Android-based extension of videoview and video playback View

1. Concepts and extensions

Videoview is a media playback display and Control control provided by the Android system. Its structure is as follows:

Prototype: videoview extendsSurfaceview ImplementsMediacontroller.Mediaplayercontrol

Class Structure:

Java. Lang. Object
Using Android. View. View
Using Android. View. surfaceview
Using Android. widget. videoview

Based on the videoview prototype, we can see that if you build a more complex and distinctive Video View,Surfaceview must be inherited and mediaplayercontrol interfaces must be implemented..WhereSurfaceviewSupports display, while mediaplayercontrol supports media control.

2. Case studies

1) videoview case

(We have not managedMediapalyerAll of these statuses makeVideoviewAnd whenVideoviewAt the time of creation,MediapalyerThe object will be created whenVideoviewWhen the object is destroyed, the mediaplayer object is released.)

Layout File

 <?  XML version = "1.0" encoding = "UTF-8"  ?> 
 <  Linearlayout  Xmlns: Android  = "Http://schemas.android.com/apk/res/android"  Android: Orientation  = "Vertical"  Android: layout_width = "Fill_parent"  
Android: layout_height  = "Fill_parent"  > 
 <  Videoview  Android: ID  = "@ + ID/video_view"  Android: layout_width  = "Match_parent"  Android: layout_height  = "Match_parent"  
Android: layout_centerinparent  = "True"  /> 
 </  Linearlayout  > 

MasterProgram:

 Public   Class Videoplayer Extends Activity Implements Mediaplayer. onerrorlistener, mediaplayer. oncompletionlistener {
 Public   Static   Final String tag = "videoplayer ";
 Private Videoview mvideoview;
 Private Uri muri;
 Private   Int Mpositionwhenpaused =-1;

 Private Mediacontroller mmediacontroller;

@ Override
 Public   Void Oncreate (bundle savedinstancestate ){
 Super . Oncreate (savedinstancestate );

Setcontentview (R. layout. Main );

//  Set the screen to landscape.  
          This . Setrequestedorientation (activityinfo. screen_orientation_landscape );

Mvideoview = (videoview) findviewbyid (R. Id. video_view );

 //  Video file  
 Muri = URI. parse (environment. getexternalstoragedirectory () + "/1.3gp ");

 //  Create media controller,The widget can control video playback, pause, reply, seek, and other operations. 
 Mmediacontroller = New Mediacontroller ( This );
Mvideoview. setmediacontroller (mmediacontroller );
}

 Public   Void Onstart (){
 //  Play video  
 Mvideoview. setvideouri (muri );
Mvideoview. Start ();

 Super . Onstart ();
}

 Public   Void Onpause (){
 //  Stop video when the activity is pause.  
 Mpositionwhenpaused = mvideoview. getcurrentposition ();
Mvideoview. stopplayback ();

 Super . Onpause ();
}

 Public   Void Onresume (){
 // Resume Video Player  
          If (Mpositionwhenpaused> = 0 ){
Mvideoview. seekto (mpositionwhenpaused );
Mpositionwhenpaused =-1;
}

 Super . Onresume ();
}

 Public   Boolean Onerror (mediaplayer player, Int Arg1, Int Arg2 ){
Return   False ;
}

 Public   Void Oncompletion (mediaplayer MP ){
 This . Finish ();
}
}

2)Custom videoview

Similar to videoview implementation, surfaceview is inherited and mediaplayercontrol is implemented.

