android - Using a ViewPager over a CameraPreview -

i've been trying create camera preview displays view pager several transparent images on preview. but, i'm getting error:

05-10 03:31:23.614: e/androidruntime(674): fatal exception: main 05-10 03:31:23.614: e/androidruntime(674): java.lang.nullpointerexception 05-10 03:31:23.614: e/androidruntime(674):  @ com.android.gs1.mainactivity$camerapreview.surfacecreated(mainactivity.java:102) 05-10 03:31:23.614: e/androidruntime(674):  @ android.view.surfaceview.updatewindow(surfaceview.java:562) 05-10 03:31:23.614: e/androidruntime(674):  @ android.view.surfaceview.access$000(surfaceview.java:82) 05-10 03:31:23.614: e/androidruntime(674):  @ android.view.surfaceview$3.onpredraw(surfaceview.java:171) 05-10 03:31:23.614: e/androidruntime(674):  @ android.view.viewtreeobserver.dispatchonpredraw(viewtreeobserver.java:590) 05-10 03:31:23.614: e/androidruntime(674):  @ android.view.viewrootimpl.performtraversals(viewrootimpl.java:1596) 05-10 03:31:23.614: e/androidruntime(674):  @ android.view.viewrootimpl.handlemessage(viewrootimpl.java:2418) 05-10 03:31:23.614: e/androidruntime(674):  @ android.os.handler.dispatchmessage(handler.java:99) 05-10 03:31:23.614: e/androidruntime(674):  @ android.os.looper.loop(looper.java:137) 05-10 03:31:23.614: e/androidruntime(674):  @ android.app.activitythread.main(activitythread.java:4340) 05-10 03:31:23.614: e/androidruntime(674):  @ java.lang.reflect.method.invokenative(native method) 05-10 03:31:23.614: e/androidruntime(674):  @ java.lang.reflect.method.invoke(method.java:511) 05-10 03:31:23.614: e/androidruntime(674):  @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:784) 05-10 03:31:23.614: e/androidruntime(674):  @ com.android.internal.os.zygoteinit.main(zygoteinit.java:551) 05-10 03:31:23.614: e/androidruntime(674):  @ dalvik.system.nativestart.main(native method) 

here code:

