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- /////////////////////////////////////////////////////////////////////////////
- // Name: windowsizing.h
- // Purpose: topic overview
- // Author: wxWidgets team
- // Licence: wxWindows licence
- /////////////////////////////////////////////////////////////////////////////
- /**
- @page overview_windowsizing Window Sizing Overview
- @tableofcontents
- It can sometimes be confusing to keep track of the various size-related
- attributes of a wxWindow, how they relate to each other, and how they interact
- with sizers. This document will attempt to clear the fog a little, and give
- some simple explanations of things.
- @section overview_windowsizing_glossary Glossary
- @li @b "Size": this is the current size of the window and it can be explicitly
- set or fetched with the wxWindow::SetSize() or wxWindow::GetSize() methods.
- This size value is the size that the widget is currently using on screen and is
- the way to change the size of something that is not being managed by a sizer.
- @li @b "Client Size": the client size represents the widget's area inside of any
- borders belonging to the widget and is the area that can be drawn upon in a
- @c EVT_PAINT event. For wxFrame, the client size also excludes the frame
- menu, tool and status bars, if any. If a window doesn't have any border
- (and is not a wxFrame with some bars) then its client size is the same as
- its size.
- @li @b "Best Size": the best size of a widget depends on what kind of widget it is,
- and usually also on the contents of the widget. For example a wxListBox's best
- size will be calculated based on how many items it has, up to a certain limit,
- or a wxButton's best size will be calculated based on its label size, but
- normally won't be smaller than the platform default button size (unless a style
- flag overrides that).
- There is a special virtual method in the C++ window classes called
- wxWindow::DoGetBestSize() that a class can override if it wants to calculate
- its own best size based on its content, however notice that usually it is
- more convenient to override DoGetBestClientSize(), see below.
- @li @b "Best Client Size": this is simply the client size corresponding to the
- best window size. When the fitting size for the given contents is computed,
- it will usually be the client size and the size of the borders needs to be
- added to obtain the full best size. For this reason, it's preferable to
- override DoGetBestClientSize() and let DoGetBestSize() compute the full
- best size.
- @li @b "Minimal Size": the minimal size of a widget is a size that is normally explicitly
- set by the programmer either with the wxWindow::SetMinSize() method or with the
- wxWindow::SetSizeHints() method.
- Most controls will also set the minimal size to the size given in the control's
- constructor if a non-default value is passed.
- Top-level windows such as wxFrame will not allow the user to resize the frame below
- the minimal size.
- @li @b "Maximum Size": just like for the minimal size, the maximum size is normally
- explicitly set by the programmer with the wxWindow::SetMaxSize() method or
- with wxWindow::SetSizeHints().
- Top-level windows such as wxFrame will not allow the user to resize the frame above
- the maximum size.
- @li @b "Initial Size": the initial size of a widget is the size given to the
- constructor of the widget, if any.
- As mentioned above most controls will also set this size value as the control's
- minimal size. If the size passed to the constructor is the default ::wxDefaultSize,
- or if the size is not fully specified (such as wxSize(150,-1)) then most controls
- will fill in the missing size components using the best size and will set the
- initial size of the control to the resulting size.
- @li @b "Virtual Size": the virtual size is the size of the potentially viewable
- area of the widget.
- The virtual size of a widget may be larger than its actual size and in this
- case scrollbars will appear to the let the user 'explore' the full contents
- of the widget.
- See wxScrolled for more info.
- @section overview_windowsizing_func Functions related to sizing
- @li wxWindow::GetEffectiveMinSize(): returns a blending of the widget's minimal size
- and best size, giving precedence to the minimal size.
- For example, if a widget's min size is set to (150, -1) and the best size is
- (80, 22) then the best fitting size is (150, 22). If the min size is (50, 20)
- then the best fitting size is (50, 20). This method is what is called by the
- sizers when determining what the requirements of each item in the sizer is,
- and is used for calculating the overall minimum needs of the sizer.
- @li wxWindow::SetInitialSize(): this is a little different than the typical size
- setters. Rather than just setting an "initial size" attribute it actually sets
- the minimal size to the value passed in, blends that value with the best size,
- and then sets the size of the widget to be the result.
- So you can consider this method to be a "Smart SetSize". This method is what is
- called by the constructor of most controls to set the minimal size and the initial
- size of the control.
- @li wxWindow::Fit(): this method sets the size of a window to fit around its children.
- If it has no children then nothing is done, if it does have children then the size
- of the window is set to the window's best size.
- @li wxSizer::Fit(): this sets the size of the window to be large enough to
- accommodate the minimum size needed by the sizer, (along with a few other
- constraints...). If the sizer is the one that is assigned to the window then
- this should be equivalent to wxWindow::Fit().
- @li wxSizer::Layout(): recalculates the minimum space needed by each item in the
- sizer, and then lays out the items within the space currently allotted to the sizer.
- @li wxWindow::Layout(): if the window has a sizer then it sets the space given to
- the sizer to the current size of the window, which results in a call to
- wxSizer::Layout(). If the window has layout constraints instead of a sizer then
- the constraints algorithm is run. The @c Layout() method is what is called by
- the default @c EVT_SIZE handler for container windows.
- */
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