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Win32: fall back to pixel location when GetPointerDeviceRects is unavailable #21337

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Merged
MrJul merged 2 commits into from
May 15, 2026
Merged

Win32: fall back to pixel location when GetPointerDeviceRects is unavailable #21337

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6b4c10b
Update WindowImpl.AppWndProc.cs
Symbai May 10, 2026
5994ca9
Merge branch 'master' into master
MrJul May 14, 2026
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24 changes: 22 additions & 2 deletions src/Windows/Avalonia.Win32/WindowImpl.AppWndProc.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1363,14 +1363,34 @@ private void UpdateInputMethod(IntPtr hkl)

Imm32InputMethod.Current.SetLanguageAndWindow(this, Hwnd, hkl);
}

// GetPointerDeviceRects is part of the WM_POINTER API (Windows 8+) but is not implemented
// by Wine/Proton. Probe once and fall back to the integer pixel location when missing,
// otherwise the P/Invoke throws EntryPointNotFoundException for every pointer message.
// See https://github.com/AvaloniaUI/Avalonia/issues/21081.
private static readonly bool s_isGetPointerDeviceRectsAvailable = ProbeGetPointerDeviceRects();

private static bool ProbeGetPointerDeviceRects()
{
var user32 = LoadLibrary("user32.dll");
return user32 != IntPtr.Zero
&& GetProcAddress(user32, nameof(GetPointerDeviceRects)) != IntPtr.Zero;
}

/// <summary>
/// Get the location of the pointer in himetric units.
/// Get the location of the pointer in screen coordinates with HIMETRIC sub-pixel precision
/// when supported, falling back to the integer pixel location on platforms that do not
/// implement <c>GetPointerDeviceRects</c> (e.g. Wine/Proton).
/// </summary>
/// <param name="info">The pointer info.</param>
/// <returns>The location of the pointer in himetric units.</returns>
/// <returns>The pointer location in screen pixels.</returns>
private Point GetHimetricLocation(POINTER_INFO info)
{
if (!s_isGetPointerDeviceRectsAvailable)
{
return new Point(info.ptPixelLocationX, info.ptPixelLocationY);
}

GetPointerDeviceRects(info.sourceDevice, out var pointerDeviceRect, out var displayRect);
var himetricLocation = new Point(
info.ptHimetricLocationRawX * displayRect.Width / (double)pointerDeviceRect.Width + displayRect.left,
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