Guidelines for projection manager
Projection manager lets you project a separate window of your app on another screen. For example, a game app can display the main game-playing window on a larger monitor and display the game controls on the local screen. Or in a multi-player word game such as Scrabble, you can display the shared game board on a projected screen and display the user’s game pieces on the local screen. In the case of a presentation app, you can display the presentation in a window on a projected screen and display notes for the presenter on the local screen.
By default, without using the projection manager, if a user connects to another display device, the app window is duplicated on the 2nd screen. When in duplicate mode, Windows automatically picks a resolution that works for both screens instead of using the screen info for the external screen, but this resolution might not be ideal for video playback or gaming. When you use the projection manager, Windows retrieves the resolution and the aspect ratio of the projection screen and optimizes the window display.
The projection manager is similar to using multiple windows for an app. This table describes when to use multiple windows and when to use projection manager.
| Scenario | Use multiple windows | Use projection manager |
|---|---|---|
| The user interacts with both windows | Recommended | Not recommended unless the external display is a touch device, such as Perceptive Pixel (PPI) by Microsoft |
| The 2nd window is for display only, not for interaction | Not recommended | Recommended |
| You expect the user to display the 2nd window on a screen that has a significantly different aspect ratio or resolution | Not recommended | Recommended |
Dos and don'ts
-
Let the user control the projection from the local app window.
The user must be able to:
- Start a new projected window.
- Resume a window's projection after it's been interrupted.
- Stop the projection after it has started.
- Swap the local and projected windows by using a control on the projected window. If the automatic placement of the windows is wrong and the projected window is placed on the local screen, the user must be able to swap the windows.
-
Use the following icons to start projecting, stop projecting, or swap the windows.
Code Icon Description U+E2B4 
Start or resume projecting U+E2B3 
Stop projecting U+E13C 
Swap projected view -
Don’t automatically start or stop the projection. Only user input should start or stop the projection.
Note You can implement "resume" functionality to make it easy for a user to restart a projection after pausing, or after switching to other apps. If a projected window leaves the screen on which it is displayed, typically because of another app projecting, use StartProjectingAsync to resume display of the projected window. You can subscribe to the VisibilityChanged event to find out when a projected window leaves the screen on which it is displayed. You can subscribe to the consolidated event to find out when a projected window is removed from the list of recently used apps or is closed.
Additional usage guidance
Styling and layout
You can choose the color and label text for icons you use to start, stop, and swap a projection. You can choose where to place the icons, but it's a good idea to place them in the bottom app bar and follow the guidance for app bar buttons.
You cannot change the placement of the projected window, because it's determined automatically. A user who has a mouse, keyboard, or touchpad, can move the projected window after it's placed.
Related topics
- For designers
- Guidelines for multiple windows
- Guidelines for app bars
- For developers
- Multiple windows sample
- Projection sample