1\section{\class{wxLayoutAlgorithm}}\label{wxlayoutalgorithm} 2 3wxLayoutAlgorithm implements layout of subwindows in MDI or SDI frames. 4It sends a wxCalculateLayoutEvent event 5to children of the frame, asking them for information about 6their size. For MDI parent frames, the algorithm allocates 7the remaining space to the MDI client window (which contains the MDI child frames). 8For SDI (normal) frames, a 'main' window is specified as taking up the 9remaining space. 10 11Because the event system is used, this technique can be applied to any windows, 12which are not necessarily 'aware' of the layout classes (no virtual functions 13in wxWindow refer to wxLayoutAlgorithm or its events). However, you 14may wish to use \helpref{wxSashLayoutWindow}{wxsashlayoutwindow} for your subwindows 15since this class provides handlers for the required events, and accessors 16to specify the desired size of the window. The sash behaviour in the base class 17can be used, optionally, to make the windows user-resizable. 18 19wxLayoutAlgorithm is typically used in IDE (integrated development environment) applications, 20where there are several resizable windows in addition to the MDI client window, or 21other primary editing window. Resizable windows might include toolbars, a project 22window, and a window for displaying error and warning messages. 23 24When a window receives an OnCalculateLayout event, it should call SetRect in 25the given event object, to be the old supplied rectangle minus whatever space the 26window takes up. It should also set its own size accordingly. 27wxSashLayoutWindow::OnCalculateLayout generates an OnQueryLayoutInfo event 28which it sends to itself to determine the orientation, alignment and size of the window, 29which it gets from internal member variables set by the application. 30 31The algorithm works by starting off with a rectangle equal to the whole frame client area. 32It iterates through the frame children, generating OnCalculateLayout events which subtract 33the window size and return the remaining rectangle for the next window to process. It 34is assumed (by wxSashLayoutWindow::OnCalculateLayout) that a window stretches the full dimension 35of the frame client, according to the orientation it specifies. For example, a horizontal window 36will stretch the full width of the remaining portion of the frame client area. 37In the other orientation, the window will be fixed to whatever size was specified by 38OnQueryLayoutInfo. An alignment setting will make the window 'stick' to the left, top, right or 39bottom of the remaining client area. This scheme implies that order of window creation is important. 40Say you wish to have an extra toolbar at the top of the frame, a project window to the left of 41the MDI client window, and an output window above the status bar. You should therefore create 42the windows in this order: toolbar, output window, project window. This ensures that the toolbar and 43output window take up space at the top and bottom, and then the remaining height in-between is used for 44the project window. 45 46wxLayoutAlgorithm is quite independent of the way in which 47OnCalculateLayout chooses to interpret a window's size and alignment. Therefore you 48could implement a different window class with a new OnCalculateLayout event handler, 49that has a more sophisticated way of laying out the windows. It might allow 50specification of whether stretching occurs in the specified orientation, for example, 51rather than always assuming stretching. (This could, and probably should, be added to the existing 52implementation). 53 54{\it Note:} wxLayoutAlgorithm has nothing to do with wxLayoutConstraints. It is an alternative 55way of specifying layouts for which the normal constraint system is unsuitable. 56 57\wxheading{Derived from} 58 59\helpref{wxObject}{wxobject} 60 61\wxheading{Include files} 62 63<wx/laywin.h> 64 65\wxheading{Event handling} 66 67The algorithm object does not respond to events, but itself generates the 68following events in order to calculate window sizes. 69 70\twocolwidtha{7cm}% 71\begin{twocollist}\itemsep=0pt 72\twocolitem{{\bf EVT\_QUERY\_LAYOUT\_INFO(func)}}{Process a wxEVT\_QUERY\_LAYOUT\_INFO event, 73to get size, orientation and alignment from a window. See \helpref{wxQueryLayoutInfoEvent}{wxquerylayoutinfoevent}.} 74\twocolitem{{\bf EVT\_CALCULATE\_LAYOUT(func)}}{Process a wxEVT\_CALCULATE\_LAYOUT event, 75which asks the window to take a 'bite' out of a rectangle provided by the algorithm. 76See \helpref{wxCalculateLayoutEvent}{wxcalculatelayoutevent}.} 77\end{twocollist} 78 79\wxheading{Data types} 80 81{\small 82\begin{verbatim} 83enum wxLayoutOrientation { 84 wxLAYOUT_HORIZONTAL, 85 wxLAYOUT_VERTICAL 86}; 87 88enum wxLayoutAlignment { 89 wxLAYOUT_NONE, 90 wxLAYOUT_TOP, 91 wxLAYOUT_LEFT, 92 wxLAYOUT_RIGHT, 93 wxLAYOUT_BOTTOM, 94}; 95\end{verbatim} 96} 97 98\wxheading{See also} 99 100\helpref{wxSashEvent}{wxsashevent}, \helpref{wxSashLayoutWindow}{wxsashlayoutwindow}, \helpref{Event handling overview}{eventhandlingoverview} 101 102\helpref{wxCalculateLayoutEvent}{wxcalculatelayoutevent},\rtfsp 103\helpref{wxQueryLayoutInfoEvent}{wxquerylayoutinfoevent},\rtfsp 104\helpref{wxSashLayoutWindow}{wxsashlayoutwindow},\rtfsp 105\helpref{wxSashWindow}{wxsashwindow} 106 107\latexignore{\rtfignore{\wxheading{Members}}} 108 109\membersection{wxLayoutAlgorithm::wxLayoutAlgorithm}\label{wxlayoutalgorithmctor} 110 111\func{}{wxLayoutAlgorithm}{\void} 112 113Default constructor. 114 115\membersection{wxLayoutAlgorithm::\destruct{wxLayoutAlgorithm}}\label{wxlayoutalgorithmdtor} 116 117\func{}{\destruct{wxLayoutAlgorithm}}{\void} 118 119Destructor. 120 121\membersection{wxLayoutAlgorithm::LayoutFrame}\label{wxlayoutalgorithmlayoutframe} 122 123\constfunc{bool}{LayoutFrame}{\param{wxFrame* }{frame}, \param{wxWindow*}{ mainWindow = NULL}} 124 125Lays out the children of a normal frame. {\it mainWindow} is set to occupy the remaining space. 126 127This function simply calls \helpref{wxLayoutAlgorithm::LayoutWindow}{wxlayoutalgorithmlayoutwindow}. 128 129\membersection{wxLayoutAlgorithm::LayoutMDIFrame}\label{wxlayoutalgorithmlayoutmdiframe} 130 131\constfunc{bool}{LayoutMDIFrame}{\param{wxMDIParentFrame* }{frame}, \param{wxRect*}{ rect = NULL}} 132 133Lays out the children of an MDI parent frame. If {\it rect} is non-NULL, the 134given rectangle will be used as a starting point instead of the frame's client area. 135 136The MDI client window is set to occupy the remaining space. 137 138\membersection{wxLayoutAlgorithm::LayoutWindow}\label{wxlayoutalgorithmlayoutwindow} 139 140\constfunc{bool}{LayoutWindow}{\param{wxWindow* }{parent}, \param{wxWindow*}{ mainWindow = NULL}} 141 142Lays out the children of a normal frame or other window. 143 144{\it mainWindow} is set to occupy the remaining space. If this is not specified, then 145the last window that responds to a calculate layout event in query mode will get the remaining space 146(that is, a non-query OnCalculateLayout event will not be sent to this window and the window will be set 147to the remaining size). 148 149