如何使用android图形类绘制箭头？

Question

如何使用图形类绘制箭头？

我使用Android图形类,基本上我试图在地图上显示路径.所以我需要在画布上打印一个箭头.帮帮我搞清楚!

谢谢!

这是我用来绘制线条的方法之一.我想在每一行的边缘打印一个箭头.

//       ArrayList<Point> ArrayListPoints = new ArrayList<Point>(); // Assign the shortest path here

//       ArrayListPoints.add(new Point(262,100));
//       ArrayListPoints.add(new Point(262,165));
//       ArrayListPoints.add(new Point(346,165));
//       ArrayListPoints.add(new Point(420,165));

       ArrayList<Point> ArrayListPointsFINAL;

    ArrayListPointsFINAL = storePath.ArrayListPoints;

    if(ArrayListPointsFINAL == null){
        System.out.println("ArrayListPointsFINAL is NULL");
    }
    else{

    ArrayList<Float> ArrayList_X = new ArrayList<Float>();
     ArrayList<Float> ArrayList_Y = new ArrayList<Float>();
     //int size = get.ArrayListPoints.size();

    for(int i=0; i<ArrayListPointsFINAL.size(); i++){
        ArrayList_X.add(Float.parseFloat(String.valueOf(ArrayListPointsFINAL.get(i).x)));
        ArrayList_Y.add(Float.parseFloat(String.valueOf(ArrayListPointsFINAL.get(i).y)));
          }   

    for(int i=1; i<ArrayList_X.size(); i++){
        Paint myPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        myPaint.setStrokeWidth(8/*1 /getResources().getDisplayMetrics().density*/);
        myPaint.setColor(0xffff0000);   //color.RED
       // myPaint.setStyle(myPaint);

       canvas.drawLine(ArrayList_X.get(i), ArrayList_Y.get(i), ArrayList_X.get(i-1), ArrayList_Y.get(i-1),myPaint);       

    }

Answer 1

希望你仍然觉得这很有用; 这是我画箭头的方法:

    private void fillArrow(Canvas canvas, float x0, float y0, float x1, float y1) {

    paint.setStyle(Paint.Style.FILL);

    float deltaX = x1 - x0;
    float deltaY = y1 - y0;
    float frac = (float) 0.1;

    float point_x_1 = x0 + (float) ((1 - frac) * deltaX + frac * deltaY);
    float point_y_1 = y0 + (float) ((1 - frac) * deltaY - frac * deltaX);

    float point_x_2 = x1;
    float point_y_2 = y1;

    float point_x_3 = x0 + (float) ((1 - frac) * deltaX - frac * deltaY);
    float point_y_3 = y0 + (float) ((1 - frac) * deltaY + frac * deltaX);

    Path path = new Path();
    path.setFillType(Path.FillType.EVEN_ODD);

    path.moveTo(point_x_1, point_y_1);
    path.lineTo(point_x_2, point_y_2);
    path.lineTo(point_x_3, point_y_3);
    path.lineTo(point_x_1, point_y_1);
    path.lineTo(point_x_1, point_y_1);
    path.close();

    canvas.drawPath(path, paint);
}

给定一条端点为p(x0,y0)和p(x1,y1)的线,该方法绘制一个箭头,其顶点为p(x1,y1).

变量

frac : 0 < frac < 1

确定箭头的大小.

干杯!