VideoWall

App Inventor Classic • App Inventor Classic • FOR APP INVENTOR 2 CLICK HERE• App Inventor Classic • App Inventor Classic

This information pertains to App Inventor 1 (Classic). For tutorials about App Inventor 2, go to the App Inventor 2 Tutorials.

What you're building

The VideoWall app tutorial demonstrates how you can control the size of a video playing in an app by using the Video Player component's Width, Height, and FullScreen features. The VideoWall uses media assets (videos stored in the app itself), but you can use the app to display videos from the internet as well.

This tutorial assumes you are familiar with the basics of App Inventor-- using the Component Designer to build a user interface, and using the Blocks Editor to specify the app's behavior. If you are not familiar with the basics, try stepping through some of the basic tutorials before continuing.

Getting Started

Connect to the App Inventor web site and start a new project. Name the new project VideoWall and set the screen's Orientation to Landscape.

Download the following video files* for use later on:

*Attributions for these videos are included at the end of this tutorial.

Introduction

The finished VideoWall app will display a wall of three videos that can be expanded to their true size and then shrunk back down again. The app will also allow you to display the videos in fullscreen. This tutorial assumes you have followed earlier tutorials to learn how the following blocks work:

This tutorial introduces the following:

Set up the Components

Use the component designer to create the interface for the VideoWall. When completed, the designer should look similar to the snapshot below.

First, you need to upload the video files. Click on the Add... button and select a video file downloaded earlier. Repeat this step to add the other two video files. Now create the interface by dragging and dropping the components from the Palette to the Viewer.

Component Type Palette Group What you'll name it Purpose of Component
HorizontalArrangement Screen Arrangement HorizontalArrangement1 Holds all other components: makes the three vertical arrangements line up side by side
VerticalArrangement Screen Arrangement VerticalArrangement1 Holds the left-most VideoPlayer and controls
VerticalArrangement Screen Arrangement VerticalArrangement2 Holds the middle VideoPlayer and controls
VerticalArrangement Screen Arrangement VerticalArrangement3 Holds the right-most VideoPlayer and controls
VideoPlayer Media VideoPlayer1 Displays the BigBuckBunny video
VideoPlayer Media VideoPlayer2 Displays the NASA video
VideoPlayer Media VideoPlayer3 Displays the Sintel video
Button Basic ResizeButton1 Resizes VideoPlayer1
Button Basic ResizeButton2 Resizes VideoPlayer2
Button Basic ResizeButton3 Resizes VideoPlayer3
Button Basic FullScreenButton1 Shows the VideoPlayer1 video in fullscreen
Button Basic FullScreenButton2 Shows the VideoPlayer2 video in fullscreen
Button Basic FullScreenButton3 Shows the VideoPlayer3 video in fullscreen

Set the properties as described below:

Component Action
HorizontalArrangement1 Set Width to Fill parent...
VerticalArrangement1, VerticalArrangement2, and VerticalArrangement3 Set Width to Fill parent...
ResizeButton1, ResizeButton2, and ResizeButton3 Set Text to "Grow" and set Width to Fill parent...
FullScreenButton1, FullScreenButton2, and FullScreenButton3 Set Text to Show FullScreen and set Width to Fill parent...
VideoPlayer1 Set Source to bigbuckbunny.3gp , set Width to Fill parent... , and set Height to 36 pixels
VideoPlayer2 Set Source to nasa.3gp , set Width to Fill parent... , and set Height to 36 pixels
VideoPlayer3 Set Source to sintel.3gp , set Width to Fill parent... , and set Height to 36 pixels

Add Behaviors to the Components

The interface is complete, but the buttons don't resize the videos yet. Open the Blocks Editor to add the behavior to the buttons. First, you'll define three variable blocks to keep track of the size of the VideoPlayers:

