Android如何重繪自定義視圖

Question

我知道這個問題已被問過其他時間，但我無法解決我的問題！

我創建我自己的視圖（RadarView），擴展視圖。但ID不更新！我嘗試使用「invalidate（）」和「postInvalidate（）」，但它們不起作用！

這裏是RadarView的代碼：

'公共類RadarView擴展視圖{

private HashMap<Integer, RadarData> allNodes; 
    private int myId; 
    private double distance=0.0; //in degree 
    private double meeterDistance =0.0; // in meeters 
    private Paint paint,node,nodeText; 

    public RadarView(Context context, HashMap<Integer,RadarData> allNodes, int myId){ 
     super(context); 
     this.allNodes = allNodes; 
     this.myId=myId; 
     paint = new Paint(); 
     paint.setStyle(Paint.Style.STROKE); 
     paint.setAntiAlias(true);   
     paint.setColor(Color.GREEN); 

     node = new Paint(); 
     node.setStyle(Paint.Style.FILL); 
     node.setAntiAlias(true);    
     node.setColor(Color.GREEN); 

     nodeText = new Paint(); 
     nodeText.setStyle(Paint.Style.STROKE); 
     nodeText.setAntiAlias(true);    
     nodeText.setColor(Color.BLACK); 
    } 

    @Override protected void onDraw(Canvas canvas) { 
     super.onDraw(canvas);  

     //here we draw the radar 
     canvas.drawCircle(canvas.getWidth()/2, canvas.getHeight()/2, canvas.getWidth()/8, paint); 
     canvas.drawCircle(canvas.getWidth()/2, canvas.getHeight()/2, canvas.getWidth()/4, paint); 
     canvas.drawCircle(canvas.getWidth()/2, canvas.getHeight()/2, canvas.getWidth()/2.7f, paint); 
     canvas.drawCircle(canvas.getWidth()/2, canvas.getHeight()/2, canvas.getWidth()/2, paint); 
     canvas.drawLine(canvas.getWidth()/2, 0, canvas.getWidth()/2, canvas.getHeight(), paint); 
     canvas.drawLine(0, canvas.getHeight()/2, canvas.getWidth(), canvas.getHeight()/2, paint); 
     canvas.drawLine(canvas.getWidth() - canvas.getWidth()/4, canvas.getHeight()/10, canvas.getWidth() - canvas.getWidth()/4 +canvas.getWidth()/8, canvas.getHeight()/10, paint); 

     //then we add nodes in the view, if at least one exist 
     if(allNodes!=null){ 
      RadarData me = allNodes.get(myId); 
      RadarData moreDistant = me; 
      Set<Integer> set = allNodes.keySet(); 
      set.remove(myId); 
      for (Integer key : set){ 
       RadarData element = allNodes.get(key); 
       //calculate if it's the more distant, in that case variable "moreDistant" is updated 
       if(distance<calculateDistance(element,me)){ 
        distance=calculateDistance(element,me); 
        moreDistant=element; 
       } 
      } 
      for (Integer key : set){ 
       drawNode(canvas,allNodes.get(key), me); 
      } 
      canvas.drawText("Unit: "+approximateDistance()/4+"degree", canvas.getWidth() - canvas.getWidth()/4, canvas.getHeight()/11, paint); 
     } 
} 

    private double approximateDistance(){ 
     int aux=(int) (distance*100); 
     return aux/100; 
    } 
    private void drawNode(Canvas canvas,RadarData element, RadarData me) { 
     int radius=canvas.getWidth()/2; 
     double x=element.getLongitude()-me.getLongitude(); 
     double y=element.getLatitude() - me.getLatitude(); 
     int xInTheView=(int)(radius + x*radius/distance); 
     int yInTheView=(int)(canvas.getHeight()/2 -y*radius/distance); 

     canvas.drawCircle(xInTheView, yInTheView, radius/10, node); 
     canvas.drawText(""+element.getId(), xInTheView, yInTheView, nodeText); 
    } 

    private double calculateDistance(RadarData element, RadarData me) { 
     return Math.hypot(element.getLatitude()-me.getLatitude(), 
       element.getLongitude()-me.getLongitude()); 
    } 

} `

在主要活動我把它當GPS位置的變化：

private void updateRadarView(Location location) { 
    if(location!=null){ 
     RadarData newState= new RadarData(myId, location.getLatitude(), location.getLongitude(), RadarData.RUNNING); 
     allNodes = connectionHandler.request(newState); 
     radarView = new RadarView(this,allNodes,myId); 
     setContentView(radarView); 
    } 

} 

正如你所看到的，我重新創建radarView和然後使用setContentView來更新它，但我認爲這不是一個好的解決方案。任何想法？

Answer 1

你爲什麼不創建setNodes(HashMap<Integer,RadarData> allNodes)方法到您的RadarView和每次當你需要設置radarView的數據時，把它叫做：我的意思radarView.setNodes(allNodes)，而不是每次都重新創建？