An Activity which produces a "Lightbox"-type UI, where the entire screen except an image is dimmed - putting the image front and centre for your users. Compatible with Chris Banes' PhotoView, or the standard ImageView widget.

act_lightbox.xml

<?xml version="1.0" encoding="utf-8"?>
<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/lightboxView"
    android:background="@android:color/white" />

act_lightbox_photoview.xml

<?xml version="1.0" encoding="utf-8"?>
<uk.co.senab.photoview.PhotoView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/lightboxView"
    android:background="@android:color/white" />

LightboxActivity.java

/**
*  Copyright 2013 Alex Curran
* 
*  Licensed under the Apache License, Version 2.0 (the "License");
*  you may not use this file except in compliance with the License.
*  You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0
*
*  Unless required by applicable law or agreed to in writing, software
*  distributed under the License is distributed on an "AS IS" BASIS,
*  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*  See the License for the specific language governing permissions and
*  limitations under the License.
*
*/

package com.espian.formulae.utils;

import android.app.Activity;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
import com.espian.formulae.lib.R;

/**
 * An {@link Activity} which produces a "Lightbox"-type UI, where the entire screen bar the
 * image is dimmed. Start the Activity with an {@link Intent} which has an extra with
 * the key LightboxActivity.SOURCE_VALUE, which is either a Bitmap or resource id.
 *
 * The system is flexible should you wish to supply it with data that isn't a Bitmap or
 * resource id. Overriding LightboxActivity and implementing getBitmapFromResource(..)
 * allows you to supply your own logic for retrieving an image.
 *
 * You can optionally override shouldDimUi(), which allows the system chrome to be
 * put in a low-profile mode. This is disabled by default.
 *
 * @author Alex Curran
 */
public class LightboxActivity extends Activity {

    public static final int SOURCE_INVALID = -1;
	public static final int SOURCE_RESOURCE = 0;
	public static final int SOURCE_BITMAP = 2;
	public static final int SOURCE_OTHER = 3;

	public static final String SOURCE_TYPE = "source_type";
	public static final String SOURCE_VALUE = "source_value";

	public void onCreate(Bundle saved) {
		super.onCreate(saved);
		setContentView(R.layout.act_lightbox);

        ImageView lightbox = (ImageView) findViewById(R.id.lightboxView);
        Object source = getIntent().getExtras().get(SOURCE_VALUE);
        int sourceType = getIntent().getIntExtra(SOURCE_TYPE, SOURCE_INVALID);

        // If the developer hasn't supplied a source type, try to guess it
        // with some pretty crude heuristics...
        if (sourceType == SOURCE_INVALID) {
            if (source == null) throw new NullPointerException("LightboxActivity has no source.");
            if (source instanceof Bitmap) sourceType = SOURCE_BITMAP;
            if (source instanceof Integer) sourceType = SOURCE_RESOURCE;
        }

        // Else continue on with figuring out what our source is
        switch (sourceType) {

            case SOURCE_INVALID:
                throw new IllegalArgumentException("LightboxActivity not supplied with a valid source.");

            case SOURCE_BITMAP:
                lightbox.setImageBitmap((Bitmap) source);
                break;

            case SOURCE_RESOURCE:
                lightbox.setImageResource((Integer) source);
                break;

            case SOURCE_OTHER:
                lightbox.setImageBitmap(getBitmapFromSource(source));
                break;

        }

        if (shouldDimUi()) {
            lightbox.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE);
        }

	}

    /**
     * Used in conjuction with SOURCE_OTHER. Must be overridden in a subclass
     * @param sourceValue The object extra from the intent with key "source_value"
     * @return A manually generated Bitmap
     */
    public Bitmap getBitmapFromSource(Object sourceValue) {
        return null;
    }

    /**
     * Determine whether the System UI should be dimmed whilst this Activity is
     * shown. Override the default value in a subclass should you wish to change it
     * @return
     */
    public boolean shouldDimUi() {
        return false;
    }

}

styles_lightbox.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="Theme.Lightbox" parent="android:Theme" >
        <item name="android:windowIsTranslucent">true</item>
        <item name="android:windowBackground">@android:color/transparent</item>
        <item name="android:windowContentOverlay">@null</item>
        <item name="android:windowNoTitle">true</item>
        <item name="android:windowIsFloating">true</item>
        <item name="android:backgroundDimEnabled">true</item>
    </style>
</resources>