.. _navigation-toolbar:

Interactive navigation
======================

.. image:: ../_static/toolbar.png

All figure windows come with a navigation toolbar, which can be used
to navigate through the data set.  Here is a description of each of
the buttons at the bottom of the toolbar

.. image:: ../mpl_data/images/home.png

.. image:: ../mpl_data/images/back.png

.. image:: ../mpl_data/images/forward.png

The ``Forward`` and ``Back`` buttons
    These are akin to the web browser forward and back buttons.  They
    are used to navigate back and forth between previously defined
    views.  They have no meaning unless you have already navigated
    somewhere else using the pan and zoom buttons.  This is analogous
    to trying to click ``Back`` on your web browser before visiting a
    new page --nothing happens.  ``Home`` always takes you to the
    first, default view of your data.  For ``Home``, ``Forward`` and
    ``Back``, think web browser where data views are web pages.  Use
    the pan and zoom to rectangle to define new views.

.. image:: ../mpl_data/images/move.png

The ``Pan/Zoom`` button
    This button has two modes: pan and zoom.  Click the toolbar button
    to activate panning and zooming, then put your mouse somewhere
    over an axes.  Press the left mouse button and hold it to pan the
    figure, dragging it to a new position.  When you release it, the
    data under the point where you pressed will be moved to the point
    where you released.  If you press 'x' or 'y' while panning the
    motion will be contrained to the x or y axis, respectively.  Press
    the right mouse button to zoom, dragging it to a new position.
    The x axis will be zoomed in proportionate to the rightward
    movement and zoomed out proportionate to the leftward movement.
    Ditto for the yaxis and up/down motions.  The point under your
    mouse when you begin the zoom remains stationary, allowing you to
    zoom to an arbitrary point in the figure.  You can use the
    modifier keys 'x', 'y' or 'CONTROL' to constrain the zoom to the x
    axes, the y axes, or aspect ratio preserve, respectively.

    With polar plots, the pan and zoom functionality behaves
    differently.  The radius axis labels can be dragged using the left
    mouse button.  The radius scale can be zoomed in and out using the
    right mouse button.

.. image:: ../mpl_data/images/zoom_to_rect.png

The ``Zoom-to-rectangle`` button
    Click this toolbar button to activate this mode.  Put your mouse
    somewhere over and axes and press the left mouse button.  Drag the
    mouse while holding the button to a new location and release.  The
    axes view limits will be zoomed to the rectangle you have defined.
    There is also an experimental 'zoom out to rectangle' in this mode
    with the right button, which will place your entire axes in the
    region defined by the zoom out rectangle.

.. image:: ../mpl_data/images/subplots.png

The ``Subplot-configuration`` button
    Use this tool to configure the parameters of the subplot: the
    left, right, top, bottom, space between the rows and space between
    the columns.

.. image:: ../mpl_data/images/filesave.png

The ``Save`` button
    Click this button to launch a file save dialog.  You can save
    files with the following extensions: ``png``, ``ps``, ``eps``,
    ``svg`` and ``pdf``.


If you are using :mod:`matplotlib.pyplot` the toolbar will be created
automatically for every figure.  If you are writing your own user
interface code, you can add the toolbar as a widget.  The exact syntax
depends on your UI, but we have examples for every supported UI in the
``matplotlib/examples/user_interfaces`` directory.  Here is some
example code for GTK::


    from matplotlib.figure import Figure
    from matplotlib.backends.backend_gtkagg import FigureCanvasGTKAgg as FigureCanvas
    from matplotlib.backends.backend_gtkagg import NavigationToolbar2GTKAgg as NavigationToolbar

    win = gtk.Window()
    win.connect("destroy", lambda x: gtk.main_quit())
    win.set_default_size(400,300)
    win.set_title("Embedding in GTK")

    vbox = gtk.VBox()
    win.add(vbox)

    fig = Figure(figsize=(5,4), dpi=100)
    ax = fig.add_subplot(111)
    ax.plot([1,2,3])

    canvas = FigureCanvas(fig)  # a gtk.DrawingArea
    vbox.pack_start(canvas)
    toolbar = NavigationToolbar(canvas, win)
    vbox.pack_start(toolbar, False, False)

    win.show_all()
    gtk.main()





