PowerToys/TESTING_NOTES.md

Testing Notes for PDF Fullscreen Toggle Fix

Issue

[Peek] How do I un-fullscreen a PDF? (#Issue number to be filled)

Summary of Changes

Fixed the PDF fullscreen toggle functionality in Peek. When viewing PDFs in Peek, clicking the fullscreen button now properly toggles between fullscreen and windowed modes.

Files Changed

1. src/modules/peek/Peek.FilePreviewer/Controls/BrowserControl.xaml.cs

   • Added FullScreenChangedHandler delegate and FullScreenChanged event
   • Subscribed to CoreWebView2.ContainsFullScreenElementChanged event
   • Added event handler CoreWebView2_ContainsFullScreenElementChanged

2. src/modules/peek/Peek.FilePreviewer/FilePreview.xaml

   • Wired up FullScreenChanged event handler to BrowserControl

3. src/modules/peek/Peek.FilePreviewer/FilePreview.xaml.cs

   • Added FullScreenChanged event
   • Added BrowserPreview_FullScreenChanged event handler to propagate state

4. src/modules/peek/Peek.UI/PeekXAML/MainWindow.xaml

   • Wired up FullScreenChanged event handler to FilePreview

5. src/modules/peek/Peek.UI/PeekXAML/MainWindow.xaml.cs

   • Added FilePreviewer_FullScreenChanged event handler
   • Toggles between AppWindowPresenterKind.FullScreen and AppWindowPresenterKind.Default

Manual Testing Steps

Prerequisites

1. Build PowerToys with the changes
2. Have a PDF file ready for testing

Test Case 1: Enter and Exit Fullscreen

1. Open File Explorer
2. Select a PDF file
3. Press Ctrl+Space to open Peek
4. Verify PDF is displayed correctly
5. Click the fullscreen button in the PDF viewer (usually in bottom-right corner)
6. EXPECTED: Window enters fullscreen mode, titlebar disappears
7. Click the fullscreen button again
8. EXPECTED: Window exits fullscreen mode, titlebar reappears

Test Case 2: Escape Key Still Works

1. Open a PDF in Peek
2. Click the fullscreen button to enter fullscreen
3. Press Escape key
4. EXPECTED: Window exits fullscreen AND Peek closes (existing behavior)

Test Case 3: Multiple Toggle Cycles

1. Open a PDF in Peek
2. Click fullscreen button (enter fullscreen)
3. Click fullscreen button (exit fullscreen)
4. Click fullscreen button (enter fullscreen again)
5. Click fullscreen button (exit fullscreen again)
6. EXPECTED: All toggles work correctly without any stuck states

Test Case 4: Navigation Between Files

1. Select multiple PDF files in File Explorer
2. Open Peek with Ctrl+Space
3. Enter fullscreen mode
4. Use arrow keys to navigate to next/previous PDF
5. EXPECTED: Fullscreen state persists across file navigation

Test Case 5: Non-PDF Files

1. Open a non-PDF file (e.g., image, text file) in Peek
2. EXPECTED: No fullscreen button appears, behavior unchanged

Expected Behavior

Before Fix

• Clicking fullscreen button hides titlebar but doesn't properly put window in fullscreen
• Clicking fullscreen button again does nothing (stuck in pseudo-fullscreen)
• Only way to exit is pressing Escape (which closes Peek entirely)

After Fix

• Clicking fullscreen button properly enters fullscreen mode
• Titlebar automatically hides
• Window fills entire screen
• Clicking fullscreen button again exits fullscreen
• Titlebar reappears
• Window returns to previous size/position

Technical Details

The fix leverages WebView2's ContainsFullScreenElementChanged event which fires when:

1. User clicks the PDF viewer's fullscreen button (enters fullscreen)
2. User clicks the fullscreen button again (exits fullscreen)

The event chain is:

1. CoreWebView2.ContainsFullScreenElementChanged fires in BrowserControl
2. BrowserControl raises FullScreenChanged event
3. FilePreview propagates the event to MainWindow
4. MainWindow calls AppWindow.SetPresenter() with appropriate presenter kind

Verification

After testing, verify:

• PDF fullscreen button enters fullscreen mode
• PDF fullscreen button exits fullscreen mode (toggle works)
• Titlebar visibility toggles correctly
• Window size changes correctly
• Escape key still closes Peek when in fullscreen
• Navigation between PDFs maintains fullscreen state
• No regressions with other file types