java - How to show 2 camera preview side by side?[For cardboard apps]

Question

I am trying to build a Cardboard android application that shows 2 camera view side by side. [Just like the camera view works for VRCinema Android app.]

So I studies the Cardboard code from GitHub, made some modification and so far I am able to use the imageView to replicate the same image side by side.

and the Code so far looks like this.

AndroidManifest.XML

    <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="com.google.vrtoolkit.cardboard.samples.treasurehunt" >

    <uses-permission android:name="android.permission.NFC" />
    <uses-permission android:name="android.permission.VIBRATE" />
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-feature android:name="android.hardware.camera" android:required="false" />
    <uses-feature android:name="android.hardware.camera.autofocus" android:required="false" />
    <uses-feature android:name="android.hardware.camera.front" android:required="false" />


    <uses-sdk android:minSdkVersion="14"/>
    <uses-feature android:glEsVersion="0x00020000" android:required="true" />

    <application
            android:allowBackup="true"
            android:icon="@drawable/ic_launcher"
            android:label="@string/app_name" >

        <activity
                android:screenOrientation="landscape"
                android:name=".MainActivity"
                android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

common_ui.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/ui_layout"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >


    <com.google.vrtoolkit.cardboard.CardboardView
        android:id="@+id/cardboard_view"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true" />

    <com.google.vrtoolkit.cardboard.samples.treasurehunt.CardboardOverlayView
        android:id="@+id/overlay"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_centerInParent="true" />



</RelativeLayout>

CardboardOverlayView.java

package com.google.vrtoolkit.cardboard.samples.treasurehunt;

        import android.content.Context;
        import android.graphics.Color;
        import android.graphics.Typeface;
        import android.util.AttributeSet;
        import android.util.TypedValue;
        import android.view.Gravity;
        import android.view.View;
        import android.view.ViewGroup;
        import android.view.animation.AlphaAnimation;
        import android.view.animation.Animation;
        import android.widget.ImageView;
        import android.widget.LinearLayout;
        import android.widget.TextView;

/**
 * Contains two sub-views to provide a simple stereo HUD.
 */
public class CardboardOverlayView extends LinearLayout {
    private static final String TAG = CardboardOverlayView_bkp1.class.getSimpleName();
    private final CardboardOverlayEyeView mLeftView;
    private final CardboardOverlayEyeView mRightView;
    private AlphaAnimation mTextFadeAnimation;

    public CardboardOverlayView(Context context, AttributeSet attrs) {
        super(context, attrs);
        setOrientation(HORIZONTAL);

        LayoutParams params = new LayoutParams(
                LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT, 1.0f);
        params.setMargins(0, 0, 0, 0);

        mLeftView = new CardboardOverlayEyeView(context, attrs);
        mLeftView.setLayoutParams(params);
        addView(mLeftView);

        mRightView = new CardboardOverlayEyeView(context, attrs);
        mRightView.setLayoutParams(params);
        addView(mRightView);

        // Set some reasonable defaults.
        setDepthOffset(0.016f);
        setColor(Color.rgb(150, 255, 180));
        setVisibility(View.VISIBLE);

        mTextFadeAnimation = new AlphaAnimation(1.0f, 0.0f);
        mTextFadeAnimation.setDuration(5000);
    }

    public void show3DToast(String message) {
        setText(message);
        setTextAlpha(1f);
        mTextFadeAnimation.setAnimationListener(new EndAnimationListener() {
            @Override
            public void onAnimationEnd(Animation animation) {
                setTextAlpha(0f);
            }
        });
        startAnimation(mTextFadeAnimation);
    }

    public void show3DImage() {
        setImg();

    }

    private abstract class EndAnimationListener implements Animation.AnimationListener {
        @Override public void onAnimationRepeat(Animation animation) {}
        @Override public void onAnimationStart(Animation animation) {}
    }

    private void setDepthOffset(float offset) {
        mLeftView.setOffset(offset);
        mRightView.setOffset(-offset);
    }


    //---------------------------------------------------------------------------------------------
    private void setImg(){
        mLeftView.imageView.setImageResource(R.drawable.mona_lisa);
        mRightView.imageView.setImageResource(R.drawable.mona_lisa);

    }
    //------------------------------------------------------------------------------------------

    private void setText(String text) {
        mLeftView.setText(text);
        mRightView.setText(text);
    }

    private void setTextAlpha(float alpha) {
        mLeftView.setTextViewAlpha(alpha);
        mRightView.setTextViewAlpha(alpha);
    }

    private void setColor(int color) {
        mLeftView.setColor(color);
        mRightView.setColor(color);
    }

