使用View绘制矩形，多边形

使用View绘制矩形，多边形

 import android.app.Activity;
 import android.os.Bundle;
 import android.content.Context;
 import android.graphics.Canvas;
 import android.graphics.Paint;
 import android.graphics.RectF;
 import android.graphics.Color;
 import android.view.View;

 public class DrawActivity extends Activity {

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(new DrawView(this));
     }

     private static class DrawView extends View {
         //绘画类，设置绘图的样式和颜色。
         private Paint[] mPaints;

         private Paint mFramePaint;
         //矩形（上，下，左，右）
         private RectF[] mOvals;
         private RectF mBigOval;

         private float mStart;
         private float mSweep;
         private int mBigIndex;
         private boolean[] mUseCenters;

         private static final float START_INC = 0;  //开始角度
         private static final float SWEEP_INC = 2;  //扫除的角度


         public DrawView(Context context) {
             super(context);

             mPaints = new Paint[4];
             mUseCenters = new boolean[4];
             mOvals = new RectF[4];

             mPaints[0] = new Paint();
             mPaints[0].setAntiAlias(true);  //抗锯齿
             mPaints[0].setColor(0x88111111);
             mUseCenters[0] = false;    //为true绕中心绘图

             mPaints[1] = new Paint(mPaints[0]);
             mPaints[1].setStyle(Paint.Style.FILL); //填充实心
             mPaints[1].setColor(0x88FF0000);
             mUseCenters[1] = true;

             mPaints[2] = new Paint(mPaints[0]);
             mPaints[2].setStyle(Paint.Style.STROKE);
             mPaints[2].setStrokeWidth(10);  //画笔的宽度
             mPaints[2].setColor(0x8800FF00);
             mUseCenters[2] = false;

             mPaints[3] = new Paint(mPaints[2]);
             mPaints[3].setStyle(Paint.Style.FILL_AND_STROKE);
             mPaints[3].setColor(0x880000FF);
             mUseCenters[3] = true;

             mBigOval = new RectF(40, 10, 280, 250);

             mOvals[0] = new RectF( 10, 270,  70, 330);
             mOvals[1] = new RectF( 90, 270, 150, 330);
             mOvals[2] = new RectF(170, 270, 230, 330);
             mOvals[3] = new RectF(250, 270, 310, 330);

             mFramePaint = new Paint();
             mFramePaint.setAntiAlias(true);
             mFramePaint.setStyle(Paint.Style.STROKE);
             mFramePaint.setStrokeWidth(2);
         }

         private void drawArcs(Canvas canvas, RectF oval,
             boolean useCenter, Paint paint) {
             canvas.drawRect(oval, mFramePaint);
             canvas.drawArc(oval, mStart, mSweep, useCenter, paint);
         }

         @Override
         protected void onDraw(Canvas canvas) {
             canvas.drawColor(Color.WHITE);

             drawArcs(canvas, mBigOval, mUseCenters[mBigIndex],
                      mPaints[mBigIndex]);

             for (int i = 0; i < 4; i++) {
                 drawArcs(canvas, mOvals[i], mUseCenters[i], mPaints[i]);
             }

             mSweep += SWEEP_INC;
             if (mSweep > 360) {
                 mSweep -= 360;
                 mStart += START_INC;   //0+0=0,起始角度始终为0
                 if (mStart >= 360) {
                     mStart -= 360;
                 }
                 mBigIndex = (mBigIndex + 1) % mOvals.length;
             }
             System.out.println("mSweep-->"+mSweep);
             System.out.println("mStart-->"+mStart);
             invalidate(); //重绘视图
         }
     }
 }

android上所有的视图都继承View类。我们可以继承View,然后再OnDraw()方法里绘图，

OnDraw()方法不需要我们去调用，使用 invalidate(); 可重绘视图