Android图形绘制基础(二)

mainActivity如下:

package com.cn;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class MainActivity extends Activity {
    private SurfaceViewTest mSurfaceViewTest;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mSurfaceViewTest=new SurfaceViewTest(MainActivity.this);
        setContentView(mSurfaceViewTest);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
}

SurfaceViewTest如下:

package com.cn;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.RectF;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
//注意
//1 矩形构造方法
//RectF rectF=new RectF(10, 10, 100, 100);
//RectF(float left, float top, float right, float bottom)
//must ensure that left <= right and top <= bottom
//第一个,第二个参数float left, float top
//表示矩形的起始点(即左上角的点)
//第一个,第二个参数float right, float bottom
//表示矩形的终止点(即右下角的点)

//2 绘制椭圆
//并没有想象中的"直接"绘制椭圆的方法
//而是在一个矩形中绘制了椭圆
//因为一个矩形就定位了椭圆
public class SurfaceViewTest extends SurfaceView implements SurfaceHolder.Callback{
	private Context mContext;
	private Paint mPaint;
	public SurfaceViewTest(Context context) {
		super(context);
		this.mContext=context;
		//设置生命周期回调接口的实现
		this.getHolder().addCallback(this);
		mPaint=new Paint();
		//抗锯齿
		mPaint.setAntiAlias(true);
	}

	@Override
	protected void onDraw(Canvas canvas) {
		super.onDraw(canvas);
		//-------->绘制白色矩形背景
		//设置画笔颜色
		mPaint.setColor(Color.WHITE);
		//绘制白色矩形背景
		canvas.drawRect(0, 0, 350, 450, mPaint);
		mPaint.reset();
		
		//-------->绘制直线
		mPaint.setColor(Color.RED);
		//设置线条宽度
		mPaint.setStrokeWidth(10);
		canvas.drawLine(30, 10, 200, 70, mPaint);
		mPaint.reset();
		
		//-------->绘制带边框的空心矩形(实心矩形)
		mPaint.setStrokeWidth(5);
		mPaint.setARGB(50, 0, 255, 0);
		//注释掉下一句即为实心矩形
		mPaint.setStyle(Style.STROKE);
		RectF rectF1=new RectF(10, 10, 150, 150);
		canvas.drawRect(rectF1, mPaint);
		mPaint.reset();
		
		//-------->绘制空心圆(实心圆)
		mPaint.setColor(Color.GREEN);
		mPaint.setAntiAlias(true);
		//注释掉下一句即为实心圆
		mPaint.setStyle(Style.STROKE);
		canvas.drawCircle(150, 200, 30, mPaint);
		mPaint.reset();
		
		//-------->绘制椭圆充满矩形
		mPaint.setColor(Color.YELLOW);
		RectF rectF2=new RectF(10, 230, 200, 300);
		canvas.drawOval(rectF2, mPaint);
		mPaint.reset();
		
		//-------->绘制文字
		mPaint.setColor(Color.BLACK);
		mPaint.setTextSize(25);
		//设置文字下划线
		mPaint.setUnderlineText(true);
		canvas.drawText("大家好,Hello world", 50, 340, mPaint);
		mPaint.reset();
	}
	
	//实现SurfaceHolder.Callback中的方法
	public void surfaceCreated(SurfaceHolder holder) {
		Canvas canvas=holder.lockCanvas();
		try {
			synchronized (holder) {
			   onDraw(canvas);	
			}
		} catch (Exception e) {
		}finally{
			if (canvas!=null) {
				holder.unlockCanvasAndPost(canvas);
			}
		}
	}
	//实现SurfaceHolder.Callback中的方法
	public void surfaceChanged(SurfaceHolder holder, int format, int width,int height) {
	}
	//实现SurfaceHolder.Callback中的方法
	public void surfaceDestroyed(SurfaceHolder holder) {
	}

}