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 licence
   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 "Size": this is the current size of the window and it can be explicitly
  28     set or fetched with the wxWindow::SetSize() or wxWindow::GetSize() methods.
  29     This size value is the size that the widget is currently using on screen and is
  30     the way to change the size of something that is not being managed by a sizer.
  31
  32 @li @b "Client Size": the client size represents the widget's area inside of any
  33     borders belonging to the widget and is the area that can be drawn upon in a
  34     @c EVT_PAINT event. For wxFrame, the client size also excludes the frame
  35     menu, tool and status bars, if any. If a window doesn't have any border
  36     (and is not a wxFrame with some bars) then its client size is the same as
  37     its size.
  38
  39 @li @b "Best Size": the best size of a widget depends on what kind of widget it is,
  40     and usually also on the contents of the widget. For example a wxListBox's best
  41     size will be calculated based on how many items it has, up to a certain limit,
  42     or a wxButton's best size will be calculated based on its label size, but
  43     normally won't be smaller than the platform default button size (unless a style
  44     flag overrides that).
  45     There is a special virtual method in the C++ window classes called
  46     wxWindow::DoGetBestSize() that a class can override if it wants to calculate
  47     its own best size based on its content, however notice that usually it is
  48     more convenient to override DoGetBestClientSize(), see below.
  49
  50 @li @b "Best Client Size": this is simply the client size corresponding to the
  51     best window size. When the fitting size for the given contents is computed,
  52     it will usually be the client size and the size of the borders needs to be
  53     added to obtain the full best size. For this reason, it's preferable to
  54     override DoGetBestClientSize() and let DoGetBestSize() compute the full
  55     best size.
  56
  57 @li @b "Minimal Size": the minimal size of a widget is a size that is normally explicitly
  58     set by the programmer either with the wxWindow::SetMinSize() method or with the
  59     wxWindow::SetSizeHints() method.
  60     Most controls will also set the minimal size to the size given in the control's
  61     constructor if a non-default value is passed.
  62     Top-level windows such as wxFrame will not allow the user to resize the frame below
  63     the minimal size.
  64
  65 @li @b "Maximum Size": just like for the minimal size, the maximum size is normally
  66     explicitly set by the programmer with the wxWindow::SetMaxSize() method or
  67     with wxWindow::SetSizeHints().
  68     Top-level windows such as wxFrame will not allow the user to resize the frame above
  69     the maximum size.
  70
  71 @li @b "Initial Size": the initial size of a widget is the size given to the
  72     constructor of the widget, if any.
  73     As mentioned above most controls will also set this size value as the control's
  74     minimal size. If the size passed to the constructor is the default ::wxDefaultSize,
  75     or if the size is not fully specified (such as wxSize(150,-1)) then most controls
  76     will fill in the missing size components using the best size and will set the
  77     initial size of the control to the resulting size.
  78
  79 @li @b "Virtual Size": the virtual size is the size of the potentially viewable
  80     area of the widget.
  81     The virtual size of a widget may be larger than its actual size and in this
  82     case scrollbars will appear to the let the user 'explore' the full contents
  83     of the widget.
  84     See wxScrolled for more info.
  85
  86
  87 @section overview_windowsizing_func Functions related to sizing
  88
  89 @li wxWindow::GetEffectiveMinSize(): returns a blending of the widget's minimal size
  90     and best size, giving precedence to the minimal size.
  91     For example, if a widget's min size is set to (150, -1) and the best size is
  92     (80, 22) then the best fitting size is (150, 22). If the min size is (50, 20)
  93     then the best fitting size is (50, 20). This method is what is called by the
  94     sizers when determining what the requirements of each item in the sizer is,
  95     and is used for calculating the overall minimum needs of the sizer.
  96
  97 @li wxWindow::SetInitialSize(): this is a little different than the typical size
  98     setters. Rather than just setting an "initial size" attribute it actually sets
  99     the minimal size to the value passed in, blends that value with the best size,
 100     and then sets the size of the widget to be the result.
 101     So you can consider this method to be a "Smart SetSize". This method is what is
 102     called by the constructor of most controls to set the minimal size and the initial
 103     size of the control.
 104
 105 @li wxWindow::Fit(): this method sets the size of a window to fit around its children.
 106     If it has no children then nothing is done, if it does have children then the size
 107     of the window is set to the window's best size.
 108
 109 @li wxSizer::Fit(): this sets the size of the window to be large enough to
 110     accommodate the minimum size needed by the sizer, (along with a few other
 111     constraints...). If the sizer is the one that is assigned to the window then
 112     this should be equivalent to wxWindow::Fit().
 113
 114 @li wxSizer::Layout(): recalculates the minimum space needed by each item in the
 115     sizer, and then lays out the items within the space currently allotted to the sizer.
 116
 117 @li wxWindow::Layout(): if the window has a sizer then it sets the space given to
 118     the sizer to the current size of the window, which results in a call to
 119     wxSizer::Layout(). If the window has layout constraints instead of a sizer then
 120     the constraints algorithm is run. The @c Layout() method is what is called by
 121     the default @c EVT_SIZE handler for container windows.
 122
 123 */
 124