ArcsDemo

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package com.example.xfermodesdemo;

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

public class ArcsActivity extends Activity {
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(new SampleView(this));
	}

	private static class SampleView extends View {
		private Paint[] mPaints;
		private Paint mFramePaint;// 大图形画笔
		private boolean[] mUseCenters;
		private RectF[] mOvals;
		private RectF mBigOval;
		private float mStart;
		private float mSweep;
		private int mBigIndex;

		private static final float SWEEP_INC = 2;
		private static final float START_INC = 15;

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

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

			//圆1 Paint.Style.FILL
			//center false
			mPaints[0] = new Paint();
			mPaints[0].setAntiAlias(true);// 抗锯齿
			mPaints[0].setStyle(Paint.Style.FILL);
			mPaints[0].setColor(0x88FF0000);
			mUseCenters[0] = false;

			//圆2 Paint.Style.FILL
			//center true
			mPaints[1] = new Paint(mPaints[0]);
			mPaints[1].setColor(0x8800FF00);
			mUseCenters[1] = true;

			//圆3 Paint.Style.STROKE
			//center false
			mPaints[2] = new Paint(mPaints[0]);
			mPaints[2].setStyle(Paint.Style.STROKE);
			mPaints[2].setStrokeWidth(4);
			mPaints[2].setColor(0x880000FF);
			mUseCenters[2] = false;

			//圆4 Paint.Style.STROKE
			//center true
			mPaints[3] = new Paint(mPaints[2]);
			mPaints[3].setColor(0x88888888);
			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(0);
		}

		private void drawArcs(Canvas canvas, RectF oval, boolean useCenter,
				Paint paint) {
			canvas.drawRect(oval, mFramePaint);
			canvas.drawArc(oval, mStart, mSweep, useCenter, paint);//绘制椭圆的函数
		}

		@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;
				if (mStart >= 360) {
					mStart -= 360;
				}
				mBigIndex = (mBigIndex + 1) % mOvals.length;
			}
			invalidate();
		}
	}
}