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1 \section{\class{wxBoxSizer}}\label{wxboxsizer}
2
3 The basic idea behind a box sizer is that windows will most often be laid out in rather
4 simple basic geomerty, typically in a row or a column or several hierachies of either.
5
6 As an exmaple, we will construct a dialog that will contain a text field at the top and
7 two buttons at the bottom. This can be seen as a top-hierarchy column with the text at
8 the top and buttons at the bottom and a low-hierchary row with an OK button to the left
9 and a Cancel button to the right. In many cases (particulary dialogs under Unix and
10 normal frames) the main window will be resizable by the user and this change of size
11 will have to get propagated to its children. In our case, we want the text area to grow
12 with the dialog, whereas the button shall have a fixed size. In addition, there will be
13 a thin border around all controls to make the dialog look nice and - to make matter worse -
14 the buttons shall be centred as the width of the dialog changes.
15
16 It is the unique feature of a box sizer, that it can grow in both directions (height and
17 width) but can distribute its growth in the main direction (horizontal for a row) {\it unevenly}
18 among its children. In our example case, the vertical sizer is supposed to propagate all its
19 height changes to only the text area, not to the button area. This is determined by the {\it option} parameter
20 when adding a window (or another sizer) to a sizer. It is interpreted
21 as a weight factor, i.e. it can be zero, indicating that the window may not be resized
22 at all, or above zero. If several windows have a value above zero, the value is interpreted
23 relative to the sum of all weight factors of the sizer, so when adding two windows with
24 a value of 1, they will both get resized equally much and each half as much as the sizer
25 owning them. Then what do we do when a column sizer changes its width? This behaviour is
26 controlled by {\it flags} (the second parameter of the Add() function): Zero or no flag indicates that
27 the window will get aligned at the left (in a column sizer) and the top (row sizer), whereas
28 wxALIGN\_RIGHT and wxALIGN\_BOTTOM will do what they say. The item can also be centered
29 using the wxCENTRE flag (same as wxCENTER) or it can be forced to grow with the sizer (using
30 the wxGROW flag (same as wxEXPAND)).
31
32 As mentioned above, any window belonging to a sizer may have border, and it can be specified
33 which of the four sides may have this border, using the wxTOP, wxLEFT, wxRIGHT and wxBOTTOM
34 constants or wxALL for all directions (and you may also use wxNORTH, wxWEST etc instead). These
35 flags can be used in combintaion with the alignement flags above as the second paramter of the
36 Add() method using the binary or operator |. The sizer of the border also must be made known,
37 and it is the third parameter in the Add() method. This means, that the entire behaviour of
38 a sizer and its children can be controlled by the three parameters of the Add() method.
39
40 \begin{verbatim}
41 // we want to get a dialog that is stretchable because it
42 // has a text ctrl at the top and two buttons at the bottom
43
44 MyDialog::MyDialog(wxFrame *parent, wxWindowID id, const wxString &title ) :
45 wxDialog( parent, id, title, wxDefaultPosition, wxDefaultSize, wxDIALOG_STYLE | wxRESIZE_BORDER )
46 {
47 wxBoxSizer *topsizer = new wxBoxSizer( wxVERTICAL );
48
49 // create text ctrl with minimal size 100x60
50 topsizer->Add(
51 new wxTextCtrl( this, -1, "My text.", wxDefaultPosition, wxSize(100,60), wxTE_MULTILINE),
52 1, // make vertically stretchable
53 wxEXPAND | // make horizontally stretchable
54 wxALL, // and make border all around
55 10 ); // set border width to 10
56
57
58 wxBoxSizer *button_sizer = new wxBoxSizer( wxHORIZONTAL );
59 button_sizer->Add(
60 new wxButton( this, wxID_OK, "OK" ),
61 0, // make horizontally unstretchable
62 wxALL, // make border all around (implicit top alignment)
63 10 ); // set border width to 10
64 button_sizer->Add(
65 new wxButton( this, wxID_CANCEL, "Cancel" ),
66 0, // make horizontally unstretchable
67 wxALL, // make border all around (implicit top alignment)
68 10 ); // set border width to 10
69
70 topsizer->Add(
71 button_sizer,
72 0, // make vertically unstretchable
73 wxCENTER ); // no border and centre horizontally
74
75 SetAutoLayout( TRUE ); // tell dialog to use sizer
76 SetSizer( topsizer ); // actually set the sizer
77
78 topsizer->Fit( this ); // set size to minimum size as calculated by the sizer
79 topsizer->SetSizeHints( this ); // set size hints to honour mininum size
80 }
81 \end{verbatim}
82
83 \wxheading{Derived from}
84
85 \helpref{wxSizer}{wxsizer}
86 \helpref{wxObject}{wxobject}
87
88 \membersection{wxBoxSizer::wxBoxSizer}\label{wxboxsizerwxboxsizer}
89
90 \func{}{wxBoxSizer}{\param{int }{orient}}
91
92 Constructor for a wxBoxSizer. {\it orient} may be either of wxVERTICAL
93 or wxHORIZONTAL for creating either a column sizer or a row sizer.
94
95 \membersection{wxBoxSizer::RecalcSizes}\label{wxboxsizerrecalcsizes}
96
97 \func{void}{RecalcSizes}{\void}
98
99 Implements the calculation of a box sizer's dimensions and then sets
100 the size of its its children (calling \helpref{wxWindow::SetSize}{wxwindowsetsize}
101 if the child is a window). It is used internally only and must not be called
102 by the users. Documented for information.
103
104 \membersection{wxBoxSizer::CalcMin}\label{wxboxsizercalcmin}
105
106 \func{wxSize}{CalcMin}{\void}
107
108 Implements the calculation of a box sizer's minimal. It is used internally
109 only and must not be called by the users. Documented for information.
110
111 \membersection{wxBoxSizer::GetOrientation}\label{wxboxsizergetorientation}
112
113 \func{int}{GetOrientation}{\void}
114
115 Returns the orientation of the boxsizer, either of wxVERTICAL
116 or wxHORIZONTAL.
117