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git.saurik.com Git - wxWidgets.git/blob - docs/doxygen/overviews/windowsizing.h
1 /////////////////////////////////////////////////////////////////////////////
2 // Name: windowsizing.h
3 // Purpose: topic overview
4 // Author: wxWidgets team
6 // Licence: wxWindows licence
7 /////////////////////////////////////////////////////////////////////////////
11 @page overview_windowsizing Window Sizing Overview
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.
18 @li @ref overview_windowsizing_glossary
19 @li @ref overview_windowsizing_func
25 @section overview_windowsizing_glossary Glossary
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
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.
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
45 @li @b "Maximum Size": just like for the minimal size, the maximum size is normally
46 explicitly 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
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.
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
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.
69 @li @b "Virtual Size": the virtual size is the size of the potentially viewable
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
74 See wxScrolled for more info.
77 @section overview_windowsizing_func Functions related to sizing
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.
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
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.
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().
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.
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.