Question

我在Canvas上有一些多边形。我如何倾听点击任何多边形？

我有一个方法

public void drawPolygon(ChartPolygon polygon) {

        List<Point> points = polygon.getPoints();
        int size = points.size();
        if (size < 2) {
            return;
        }

        Paint polyPaint = new Paint();
        polyPaint.setColor(polygon.getColor());
        polyPaint.setStyle(Style.FILL);

        Path polyPath = new Path();
        polyPath.moveTo(points.get(0).getX(), points.get(0).getY());
        for (Point point : points) {
            polyPath.lineTo(point.getX(), point.getY());
        }
        canvas.drawPath(polyPath, polyPaint);
    }

Answer 1

我会保留一份区域列表。无论何时绘制新的多边形，使用与绘制相同的路径来定义新的区域：

Region r = new Region();
r.setPath(path, clip);
regionList.add(r);

可以定义

剪辑，例如由

 Region clip = new Region(0, 0, canvas.getWidth(), canvas.getHeight());

最后，当您通过regionList检测onTouchListener循环中的触摸并检查时，触摸点（由x和y给出）是否在区域内：

for (int i = 0; i < regionList.size(); i++) {
    Region r = regionList.get(i);
    if (r.contains(x,y) {
        selectedRegionIndex = i;
        break;
    }
}

Answer 2

阅读this post，这篇文章可以帮助您

首先，您可以在屏幕中获得点击事件的X和Y位置。您可以在Activity extends

中实现onTouchEvent函数

@Override
public boolean onTouchEvent(MotionEvent event) {
    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:

        if (topTouchArea.contains(event.getX(), event.getY())) {                
            currentTouch = TOUCH_TOP;
        } else if (RightTouchArea.contains(event.getX(),event.getY())) {                
            currentTouch = TOUCH_RIGHT;
        } else if (LeftTouchArea.contains(event.getX(),event.getY())) {            
            currentTouch = TOUCH_LEFT;
        } else {
            return false; //Return false if user touches none of the corners
        }
        return true; 
     }
  }

现在（总是在你的onTouchEvent中）函数，你可以评估多边形的位置和区域。

case MotionEvent.ACTION_MOVE:

        switch (currentTouch) {
        case TOUCH_TOP:              
             top.x = event.getX();
             top.y = event.getY();                            
             invalidate();
             return true;
        case TOUCH_RIGHT:                
             Right.x = event.getX();
             Right.y = event.getY();                
             invalidate();
             return true;
        case TOUCH_LEFT:                 
             Left.x = event.getX();
             Left.y = event.getY();             
             invalidate();
             return true;       
        }         

    case MotionEvent.ACTION_UP:

        switch (currentTouch) {
        case TOUCH_TOP:
             top.x = event.getX();
             top.y = event.getY();                
             invalidate();
             currentTouch = NONE;
             return true;
        case TOUCH_RIGHT:
             Right.x = event.getX();
             Right.y = event.getY();             
             invalidate();
             currentTouch = NONE;
             return true;
        case TOUCH_LEFT:
            Left.x = event.getX();
             Left.y = event.getY();               
             invalidate();
             currentTouch = NONE;
             return true;      
        }         
        return false;

所有帖子都在article link

中

在Android Canvas多边形上单击

2 个答案: