docs/doxygen/overviews/windowsizing.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        windowsizing.h
   3 // Purpose:     topic overview
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /**
  10
  11 @page overview_windowsizing Window Sizing Overview
  12
  13 It can sometimes be confusing to keep track of the various size-related
  14 attributes of a wxWindow, how they relate to each other, and how they interact
  15 with sizers. This document will attempt to clear the fog a little, and give
  16 some simple explanations of things.
  17
  18 @li @ref overview_windowsizing_glossary
  19 @li @ref overview_windowsizing_func
  20
  21
  22 <hr>
  23
  24
  25 @section overview_windowsizing_glossary Glossary
  26
  27 @li @b "Best Size": the best size of a widget depends on what kind of widget it is,
  28     and usually also on the contents of the widget. For example a wxListBox's best
  29     size will be calculated based on how many items it has, up to a certain limit,
  30     or a wxButton's best size will be calculated based on its label size, but
  31     normally won't be smaller than the platform default button size (unless a style
  32     flag overrides that).
  33     There is a special virtual method in the C++ window classes called
  34     wxWindow::DoGetBestSize() that a class needs to override if it wants to calculate
  35     its own best size based on its content.
  36
  37 @li @b "Minimal Size": the minimal size of a widget is a size that is normally explicitly
  38     set by the programmer either with the wxWindow::SetMinSize() method or with the
  39     wxWindow::SetSizeHints() method.
  40     Most controls will also set the minimal size to the size given in the control's
  41     constructor if a non-default value is passed.
  42     Top-level windows such as wxFrame will not allow the user to resize the frame below
  43     the minimal size.
  44
  45 @li @b "Maximum Size": just like for the minimal size, the maximum size is normally
  46     explicitely set by the programmer with the wxWindow::SetMaxSize() method or
  47     with wxWindow::SetSizeHints().
  48     Top-level windows such as wxFrame will not allow the user to resize the frame above
  49     the maximum size.
  50
  51 @li @b "Size": the size of a widget can be explicitly set or fetched with the
  52     wxWindow::SetSize() or wxWindow::GetSize() methods.
  53     This size value is the size that the widget is currently using on screen and is
  54     the way to change the size of something that is not being managed by a sizer.
  55
  56 @li @b "Client Size": the client size represents the widget's area inside of any
  57     borders belonging to the widget and is the area that can be drawn upon in a
  58     @c EVT_PAINT event. If a widget doesn't have a border then its client size is
  59     the same as its size.
  60
  61 @li @b "Initial Size": the initial size of a widget is the size given to the
  62     constructor of the widget, if any.
  63     As mentioned above most controls will also set this size value as the control's
  64     minimal size. If the size passed to the constructor is the default ::wxDefaultSize,
  65     or if the size is not fully specified (such as wxSize(150,-1)) then most controls
  66     will fill in the missing size components using the best size and will set the
  67     initial size of the control to the resulting size.
  68
  69 @li @b "Virtual Size": the virtual size is the size of the potentially viewable
  70     area of the widget.
  71     The virtual size of a widget may be larger than its actual size and in this
  72     case scrollbars will appear to the let the user 'explore' the full contents
  73     of the widget.
  74     See wxScrolled for more info.
  75
  76
  77 @section overview_windowsizing_func Functions related to sizing
  78
  79 @li wxWindow::GetEffectiveMinSize(): returns a blending of the widget's minimal size
  80     and best size, giving precedence to the minimal size.
  81     For example, if a widget's min size is set to (150, -1) and the best size is
  82     (80, 22) then the best fitting size is (150, 22). If the min size is (50, 20)
  83     then the best fitting size is (50, 20). This method is what is called by the
  84     sizers when determining what the requirements of each item in the sizer is,
  85     and is used for calculating the overall minimum needs of the sizer.
  86
  87 @li wxWindow::SetInitialSize(): this is a little different than the typical size
  88     setters. Rather than just setting an "initial size" attribute it actually sets
  89     the minimal size to the value passed in, blends that value with the best size,
  90     and then sets the size of the widget to be the result.
  91     So you can consider this method to be a "Smart SetSize". This method is what is
  92     called by the constructor of most controls to set the minimal size and the initial
  93     size of the control.
  94
  95 @li wxWindow::Fit(): this method sets the size of a window to fit around its children.
  96     If it has no children then nothing is done, if it does have children then the size
  97     of the window is set to the window's best size.
  98
  99 @li wxSizer::Fit(): this sets the size of the window to be large enough to
 100     accommodate the minimum size needed by the sizer, (along with a few other
 101     constraints...). If the sizer is the one that is assigned to the window then
 102     this should be equivalent to wxWindow::Fit().
 103
 104 @li wxSizer::Layout(): recalculates the minimum space needed by each item in the
 105     sizer, and then lays out the items within the space currently allotted to the sizer.
 106
 107 @li wxWindow::Layout(): if the window has a sizer then it sets the space given to
 108     the sizer to the current size of the window, which results in a call to
 109     wxSizer::Layout(). If the window has layout constraints instead of a sizer then
 110     the constraints algorithm is run. The @c Layout() method is what is called by
 111     the default @c EVT_SIZE handler for container windows.
 112
 113 */
 114