使用View繪制矩形，多邊形

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 { //繪畫類，設置繪圖的樣式和顏色。 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; //開始角度 private static final float SWEEP_INC = 2; //掃除的角度 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); //抗鋸齒 mPaints[0].setColor(0x88111111); mUseCenters[0] = false; //為true繞中心繪圖 mPaints[1] = new Paint(mPaints[0]); mPaints[1].setStyle(Paint.Style.FILL); //填充實心 mPaints[1].setColor(0x88FF0000); mUseCenters[1] = true; mPaints[2] = new Paint(mPaints[0]); mPaints[2].setStyle(Paint.Style.STROKE); mPaints[2].setStrokeWidth(10); //畫筆的寬度 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,起始角度始終為0 if (mStart >= 360) { mStart -= 360; } mBigIndex = (mBigIndex + 1) % mOvals.length; } System.out.println("mSweep-->"+mSweep); System.out.println("mStart-->"+mStart); invalidate(); //重繪視圖 } } }
android上所有的視圖都繼承View類。我們可以繼承View,然后再OnDraw()方法里繪圖，

OnDraw()方法不需要我們去調用，使用 invalidate(); 可重繪視圖