added null pointer check and assert

[wxWidgets.git] / docs / latex / wx / varhvscrollhelper.tex

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%% Name:        varhvscrollhelper.tex
%% Purpose:     wxVarHVScrollHelper Documentation
%% Author:      Bryan Petty
%% Modified by: 
%% Created:     2007-04-04
%% RCS-ID:      $Id$
%% Copyright:   (c) 2007 wxWidgets Team
%% License:     wxWindows Licence
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\section{\class{wxVarHVScrollHelper}}\label{wxvarhvscrollhelper}

This class provides functions wrapping the 
\helpref{wxVarHScrollHelper}{wxvarhscrollhelper} and
\helpref{wxVarVScrollHelper}{wxvarvscrollhelper} classes, targeted for
scrolling a window in both axis using
\helpref{wxHVScrolledWindow}{wxhvscrolledwindow}. Since this class is also
the join class of the horizontal and vertical scrolling functionality, it
also addresses some wrappers that help avoid the need to specify class scope
in your wxHVScrolledWindow-derived class when using wxVarScrollHelperBase
functionality.

Like all three of it's scroll helper base classes, this class is mostly only
useful to those classes built into wxWidgets deriving from here, and this
documentation is mostly only provided for referencing those functions
provided. You will likely want to derive your window from wxHVScrolledWindow
rather than from here directly.

\wxheading{Derived from}

\helpref{wxVarVScrollHelper}{wxvarvscrollhelper}\\
\helpref{wxVarScrollHelperBase}{wxvarscrollhelperbase}

\helpref{wxVarHScrollHelper}{wxvarhscrollhelper}\\
\helpref{wxVarScrollHelperBase}{wxvarscrollhelperbase}

\wxheading{Include files}

<wx/vscroll.h>

\wxheading{Library}

\helpref{wxCore}{librarieslist}

\wxheading{See also}

\helpref{wxHScrolledWindow}{wxhscrolledwindow},
\rtfsp\helpref{wxHVScrolledWindow}{wxhvscrolledwindow},
\rtfsp\helpref{wxVScrolledWindow}{wxvscrolledwindow}

\latexignore{\rtfignore{\wxheading{Members}}}


\membersection{wxVarHVScrollHelper::wxVarHVScrollHelper}\label{wxvarhvscrollhelperwxvarhvscrollhelper}

\func{}{wxVarHVScrollHelper}{\param{wxWindow* }{winToScroll}}

Constructor taking the target window to be scrolled by this helper class.
This will attach scroll event handlers to the target window to catch and
handle scroll events appropriately.


\membersection{wxVarHVScrollHelper::EnablePhysicalScrolling}\label{wxvarhvscrollhelperenablephysicalscrolling}

\func{void}{EnablePhysicalScrolling}{\param{bool }{vscrolling = true}, \param{bool }{hscrolling = true}}

With physical scrolling on (when this is {\tt true}), the device origin is
changed properly when a \rtfsp\helpref{wxPaintDC}{wxpaintdc} is prepared,
children are actually moved and laid out properly, and the contents of the
window (pixels) are actually moved. When this is {\tt false}, you are
responsible for repainting any invalidated areas of the window yourself to
account for the new scroll position.

\wxheading{Parameters}

\docparam{vscrolling}{Specifies if physical scrolling should be turned on when scrolling vertically.}

\docparam{hscrolling}{Specifies if physical scrolling should be turned on when scrolling horizontally.}


\membersection{wxVarHVScrollHelper::GetRowColumnCount}\label{wxvarhvscrollhelpergetrowcolumncount}

\constfunc{wxSize}{GetRowColumnCount}{\void}

Returns the number of columns and rows the target window contains.

\wxheading{See also}

\helpref{SetRowColumnCount()}{wxvarhvscrollhelpersetrowcolumncount}


\membersection{wxVarHVScrollHelper::GetVisibleBegin}\label{wxvarhvscrollhelpergetvisiblebegin}

\constfunc{wxPosition}{GetVisibleBegin}{\void}

Returns the index of the first visible column and row based on the current
scroll position.


\membersection{wxVarHVScrollHelper::GetVisibleEnd}\label{wxvarhvscrollhelpergetvisibleend}

\constfunc{wxPosition}{GetVisibleEnd}{\void}

Returns the index of the last visible column and row based on the scroll
position. This includes any partially visible columns or rows.


\membersection{wxVarHVScrollHelper::VirtualHitTest}\label{wxvarhvscrollhelpervirtualhittest}

\constfunc{wxPosition}{VirtualHitTest}{\param{wxCoord }{x}, \param{wxCoord }{y}}

\constfunc{wxPosition}{VirtualHitTest}{\param{const wxPoint\& }{pos}}

Returns the virtual scroll unit under the device unit given accounting for
scroll position or {\tt wxNOT\_FOUND} (for the row, column, or possibly both
values) if none.


\membersection{wxVarHVScrollHelper::IsVisible}\label{wxvarhvscrollhelperisvisible}

\constfunc{bool}{IsVisible}{\param{size\_t }{row}, \param{size\_t }{column}}

\constfunc{bool}{IsVisible}{\param{const wxPosition\& }{pos}}

Returns {\tt true} if both the given row and column are currently visible
(even if only partially visible) or {\tt false} otherwise.


\membersection{wxVarHVScrollHelper::RefreshRowColumn}\label{wxvarhvscrollhelperrefreshrowcolumn}

\func{virtual void}{RefreshRowColumn}{\param{size\_t }{row}, \param{size\_t }{column}}

\func{virtual void}{RefreshRowColumn}{\param{const wxPosition\& }{pos}}

Triggers a refresh for just the area shared between the given row and column
of the window if it is visible.


\membersection{wxVarHVScrollHelper::RefreshRowsColumns}\label{wxvarhvscrollhelperrefreshrowscolumns}

\func{virtual void}{RefreshRowsColumns}{\param{size\_t }{fromRow}, \param{size\_t }{toRow}, \param{size\_t }{fromColumn}, \param{size\_t }{toColumn}}

\func{virtual void}{RefreshRowsColumns}{\param{const wxPosition\& }{from}, \param{const wxPosition\& }{to}}

Triggers a refresh for the visible area shared between all given rows and
columns (inclusive) of the window. If the target window for both orientations
is the same, the rectangle of cells is refreshed; if the target windows
differ, the entire client size opposite the orientation direction is
refreshed between the specified limits.


\membersection{wxVarHVScrollHelper::ScrollToRowColumn}\label{wxvarhvscrollhelperscrolltorowcolumn}

\func{bool}{ScrollToRowColumn}{\param{size\_t }{row}, \param{size\_t }{column}}

\func{bool}{ScrollToRowColumn}{\param{const wxPosition\& }{pos}}

Scroll to the specified row and column. It will become the first visible row
and column in the window. Returns {\tt true} if we scrolled the window,
{\tt false} if nothing was done.


\membersection{wxVarHVScrollHelper::SetRowColumnCount}\label{wxvarhvscrollhelpersetrowcolumncount}

\func{void}{SetRowColumnCount}{\param{size\_t }{rowCount}, \param{size\_t }{columnCount}}

Set the number of rows and columns the target window will contain. The
derived class must provide the sizes for all rows and columns with indices up
to the ones given here in it's \helpref{OnGetRowHeight()}{wxvarvscrollhelperongetrowheight}
and \helpref{OnGetColumnWidth()}{wxvarhscrollhelperongetcolumnwidth} implementations,
respectively.

\wxheading{See also}

\helpref{GetRowColumnCount()}{wxvarhvscrollhelpergetrowcolumncount}