Inheritance diagram for wx.Sizer:
wx.Sizer is the abstract base class used for laying out subwindows in a window. You cannot use wx.Sizer directly; instead, you will have to use one of the sizer classes derived from it. Currently there are wx.BoxSizer, wx.StaticBoxSizer, wx.GridSizer, wx.FlexGridSizer and wx.GridBagSizer.
The layout algorithm used by sizers in wxWidgets is closely related to layout in other GUI toolkits, such as Java’s AWT, the GTK toolkit or the Qt toolkit. It is based upon the idea of the individual subwindows reporting their minimal required size and their ability to get stretched if the size of the parent window has changed. This will most often mean that the programmer does not set the original size of a dialog in the beginning, rather the dialog will be assigned a sizer and this sizer will be queried about the recommended size. The sizer in turn will query its children, which can be normal windows, empty space or other sizers, so that a hierarchy of sizers can be constructed.
Note
Note that wx.Sizer does not derive from wx.Window and thus does not interfere with tab ordering and requires very little resources compared to a real window on screen.
What makes sizers so well fitted for use in wxWidgets is the fact that every control reports its own minimal size and the algorithm can handle differences in font sizes or different window (dialog item) sizes on different platforms without problems. If e.g. the standard font as well as the overall design of Motif widgets requires more space than on Windows, the initial dialog size will automatically be bigger on Motif than on Windows.
Sizers may also be used to control the layout of custom drawn items on the window. The Add, Insert, and Prepend functions return a pointer to the newly added wx.SizerItem. Just add empty space of the desired size and attributes, and then use the wx.SizerItem.GetRect method to determine where the drawing operations should take place.
A simple example on how to use sizers (self refers to a panel, for example):
sizer = wx.BoxSizer(wx.HORIZONTAL)
button = wx.Button(self, -1, "Hello from wxPython!")
sizer.Add(button, 0, wx.EXPAND | wx.ALL, 15)
self.SetSizer(sizer)
sizer.Layout()
Note
wxPython note: If you wish to create a sizer class in wxPython you should derive the class from wx.PySizer in order to get Python-aware capabilities for the various virtual methods.
wx.BoxSizer, wx.FlexGridSizer, wx.GridBagSizer, wx.GridSizer, wx.PySizer, wx.StaticBoxSizer, wx.StdDialogButtonSizer
Appends a child to the sizer. wx.Sizer itself is an abstract class, but the parameters are equivalent in the derived classes that you will instantiate to use it so they are described here:
window: The window to be added to the sizer. Its initial size (either set explicitly by the user or calculated internally when using wx.DefaultSize) is interpreted as the minimal and in many cases also the initial size.
sizer: The (child-)sizer to be added to the sizer. This allows placing a child sizer in a sizer and thus to create hierarchies of sizers (typically a vertical box as the top sizer and several horizontal boxes on the level beneath).
width and height: The dimension of a spacer to be added to the sizer. Adding spacers to sizers gives more flexibility in the design of dialogs; imagine for example a horizontal box with two buttons at the bottom of a dialog: you might want to insert a space between the two buttons and make that space stretchable using the proportion flag and the result will be that the left button will be aligned with the left side of the dialog and the right button with the right side – the space in between will shrink and grow with the dialog.
proportion: Although the meaning of this parameter is undefined in wx.Sizer, it is used in wx.BoxSizer to indicate if a child of a sizer can change its size in the main orientation of the wx.BoxSizer – where 0 stands for not changeable and a value of more than zero is interpreted relative to the value of other children of the same wx.BoxSizer. For example, you might have a horizontal wx.BoxSizer with three children, two of which are supposed to change their size with the sizer. Then the two stretchable windows would get a value of 1 each to make them grow and shrink equally with the sizer’s horizontal dimension.
