AS3 zooming in and out where mouse clicked not at

问题:

I am trying to have a masked mouse panned image zoom in and out with a click and a double click mouse event. I got the image to zoom but it always zooms in on the left edge registration point, not where I click. I have absolutely no idea how to code this and have spent the whole day on the internet trying to figure it out with no luck. I am hoping someone can help me to figure this out!

import com.greensock.*;//Greensock Tweening Platform.

//Variables
var percX:Number;
var percY:Number;
var destX:Number;
var destY:Number;

//Image panned and masked
this.mask = mask_mc;
stage.addEventListener(MouseEvent.MOUSE_MOVE,mousemove);
function mousemove(e:MouseEvent) {
    if (mask_mc.hitTestPoint(stage.mouseX,stage.mouseY,false)) {
        if (imgLoader.width>mask_mc.width) {//Avoids Scrolling if image is under mask area width
            percX = mask_mc.mouseX/mask_mc.width;
        }
        if (imgLoader.height>mask_mc.height) {//Avoids Scrolling if image is under mask area height
            percY = mask_mc.mouseY/mask_mc.height;
        }
        destX = -(imgLoader.width-mask_mc.width)*percX;
        destY = -(imgLoader.height-mask_mc.height)*percY;
        TweenMax.to(imgLoader,.5,{x:destX,y:destY});
    }
}
//Add listeners for the imgLoader movie clip.
imgLoader.doubleClickEnabled = true;  
imgLoader.addEventListener(MouseEvent.CLICK, increaseSize);
imgLoader.addEventListener(MouseEvent.DOUBLE_CLICK, decreaseSize);

//This function increases the scale of the image
function increaseSize(event:MouseEvent):void{
TweenLite.to(imgLoader, 1, {scaleX:2, scaleY:2});
}

//This function decreases the scale of the image
function decreaseSize(event:MouseEvent):void{
TweenLite.to(imgLoader, 1, {scaleX:1, scaleY:1});
}

回答1:

This answer is derived from here

Add this function:

function scaleAroundMouse(objectToScale:DisplayObject, scaleAmount:Number, bounds:Rectangle = null, onComplete:Function = null):TweenLite {
    // scaling will be done relatively
    var relScaleX:Number = scaleAmount / objectToScale.scaleX;
    var relScaleY:Number = scaleAmount / objectToScale.scaleY;
    // map vector to centre point within parent scope

    var scalePoint:Point = objectToScale.localToGlobal( new Point(objectToScale.mouseX, objectToScale.mouseY));
    scalePoint = objectToScale.parent.globalToLocal( scalePoint );
    // current registered postion AB
    var AB:Point = new Point( objectToScale.x, objectToScale.y );
    // CB = AB - scalePoint, objectToScale vector that will scale as it runs from the centre
    var CB:Point = AB.subtract( scalePoint );
    CB.x *= relScaleX;
    CB.y *= relScaleY;
    // recaulate AB, objectToScale will be the adjusted position for the clip
    AB = scalePoint.add( CB );
    // set actual properties

    if(bounds){
     var limits:Rectangle = new Rectangle(
        bounds.x + (bounds.width - (objectToScale.width * relScaleX)),
        bounds.y + (bounds.height - (objectToScale.height * relScaleY)),
        (objectToScale.width * relScaleX) - bounds.width,
        (objectToScale.height * relScaleY) - bounds.height
     );

     if(AB.x < limits.x) AB.x = limits.x;
     if(AB.x > limits.x + limits.width) AB.x = limits.x + limits.width;
     if(AB.y < limits.y) AB.y = limits.y;
     if(AB.y > limits.y + limits.height) AB.y = limits.y + limits.height;       
    }

    return TweenLite.to(objectToScale,1,{onComplete: onComplete, scaleX: scaleAmount, scaleY: scaleAmount, x: AB.x, y: AB.y);
}

Then update your sizing function to this:

function increaseSize(event:MouseEvent):void{
    stopMouseMove();
    scaleAroundMouse(imgLoader, 2, null, resumeMouseMove);
}

function decreaseSize(event:MouseEvent):void{
    stopMouseMove();
    scaleAroundMouse(imgLoader, 1, null, resumeMouseMove);
}

function stopMouseMove():void {
   stage.removeEventListener(MouseEvent.MOUSE_MOVE,mousemove);
}

function resumeMouseMove():void {
   stage.addEventListener(MouseEvent.MOUSE_MOVE,mousemove);
}

I also added a bounds parameter to the function. This is useful if you never want the edges of you content to be visible within the mask. So if you could use it by passing the bounds of your mask to the function:

scaleAroundMouse(imgLoader, 1, myMask.getBounds(this));

回答2:

This example uses zoom effect classes that may help achieve the zoom effect you are looking for http://graphics-geek.blogspot.com/2010/06/video-image-zoom-effect-in-flex-4.html.

回答3:

var mat:Matrix=new Matrix();
mat.translate(-p.x,-p.y);
mat.scale(desiredScale,desiredScale);
mat.translate(p.x,p.y);
yourObject.transform.matrix=mat;

That is taken from a question I posted about a month ago. You can see it here. While I didn't end up going with that specific snippet (I actually went with a modified version of the script LondongDrugs_MediaServ posted), it will work and is much easier to understand and implement.