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authorLuke Shumaker <lukeshu@lukeshu.com>2017-05-23 14:03:15 -0400
committerLuke Shumaker <lukeshu@lukeshu.com>2017-05-24 18:35:37 -0400
commit0a8c4d48bbf71b83a575ec89b41aebc4439242ae (patch)
treee7b7bcc9eeaf108bc3053511cf41f27446c5025c /vncviewer
parent5fa609df53fa72ff7b16adff663414edbf8e0815 (diff)
downloadtigervnc-0a8c4d48bbf71b83a575ec89b41aebc4439242ae.tar.gz
tigervnc-0a8c4d48bbf71b83a575ec89b41aebc4439242ae.zip
vncviewer: Fix scrollbar visibility
Have a window that is sized to the remote screen. Now shrink the window vertically, making it shorter than the remote screen in one axis. The vertical scrollbar appears. However, the horizontal scrollbar does not appear, despite the rightmost ~24 pixels (Fl::scrollbar_size()) being hidden by the vertical scroll bar. Fix that. For clarity, move the fullscreen checks into a separate `if` statement, rather than keeping the size and fullscreen checks together. I think the comment does a decent job of explaining and justifying the check's logic, but if you require further convincing, perhaps this alternate explanation will help: The check for the X-axis is if ((w() - (h() < viewport->h() ? Fl::scrollbar_size() : 0) < viewport->w()) To be a bit more verbose and repetitive, we can split that ternary in to two separate checks, and add some comments: if ( (w() - < viewport->w()) // X needs a scrollbar || ( (w() - Fl::scrollbar_size() < viewport->w()) && (h() < viewport->h()) ) //( X doesn't need a scrollbar unless Y does ) && ( Y does need one ) ) ) Within the "Y does need one" check, we don't need to worry about the case where `h() - Fl::scrollbar_size() < viewport-h()` is true, because if both axes are saying "I don't need a scrollbar unless you do", then neither needs one.
Diffstat (limited to 'vncviewer')
-rw-r--r--vncviewer/DesktopWindow.cxx34
1 files changed, 27 insertions, 7 deletions
diff --git a/vncviewer/DesktopWindow.cxx b/vncviewer/DesktopWindow.cxx
index 47fe8f89..e2ed0887 100644
--- a/vncviewer/DesktopWindow.cxx
+++ b/vncviewer/DesktopWindow.cxx
@@ -1046,15 +1046,35 @@ void DesktopWindow::repositionWidgets()
// Scrollbars visbility
- if (!fullscreen_active() && (w() < viewport->w()))
- hscroll->show();
- else
+ if (fullscreen_active()) {
hscroll->hide();
-
- if (!fullscreen_active() && (h() < viewport->h()))
- vscroll->show();
- else
vscroll->hide();
+ } else {
+ // Decide whether to show a scrollbar by checking if the window
+ // size (possibly minus scrollbar_size) is less than the viewport
+ // (remote framebuffer) size.
+ //
+ // We decide whether to subtract scrollbar_size on an axis by
+ // checking if the other axis *definitely* needs a scrollbar. You
+ // might be tempted to think that this becomes a weird recursive
+ // problem, but it isn't: If the window size is less than the
+ // viewport size (without subtracting the scrollbar_size), then
+ // that axis *definitely* needs a scrollbar; if the check changes
+ // when we subtract scrollbar_size, then that axis only *maybe*
+ // needs a scrollbar. If both axes only "maybe" need a scrollbar,
+ // then neither does; so we don't need to recurse on the "maybe"
+ // cases.
+
+ if (w() - (h() < viewport->h() ? Fl::scrollbar_size() : 0) < viewport->w())
+ hscroll->show();
+ else
+ hscroll->hide();
+
+ if (h() - (w() < viewport->w() ? Fl::scrollbar_size() : 0) < viewport->h())
+ vscroll->show();
+ else
+ vscroll->hide();
+ }
// Scrollbars positions