Android 2D图像显示

本文介绍在Android如何显示2D图像

1）使用XML，代码如下

 <ImageView android:layout_width="wrap_content"android:layout_height="wrap_content"android:src="@drawable/android"/>

（代码比较简单，不做解析了！！）

 

2）继承View

根据public void setContentView (View view) ，新建一个继承View的类，并重写onDraw函数。代码如下：

package android.szu.edu.cn;import android.app.Activity;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.os.Bundle;import android.view.View;import android.view.Window;public class Show2DImage extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); //setContentView(R.layout.main); setContentView(new Panel(this)); } class Panel extends View{public Panel(Context context) {super(context);// TODO Auto-generated constructor stub} public void onDraw(Canvas canvas){Bitmap _scratch = BitmapFactory.decodeResource(getResources(), R.drawable.icon);canvas.drawColor(Color.BLACK);canvas.drawBitmap(_scratch, 10, 10, null);} }}

 

3）利用SurfaceView和Thread

package android.szu.edu.cn;import android.app.Activity;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.os.Bundle;import android.view.SurfaceHolder;import android.view.SurfaceView;import android.view.Window;public class Show2DImage extends Activity {/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);requestWindowFeature(Window.FEATURE_NO_TITLE);// setContentView(R.layout.main);setContentView(new Panel(this));}// class Panel extends View{//// public Panel(Context context) {// super(context);// // TODO Auto-generated constructor stub// }// // public void onDraw(Canvas canvas){// Bitmap _scratch = BitmapFactory.decodeResource(getResources(),// R.drawable.icon);// canvas.drawColor(Color.BLACK);// canvas.drawBitmap(_scratch, 10, 10, null);// }// }class Panel extends SurfaceView implements SurfaceHolder.Callback {private Draw2DThread _thread;public Panel(Context context) {super(context);getHolder().addCallback(this);_thread = new Draw2DThread(getHolder(), this);}public void onDraw(Canvas canvas) {Bitmap _scratch = BitmapFactory.decodeResource(getResources(),R.drawable.android);canvas.drawColor(Color.BLACK);canvas.drawBitmap(_scratch, 10, 10, null);}@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width,int height) {// TODO Auto-generated method stub}@Overridepublic void surfaceCreated(SurfaceHolder holder) {// TODO Auto-generated method stub_thread.setRunning(true);_thread.start();}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {// TODO Auto-generated method stubboolean retry = true;_thread.setRunning(false);while (retry) {try {_thread.join();retry = false;} catch (InterruptedException e) {// TODO: handle exception}}}}class Draw2DThread extends Thread {private SurfaceHolder _surfaceHolder;private Panel _panel;private boolean _run;public Draw2DThread(SurfaceHolder surfaceHolder, Panel panel) {_surfaceHolder = surfaceHolder;_panel = panel;}public void setRunning(boolean run) {_run = run;}public void run() {Canvas c;while (_run) {c = null;try {c = _surfaceHolder.lockCanvas(null);synchronized (_surfaceHolder) {_panel.onDraw(c);}} finally {if (c != null) {_surfaceHolder.unlockCanvasAndPost(c);}}}}}}

第三种方法，可以快速地描绘界面，使用SurfaceView可以让其它非UI线程直接对画面进行操作。