Android view and surfaceview

In Android games, only the control class is the display Class View. Surfaceview is a display class derived from the view base class.Three commonly used views in android game development are view, surfaceview, and glsurfaceview.

View: display view, built-in canvas, drawing function, touch screen event, button event function, etc;The screen must be updated in the main UI thread, which is slow.

Surfaceview: Expanded View Class Based on view, more suitable for 2D game development;Is a subclass of the view, similar to the double easing mechanism, to update the screen in the new thread, so refreshing the interface is faster than the view.

Glsurfaceview: Expanded View Class Based on surfaceview, dedicated to 3D game development view;It is a subclass of surfaceview and is dedicated to OpenGL.

In 2D game development, there are roughly two game frameworks: View and surfaceview.Difference between view and surfaceview:

 View: You must update the screen in the main UI thread for passive update.

Surfaceview: both the UI thread and sub-thread can be used. Re-draw the screen in a new thread to take the initiative to update the screen.

Updating the screen in the main UI thread may cause problems. For example, if you update the screen for a long time, your main UI thread will be blocked by the function you are painting. Then, messages such as buttons and touch screens cannot be responded.
When surfaceview is used to update the screen in a new thread, it will not block your main UI thread. But this also brings about another problem: event synchronization, involving thread synchronization.

 

Based on the above, the game features are generally divided into two categories.

1. passively update the image. For example, you can use view for chess. Because image update relies on ontouch for update, you can use invalidate directly. In this case, this touch and the next touch take a longer time and will not be affected.

2. Actively update. For example, a person is always running. This requires a separate thread to repeatedly repaint the state of the person, to avoid blocking the main UI thread. Obviously, the view is not suitable and needs surfaceview for control.

Below is a basic framework using sufaceview:

 Import Android. App. activity;
 Import Android. content. context;
 Import Android. Graphics. Canvas;
 Import Android. Graphics. color;
 Import Android. Graphics. paint;
 Import Android. OS. Bundle;
 Import Android. View. surfaceholder;
 Import Android. View. surfaceview;

 Public   Class Testsurfaceview Extends Activity {
 /**  Called when the activity is first created.  */   
@ Override
 Public   Void Oncreate (bundle savedinstancestate ){
 Super . Oncreate (savedinstancestate );
Setcontentview ( New Myview (This ));
}

 Class Myview Extends Surfaceview Implements Surfaceholder. Callback, runnable {
Surfaceholder holder = Null ;
Paint paint;
 Public Myview (context ){
 Super (Context );
 //  Todo auto-generated constructor stub 
 Holder = getholder ();
Holder. addcallback ( This );
Paint = New Paint (paint. anti_alias_flag );
Paint. setcolor (color. Red );

 This . Setfocusable ( True );
}

@ 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 t = New Thread ( This );
T. Start ();
}

@ Override
 Public   Void Surfacedestroyed (surfaceholder holder ){
 //  Todo auto-generated method stub  
 Isrunning = False ;
}

@ Override
 Protected   Void Ondraw (canvas ){
 //  Todo auto-generated method stub  
 Canvas = holder. lockcanvas ();
 //  Screen Flushing  
 Canvas. drawcolor (color. Black );

Canvas. drawcircle (X, Y, 10, paint );

Holder. unlockcanvasandpost (canvas );
}
Private   Void Paint (paint ){
Canvas canvas = holder. lockcanvas ();
 //  Screen Flushing  
 Canvas. drawcolor (color. Black );

Canvas. drawcircle (X, Y, 10, paint );

Holder. unlockcanvasandpost (canvas );
}

 Boolean Isrunning = True ;
@ Override
Public   Void Run (){
 //  Todo auto-generated method stub  
              While (Isrunning ){
 //  Ondraw (null );  
 Paint (paint );
Move ();
 Try {
Thread. Sleep (50 );
}Catch (Interruptedexception e ){
 //  Todo auto-generated Catch Block  
 E. printstacktrace ();
}

}
}

 Private   Int X, Y;
 Private   Void Move (){
X + = 2;
Y + = 2;
}
}

}