This bug could be observed by running the WidgetsDemo Drag+Drop pane on
Windows 10, and dragging an item between two displays at different scale
factors.
This is issue is a regression introduced in
9817a2bb66. The regression was caused by
the change in mouse position calculation. The incorrect version switched
to using ClientToScreen, but the correct version used
getPointFromLocalLParam.
The function getPointFromLocalLParam was replaced by clientLParamToPoint
in 24ab3cb6a3, and is restored by this
commit.
This change intends to address a bug observed only on Windows 10 with a
display scale factor of 125%.
When the native titlebar is enabled, and the window's border-resizer is
used to resize the window slowly the with mouse, the client area of the
window may move to the wrong location, or be drawn with some areas
obscured/clipped. This is especially observable when resizing the
WidgetsDemo to its smallest size, and then dragging the right border a
single pixel to the right. On my computer, this consistently causes the
client area to display at the wrong location.
I haven't been able to find any obvious bug in JUCE that might cause
this behaviour. In particular, it seems that the window begins
displaying incorrectly *before* the window ever actually resizes.
During the resize, the system sends events (WM_SIZING and
WM_WINDOWPOSCHANGING) to the window, and according to the documentation,
the window may modify the message parameters in order to constrain the
new window size. When running on a scaled display, JUCE attempts to map
the logical client area size to a sensible size in physical pixels, and
uses the sizing messages to enforce this size requirement.
In the case of the broken window rendering, the system requests a new
window size, which JUCE rejects. The window's display state doesn't
change, so the swap chain does not resize, and the swap chain does not
present. Put another way, the broken rendering happens *independently*
of JUCE modifying the swap chain in any way. Therefore, I believe that the
bug is introduced elsewhere, potentially by Windows itself.
I also checked to see whether the issue could be caused by mishandling
of the NCCALCSIZE message, which is normally used to configure the
relative positions of the client and nonclient areas. However, in the
buggy case, NCCALCSIZE is not sent until *after* the first 'broken'
frame is painted - and even then, the implementation immediately falls
back to DefWindowProc.
Given that the issue appears to be a bug in Windows, the proposed change
is a workaround, rather than a true fix. It appears as though the
problem goes away when WM_WINDOWPOSCHANGING does not modify the
requested bounds. Therefore, for windows with native titlebars, we rely
on the constraints to be applied in WM_SIZING only, when sizing the
window in a sizemove gesture.
Previously, for windows with a native titlebar and a constrainer, the
window could be restored at the wrong size. This happened because
findPhysicalBorderSize() may return nonsensical values when called
during a SC_RESTORE, which in turn produces an unexpected window size
when adding the bogus border size to the constrained client area size.
We now avoid trying to constrain the window if we're unable to determine
the correct border size. I think this is only likely to happen during
SC_RESTORE, in which case the system should have a pretty good idea of
where the window should go, and constraining should not be necessary.
The buggy behaviour could be seen in a blank GUI app project by setting
a native titlebar and calling setResizable (false, false). The resulting
window would still display a resize cursor when hovering the window
border.
This reverts 515e9b9f89.
In order to avoid recursive calls through WM_NCHITTEST, we remove calls
to Component::contains in DocumentWindow::findControlAtPoint.
Previously, maximising a frameless window on a secondary display could
result in the window's coordinates being computed incorrectly, leading
to graphical glitches.
The docs for WS_MINIMIZEBOX and WS_MAXIMIZEBOX specify that WS_SYSMENU must be specified.
The docs for WS_SYSMENU specify that WS_CAPTION must be specified.
When handling WM_NCCALCSIZE, we reduce the size of the client area when
the window is maximised. If we don't do this, then the client area
matches the top-level window area, which is larger than the display's
safe area. As a result, the window appears too large, and the edges are
obscured under the edges of the display.
After reducing the client area in WM_NCCALCSIZE, the client area is no
longer equal to the top-level window area, so getBounds() must be
updated to return the window's *client* area rather than the top-level
window area.
Without this change, the mouse state was not always updated after
releasing the mouse, leaving the current modifier keys with the
left-mouse-button bit set. This was particularly evident in standalone
plugins, where clicking the 'options' button in the titlebar, then
immediately clicking the titlebar could "stick" the window to the mouse,
making it impossible to interact with the window normally.