Block Type Drawer Purpose
def variable Definition Defines the vid1_zoomed variable (rename it)
def variable Definition Defines the vid2_zoomed variable (rename it)
def variable Definition Defines the vid3_zoomed variable (rename it)

The three variables should like this:

Create the resizeVideoPlayer Procedure block. There are three VideoPlayers in the app, but you'll use one Procedure block to resize all three. To accomplish this simplicity, you will use the Advance blocks component Any VideoPlayer blocks. Create the resizeVideoPlayer Procedure block using the following blocks:

Block Type Drawer Purpose
Procedure Definition Defines the resizeVideoPlayer procedure
name (x5) Definition Defines the VideoPlayer argument for the resizeVideoPlayer procedure
name (x2) Definition Defines the zoomed argument for the resizeVideoPlayer procedure
name (x3) Definition Defines the button argument for the resizeVideoPlayer procedure
ifelse Control Defines the ifelse block that chooses whether the VideoPlayer is shrunk or expanded
= block Logic Defines the equals block for testing if the zoomed block is true
true Logic Defines the block that zoomed is compared to
VideoPlayer.Width (x2) Any VideoPlayer Sets the VideoPlayer Width to a number
Number (-1) (x2) Math Width to set VideoPlayer to
VideoPlayer.Height (x2) Any VideoPlayer Sets the VideoPlayer Height to a number
Number (x2), values of 26 and 144 Math Height to set VideoPlayer to
Button.text Any Button Changes the button text
Text Text Text to set button to. Make one text block text's Shrink and the other's Grow.

The resizeVideoPlayer block should look like the following:

The resizeVideoPlayer block will be explained later after you create the blocks for responding to button clicks.

Create the Click Blocks

The blocks you will create respond to clicks on the ResizeButton buttons. To build the three blocks, you will need the following blocks:

Block Type Drawer Purpose
ResizeButton1.Click ResizeButton1 Defines the block for responding to clicks on ResizeButton1
ResizeButton2.Click ResizeButton2 Defines the block for responding to clicks on ResizeButton2
ResizeButton3.Click ResizeButton3 Defines the block for responding to clicks on ResizeButton3
ResizeVideoPlayer (x3) My Definitions Starts the resizeVideoPlayer block for resizing a VideoPlayer
not (x3) Logic Defines the block for switching the various zoomed block values
set global vid1_zoomed My Definitions Sets the vid1_zoomed block to a different value
set global vid2_zoomed My Definitions Sets the vid2_zoomed block to a different value
set global vid3_zoomed My Definitions Sets the vid3_zoomed block to a different value
global vid1_zoomed My Definitions Used to change the vid1_zoomed value.
global vid2_zoomed My Definitions Used to change the vid2_zoomed value.
global vid3_zoomed My Definitions Used to change the vid3_zoomed value.
component ResizeButton1 ResizeButton1 Passed to the resizeVideoPlayer procedure
component ResizeButton2 ResizeButton2 Passed to the resizeVideoPlayer procedure
component ResizeButton3 ResizeButton3 Passed to the resizeVideoPlayer procedure
component VideoPlayer1 VideoPlayer1 Passed to the resizeVideoPlayer procedure
component VideoPlayer2 VideoPlayer2 Passed to the resizeVideoPlayer procedure
component VideoPlayer3 VideoPlayer3 Passed to the resizeVideoPlayer procedure

The blocks should look like the following:

Most blocks in App Inventor require you to know exactly what component your app will manipulate when you design the app. For some apps, you will have several of the same type of component and you want to program the same behavior for all of the similar components (like the VideoPlayer blocks in this app). The blocks in the Advanced section allow you to build some general manipulation on some type of component. When you built the resizeVideoPlayer procedure block, you didn't know specifically which VideoPlayer would be used in the procedure. The resizeVideoPlayer works on VideoPlayers; but not until the resizeVideoPlayer block is used in the ResizeButton1.Click block (for example) is the specific VideoPlayer known.