flag: This parameter can be used to set a number of flags which can be combined using the binary OR operator |. Two main behaviours are defined using these flags. One is the border around a window: the border parameter determines the border width whereas the flags given here determine which side(s) of the item that the border will be added. The other flags determine how the sizer item behaves when the space allotted to the sizer changes, and is somewhat dependent on the specific kind of sizer used:
Sizer Flag |
Description |
---|---|
wx.TOP |
These flags are used to specify which side(s) of the sizer item the border width will apply to. |
wx.BOTTOM |
|
wx.LEFT |
|
wx.RIGHT |
|
wx.ALL |
|
wx.EXPAND |
The item will be expanded to fill the space assigned to the item. |
wx.SHAPED |
The item will be expanded as much as possible while also maintaining its aspect ratio |
wx.FIXED_MINSIZE |
Normally wx.Sizers will use wx.Window.GetAdjustedBestSize to determine what the minimal size of window items should be, and will use that size to calculate the layout. This allows layouts to adjust when an item changes and its best size becomes different. If you would rather have a window item stay the size it started with then use wx.FIXED_MINSIZE. |
wx.RESERVE_SPACE_EVEN_IF_HIDDEN |
Normally wx.Sizers don’t allocate space for hidden windows or other items. This flag overrides this behavior so that sufficient space is allocated for the window even if it isn’t visible. This makes it possible to dynamically show and hide controls without resizing parent dialog, for example. This function is new since wxWidgets version 2.8.8 |
wx.ALIGN_CENTER or wx.ALIGN_CENTRE |
The wx.ALIGN* flags allow you to specify the alignment of the item within the space allotted to it by the sizer, adjusted for the border if any. |
wx.ALIGN_LEFT |
|
wx.ALIGN_RIGHT |
|
wx.ALIGN_TOP |
|
wx.ALIGN_BOTTOM |
|
wx.ALIGN_CENTER_VERTICAL or wx.ALIGN_CENTRE_VERTICAL |
|
wx.ALIGN_CENTER_HORIZONTAL or wx.ALIGN_CENTRE_HORIZONTAL |
Parameters:
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Similar to Add but uses the wx.SizerFlags convenience class for setting the various flags, options and borders.
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Adds a wx.SizerItem to the sizer.
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AddMany is a convenience method for adding several items to a sizer at one time. Simply pass it a list of tuples, where each tuple consists of the parameters that you would normally pass to the Add method.
Parameters:
Compatibility alias for Add.
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Adds non-stretchable space to the sizer. More readable way of calling Add(size, size, 0).
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Adds stretchable space to the sizer. More readable way of calling Add(0, 0, prop).
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Compatibility alias for Add.
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This method is abstract and has to be overwritten by any derived class. Here, the sizer will do the actual calculation of its children minimal sizes.
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Detaches all children from the sizer. If delete_windows is True then child windows will also be deleted.
Parameters:
Computes client area size for window so that it matches the sizer’s minimal size.
Unlike GetMinSize, this method accounts for other constraints imposed on window, namely display’s size (returned size will never be too large for the display) and maximum window size if previously set by wx.Window.SetMaxSize.
The returned value is suitable for passing to wx.Window.SetClientSize.
This function is new since wxWidgets version 2.8.8
Parameters:
Returns:
See also
Like ComputeFittingClientSize, but converts the result into window size.
The returned value is suitable for passing to wx.Window.SetSize or wx.Window.SetMinSize.
This function is new since wxWidgets version 2.8.8
Parameters:
Returns:
See also
Detaches an item from the sizer without destroying it. This method does not cause any layout or resizing to take place, call Layout to do so.
The item parameter can be either a window, a sizer, or the zero-based index of the item to be detached. Returns True if the child item was found and detached.
Parameters:
Returns:
bool
See also
Tell the sizer to resize the window to match the sizer’s minimal size. This is commonly done in the constructor of the window itself. Returns the new size.
Parameters:
Returns:
Note
For a top level window this is the total window size, not client size.
Tell the sizer to resize the virtual size of the window to match the sizer’s minimal size. This will not alter the on screen size of the window, but may cause the addition/removal/alteration of scrollbars required to view the virtual area in windows which manage it.
Parameters:
Returns the list of the items in this sizer. The elements of the list wx.SizerItemList are objects of type wx.SizerItem.
Returns:
list
Returns the wx.SizerItem which holds the item given. The item parameter can be either a window, a sizer, or the zero-based index of the item to be found.
Use parameter recursive to search in subsizers too.
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Returns the minimal size of the sizer. This is either the combined minimal size of all the children and their borders or the minimal size set by SetMinSize, depending on which is bigger.
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Note
Note that the returned value is client size, not window size. In particular, if you use the value to set toplevel window’s minimal or actual size, you should convert it using wx.Window.ClientToWindowSize before passing it to wx.Window.SetMinSize or wx.Window.SetSize.
A convenience method for Show(item, False, recursive)
Returns True if the child item was found, False otherwise.
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Returns:
bool
Inserts a new item into the list of items managed by this sizer before the item at index before.
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See also
Similar to Insert, but uses the wx.SizerFlags convenience class for setting the various flags, options and borders.
Parameters:
Returns:
See also
Inserts a wx.SizerItem to the sizer at the position given by index.
Parameters:
Compatibility alias for Insert.
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Inserts non-stretchable space to the sizer. More readable way of calling Insert(size, size, 0).
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Inserts stretchable space to the sizer. More readable way of calling Insert(0, 0, prop).
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Compatibility alias for Insert.
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Determines if the item is currently shown. To make a sizer item disappear or reappear, use Show followed by Layout. The item parameter can be either a window, a sizer, or the zero-based index of the item.
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bool
Same as Add, but prepends the items to the beginning of the list of items (windows, subsizers or spaces) owned by this sizer.
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Similar to Prepend but uses the wx.SizerFlags convenience class for setting the various flags, options and borders.
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Prepends a wx.SizerItem to the sizer.
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Compatibility alias for Prepend.
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Prepends non-stretchable space to the sizer. More readable way of calling Prepend(size, size, 0).
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Prepends stretchable space to the sizer. More readable way of calling Prepend(0, 0, prop).
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Compatibility alias for Prepend.
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Removes an item from the sizer and destroys it. This method does not cause any layout or resizing to take place, call Layout to update the layout on screen after removing a child from the sizer. The item parameter can be either a window, a sizer, or the zero-based index of an item to remove.
Returns True if the child item was found and removed.
Parameters:
Returns:
bool
Detaches the given olditem from the sizer and replaces it with item which can be a window, sizer, or wx.SizerItem. The detached child is destroyed only if it is not a window, (because windows are owned by their parent, not the sizer.)
The recursive parameter can be used to search for the given element recursivly in subsizers.
This method does not cause any layout or resizing to take place, call Layout to do so.
Returns True if the child item was found and removed.
Parameters:
Returns:
bool
Set (or unset) the window this sizer is used in.
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Call this to force the sizer to take the given dimension and thus force the items owned by the sizer to resize themselves according to the rules defined by the parameter in the Add and Prepend methods.
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Sets the minimum size that will be allocated for an item in the sizer. The item parameter can be either a window, a sizer, or the zero-based index of the item. If a window or sizer is given then it will be searched for recursivly in subsizers if neccessary.
Parameters:
Call this to give the sizer a minimal size. Normally, the sizer will calculate its minimal size based purely on how much space its children need. After calling this method GetMinSize will return either the minimal size as requested by its children or the minimal size set here, depending on which is bigger.
Parameters:
This method first calls Fit and then SetSizeHints on the window passed to it. This only makes sense when window is actually a wx.TopLevelWindow such as a wx.Frame or a wx.Dialog, since SetSizeHints only has any effect in these classes. It does nothing in normal windows or controls.
This method is commonly invoked in the constructor of a toplevel window itself if the toplevel window is resizable.
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Tell the sizer to set the minimal size of the window virtual area to match the sizer’s minimal size. For windows with managed scrollbars this will set them appropriately.
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See also
Shows or hides the item. To make a sizer item disappear or reappear, use Show() followed by Layout.
Use parameter recursive to show or hide elements found in subsizers.
Returns True if the child item was found, False otherwise.
Parameters:
Returns:
bool
Recursively call wx.SizerItem.Show on all sizer items.
Parameters: