- @b An alignment: Often, a dialog item is given more space than its minimal size
- plus its border. Depending on what flags are used for the respective dialog
- item, the dialog item can be made to fill out the available space entirely, i.e.
- it will grow to a size larger than the minimal size, or it will be moved to either
- the centre of the available space or to either side of the space. The following
- sample shows a listbox and three buttons in a horizontal box sizer; one button
- is centred, one is aligned at the top, one is aligned at the bottom:
-
-
-
- @b A stretch factor: If a sizer contains more than one child and it is offered
- more space than its children and their borders need, the question arises how to
- distribute the surplus space among the children. For this purpose, a stretch
- factor may be assigned to each child, where the default value of 0 indicates that the child
- will not get more space than its requested minimum size. A value of more than zero
- is interpreted in relation to the sum of all stretch factors in the children
- of the respective sizer, i.e. if two children get a stretch factor of 1, they will
- get half the extra space each @e independent of whether one control has a minimal
- sizer inferior to the other or not. The following sample shows a dialog with
- three buttons, the first one has a stretch factor of 1 and thus gets stretched,
- whereas the other two buttons have a stretch factor of zero and keep their
- initial width:
-
-
-
- Within wxDesigner, this stretch factor gets set from the @e Option menu.
-
- @section sizershiding Hiding controls using sizers
-
- You can hide controls contained in sizers the same way you would hide any control,
- using the wxWindow::Show method.
- However, wxSizer also offers a separate method which can tell the sizer not to
- consider that control in its size calculations. To hide a window using the sizer,
- call wxSizer::Show. You must then call Layout on the sizer
- to force an update.
- This is useful when hiding parts of the interface, since you can avoid removing
- the controls from the sizer and having to add them back later.
- Note: This is supported only by wxBoxSizer and wxFlexGridSizer.
- @b wxBoxSizer
- #wxBoxSizer can lay out its children either vertically
- or horizontally, depending on what flag is being used in its constructor.
- When using a vertical sizer, each child can be centered, aligned to the
- right or aligned to the left. Correspondingly, when using a horizontal
- sizer, each child can be centered, aligned at the bottom or aligned at
- the top. The stretch factor described in the last paragraph is used
- for the main orientation, i.e. when using a horizontal box sizer, the
- stretch factor determines how much the child can be stretched horizontally.
- The following sample shows the same dialog as in the last sample,
- only the box sizer is a vertical box sizer now:
-
-
-
- @b wxStaticBoxSizer
- #wxStaticBoxSixer is the same as a wxBoxSizer, but surrounded by a
- static box. Here is a sample:
-
-
-
- @b wxGridSizer
- #wxGridSizer is a two-dimensional sizer. All children are given the
- same size, which is the minimal size required by the biggest child, in
- this case the text control in the left bottom border. Either the number
- of columns or the number or rows is fixed and the grid sizer will grow
- in the respectively other orientation if new children are added:
-
-
-
- For programming information, see #wxGridSizer.
- @b wxFlexGridSizer
- Another two-dimensional sizer derived from
- wxGridSizer. The width of each column and the height of each row
- are calculated individually according to the minimal requirements
- from the respectively biggest child. Additionally, columns and
- rows can be declared to be stretchable if the sizer is assigned
- a size different from the one it requested. The following sample shows
- the same dialog as the one above, but using a flex grid sizer:
-
-
-
-
- @section boxsizerprogramming Programming with wxBoxSizer
-
- The basic idea behind a #wxBoxSizer is that windows will most often be laid out in rather
- simple basic geometry, typically in a row or a column or several hierarchies 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-hierarchy row with an OK button to the left
- and a Cancel button to the right. In many cases (particularly 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) @e 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 @e proportion 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 @e 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 a 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.
-
- @code
- // 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 )
- : wxDialog(parent, id, title, wxDefaultPosition, wxDefaultSize,
- wxDEFAULT_DIALOG_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
-
- SetSizerAndFit(topsizer); // use the sizer for layout and size window
- // accordingly and prevent it from being resized
- // to smaller size
- }
- @endcode
-
- Note that the new way of specifying flags to wxSizer is via #wxSizerFlags. This class greatly eases the burden of passing flags to a wxSizer.
- Here's how you'd do the previous example with wxSizerFlags:
-
- @code
- // 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 )
- : wxDialog(parent, id, title, wxDefaultPosition, wxDefaultSize,
- wxDEFAULT_DIALOG_STYLE | wxRESIZE_BORDER)
- {
- wxBoxSizer *topsizer = new wxBoxSizer( wxVERTICAL );
-
- // create text ctrl with minimal size 100x60 that is horizontally and
- // vertically stretchable with a border width of 10
- topsizer-Add(
- new wxTextCtrl( this, -1, "My text.", wxDefaultPosition, wxSize(100,60), wxTE_MULTILINE),
- wxSizerFlags(1).Align().Expand().Border(wxALL, 10));
-
- wxBoxSizer *button_sizer = new wxBoxSizer( wxHORIZONTAL );
-
- //create two buttons that are horizontally unstretchable,
- // with an all-around border with a width of 10 and implicit top alignment
- button_sizer-Add(
- new wxButton( this, wxID_OK, "OK" ),
- wxSizerFlags(0).Align().Border(wxALL, 10));
-
- button_sizer-Add(
- new wxButton( this, wxID_CANCEL, "Cancel" ),
- wxSizerFlags(0).Align().Border(wxALL, 10));
-
- //create a sizer with no border and centered horizontally
- topsizer-Add(
- button_sizer,
- wxSizerFlags(0).Center() );
-
- SetSizerAndFit(topsizer); // use the sizer for layout and set size and hints
- }
- @endcode
-
-
-
- @section gridsizerprogramming Programming with wxGridSizer
-
- #wxGridSizer is a sizer which lays out its children in a two-dimensional
- table with all table fields having the same size,
- i.e. the width of each field is the width of the widest child,
- the height of each field is the height of the tallest child.
-
- @section flexgridsizerprogramming Programming with wxFlexGridSizer
-
- #wxFlexGridSizer is a sizer which lays out its children in a two-dimensional
- table with all table fields in one row having the same
- height and all fields in one column having the same width, but all
- rows or all columns are not necessarily the same height or width as in
- the #wxGridSizer.
-
- @section staticboxsizerprogramming Programming with wxStaticBoxSizer
-
- #wxStaticBoxSizer is a sizer derived from wxBoxSizer but adds a static
- box around the sizer. Note that this static box has to be created
- separately.
-
- @section createbuttonsizer CreateButtonSizer
-
- As a convenience, CreateButtonSizer ( long flags ) can be used to create a standard button sizer
- in which standard buttons are displayed. The following flags can be passed to this function:
-
-
- @code
- wxYES_NO // Add Yes/No subpanel
- wxYES // return wxID_YES
- wxNO // return wxID_NO
- wxNO_DEFAULT // make the wxNO button the default, otherwise wxYES or wxOK button will be default
-
- wxOK // return wxID_OK
- wxCANCEL // return wxID_CANCEL
- wxHELP // return wxID_HELP