Math 将小图像中的rect映射到大图像（以便执行copyPixels操作）

我认为这是一个相对简单的数学问题，但我花了一天的时间用头撞它，只有凹痕，没有答案

我在actionscript 3中编写代码-功能是：

运行时加载的大型图像。bitmapData被存储，并且创建了一个较小的版本以显示在可用的屏幕区域上，我可能最终只是缩放大图像，因为它在内存中

用户可以在较小的图像上创建一个矩形热点。功能将更加复杂：多个具有透明度的矩形：例如带孔的圆环形状，等等

3当用户单击热点时，热点的矩形将映射到较大的图像，并使用较大的位图数据创建新的位图标注。这样做的原因是，详图索引的质量将优于仅放大热点区域的质量

下图显示了我目前所处的位置——蓝色矩形是点击的热点。左上角是从较大图像复制的详图索引。我有正确的纵横比，但我没有正确映射到更大的图像

下面是丑陋的代码。。。对不起，这篇文章太长了-我只是觉得我应该提供尽可能多的信息。谢谢你的提示

-跟踪我的数据值

*源位图数据1152 864

缩放到rect 800 600

缩放位图数据800 600

选择位图数据58 56

比例选择83 80

比率1.44

在x=544，y=237，w=58，h=56之前

x=544，y=237，w=225.04，h=217.28 *

图片如下：

谢谢

public function onExpandCallout(event:MouseEvent):void{
// TODO: build this on startup or only on click? Speed vs memory

if (calloutState == true) return;

if (maskBitmapData.getPixel32(event.localX, event.localY) != 0){

    calloutState = true;

    //create bitmap from source using scaled selection rect
    var ratio:Number =  (sourceBMD.width /targetRect.width);
    var sRect:Rectangle = hotSpotSprite.getBounds(bkgnImageSprite);
    var destRect:Rectangle = new Rectangle(sRect.x * ratio, sRect.y * ratio, sRect.width * ratio, sRect.height * ratio);
    calloutBitmapData = new BitmapData(destRect.width, destRect.height, true, 0xFFFFFFFF);
    calloutBitmap = new Bitmap(calloutBitmapData);

    //-- scale alpha mask
    var scaledMaskBitmapData:BitmapData =  new BitmapData(destRect.width, destRect.height, true, 0x00000000);
    var maskScale:Number = scaledMaskBitmapData.width / maskBitmapData.width;
    var mMatrix:Matrix = new Matrix(maskScale, 0, 0, maskScale);
    scaledMaskBitmapData.draw(maskBitmapData,mMatrix,null,null,null, false);

    // copy source with scaled alpha  
    calloutBitmapData.copyPixels(sourceBMD, destRect, new Point(), scaledMaskBitmapData, new Point());

    scaledMaskBitmapData = null;

    // apply filter to bitmap
    var myDropShadowFilter:DropShadowFilter = new DropShadowFilter();
    myDropShadowFilter.distance = 12;
    myDropShadowFilter.alpha = .3
    myDropShadowFilter.strength = 1;
    myDropShadowFilter.blurX = 8;
    myDropShadowFilter.blurY = 8;
    calloutBitmap.filters = [myDropShadowFilter];

    //place on screen
    calloutSprite = new Sprite();
    calloutSprite.addChild(calloutBitmap)
    calloutSprite.x = offsetPt.x;
    calloutSprite.y = offsetPt.y;
    // ADD TO PARENT DisplayContainer
    calloutLayer.addChild(calloutSprite);

    //              calloutSprite.scaleX = 2;
    //              calloutSprite.scaleY = 2;
    calloutSprite.doubleClickEnabled = true;

    calloutSprite.addEventListener(MouseEvent.DOUBLE_CLICK, onCollapseCallout); 
    calloutSprite.addEventListener(MouseEvent.MOUSE_DOWN, onStartDrag); 
    calloutSprite.addEventListener(MouseEvent.MOUSE_UP, onStopDrag);    
}

}

public function onExpandCallout(event:MouseEvent):void{
// TODO: build this on startup or only on click? Speed vs memory

if (calloutState == true) return;

if (maskBitmapData.getPixel32(event.localX, event.localY) != 0){

    calloutState = true;

    //create bitmap from source using scaled selection rect
    var ratio:Number =  (sourceBMD.width /targetRect.width);
    var sRect:Rectangle = hotSpotSprite.getBounds(bkgnImageSprite);
    var destRect:Rectangle = new Rectangle(sRect.x * ratio, sRect.y * ratio, sRect.width * ratio, sRect.height * ratio);
    calloutBitmapData = new BitmapData(destRect.width, destRect.height, true, 0xFFFFFFFF);
    calloutBitmap = new Bitmap(calloutBitmapData);

    //-- scale alpha mask
    var scaledMaskBitmapData:BitmapData =  new BitmapData(destRect.width, destRect.height, true, 0x00000000);
    var maskScale:Number = scaledMaskBitmapData.width / maskBitmapData.width;
    var mMatrix:Matrix = new Matrix(maskScale, 0, 0, maskScale);
    scaledMaskBitmapData.draw(maskBitmapData,mMatrix,null,null,null, false);

    // copy source with scaled alpha  
    calloutBitmapData.copyPixels(sourceBMD, destRect, new Point(), scaledMaskBitmapData, new Point());

    scaledMaskBitmapData = null;

    // apply filter to bitmap
    var myDropShadowFilter:DropShadowFilter = new DropShadowFilter();
    myDropShadowFilter.distance = 12;
    myDropShadowFilter.alpha = .3
    myDropShadowFilter.strength = 1;
    myDropShadowFilter.blurX = 8;
    myDropShadowFilter.blurY = 8;
    calloutBitmap.filters = [myDropShadowFilter];

    //place on screen
    calloutSprite = new Sprite();
    calloutSprite.addChild(calloutBitmap)
    calloutSprite.x = offsetPt.x;
    calloutSprite.y = offsetPt.y;
    // ADD TO PARENT DisplayContainer
    calloutLayer.addChild(calloutSprite);

    //              calloutSprite.scaleX = 2;
    //              calloutSprite.scaleY = 2;
    calloutSprite.doubleClickEnabled = true;

    calloutSprite.addEventListener(MouseEvent.DOUBLE_CLICK, onCollapseCallout); 
    calloutSprite.addEventListener(MouseEvent.MOUSE_DOWN, onStartDrag); 
    calloutSprite.addEventListener(MouseEvent.MOUSE_UP, onStopDrag);    
}