位图的九宫缩放

AS3中只有矢量图才支持9格缩放, 而位图设置了scale9Grid也不起作用;

解决方法:  1, 把位图打散成矢量图,然后切成9分,再合并;    BitmapSlice9.zip.      

我一般都采用这种方式, 但这个方法有个瑕疵,  图像拉伸后,经常出现虚边 和 细缝;

2.另一中方法是用程序控制，原理很简单:用程序把位图切成九块,装里一个Sprite里,然后重写Sprite的width和height这两个方法,根据改变大小来重新设置位图的各个位置.这样就实现了位图的不变形缩放.

package
{
        import flash.display.Sprite;
        import flash.display.Bitmap;
        import flash.display.BitmapData;
        import flash.geom.Rectangle;
        import flash.geom.Point;
        
        public class BitmapScale9Grid extends Sprite
        {
                private var source : Bitmap;
                private var scaleGridTop : Number;
                private var scaleGridBottom : Number;
                private var scaleGridLeft : Number;
                private var scaleGridRight : Number;
                
                private var leftUp : Bitmap;
                private var leftCenter : Bitmap;
                private var leftBottom : Bitmap;
                private var centerUp : Bitmap;
                private var center : Bitmap;
                private var centerBottom : Bitmap;
                private var rightUp : Bitmap;
                private var rightCenter : Bitmap;
                private var rightBottom : Bitmap;
                
                private var _width : Number;
                private var _height : Number;
                
                private var minWidth : Number;
                private var minHeight : Number;
                
                public function BitmapScale9Grid(source:Bitmap, scaleGridTop:Number, scaleGridBottom:Number, scaleGridLeft:Number, scaleGridRight:Number ) 
                {
                        this.source = source;
                        this.scaleGridTop = scaleGridTop;
                        this.scaleGridBottom = scaleGridBottom;
                        this.scaleGridLeft = scaleGridLeft;
                        this.scaleGridRight = scaleGridRight;
                        init();
                        
                }
                
                private function init() : void {
                        _width = source.width;
                        _height = source.height;
                        
                        leftUp = getBitmap(0, 0, scaleGridLeft, scaleGridTop);
                        this.addChild(leftUp);
                        
                        leftCenter = getBitmap(0, scaleGridTop, scaleGridLeft, scaleGridBottom - scaleGridTop);
                        this.addChild(leftCenter);
                        
                        leftBottom = getBitmap(0, scaleGridBottom, scaleGridLeft, source.height - scaleGridBottom);
                        this.addChild(leftBottom);
                        
                        centerUp = getBitmap(scaleGridLeft, 0, scaleGridRight - scaleGridLeft, scaleGridTop);
                        this.addChild(centerUp);
                        
                        center = getBitmap(scaleGridLeft, scaleGridTop, scaleGridRight - scaleGridLeft, scaleGridBottom - scaleGridTop);
                        this.addChild(center);
                        
                        centerBottom = getBitmap(scaleGridLeft, scaleGridBottom, scaleGridRight - scaleGridLeft, source.height - scaleGridBottom);
                        this.addChild(centerBottom);
                        
                        rightUp = getBitmap(scaleGridRight, 0, source.width - scaleGridRight, scaleGridTop);
                        this.addChild(rightUp);
                        
                        rightCenter = getBitmap(scaleGridRight, scaleGridTop, source.width - scaleGridRight, scaleGridBottom - scaleGridTop);
                        this.addChild(rightCenter);
                        
                        rightBottom = getBitmap(scaleGridRight, scaleGridBottom, source.width - scaleGridRight, source.height - scaleGridBottom);
                        this.addChild(rightBottom);
                        
                        minWidth = leftUp.width + rightBottom.width;
                        minHeight = leftBottom.height + rightBottom.height;
                }
                
                private function getBitmap(x:Number, y:Number, w:Number, h:Number) : Bitmap {
                        var bit:BitmapData = new BitmapData(w, h);
                        bit.copyPixels(source.bitmapData, new Rectangle(x, y, w, h), new Point(0, 0));
                        var bitMap:Bitmap = new Bitmap(bit);
                        bitMap.x = x;
                        bitMap.y = y;
                        return bitMap;
                }
                
                override public function set width(w : Number) : void {
                        if(w < minWidth) {
                                w = minWidth;
                        }
                        _width = w;
                        refurbishSize();
                }
                
                override public function set height(h : Number) : void {
                        if(h < minHeight) {
                                h = minHeight;
                        }
                        _height = h;
                        refurbishSize();
                }
                
                private function refurbishSize() : void {
                        leftCenter.height = _height - leftUp.height - leftBottom.height;
                        leftBottom.y = _height - leftBottom.height;
                        centerUp.width = _width - leftUp.width - rightUp.width;
                        center.width = centerUp.width;
                        center.height = leftCenter.height;
                        centerBottom.width = center.width;
                        centerBottom.y = leftBottom.y;
                        rightUp.x = _width - rightUp.width;
                        rightCenter.x = rightUp.x;
                        rightCenter.height = center.height;
                        rightBottom.x = rightUp.x;
                        rightBottom.y = leftBottom.y;
                }
        }
}