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