 Public   Class Customervideoview Extends SurfaceviewImplements  
Mediaplayercontrol {
 Private   Static String tag = "customer. videoplayer ";
 Private   Boolean Pause;
 Private   Boolean Seekbackward;
 Private   Boolean Seekforward;
 Private Uri videouri;
 Private Mediaplayer;
 Private Context context;
 Private Onpreparedlistener;
 Private   Int Videowidth;
 Private   Int Videoheight;
 Private Mediacontroller;
 Protected Surfaceholder;
 Private Callback surfaceholdercallback =New Surfaceholder. Callback (){
 Public   Void Surfacechanged (surfaceholder holder, Int Format, Int W,
 Int H ){
}
 Public   Void Surfacecreated (surfaceholder holder ){
Surfaceholder = holder;
 If (Mediaplayer! = Null ){
Mediaplayer. setdisplay (surfaceholder );
Resume ();
} Else {
Openvideo ();
}
}
 Public   Void Surfacedestroyed (surfaceholder holder ){
Surfaceholder = Null ;
 If (Mediacontroller! = Null ){
Mediacontroller. Hide ();
}
Release ( True );
}
};
 Private   Void Release ( Boolean Cleartargetstate ){
 If (Mediaplayer! = Null ){
Mediaplayer. Reset ();
Mediaplayer. Release ();
Mediaplayer = Null ;
}
}
 Public   Void Resume (){
 If (Surfaceholder = Null ){
 Return ;
}
 If (Mediaplayer! = Null ){
 Return ;
}
Openvideo ();
}
 Public Customervideoview (context, attributeset attrs, Int Defstyle ){
 Super (Context, attrs, defstyle );
 This . Context = context;
 This . Initvideoview ();
}
 Public Customervideoview (context, attributeset attrs ){
 Super (Context, attrs );
 This . Context = context;
 This . Initvideoview ();
}
 Public Customervideoview (context ){
 Super (Context );
 This . Context = context;
 This . Initvideoview ();
}
@ Override
 Public   Boolean Canpause (){
 Return   This . Pause;
}
@ Override
Public   Boolean Canseekbackward (){
 Return   This . Seekbackward;
}
@ Override
 Public   Boolean Canseekforward (){
 Return   This . Seekforward;
}
@ Override
 Public   Int Getbufferpercentage (){
 Return 0;
}
@ Override
 Public   Int Getcurrentposition (){
 Return Mediaplayer! = Null ? Mediaplayer. getcurrentposition (): 0;
}
@ Override
 Public   Int Getduration (){
 Return Mediaplayer! = Null ? Mediaplayer. getduration (): 0;
}
@ Override
 Public   Boolean Isplaying (){
 Return   False ;
}
@ Override
 Public   Void Pause (){
}
@ Override
 Public   Void Seekto ( Int MSEC ){
}
@ Override
 Public   Void Start (){
}
 Public   Void Setvideouri (URI ){
 This . Videouri = URI;
Openvideo ();
Requestlayout ();
Invalidate ();
}
 Private   Void Openvideo (){
This . Mediaplayer = New Mediaplayer ();
 Try {
 This . Mediaplayer. setdatasource ( This . Context, This . Videouri );
} Catch (Exception e ){
Log. E (TAG, E. getmessage ());
 Throw   New Runtimeexception (E );
}
This . Mediaplayer. prepareasync ();
 This . Mediaplayer. setaudiostreamtype (audiomanager. stream_music );
 This . Mediaplayer. setonpreparedlistener (onpreparedlistener );
Attachmediacontroller ();
}
 Private   Void Attachmediacontroller (){
 If (Mediaplayer! = Null & Mediacontroller! = Null ){
Mediacontroller. setmediaplayer ( This );
View anchorview = This . Getparent () Instanceof View? (View) This  
. Getparent (): This ;
Mediacontroller. setanchorview (anchorview );
Mediacontroller. setenabled ( True );
}
}
 Public  Void Setmediacontroller (mediacontroller Controller ){
 If (Mediacontroller! = Null ){
Mediacontroller. Hide ();
}
Mediacontroller = controller;
Attachmediacontroller ();
}
 Public   Void Setonpreparedlistener (onpreparedlistener ){
 This . Onpreparedlistener = onpreparedlistener;
}
@ Override
 Protected   Void Onmeasure ( Int Widthmeasurespec, Int Heightmeasurespec ){
 Int Width = getdefaultsize (videowidth, widthmeasurespec );
 Int Height = getdefaultsize (videoheight, heightmeasurespec );
 If (Videowidth> 0 & videoheight> 0 ){
 If (Videowidth * Height> width * videoheight ){
Height = width * videoheight/videowidth;
} Else   If (Videowidth * height <width * videoheight ){
Width = height * videowidth/videoheight;
}
}
Log. I (TAG, "setting size:" + width + 'X' + height );
Setmeasureddimension (width, height );
}
 Private   Void Initvideoview (){
Videowidth = 0;
Videoheight = 0;
Getholder (). addcallback (surfaceholdercallback );
Getholder (). settype (surfaceholder. surface_type_push_buffers );
Setfocusable ( True );
Setfocusableintouchmode ( True );
Requestfocus ();
}
}

Generally, the rendering and updating of the android interface must be performed by the main UI thread through the handler mechanism. However, to play a video, you must first change and draw the page in real time. Android provides a mechanism to draw the UI using a separate thread, that is, surfaceview.To use surfaceview, you must implement the surfaceholder. Callback interface:

• Surfacecreated: After the surface (surfaceview contains a surface instance) is created, this method is called immediately. You can initialize the interface in this method;
• Surfacechanged: when the surface status changes, such as the size, this method is called. This method is called at least once in the surfacecreated method;
• Surfacedestroyed, called when the surface is destroyed.

You cannot directly operate a surface instance. You must use surfacehandler to obtain the surfacehandler instance through the gethandler method in surfaceview.
Surfacehander has some types used to identify the data source on the surface instance interface. You can use settype to perform the following operations:

• Surface_type_normal: Native data cached by Ram
• Surface_type_hardware: the data obtained through DMA and direct memory access is the data obtained through direct Screen Writing Technology, or data accelerated by other hardware.
• Surface_type_gpu: GPU-Accelerated Data
• Surface_type_push_buffers: identifies data from other objects, such as cameras, such as video playback servers (servers with video playback in Android, all playing videos are equivalent to clients)

The constructor of customervideoview, which uses the constructor of the superclass. The initvideoview () method is executed to initialize the interface and parameters.Another major content is the openvideo () method:

• mediaplayer. prepareasync () is used to prepare for playing asynchronously. In addition, there is a prepare () method, which is synchronous, that is, it can only be played after all the downloads are completed. Obviously, use the former when playing online videos.
• the attachmediacontroller () method is used to append the control bar to the surfaceview of the video to be played. This method is not completely implemented and therefore cannot be used. You only need to set the mediaplayercontrol instance through the setmediaplayer method, onpreparedlistener is used to get the callback for successful loading, and Code is used to call the video to get the video length and current time length.