Android 2D圖像顯示

本文介紹在Android如何顯示2D圖像

1）使用XML，代碼如下

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

（代碼比較簡單，不做解析了！！）

 

2）繼承View

根據public void setContentView (View view) ，新建一個繼承View的類，並重寫onDraw函數。代碼如下：

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. */ @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); // } // } 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); } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { // TODO Auto-generated method stub } @Override public void surfaceCreated(SurfaceHolder holder) { // TODO Auto-generated method stub _thread.setRunning(true); _thread.start(); } @Override public void surfaceDestroyed(SurfaceHolder holder) { // TODO Auto-generated method stub boolean 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); } } } } } }

第三種方法，可以快速地描繪界面，使用SurfaceView可以讓其它非UI線程直接對畫面進行操作。