我以为这是一个简单的任务,但我错了。
我使用精灵来显示图像,当用户拖动它(MOUSE_DOWN和MOUSE_MOVE)时,我得到了位置MOUSE_MOVE
并计算偏移量:
var current: Point = new Point(event.localX, event.localY);
sprite.x = current.x - start.x;
sprite.y = current.y - start.y;
它可以工作但不顺利。有更好的解决方案吗?
UPDATE
经过一天的调试,终于找到了原因。
Bigger fps可以让它更流畅,但这不是这个问题的关键。
关键是我应该用stage
听MOUSE_MOVE
,而不是图像本身。当获取鼠标位置时,我应该使用event.stageX/Y
(or stage.mouseX/Y
), not event.localX/Y
. The event.localX/Y
从移动图像来看,既不稳定也不流畅,这导致了我的问题。
以下是我的工作代码,享受它:)
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);
}
}
}
来,试试这个。它只是一个简单的黑色方块,但看起来很好,直到你really开始拖动它。如前所述,将帧速率设置为更高是理想的。在这种情况下,出于内存原因,我决定将 MOUSE_DOWN 中的帧速率提高到 60fps,并在 MOUSE_UP 中将其降至 24。显然你可以随心所欲地改变它。
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;
}
确保删除 MOUSE_UP 上的 MOUSE_MOVE 事件。这是关键。否则,您会在每次 MOUSE_DOWN 上重新添加事件,并最终同时重复运行相同的代码。抱歉,我的语法不是 100% 正确;我在 CS5.5 中很快地将这些组合在一起,而不是在 Flash Builder 中进行。
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