android – 如何使路线绘图更有效率？

概述这是我用来绘制路线的代码.当我有1000点时,路线严重减慢了ui.也许有人可以提供代码片段或链接来解释如何更有效地进行路线绘制？我知道解决这个问题的一种方法是缓存位图的路径,但不知道如何做到这一点. public class PathOverlay extends Overlay{private GeoPoint startPoint;private GeoPoint finishPoint 这是我用来绘制路线的代码.当我有1000点时,路线严重减慢了ui.也许有人可以提供代码片段或链接来解释如何更有效地进行路线绘制？我知道解决这个问题的一种方法是缓存位图的路径,但不知道如何做到这一点.

public class PathOverlay extends Overlay{private GeoPoint startPoint;private GeoPoint finishPoint;private ArrayList<GeoPoint> pathPoints;private Paint paint;private Path path;private Point pathStartPoint;private Point pathEndPoint;private float dx;private float dy;public PathOverlay(GeoPoint startPoint,GeoPoint finishPoint,ArrayList<GeoPoint> pathPoints,int color){    this.startPoint = startPoint;    this.finishPoint = finishPoint;    this.pathPoints = pathPoints;    this.paint = new Paint();    this.paint.setAntiAlias(true);    this.paint.setDither(true);    this.paint.setcolor(color);    this.paint.setAlpha(150);    this.paint.setstrokeWIDth(4);    this.paint.setStyle(Paint.Style.stroke);}@OverrIDepublic voID draw(Canvas overlayCanvas,MapVIEw mapVIEw,boolean shadow) {    if(path == null) {        path = getPath(mapVIEw);    } else {        path = transformPath(mapVIEw);    }    overlayCanvas.drawPath(path,paint);    super.draw(overlayCanvas,mapVIEw,shadow);}private Path getPath(MapVIEw mapVIEw) {    Projection projection = mapVIEw.getProjection();    if(path == null) {        path = new Path();        path.setFillType(FillType.WINDING);    } else {        path.rewind();    }    Point point = new Point();    pathStartPoint = new Point();    pathEndPoint = new Point();    projection.topixels(startPoint,point);    projection.topixels(startPoint,pathStartPoint);    path.moveto(point.x,point.y);    path.addCircle(point.x,point.y,(float) 2.0,Direction.ccw);    if (pathPoints != null) {        for(int i=0;i<pathPoints.size();i++) {            projection.topixels(pathPoints.get(i),point);            path.lineto(point.x,point.y);        }    }    projection.topixels(finishPoint,point);    projection.topixels(finishPoint,pathEndPoint);    path.lineto(point.x-5,point.y);    path.addCircle(point.x-5,Direction.ccw);    return path;}private Path transformPath(MapVIEw mapVIEw) {    Projection projection = mapVIEw.getProjection();    Point sPoint = new Point();    Point ePoint = new Point();    projection.topixels(startPoint,sPoint);    projection.topixels(finishPoint,ePoint);    float sx = ((float)ePoint.x - (float)sPoint.x)/((float)pathEndPoint.x - (float)pathStartPoint.x);    float sy = ((float)ePoint.y - (float)sPoint.y)/((float)pathEndPoint.y - (float)pathStartPoint.y);    if(sx != 1.0 && sy != 1.0) {        Log.i("PathOverlay","resized");        return getPath(mapVIEw);    } else {        Log.i("PathOverlay","moved");        Matrix matrix = new Matrix();        dx = (float)sPoint.x - (float)pathStartPoint.x;        dy = (float)sPoint.y - (float)pathStartPoint.y;        matrix.postTranslate(dx,dy);        pathStartPoint = sPoint;        pathEndPoint = ePoint;        path.transform(matrix);        return path;    }}}

解决方法 您可以绘制透明Bitmap对象的路径(无论您看到适合的大小 – 它越大,路径细节越好但内存消耗越高).

确保使用Bitmap.config.ARGB_8888创建透明度.

完成此 *** 作后,您将使用两个矩形在Overlay上显示路径：

>源矩形,用于确定路径的哪个部分可见
>目标矩形,用于确定要在Overlay画布上显示此路径的位置.

你将使用Canvas.drawBitmap(Bitmap bitmap,Rect src,RectF dst,Paint paint)

不应该太困难,你已经在transformPath方法中完成了大部分重要的计算.

添加：

实际上,您可以同时执行两者的组合,将路径绘制到位图并重新绘制实际路径点.当用户在地图上移动或放大/缩小时,使用上述技术,然后在用户离开屏幕时重绘路径.

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