Note: The VideoWall app could have been designed with a specific resizing procedure for each VideoPlayer. By using the Advanced blocks in a single resizing procedure, the app is much simpler.

How the Blocks Work

Setting the Width and Height property for a VideoPlayer works exactly the same way as setting the Width and Height of a Button. For whatever positive number is set, the video playing will resize its appearance to fit that value. There are two values that are exceptions to the using positive values rule: -1 and -2. Setting VideoPlayer.Width or VideoPlayer.Height to -1 is like setting the Width or Height to Fill parent in the designer. Setting VideoPlayer.Width or VideoPlayer.Height to -2 is like setting the Width or Height to Automatic in the designer.

Warning: You can set the VideoPlayer Width and Height to any positive number you want. The VideoPlayer will change its size to match the values you set; but on some devices, the VideoPlayer does not change its size correctly. The behavior on such devices is usually unpredictable.
Test this behavior. Click on the Grow button below the BigBuckBunny video. The video's size should expand, and the text of the button should change to "Shrink". Click on the Shrink button below the BigBuckBunny video. The video's size should shrink back to its original size and the text should change back to "Grow".

Create the blocks for showing fullscreen video

You will now add the blocks for showing the videos in fullscreen mode. Use the following blocks:

Block Type Drawer Purpose
true (x3) Logic Value to set FullScreen as
FullScreenButton1.Click FullScreenButton1 Responds to clicks on FullScreenButton1
set VideoPlayer1.FullScreen VideoPlayer1 Used to show fullscreen video
FullScreenButton2.Click FullScreenButton2 Responds to clicks on FullScreenButton2
set VideoPlayer2.FullScreen VideoPlayer2 Used to show fullscreen video
FullScreenButton3.Click FullScreenButton3 Responds to clicks on FullScreenButton3
set VideoPlayer3.FullScreen VideoPlayer3 Used to show fullscreen video

The blocks should look like the following:

How the Blocks Work

The VideoPlayer.FullScreen block takes a true/false value (also called a boolean) to tell it whether to go full screen or not. Setting a VideoPlayer.FullScreen block to true causes that VideoPlayer to be displayed in fullscreen mode. If there is another VideoPlayer in fullscreen mode, that VideoPlayer's .FullScreen value is set to false and it is replaced with the current VideoPlayer. If a VideoPlayer.FullScreen is true, setting a VideoPlayer.FullScreen block to false causes the fullscreen mode to be exited and the app's interface to display. Test this behavior. Start playing the BigBuckVideo, and click on the Show FullScreen button below the BigBuckBunny video. The app's interface should disappear and some media controls with the BigBuckBunny video should appear. Use the Back button on your device or the emulator to exit fullscreen. The app's interface should appear.

Final Program

VideoWall Final Version

Package the final version of the app by choosing Package For Phone | Barcode from the Component Designer menu. When the barcode appears, use the barcode scanner on your phone to download and install the app.

Variations

Now that you have finished the first VideoWall app, you might want to build some variations. For example:

If you distribute your app to others, make sure you respect any license requirements for the videos you use.

Below are the attributions to the video files included in this demo app. The creators of the source videos that these clips are from do not endorse App Inventor.

Video File Information Attribution
bigbuckbunny.3gp A clip from the full length film (c) copyright 2008, Blender Foundation / http://www.bigbuckbunny.org
nasa.3gp A formatted version of the Mars' Whirling Dust Devil clip. Here is the original video.
sintel.3gp A clip from the full length film (c) copyright Blender Foundation | http://durian.blender.org

Scan the Sample App to your Phone

Scan the following barcode onto your phone to install and run the sample app.

Or download the apk

Download Source Code

If you'd like to work with this sample in App Inventor, download the source code to your computer, then open App Inventor, go to the My Projects page, and choose More Actions | Upload Source.

MIT is grateful to Vance Turnewitsch for developing this tutorial.

Done with VideoWall? Return to the other tutorials here.