package com.android.gs1;  import java.io.ioexception; import android.os.bundle; import android.os.parcelable; import android.app.activity; import android.content.context; import android.hardware.camera; import android.support.v4.view.pageradapter; import android.support.v4.view.viewpager; import android.util.log; import android.view.layoutinflater; import android.view.surfaceholder; import android.view.surfaceview; import android.view.view; import android.view.viewgroup; import android.widget.linearlayout; import android.widget.toast;   public class mainactivity extends activity {  viewpager vp; camera mcamera; surfaceholder mholder; static int j; private vpadapter myadapter; camerapreview preview;  public static void passpagenumber(int i){     j = i; } @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);       toast.maketext(getapplicationcontext(), "swipe left or right select option", toast.length_long).show();     vp = (viewpager) findviewbyid(r.id.viewpager);     myadapter = new vpadapter();     preview = new camerapreview(getapplicationcontext(), mcamera);     ((linearlayout) findviewbyid(r.id.preview)).addview(preview);     vp.setadapter(myadapter); }  private class camerapreview extends surfaceview implements surfaceholder.callback{       private final string tag = null;       public camerapreview(context context, camera camera) {         super(context);         // todo auto-generated constructor stub         mcamera = camera;          // install surfaceholder.callback notified when         // underlying surface created , destroyed.         mholder = getholder();         mholder.addcallback(this);          // deprecated setting, required on android versions prior 3.0       //  mholder.settype(surfaceholder.surface_type_push_buffers);     }      @override     public void surfacechanged(surfaceholder holder, int format, int width,             int height) {         // todo auto-generated method stub         if (mholder.getsurface() == null){               // preview surface not exist               return;             }              // stop preview before making changes             try {                mcamera.stoppreview();             } catch (exception e){               // ignore: tried stop non-existent preview             }              // set preview size , make resize, rotate or             // reformatting changes here              // start preview new settings             try {                 mcamera.setpreviewdisplay(mholder);                 mcamera.startpreview();              } catch (exception e){                 log.d(tag, "error starting camera preview: " + e.getmessage());             }     }      @override     public void surfacecreated(surfaceholder holder) {         // todo auto-generated method stub         try {             mcamera = camera.open();             mcamera.setpreviewdisplay(holder);             mcamera.startpreview();         } catch (ioexception e) {             log.d(tag, "error setting camera preview: " + e.getmessage());         }     }      @override     public void surfacedestroyed(surfaceholder holder) {         // todo auto-generated method stub      }  } private class vpadapter extends pageradapter{      @override     public int getcount() {         // todo auto-generated method stub         return 5;     }      @override     public boolean isviewfromobject(view view, object object) {         // todo auto-generated method stub         return view == ((linearlayout)object);     }      @override     public void destroyitem(viewgroup container, int position, object object) {         // todo auto-generated method stub         ((viewpager)container).removeview((linearlayout)object);     }      @override     public void finishupdate(viewgroup container) {         // todo auto-generated method stub      }       @override     public object instantiateitem(view container, int position) {         // todo auto-generated method stub         layoutinflater inflater = (layoutinflater)container.getcontext().getsystemservice(context.layout_inflater_service);         view v = null;          switch(position){         case 0:             v = inflater.inflate(r.layout.first, null);             break;         case 1:             v = inflater.inflate(r.layout.second, null);             break;         case 2:             v = inflater.inflate(r.layout.third, null);             break;         case 3:             v = inflater.inflate(r.layout.fourth, null);             break;         case 4:             v = inflater.inflate(r.layout.fifth, null);             break;         }           ((viewpager)container).addview(v, 0);         return v;     }     @override     public void startupdate(viewgroup container) {         // todo auto-generated method stub      }     @override     public parcelable savestate() {         // todo auto-generated method stub         return null;     }  } } 

here xml

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".mainactivity"  android:background="#545454" >  <android.support.v4.view.viewpager     android:id="@+android:id/viewpager"     android:layout_width="0dip"     android:layout_height="wrap_content"     android:layout_weight="0.49" /> <linearlayout     android:id="@+id/preview"     android:layout_width="wrap_content"     android:layout_height="wrap_content"> </linearlayout> </linearlayout> 

there 5 more xml viewpager. of them this, different name , ids.

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical"  >  <imageview android:id="@+id/image1" android:layout_width="match_parent" android:layout_height="wrap_content" android:adjustviewbounds="false" android:contentdescription="@string/description_image_1" android:scaletype="fitxy" android:src="@drawable/first" />  </linearlayout> 

thank much

edit: asked me final working version of code. here is:

