android实现使用绘图作出一种裁剪任意多边形快速算法

来源：互联网发布：python是面向对象吗编辑：程序博客网时间：2024/06/05 18:37

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;@Overrideprotected 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;}});}

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