用 event.stageX / Y （或 stage.mouseX / Y ），没有 event.localX / Y 。该 event.localX / Y 从运动图像，既不稳定，也不流畅，导致我的问题。
以下是我的工作code，乐在其中：）
包{
匹配import flash.display.Bitmap;
进口flash.display.Loader;
进口flash.display.Sprite;
进口对象类型：flash.events.Event;
进口flash.events.MouseEvent;
进口flash.geom.Matrix;
进口flash.geom.Point;
进口flash.net.URLRequest;
进口API元素flash.text.TextField;
公共类DragIssue扩展Sprite {
私有静态常量网址：字符串=财产/ m1.jpg;
私人VAR自：DragIssue;
私人VAR精灵：精灵;
私人VAR的startPoint：点;
私人VAR offsetX：数= 0;
私人VAR offsetY：数= 0;
公共职能DragIssue（）{
自=这一点;
在里面（）;
的LoadImage（）;
}
保护功能的init（）：无效{
如果（阶段== NULL）{
this.addEventListener（Event.ADDED_TO_STAGE，on_addedToStage）;
} 其他 {
stage.addEventListener（的MouseEvent.MOUSE_MOVE，的OnMouseMove）;
}
功能on_addedToStage（事件：事件）：无效{
self.removeEventListener（Event.ADDED_TO_STAGE，on_addedToStage）;
stage.addEventListener（的MouseEvent.MOUSE_MOVE，的OnMouseMove）;
}
}
公共职能的LoadImage（）：无效{
VAR装载机：装载机=新的Loader（）;
loader.contentLoaderInfo.addEventListener（引发Event.COMPLETE，imageLoaded）;
loader.load（新的URLRequest（URL））;
功能imageLoaded（事件：事件）：无效{
VAR位：位图= event.target.content为位图;
self.sprite =新的Sprite（）;
sprite.addChild（位）;
self.addChild（精灵）;
sprite.addEventListener（的MouseEvent.MOUSE_DOWN，onmousedown事件）;
sprite.addEventListener（侦听MouseEvent.MOUSE_UP，onMouseUp）;
}
}
私有函数的OnMouseMove（事件：MouseEvent）方法：无效{
如果（的startPoint）{
sprite.x = offsetX + event.stageX - startPoint.x;
sprite.y = offsetY + event.stageY - startPoint.y;
}
}
私有函数onMouseUp（事件：MouseEvent）方法：无效{
的startPoint = NULL;
offsetX = sprite.x;
offsetY = sprite.y;
}
私有函数onmousedown事件（事件：MouseEvent）方法：无效{
的startPoint =新的点（event.stageX，event.stageY）;
}
}
}
解决方案 
下面，试试这个。这只是一个简单的黑色正方形，但看起来很好，直到你的真正的开始拖拽它。正如所提到的，帧率设置为更高的东西是最理想的。在这种情况下，我决定了帧率在MOUSE_DOWN 60fps的落回至24日在MOUSE_UP内存的原因。可以很明显的改变，请您如何。
进口flash.display使用*。
进口flash.events *。
VAR STARTX：数字;
VAR startY：数字;
VAR形状：雪碧=新的Sprite（）;
shape.graphics.beginFill（0x000000处）;
shape.graphics.drawRect（0,0,50,50）;
shape.graphics.endFill（）;
this.addChild（形状）;
shape.addEventListener（的MouseEvent.MOUSE_DOWN，this.mouseDown）;
功能MOUSEDOWN（E：的MouseEvent = NULL）：无效{
stage.frameRate = 60;
STARTX = stage.mouseX - shape.x;
startY = stage.mouseY - shape.y;
stage.addEventListener（的MouseEvent.MOUSE_MOVE，this.mouseMove）;
shape.addEventListener（侦听MouseEvent.MOUSE_UP，this.mouseUp）;
}
功能的mouseMove（E：的MouseEvent = NULL）：无效{
shape.x = stage.mouseX - STARTX;
shape.y = stage.mouseY - startY;
}
功能mouseUp事件（E：的MouseEvent = NULL）：无效{
shape.removeEventListener（侦听MouseEvent.MOUSE_UP，this.mouseUp）;
stage.removeEventListener（的MouseEvent.MOUSE_MOVE，this.mouseMove）;
stage.frameRate = 24;
}
请确保您在MOUSE_UP去除MOUSE_MOVE事件。这是关键。否则，你再添加事件上的每个MOUSE_DOWN，最终重复运行相同的code，同时进行。很抱歉，我的语法是不是100％正确的;我在CS5.5扔了一起非常快的，而不是做在Flash Builder中。
I was thinking this is a simple task, but I'm wrong.
