+The basic idea behind a box sizer is that windows will most often be laid out in rather
+simple basic geomerty, typically in a row or a column or several hierachies of either.
+
+As an example, we will construct a dialog that will contain a text field at the top and
+two buttons at the bottom. This can be seen as a top-hierarchy column with the text at
+the top and buttons at the bottom and a low-hierchary row with an OK button to the left
+and a Cancel button to the right. In many cases (particulary dialogs under Unix and
+normal frames) the main window will be resizable by the user and this change of size
+will have to get propagated to its children. In our case, we want the text area to grow
+with the dialog, whereas the button shall have a fixed size. In addition, there will be
+a thin border around all controls to make the dialog look nice and - to make matter worse -
+the buttons shall be centred as the width of the dialog changes.
+
+It is the unique feature of a box sizer, that it can grow in both directions (height and
+width) but can distribute its growth in the main direction (horizontal for a row) {\it unevenly}
+among its children. In our example case, the vertical sizer is supposed to propagate all its
+height changes to only the text area, not to the button area. This is determined by the {\it option} parameter
+when adding a window (or another sizer) to a sizer. It is interpreted
+as a weight factor, i.e. it can be zero, indicating that the window may not be resized
+at all, or above zero. If several windows have a value above zero, the value is interpreted
+relative to the sum of all weight factors of the sizer, so when adding two windows with
+a value of 1, they will both get resized equally much and each half as much as the sizer
+owning them. Then what do we do when a column sizer changes its width? This behaviour is
+controlled by {\it flags} (the second parameter of the Add() function): Zero or no flag
+indicates that the window will preserve it is original size, wxGROW flag (same as wxEXPAND)
+forces the window to grow with the sizer, and wxSHAPED flag tells the window to change it is
+size proportionally, preserving original aspect ratio. When wxGROW flag is not used,
+the item can be aligned within available space. wxALIGN\_LEFT, wxALIGN\_TOP, wxALIGN\_RIGHT,
+wxALIGN\_BOTTOM, wxALIGN\_CENTER\_HORIZONTAL and wxALIGN\_CENTER\_VERTICAL do what they say.
+wxALIGN\_CENTRE (same as wxALIGN\_CENTER) is defined as (wxALIGN\_CENTER\_HORIZONTAL |
+wxALIGN\_CENTER\_VERTICAL). Default alignment is wxALIGN\_LEFT | wxALIGN\_TOP.
+
+As mentioned above, any window belonging to a sizer may have border, and it can be specified
+which of the four sides may have this border, using the wxTOP, wxLEFT, wxRIGHT and wxBOTTOM
+constants or wxALL for all directions (and you may also use wxNORTH, wxWEST etc instead). These
+flags can be used in combination with the alignment flags above as the second parameter of the
+Add() method using the binary or operator |. The sizer of the border also must be made known,
+and it is the third parameter in the Add() method. This means, that the entire behaviour of
+a sizer and its children can be controlled by the three parameters of the Add() method.
+
+\begin{verbatim}
+// we want to get a dialog that is stretchable because it
+// has a text ctrl at the top and two buttons at the bottom
+
+MyDialog::MyDialog(wxFrame *parent, wxWindowID id, const wxString &title ) :
+ wxDialog( parent, id, title, wxDefaultPosition, wxDefaultSize, wxDIALOG_STYLE | wxRESIZE_BORDER )
+{
+ wxBoxSizer *topsizer = new wxBoxSizer( wxVERTICAL );
+
+ // create text ctrl with minimal size 100x60
+ topsizer->Add(
+ new wxTextCtrl( this, -1, "My text.", wxDefaultPosition, wxSize(100,60), wxTE_MULTILINE),
+ 1, // make vertically stretchable
+ wxEXPAND | // make horizontally stretchable
+ wxALL, // and make border all around
+ 10 ); // set border width to 10
+
+
+ wxBoxSizer *button_sizer = new wxBoxSizer( wxHORIZONTAL );
+ button_sizer->Add(
+ new wxButton( this, wxID_OK, "OK" ),
+ 0, // make horizontally unstretchable
+ wxALL, // make border all around (implicit top alignment)
+ 10 ); // set border width to 10
+ button_sizer->Add(
+ new wxButton( this, wxID_CANCEL, "Cancel" ),
+ 0, // make horizontally unstretchable
+ wxALL, // make border all around (implicit top alignment)
+ 10 ); // set border width to 10
+
+ topsizer->Add(
+ button_sizer,
+ 0, // make vertically unstretchable
+ wxALIGN_CENTER ); // no border and centre horizontally
+
+ SetAutoLayout( TRUE ); // tell dialog to use sizer
+ SetSizer( topsizer ); // actually set the sizer
+
+ topsizer->Fit( this ); // set size to minimum size as calculated by the sizer
+ topsizer->SetSizeHints( this ); // set size hints to honour mininum size
projects / wxWidgets.git / blobdiff