Actually, I tried it, but I could never get it working fine. It just
shows black screen and ended up with crash (I don't remember correctly).
Should this equivalent code work in Java form?
Atsushi Eno
> Does anyone have any advice for this issue? Doesn't look liek anyone's looked
> at it!
>
> Hi.
> I'm trying to implement an activity which previews the camera and allows a
> picture to be taken.
> However I get rather mixed results with each build. One time it will work
> fine, but I might make a change such as adding a comment and re-compile and
> I get an error when setting the ISurfaceHolderCallback, then I might take
> the comment out and re-compile and I get a page fault, then I can do
> something else and it works again! It seems that it's compile/build related
> because if I build and it happens to work it will always work; but if I
> build and it crashes then it will always crash. The below failed with the
> exception shown, then I took the '.' off the end of the comment, re-compiled
> and it then worked!!!
> Is there an issue here or am I failing to set something up properly?
> I'm running this on a Dell Streak 5.
>
> This is a snapshot from ADB of one of the errors:
>
> I/ActivityManager( 146): Starting activity: Intent {
> cmp=uk.co.reach.reachcloud/reachmobilecc.PictureActivity }
> I/CameraView( 2699): Adding Callback
> F/PrintK ( 2699):<2>Exception!!! each.reachcloud: unhandled page fault
> (11) at 0xed006d4e, code 0x005
> I/MonoDroid( 2699): UNHANDLED EXCEPTION: System.NullReferenceException:
> Object reference not set to an instance of an object
> I/MonoDroid( 2699): at Android.Views.ISurfaceHolderCallbackAdapter.GetHandle
> (Android.Views.ISurfaceHolderCallback)<0x00038>
> I/MonoDroid( 2699): at Android.Views.ISurfaceHolderInvoker.AddCallback
> (Android.Views.ISurfaceHolderCallback)<0x000bf>
> I/MonoDroid( 2699): at ReachMobileCC.PictureActivity.OnResume ()<0x00073>
> I/MonoDroid( 2699): at Android.App.Activity.n_OnResume (intptr,intptr)
> <0x00033>
> I/MonoDroid( 2699): at (wrapper dynamic-method)
> object.38c0d09b-61f8-491e-b367-fbed8a6fb14a (intptr,intptr)<0x0002b>
> E/mono ( 2699):
> E/mono ( 2699): Unhandled Exception: System.NullReferenceException:
> Object reference not set to an instance of an object
> E/mono ( 2699): at
> Android.Views.ISurfaceHolderCallbackAdapter.GetHandle
> (ISurfaceHolderCallback instance) [0x00000] in<filename unknown>:0
> E/mono ( 2699): at Android.Views.ISurfaceHolderInvoker.AddCallback
> (ISurfaceHolderCallback callback) [0x00000] in<filename unknown>:0
> E/mono ( 2699): at ReachMobileCC.PictureActivity.OnResume () [0x00000]
> in<filename unknown>:0
> E/mono ( 2699): at Android.App.Activity.n_OnResume (IntPtr jnienv,
> IntPtr native__this) [0x00000] in<filename unknown>:0
> E/mono ( 2699): at (wrapper dynamic-method)
> object:38c0d09b-61f8-491e-b367-fbed8a6fb14a (intptr,intptr)
> I/ActivityManager( 146): Process uk.co.reach.reachcloud (pid 2699) has
> died.
