使用View绘制矩形，多边形

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mb61c2e9efaa57a 2022-01-05 15:37:27 ©著作权

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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
        }
    }
}