be2577e4e6
Adds some wxALIGN_* flags to increase ability to position item
within its allotted space.
Adds wxSHAPED flag that enforces proportional resizing on growable
items.
Adds a sample and updated documentation.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@4461 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
121 lines
6.0 KiB
TeX
121 lines
6.0 KiB
TeX
\section{\class{wxBoxSizer}}\label{wxboxsizer}
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The basic idea behind a box sizer is that windows will most often be laid out in rather
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simple basic geomerty, typically in a row or a column or several hierachies of either.
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As an exmaple, we will construct a dialog that will contain a text field at the top and
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two buttons at the bottom. This can be seen as a top-hierarchy column with the text at
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the top and buttons at the bottom and a low-hierchary row with an OK button to the left
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and a Cancel button to the right. In many cases (particulary dialogs under Unix and
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normal frames) the main window will be resizable by the user and this change of size
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will have to get propagated to its children. In our case, we want the text area to grow
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with the dialog, whereas the button shall have a fixed size. In addition, there will be
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a thin border around all controls to make the dialog look nice and - to make matter worse -
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the buttons shall be centred as the width of the dialog changes.
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It is the unique feature of a box sizer, that it can grow in both directions (height and
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width) but can distribute its growth in the main direction (horizontal for a row) {\it unevenly}
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among its children. In our example case, the vertical sizer is supposed to propagate all its
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height changes to only the text area, not to the button area. This is determined by the {\it option} parameter
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when adding a window (or another sizer) to a sizer. It is interpreted
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as a weight factor, i.e. it can be zero, indicating that the window may not be resized
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at all, or above zero. If several windows have a value above zero, the value is interpreted
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relative to the sum of all weight factors of the sizer, so when adding two windows with
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a value of 1, they will both get resized equally much and each half as much as the sizer
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owning them. Then what do we do when a column sizer changes its width? This behaviour is
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controlled by {\it flags} (the second parameter of the Add() function): Zero or no flag
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indicates that the window will preserve it's original size, wxGROW flag (same as wxEXPAND)
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forces the window to grow with the sizer, and wxSHAPED flag tells the window to change it's
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size proportionally, preserving original aspect ratio. When wxGROW flag is not used,
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the item can be aligned within available space. wxALIGN\_LEFT, wxALIGN\_TOP, wxALIGN\_RIGHT,
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wxALIGN\_BOTTOM, wxALIGN\_CENTER\_HORIZONTAL and wxALIGN\_CENTER\_VERTICAL do what they say.
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wxALIGN\_CENTRE (same as wxALIGN\_CENTER) is defined as (wxALIGN\_CENTER\_HORIZONTAL |
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wxALIGN\_CENTER\_VERTICAL). Default alignment is wxALIGN\_LEFT | wxALIGN\_TOP.
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As mentioned above, any window belonging to a sizer may have border, and it can be specified
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which of the four sides may have this border, using the wxTOP, wxLEFT, wxRIGHT and wxBOTTOM
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constants or wxALL for all directions (and you may also use wxNORTH, wxWEST etc instead). These
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flags can be used in combintaion with the alignement flags above as the second paramter of the
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Add() method using the binary or operator |. The sizer of the border also must be made known,
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and it is the third parameter in the Add() method. This means, that the entire behaviour of
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a sizer and its children can be controlled by the three parameters of the Add() method.
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\begin{verbatim}
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// we want to get a dialog that is stretchable because it
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// has a text ctrl at the top and two buttons at the bottom
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MyDialog::MyDialog(wxFrame *parent, wxWindowID id, const wxString &title ) :
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wxDialog( parent, id, title, wxDefaultPosition, wxDefaultSize, wxDIALOG_STYLE | wxRESIZE_BORDER )
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{
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wxBoxSizer *topsizer = new wxBoxSizer( wxVERTICAL );
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// create text ctrl with minimal size 100x60
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topsizer->Add(
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new wxTextCtrl( this, -1, "My text.", wxDefaultPosition, wxSize(100,60), wxTE_MULTILINE),
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1, // make vertically stretchable
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wxEXPAND | // make horizontally stretchable
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wxALL, // and make border all around
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10 ); // set border width to 10
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wxBoxSizer *button_sizer = new wxBoxSizer( wxHORIZONTAL );
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button_sizer->Add(
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new wxButton( this, wxID_OK, "OK" ),
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0, // make horizontally unstretchable
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wxALL, // make border all around (implicit top alignment)
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10 ); // set border width to 10
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button_sizer->Add(
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new wxButton( this, wxID_CANCEL, "Cancel" ),
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0, // make horizontally unstretchable
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wxALL, // make border all around (implicit top alignment)
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10 ); // set border width to 10
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topsizer->Add(
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button_sizer,
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0, // make vertically unstretchable
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wxALIGN_CENTER ); // no border and centre horizontally
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SetAutoLayout( TRUE ); // tell dialog to use sizer
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SetSizer( topsizer ); // actually set the sizer
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topsizer->Fit( this ); // set size to minimum size as calculated by the sizer
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topsizer->SetSizeHints( this ); // set size hints to honour mininum size
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}
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\end{verbatim}
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\wxheading{Derived from}
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\helpref{wxSizer}{wxsizer}\\
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\helpref{wxObject}{wxobject}
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\membersection{wxBoxSizer::wxBoxSizer}\label{wxboxsizerwxboxsizer}
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\func{}{wxBoxSizer}{\param{int }{orient}}
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Constructor for a wxBoxSizer. {\it orient} may be either of wxVERTICAL
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or wxHORIZONTAL for creating either a column sizer or a row sizer.
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\membersection{wxBoxSizer::RecalcSizes}\label{wxboxsizerrecalcsizes}
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\func{void}{RecalcSizes}{\void}
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Implements the calculation of a box sizer's dimensions and then sets
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the size of its its children (calling \helpref{wxWindow::SetSize}{wxwindowsetsize}
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if the child is a window). It is used internally only and must not be called
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by the users. Documented for information.
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\membersection{wxBoxSizer::CalcMin}\label{wxboxsizercalcmin}
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\func{wxSize}{CalcMin}{\void}
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Implements the calculation of a box sizer's minimal. It is used internally
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only and must not be called by the users. Documented for information.
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\membersection{wxBoxSizer::GetOrientation}\label{wxboxsizergetorientation}
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\func{int}{GetOrientation}{\void}
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Returns the orientation of the boxsizer, either of wxVERTICAL
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or wxHORIZONTAL.
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