>
> This is the activity class:
>
> using System;
> using System.Collections.Generic;
> using System.Linq;
> using System.Text;
>
> using Android.App;
> using Android.Content;
> using Android.Hardware;
> using Android.OS;
> using Android.Runtime;
> using Android.Views;
> using Android.Widget;
> using Android.Util;
>
> namespace ReachMobileCC
> {
> [Activity(Label = "@string/TakePicture", ConfigurationChanges =
> Android.Content.PM.ConfigChanges.Orientation |
> Android.Content.PM.ConfigChanges.Keyboard |
> Android.Content.PM.ConfigChanges.KeyboardHidden)]
> public class PictureActivity : Activity, ISurfaceHolderCallback,
> Camera.IPictureCallback
> {
> #region Fields
>
> private bool _previewing = false;
> private Camera _camera = null;
>
> #endregion
>
> public static byte[] JpegData { get; set; }
>
> #region Event Handlers
>
> protected override void OnCreate(Bundle bundle)
> {
> base.OnCreate(bundle);
> SetContentView(Resource.Layout.Picture);
> FindViewById<Button>(Resource.Id.TakePicture).Click +=
> TakePictureClick;
> }
>
> protected override void OnResume()
> {
> base.OnResume();
> var holder =
> FindViewById<SurfaceView>(Resource.Id.PicturePreview).Holder;
> Log.Info("CameraView", "Adding Callback");
> holder.AddCallback(this);
> Log.Info("CameraView", "Added Callback");
> holder.SetType(SurfaceType.PushBuffers);
> }
>
> public override bool OnKeyDown(Keycode keyCode, KeyEvent e)
> {
> if (keyCode == Keycode.Back&& _previewing)
> {
> StopPreviewAndExit(false);
> return true;
> }
> if ((keyCode == Keycode.Camera || keyCode == Keycode.DpadCenter)
> && _previewing)
> {
> TakePictureClick(this, new EventArgs());
> return true;
> }
> return base.OnKeyDown(keyCode, e);
> }
>
> void TakePictureClick(object sender, EventArgs e)
> {
> if (_camera != null)
> _camera.TakePicture(null, null, this);
> }
>
> #endregion
>
> #region ISurfaceHolderCallback Members
>
> public void SurfaceChanged(ISurfaceHolder holder, int format, int
> width, int height)
> {
> if (_camera != null)
> {
> if (_previewing) _camera.StopPreview();
> var parameters = _camera.GetParameters();
> var previewSize =
> GetNearestPreviewSize(parameters.SupportedPreviewSizes, width, height);
> parameters.SetPreviewSize(previewSize.Width,
> previewSize.Height);
> if
> (parameters.SupportedFocusModes.Contains(Camera.Parameters.FocusModeAuto))
> parameters.FocusMode = Camera.Parameters.FocusModeAuto;
> else if
> (parameters.SupportedFocusModes.Contains(Camera.Parameters.FocusModeInfinity))
> parameters.FocusMode =
> Camera.Parameters.FocusModeInfinity;
> parameters.SetRotation(90); // TODO: Match to window
> orientation.
> _camera.SetParameters(parameters);
> _camera.SetPreviewDisplay(holder);
> _camera.StartPreview();
> _previewing = true;
> }
> }
>
> public void SurfaceCreated(ISurfaceHolder holder)
> {
> _camera = Android.Hardware.Camera.Open();
> }
>
> public void SurfaceDestroyed(ISurfaceHolder holder)
> {
> StopPreview();
> }
>
> #endregion
>
> #region IPictureCallback Members
>
> public void OnPictureTaken(byte[] data, Android.Hardware.Camera
> camera)
> {
> JpegData = data;
> StopPreviewAndExit(true);
> }
>
> #endregion
>
> #region Helper Methods
>
> private Camera.Size GetNearestPreviewSize(IList<Camera.Size> sizes,
> int width, int height)
> {
> Camera.Size nearestSize = sizes[0];
> int diff = 99999;
> foreach (var size in sizes)
> {
> if (size.Width> width || size.Height> height) continue;
> var comp = (width - size.Width) + (height - size.Height);
> if (comp< diff)
> {
> comp = diff;
> nearestSize = size;
> }
> }
> return nearestSize;
> }
>
> public void StopPreview()
> {
> if (_camera != null)
> {
> _camera.StopPreview();
> _camera.Release();
> _camera = null;
> }
> }
>
> public void StopPreviewAndExit(bool ok)
> {
> StopPreview();
> SetResult(ok ? Result.Ok : Result.Canceled, new
> Intent(this.ApplicationContext, typeof(PictureActivity)));
> Finish();
> }
>
> #endregion
> }
> }
>
> This is the layout:
>
> <?xml version="1.0" encoding="utf-8"?>
> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android";
> android:layout_width="fill_parent"
> android:layout_height="fill_parent">
> <Button
> android:id="@+id/TakePicture"
> android:layout_width="fill_parent"
> android:layout_height="wrap_content"
> android:text="@string/TakePicture"
> android:layout_alignParentBottom="true"
> />
> <SurfaceView
> android:id="@+id/PicturePreview"
> android:layout_width="fill_parent"
> android:layout_height="fill_parent"
> android:layout_above="@id/TakePicture"
> />
> </RelativeLayout>
>
>
> --
> View this message in context:
> http://mono-for-android.1047100.n5.nabble.com/SurfaceHolder-AddCallback-random-errors-tp4669293p4678027.html
> Sent from the Mono for Android mailing list archive at Nabble.com.
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