public class mainactivity extends activity {  viewpager vp; vpadapter myadapter; camera camera = null; surfaceholder previewholder = null; private surfaceview preview = null; private boolean inpreview = false; private boolean cameraconfigured = false; public static string[] arrayurl; public static boolean urlspassed; private view mcontentview; private view mloadingview;  private int mshortanimationduration;   @suppresswarnings("deprecation") @suppresslint("newapi") @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     requestwindowfeature(window.feature_no_title);     setcontentview(r.layout.activity_main);     toast.maketext(getapplicationcontext(), "swipe left or right select option", toast.length_short).show();     //new code      mcontentview = findviewbyid(r.id.content);     mloadingview = findviewbyid(r.id.loading_spinner);     mcontentview.setvisibility(view.gone);     mshortanimationduration = getresources().getinteger(             android.r.integer.config_shortanimtime);     //new code     preview=(surfaceview)findviewbyid(r.id.preview);     preview.setzorderontop(false);     previewholder=preview.getholder();     previewholder.addcallback(surfacecallback);     previewholder.settype(surfaceholder.surface_type_push_buffers);  } private void crossfade() {      // set content view 0% opacity visible, visible     // (but transparent) during animation.     mcontentview.setalpha(0f);     mcontentview.setvisibility(view.visible);      // animate content view 100% opacity, , clear animation     // listener set on view.     mcontentview.animate()             .alpha(1f)             .setduration(mshortanimationduration)             .setlistener(null);      // animate loading view 0% opacity. after animation ends,     // set visibility gone optimization step (it won't     // participate in layout passes, etc.)     mloadingview.animate()             .alpha(0f)             .setduration(mshortanimationduration)             .setlistener(new animatorlisteneradapter() {                 @override                 public void onanimationend(animator animation) {                     mloadingview.setvisibility(view.gone);                 }             }); }     public static void assignurl(string[] urls){     arrayurl = urls; }      public static void urlspassed(boolean transfer){         urlspassed = transfer;     }  @override   public void onresume() {     super.onresume();     camera=camera.open(); }   @override  public boolean oncreateoptionsmenu(menu menu) {   getmenuinflater().inflate(r.menu.main, menu);   return true;  } @override   public void onpause() {     if (inpreview) {       camera.stoppreview();     }      camera.release();     camera=null;     inpreview=false;      super.onpause();   }  private camera.size getbestpreviewsize(int width, int height,camera.parameters parameters) {      camera.size result=null;     (camera.size size : parameters.getsupportedpreviewsizes()) {         if (size.width<=width && size.height<=height) {             if (result==null) {                 result=size;             }             else {                 int resultarea=result.width*result.height;                 int newarea=size.width*size.height;                  if (newarea>resultarea) {                     result=size;                 }             }         }     }      return(result); } private void initpreview(int width, int height) {     if (camera!=null && previewholder.getsurface()!=null) {       try {         camera.setpreviewdisplay(previewholder);       }       catch (throwable t) {         log.e("previewdemo-surfacecallback",               "exception in setpreviewdisplay()", t);         toast           .maketext(mainactivity.this, t.getmessage(), toast.length_long)           .show();       }        if (!cameraconfigured) {         camera.parameters parameters=camera.getparameters();         camera.size size=getbestpreviewsize(width, height,                                             parameters);          if (size!=null) {           parameters.setpreviewsize(size.width, size.height);           camera.setparameters(parameters);           cameraconfigured=true;         }       }     }   }   private void startpreview() {         if (cameraconfigured && camera!=null) {           camera.startpreview();           inpreview=true;           crossfade();           if(urlspassed){             myadapter = new vpadapter(this,  arrayurl);             vp = (viewpager) findviewbyid(r.id.viewpager);             vp.setadapter(myadapter);             vp.setcurrentitem(0);           }         }       }   surfaceholder.callback surfacecallback=new surfaceholder.callback() {         @override         public void surfacecreated(surfaceholder holder) {           // no-op -- wait until surfacechanged()         }          @override         public void surfacechanged(surfaceholder holder, int format, int width,int height) {             camera.parameters parameters = camera.getparameters();           parameters.setfocusmode(camera.parameters.focus_mode_auto);           camera.setparameters(parameters);           initpreview(width, height);           startpreview();           camera.autofocus(null);         }          @override         public void surfacedestroyed(surfaceholder holder) {           // no-op         }       };  } 

for future people struggling kind of problem. found solution:

first, whatever set in top of preview must placed after surfaceview in layout. instance:

<relativelayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     tools:context=".mainactivity"      android:background="#ffff">      <android.view.surfaceview         android:id="@+id/preview"         android:layout_width="4978dp"         android:layout_height="5131dp">     </android.view.surfaceview>      <android.support.v4.view.viewpager         android:id="@+android:id/viewpager"         android:layout_width="fill_parent"         android:layout_height="fill_parent"/> </relativelayout> 

second, in java file, surfaceview must setzorderontop false. instance:

surfaceview preview=(surfaceview)findviewbyid(r.id.preview); preview.setzorderontop(false); 

third, set layout on top of camerapreview after calling startpreview function in camera.

that's it.