I used a sprite to display an image, and when user drag it(MOUSE_DOWN and MOUSE_MOVE), I got the position in MOUSE_MOVE and calculated the offsets:
var current: Point = new Point(event.localX, event.localY);
sprite.x = current.x - start.x;
sprite.y = current.y - start.y;
It works but not smooth. Is there a better solution?
UPDATE
After a day of debugging, I finally found the reason.
Bigger fps can make it smoother, but it's not the key of this question.
The key is I should use stage to listen MOUSE_MOVE, not the image itself. And when getting the mouse position, I should use event.stageX/Y(or stage.mouseX/Y), not event.localX/Y. The event.localX/Y from the moving image, is neither stable nor smooth, that causes my problem.
Following is my working code, enjoy it :)
package {
import flash.display.Bitmap;
import flash.display.Loader;
import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;
import flash.geom.Matrix;
import flash.geom.Point;
import flash.net.URLRequest;
import flash.text.TextField;
public class DragIssue extends Sprite {
private static const URL: String = "assets/m1.jpg";
private var self: DragIssue;
private var sprite: Sprite;
private var startPoint: Point;
private var offsetX: Number = 0;
private var offsetY: Number = 0;
public function DragIssue() {
self = this;
init();
loadImage();
}
protected function init(): void {
if (stage == null) {
this.addEventListener(Event.ADDED_TO_STAGE, on_addedToStage);
} else {
stage.addEventListener(MouseEvent.MOUSE_MOVE, onMouseMove);
}
function on_addedToStage(event: Event): void {
self.removeEventListener(Event.ADDED_TO_STAGE, on_addedToStage);
stage.addEventListener(MouseEvent.MOUSE_MOVE, onMouseMove);
}
}
public function loadImage(): void {
var loader: Loader = new Loader();
loader.contentLoaderInfo.addEventListener(Event.COMPLETE, imageLoaded);
loader.load(new URLRequest(URL));
function imageLoaded(event: Event): void {
var bitmap: Bitmap = event.target.content as Bitmap;
self.sprite = new Sprite();
sprite.addChild(bitmap);
self.addChild(sprite);
sprite.addEventListener(MouseEvent.MOUSE_DOWN, onMouseDown);
sprite.addEventListener(MouseEvent.MOUSE_UP, onMouseUp);
}
}
private function onMouseMove(event: MouseEvent): void {
if (startPoint) {
sprite.x = offsetX + event.stageX - startPoint.x;
sprite.y = offsetY + event.stageY - startPoint.y;
}
}
private function onMouseUp(event: MouseEvent): void {
startPoint = null;
offsetX = sprite.x;
offsetY = sprite.y;
}
private function onMouseDown(event: MouseEvent): void {
startPoint = new Point(event.stageX, event.stageY);
}
}
}
解决方案
Here, try this. It's just a simple black square, but it looks fine until you really start dragging it around. As was mentioned, setting the framerate to something higher is ideal. In this case, I decided to up the framerate to 60fps in the MOUSE_DOWN and drop it back to 24 in MOUSE_UP for memory reasons. You can obviously change that how you please.
import flash.display.*;
import flash.events.*;
var startX:Number;
var startY:Number;
var shape:Sprite = new Sprite();
shape.graphics.beginFill(0x000000);
shape.graphics.drawRect(0,0,50,50);
shape.graphics.endFill();
this.addChild(shape);
shape.addEventListener(MouseEvent.MOUSE_DOWN,this.mouseDown);
function mouseDown(e:MouseEvent = null):void{
stage.frameRate = 60;
startX = stage.mouseX - shape.x;
startY = stage.mouseY - shape.y;
stage.addEventListener(MouseEvent.MOUSE_MOVE,this.mouseMove);
shape.addEventListener(MouseEvent.MOUSE_UP,this.mouseUp);
}
function mouseMove(e:MouseEvent = null):void{
shape.x = stage.mouseX - startX;
shape.y = stage.mouseY - startY;
}
function mouseUp(e:MouseEvent = null):void{
shape.removeEventListener(MouseEvent.MOUSE_UP,this.mouseUp);
stage.removeEventListener(MouseEvent.MOUSE_MOVE,this.mouseMove);
stage.frameRate = 24;
}
Make sure you are removing the MOUSE_MOVE event on MOUSE_UP. That is key. Otherwise, you re-add the event on every MOUSE_DOWN and end up running the same code repeatedly, simultaneously. Sorry my syntax isn't 100% proper; I threw this together really quick in CS5.5 rather than doing it in Flash Builder.
