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Simplify and make more robust wxHtmlWindow layout logic

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Rewrite CreateLayout() using SetVirtualSize() to avoid trying to detect
whether the vertical scrollbar is shown manually. This is simpler and
avoids the problem of entering infinite loop if the scrollbar size used
by this function (based on wxSystemSettings::GetMetric(wxSYS_VSCROLL_X))
wasn't correct, as used to be the case for wxGTK until the recent commit
900752b152 and might still be the case in
the other ports.

Closes #18141.
This commit is contained in:
trivia21
2018-06-24 00:25:21 +02:00
committed by Vadim Zeitlin
parent e753dc6072
commit 107e66e725
2 changed files with 20 additions and 87 deletions
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1
docs/changes.txt
View File

@@ -95,6 +95,7 @@ All (GUI):
- Revert to left-aligning wxSpinCtrl contents by default.
- Make wxRibbonButtonBar buttons more customizable (Max Maisel).
- Add wxHtmlEasyPrinting::SetPromptMode() (pavel-t).
- Fix possible infinite loop in wxHtmlWindow layout (trivia21).
wxGTK:

106
src/html/htmlwin.cpp
View File

@@ -351,6 +351,8 @@ bool wxHtmlWindow::Create(wxWindow *parent, wxWindowID id,
SetPage(wxT("<html><body></body></html>"));
SetInitialSize(size);
if ( !HasFlag(wxHW_SCROLLBAR_NEVER) )
SetScrollRate(wxHTML_SCROLL_STEP, wxHTML_SCROLL_STEP);
return true;
}
@@ -715,20 +717,9 @@ void wxHtmlWindow::OnSetTitle(const wxString& title)
}
// return scroll steps such that a) scrollbars aren't shown needlessly
// and b) entire content is viewable (i.e. round up)
static int ScrollSteps(int size, int available)
{
if ( size <= available )
return 0;
else
return (size + wxHTML_SCROLL_STEP - 1) / wxHTML_SCROLL_STEP;
}
void wxHtmlWindow::CreateLayout()
{
// SetScrollbars() results in size change events -- and thus a nested
// ShowScrollbars() results in size change events -- and thus a nested
// CreateLayout() call -- on some platforms. Ignore nested calls, toplevel
// CreateLayout() will do the right thing eventually.
static wxRecursionGuardFlag s_flagReentrancy;
@@ -739,88 +730,29 @@ void wxHtmlWindow::CreateLayout()
if (!m_Cell)
return;
int clientWidth, clientHeight;
GetClientSize(&clientWidth, &clientHeight);
const int vscrollbar = wxSystemSettings::GetMetric(wxSYS_VSCROLL_X);
const int hscrollbar = wxSystemSettings::GetMetric(wxSYS_HSCROLL_Y);
if ( HasScrollbar(wxHORIZONTAL) )
clientHeight += hscrollbar;
if ( HasScrollbar(wxVERTICAL) )
clientWidth += vscrollbar;
if ( HasFlag(wxHW_SCROLLBAR_NEVER) )
{
SetScrollbars(1, 1, 0, 0); // always off
m_Cell->Layout(clientWidth);
m_Cell->Layout(GetClientSize().GetWidth());
}
else // !wxHW_SCROLLBAR_NEVER
else // Do show scrollbars if necessary.
{
// Lay the content out with the assumption that it's too large to fit
// in the window (this is likely to be the case):
m_Cell->Layout(clientWidth - vscrollbar);
// Get client width if a vertical scrollbar is shown
// (which is usually the case).
ShowScrollbars(wxSHOW_SB_DEFAULT, wxSHOW_SB_ALWAYS);
const int widthWithVScrollbar = GetClientSize().GetWidth();
// If the layout is wider than the window, horizontal scrollbar will
// certainly be shown. Account for it here for subsequent computations.
if ( m_Cell->GetWidth() > clientWidth )
clientHeight -= hscrollbar;
// Let wxScrolledWindow decide whether it needs to show the vertical
// scrollbar for the given contents size.
ShowScrollbars(wxSHOW_SB_DEFAULT, wxSHOW_SB_DEFAULT);
m_Cell->Layout(widthWithVScrollbar);
SetVirtualSize(m_Cell->GetWidth(), m_Cell->GetHeight());
if ( m_Cell->GetHeight() <= clientHeight )
// Check if the vertical scrollbar was hidden.
const int newClientWidth = GetClientSize().GetWidth();
if ( newClientWidth != widthWithVScrollbar )
{
// we fit into the window, hide vertical scrollbar:
SetScrollbars
(
wxHTML_SCROLL_STEP, wxHTML_SCROLL_STEP,
ScrollSteps(m_Cell->GetWidth(), clientWidth - vscrollbar),
0
);
// ...and redo the layout to use the extra space
m_Cell->Layout(clientWidth);
}
else
{
// If the content doesn't fit into the window by only a small
// margin, chances are that it may fit fully with scrollbar turned
// off. It's something worth trying but on the other hand, we don't
// want to waste too much time redoing the layout (twice!) for
// long -- and thus expensive to layout -- pages. The cut-off value
// is an arbitrary heuristics.
static const int SMALL_OVERLAP = 60;
if ( m_Cell->GetHeight() <= clientHeight + SMALL_OVERLAP )
{
m_Cell->Layout(clientWidth);
if ( m_Cell->GetHeight() <= clientHeight )
{
// Great, we fit in. Hide the scrollbar.
SetScrollbars
(
wxHTML_SCROLL_STEP, wxHTML_SCROLL_STEP,
ScrollSteps(m_Cell->GetWidth(), clientWidth),
0
);
return;
}
else
{
// That didn't work out, go back to previous layout. Note
// that redoing the layout once again here isn't as bad as
// it looks -- thanks to the small cut-off value, it's a
// reasonably small page.
m_Cell->Layout(clientWidth - vscrollbar);
}
}
// else: the page is very long, it will certainly need scrollbar
SetScrollbars
(
wxHTML_SCROLL_STEP, wxHTML_SCROLL_STEP,
ScrollSteps(m_Cell->GetWidth(), clientWidth - vscrollbar),
ScrollSteps(m_Cell->GetHeight(), clientHeight),
m_xScrollPosition, m_yScrollPosition
);
m_Cell->Layout(newClientWidth);
SetVirtualSize(m_Cell->GetWidth(), m_Cell->GetHeight());
}
}
}