Android圖形繪製基礎(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 矩形構造方法//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//第一個,第二個參數float left, float top//表示矩形的起始點(即左上方的點)//第一個,第二個參數float right, float bottom//表示矩形的終止點(即右下角的點)//2 繪製橢圓//並沒有想象中的"直接"繪製橢圓的方法//而是在一個矩形中繪製了橢圓//因為一個矩形就定位了橢圓public class SurfaceViewTest extends SurfaceView implements SurfaceHolder.Callback{private Context mContext;private Paint mPaint;public SurfaceViewTest(Context context) {super(context);this.mContext=context;//設定生命週期回調介面的實現this.getHolder().addCallback(this);mPaint=new Paint();//消除鋸齒mPaint.setAntiAlias(true);}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);//-------->繪製白色矩形背景//設定畫筆顏色mPaint.setColor(Color.WHITE);//繪製白色矩形背景canvas.drawRect(0, 0, 350, 450, mPaint);mPaint.reset();//-------->繪製直線mPaint.setColor(Color.RED);//設定線條寬度mPaint.setStrokeWidth(10);canvas.drawLine(30, 10, 200, 70, mPaint);mPaint.reset();//-------->繪製帶邊框的空心矩形(實心矩形)mPaint.setStrokeWidth(5);mPaint.setARGB(50, 0, 255, 0);//注釋掉下一句即為實心矩形mPaint.setStyle(Style.STROKE);RectF rectF1=new RectF(10, 10, 150, 150);canvas.drawRect(rectF1, mPaint);mPaint.reset();//-------->繪製空心圓(實心圓)mPaint.setColor(Color.GREEN);mPaint.setAntiAlias(true);//注釋掉下一句即為實心圓mPaint.setStyle(Style.STROKE);canvas.drawCircle(150, 200, 30, mPaint);mPaint.reset();//-------->繪製橢圓充滿矩形mPaint.setColor(Color.YELLOW);RectF rectF2=new RectF(10, 230, 200, 300);canvas.drawOval(rectF2, mPaint);mPaint.reset();//-------->繪製文字mPaint.setColor(Color.BLACK);mPaint.setTextSize(25);//設定文字底線mPaint.setUnderlineText(true);canvas.drawText("大家好,Hello world", 50, 340, mPaint);mPaint.reset();}//實現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);}}}//實現SurfaceHolder.Callback中的方法public void surfaceChanged(SurfaceHolder holder, int format, int width,int height) {}//實現SurfaceHolder.Callback中的方法public void surfaceDestroyed(SurfaceHolder holder) {}}