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use unscaled mouse coordintes for convex hull test (dotnet#6332)
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dotnet#6332
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@SamBent @lindexi
SamBent authored and lindexi committed Apr 14, 2022
1 parent 88ea4c0 commit 14a1e0e
Showing 1 changed file with 48 additions and 31 deletions.
79 changes: 48 additions & 31 deletions ...osoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Controls/PopupControlService.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1558,39 +1558,56 @@ private void AddPoints(PointList points, in NativeMethods.RECT rect, bool rectIs
// Test whether the current mouse point lies within the convex hull
internal bool ContainsMousePoint()
{
IInputElement rootElement = _source.RootVisual as IInputElement;
if (rootElement != null)
// get the coordinates of the current mouse point, relative to the Active source
PresentationSource mouseSource = Mouse.PrimaryDevice.CriticalActiveSource;
System.Windows.Point pt = Mouse.PrimaryDevice.NonRelativePosition;

// translate the point to our source's coordinates, if necessary
// (e.g. if the tooltip's owner comes from a window with capture,
// such as the popup of a ComboBox)
if (mouseSource != _source)
{
// get the coordinates of the current mouse point, relative to our PresentationSource
System.Windows.Point pt = Mouse.PrimaryDevice.GetPosition(rootElement);

// check whether the point lies within the hull
return ContainsPoint(_source, (int)pt.X, (int)pt.Y);

// NOTE: GetPosition doesn't actually return the position of the current mouse point,
// but rather the last recorded position. (See MouseDevice.GetScreenPositionFromSystem,
// which says that "Win32 has issues reliably returning where the mouse is".)
// This causes a small problem when (a) the PresentationSource has capture, e.g.
// the popup of a ComboBox, and (b) the mouse moves to a position that lies outside both the
// capturing PresentationSource (popup window) and the input-providing PresentationSource
// (main window). The MouseDevice only records positions within the input-providing
// PresentationSource, so we'll test the position where the mouse left the main window,
// rather than the current position.
// This means we may leave a tooltip open even when the mouse leaves its SafeArea,
// but only when the tooltip belongs to a capturing source, and the "leaving the SafeArea"
// action occurs outside the surrounding main window. For our example, it can happen
// when the ComboBox is close to the edge of the main window so that a tooltip from its
// popup content extends beyond the main window.
// This can only be fixed by changing MouseDevice.GetScreenPositionFromSystem to
// use a "better way" to find the current mouse position, which allegedly needs work from the OS.
// But we can live with this behavior, because
// * this is a corner case - tooltips from popup content that extend beyond the main window
// * the effect is transient - the tooltip will close when the user dismisses the popup
// * there's no accessibility issue - WCAG 2.1 only requires that the tooltip stays open under
// proscribed conditions, not that it has to close when the conditions cease to apply
System.Windows.Point ptScreen = PointUtil.ClientToScreen(pt, mouseSource);
pt = PointUtil.ScreenToClient(ptScreen, _source);
}
else
return false;

#if DEBUG
// NonRelativePosition returns the mouse point in unscaled screen coords, relative
// to the active window's client area (despite the name).
// Compute the point a different way, and check that it agrees. The second
// way uses public API, but in our case ends up doing a lot of transforms
// and multiplications that should simply cancel each other out.
System.Windows.Interop.HwndSource hwndSource = _source as System.Windows.Interop.HwndSource;
IInputElement rootElement = hwndSource?.RootVisual as IInputElement;
Debug.Assert(hwndSource != null && rootElement != null, "expect non-null hwndSource and rootElement");
System.Windows.Point pt2 = hwndSource.TransformToDevice(Mouse.PrimaryDevice.GetPosition(rootElement));
Debug.Assert(((int)pt.X == (int)Math.Round(pt2.X)) && ((int)pt.Y == (int)Math.Round(pt2.Y)), "got incorrect mouse point");
#endif

// check whether the point lies within the hull
return ContainsPoint(_source, (int)pt.X, (int)pt.Y);

// NOTE: NonRelativePosition doesn't actually return the position of the current mouse point,
// but rather the last recorded position. (See MouseDevice.GetScreenPositionFromSystem,
// which says that "Win32 has issues reliably returning where the mouse is".)
// This causes a small problem when (a) the PresentationSource has capture, e.g.
// the popup of a ComboBox, and (b) the mouse moves to a position that lies outside both the
// capturing PresentationSource (popup window) and the input-providing PresentationSource
// (main window). The MouseDevice only records positions within the input-providing
// PresentationSource, so we'll test the position where the mouse left the main window,
// rather than the current position.
// This means we may leave a tooltip open even when the mouse leaves its SafeArea,
// but only when the tooltip belongs to a capturing source, and the "leaving the SafeArea"
// action occurs outside the surrounding main window. For our example, it can happen
// when the ComboBox is close to the edge of the main window so that a tooltip from its
// popup content extends beyond the main window.
// This can only be fixed by changing MouseDevice.GetScreenPositionFromSystem to
// use a "better way" to find the current mouse position, which allegedly needs work from the OS.
// But we can live with this behavior, because
// * this is a corner case - tooltips from popup content that extend beyond the main window
// * the effect is transient - the tooltip will close when the user dismisses the popup
// * there's no accessibility issue - WCAG 2.1 only requires that the tooltip stays open under
// proscribed conditions, not that it has to close when the conditions cease to apply
}

// Test whether a given mouse point (x,y) lies within the convex hull
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