    /**
     * A simple view group containing some horizontally centered text underneath a horizontally
     * centered image.
     *
     * This is a helper class for CardboardOverlayView.
     */
    private class CardboardOverlayEyeView extends ViewGroup {
        private final ImageView imageView;
        private final TextView textView;
        private float offset;

        public CardboardOverlayEyeView(Context context, AttributeSet attrs) {
            super(context, attrs);
            imageView = new ImageView(context, attrs);
            imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
            imageView.setAdjustViewBounds(true);  // Preserve aspect ratio.
            addView(imageView);

            textView = new TextView(context, attrs);
            textView.setTextSize(TypedValue.COMPLEX_UNIT_DIP, 14.0f);
            textView.setTypeface(textView.getTypeface(), Typeface.BOLD);
            textView.setGravity(Gravity.CENTER);
            textView.setShadowLayer(3.0f, 0.0f, 0.0f, Color.DKGRAY);
            addView(textView);
        }

        public void setColor(int color) {
            //imageView.setColorFilter(color);
            textView.setTextColor(color);
        }

        public void setText(String text) {
            textView.setText(text);
        }

        public void setTextViewAlpha(float alpha) {
            textView.setAlpha(alpha);
        }

        public void setOffset(float offset) {
            this.offset = offset;
        }

        @Override
        protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
            // Width and height of this ViewGroup.
            final int width = right - left;
            final int height = bottom - top;

            // The size of the image, given as a fraction of the dimension as a ViewGroup. We multiply
            // both width and heading with this number to compute the image's bounding box. Inside the
            // box, the image is the horizontally and vertically centered.
            final float imageSize = 1.0f;

            // The fraction of this ViewGroup's height by which we shift the image off the ViewGroup's
            // center. Positive values shift downwards, negative values shift upwards.
            final float verticalImageOffset = -0.07f;

            // Vertical position of the text, specified in fractions of this ViewGroup's height.
            final float verticalTextPos = 0.52f;

            // Layout ImageView
            float imageMargin = (1.0f - imageSize) / 2.0f;
            float leftMargin = (int) (width * (imageMargin + offset));
            float topMargin = (int) (height * (imageMargin + verticalImageOffset));
            imageView.layout(
                    (int) leftMargin, (int) topMargin,
                    (int) (leftMargin + width * imageSize), (int) (topMargin + height * imageSize));

            // Layout TextView
            leftMargin = offset * width;
            topMargin = height * verticalTextPos;
            textView.layout(
                    (int) leftMargin, (int) topMargin,
                    (int) (leftMargin + width), (int) (topMargin + height * (1.0f - verticalTextPos)));
        }
    }
}

MainActivity.Java

package com.google.vrtoolkit.cardboard.samples.treasurehunt;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.hardware.Camera;
import android.net.Uri;
import android.os.Bundle;
import android.os.Vibrator;
import android.util.Log;
import android.widget.ImageView;
import com.google.vrtoolkit.cardboard.*;
import javax.microedition.khronos.egl.EGLConfig;
import java.nio.FloatBuffer;

/**
 * A Cardboard sample application.
 */
public class MainActivity extends CardboardActivity implements CardboardView.StereoRenderer {


    private static final int CAMERA_REQUEST = 1888;

    private static final String TAG = "MainActivity";
    private static final int CAPTURE_IMAGE_ACTIVITY_REQ = 0;

    Uri fileUri = null;
    ImageView photoImage = null;

    private static final float CAMERA_Z = 0.01f;
    private static final float TIME_DELTA = 0.3f;

    private static final float YAW_LIMIT = 0.12f;
    private static final float PITCH_LIMIT = 0.12f;

    // We keep the light always position just above the user.
    private final float[] mLightPosInWorldSpace = new float[]{0.0f, 2.0f, 0.0f, 1.0f};
    private final float[] mLightPosInEyeSpace = new float[4];

    private static final int COORDS_PER_VERTEX = 3;

    private final WorldLayoutData DATA = new WorldLayoutData();

    private FloatBuffer mFloorVertices;
    private FloatBuffer mFloorColors;
    private FloatBuffer mFloorNormals;

    private FloatBuffer mCubeVertices;
    private FloatBuffer mCubeColors;
    private FloatBuffer mCubeFoundColors;
    private FloatBuffer mCubeNormals;

    private int mGlProgram;
    private int mPositionParam;
    private int 

Answer 1

Basically you need to draw the camera into an OpenGL texture and show the texture.

I wrote two versions of this here, feel free to modify the code and add pull requests: https://github.com/Sveder/CardboardPassthrough