Android使用绘图创建任意多边形

Bertha 。 2022-09-20 09:13 250阅读 0赞

在一个重写的View，主要绘制在View的OnDraw()方法中，

首先：先绘制出几个点，当然是任意多

最后一个点和第一个点闭合在一起之后，画点结束

然后可以随意拖动达到裁减的效果

当然裁剪的功能没有实现

代码如下

View--------:
    
    --**************************************************************
    
    public class MyView extends View{
    
    
    public int doWhat = 0;
    ArrayList<HashMap<String,Float>> list = new ArrayList<HashMap<String,Float>>();
    
    public MyView(Context context) {
    super(context);
    setBackgroundResource(R.drawable.youxibiajii);
    }
    
    protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    Paint paint = new Paint();
    paint.setColor(Color.GREEN);
    
    for (int i = 0; i < list.size(); i++) {
    canvas.drawCircle(list.get(i).get("x"), list.get(i).get("y")
    , 10, paint);
    if(i>0){
    canvas.drawLine(list.get(i-1).get("x"), list.get(i-1).get("y"),
    list.get(i).get("x"), list.get(i).get("y"), paint);
    }
    }
    
    }
    
    
    *******************************************************************************************
    
    Activity-------******************************************************************
    
    public class MainActivity extends Activity {
    public static float  ScreenW,ScreenH;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    DisplayMetrics dis = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(dis);
    ScreenW = dis.widthPixels;
    ScreenH = dis.heightPixels;
    final MyView view = new MyView(this);
    setContentView(view);
    view.setOnTouchListener(new OnTouchListener() {
    public boolean onTouch(View arg0, MotionEvent event) {
    float startX = event.getRawX();
    float startY = event.getRawY();
    if(view.doWhat == 0){//画点
    switch(event.getAction()){
    case KeyEvent.ACTION_DOWN:
    HashMap<String,Float> map = new HashMap<String, Float>();
    
    
    if(view.list.size()>2&&
    (startX>view.list.get(0).get("x")-20&&startY>view.list.get(0).get("y")-20)
    &&(startX<view.list.get(0).get("x")+20&&startY<view.list.get(0).get("y")+20)){
    map.put("x", view.list.get(0).get("x"));
    map.put("y", view.list.get(0).get("y"));
    view.list.add(map);
    view.doWhat = 1;
    break;
    }
    map.put("x", startX);
    map.put("y", startY);
    view.list.add(map);
    break;
    }
    }
    else{//拖动
    for (int i = 0; i < view.list.size(); i++) {
    if((startX>view.list.get(i).get("x")-15&&startY>view.list.get(i).get("y")-15)
    &&(startX<view.list.get(i).get("x")+15&&startY<view.list.get(i).get("y")+15)){
    if(i==0){
    view.list.get(i).put("x", startX);
    view.list.get(i).put("y", startY);
    view.list.get(view.list.size()-1).put("x", startX);
    view.list.get(view.list.size()-1).put("y", startY);
    }
    else{
    view.list.get(i).put("x", startX);
    view.list.get(i).put("y", startY);
    }
    break;
    }
    }
    }
    view.invalidate();
    return true;
    }
    });
    }
    
    
    *********************************************
    
    over
    
    Thanks***