Get Info
========

In the Outline View the Get Info command can generate one of four different
dialogs depending on what is selected. If a single thing is selected, and that
thing is a point then the :ref:`point info <getinfo.Point>` dialog is brought
up, if it is a reference then the
:ref:`reference dialog <getinfo.GetReferenceInfo>` is brought up, if it is a
background image then the :ref:`image dialog <getinfo.Image>` is brought up. If
it is an anchor point then the :ref:`anchor point <getinfo.Anchors>` dialog is
brought up.


.. _getinfo.Point:

Point Info
----------

.. image:: /images/pointinfo.png
   :align: right

This shows information about the current point. The Base position is where the
point itself is.

The Next CP shows both the location of the next control point, and the offset to
that point from the base (and whether this setting is the default for that
point, if this point is the last on an open contour then the [] Default button
will be grey), underneath the offsets it shows the same information in a
different format -- as a distance from the point itself, and the angle to it.

The Prev CP does the same for the previous control point.

You may change any of these and the change is reflected in the outline view.
Your changes are constrained by the point type (for instance with tangent
points, you may not change the angle fields as these are fixed).

FontForge also shows you the curvature of the two splines on either side of the
point. In a perfect world these will be equal for curve points and the join will
appear smooth. It also shows the difference between the two. The curvature is
the reciprical of the radius of the circle tangent to the curve (a straight line
has curvature 0 because it is a circle with infinite radius so its reciprical is
0). For most curves in letters this radius is fairly large when expressed in
em-units (and its reciprical is correspondingly small). To make it easier to
read, FontForge scales it by the em-size of the font -- this is equivalent to
expressing it in units where 1 corresponds to an em (rather than 1000 or 2048).

.. image:: /images/pointinfo-interp.png
   :align: right

You may also change whether a point is a curve, corner or tangent point
(Caution: Changing from a corner point to a curve point and back to a corner
point is NOT a no op. It may change the control points) You may move on to the
next or previous point on the path, or the next/previous point of the current
contour. If you cancel then all changes to all points are canceled.

The colors of the labels reflect the colors of the items they refer to. The
point itself will be drawn in red, the previous control point will be drawn in
magenta and the next control point will be drawn in dull cyan.

When editing truetype interpolated points it is more important to view the
control points and let the base point continue to be interpolated. The <> Normal
and <>Interpolated radio buttons control which view is active.

Pressing <> Interpolated may move the point to position it correctly for
interpolation.


.. _getinfo.HintMask:

Hint Mask
^^^^^^^^^

.. image:: /images/charwithhintmask.png
.. image:: /images/hintmaskinfo.png

If you want to control what hints are active at a given point (and at all
subsequent points until an new hintmask is given) you can use the hint mask
pane. This provides you with a list of all hints in the current glyph, you
should select the ones which you want active.

As you select hints, the glyph view will darken those hints so you can see what
you've selected.

Points with circles drawn around them have hintmasks.

According to Adobe's documentation you should never have two hints which
conflict active at the same time. FontForge will warn you if you do this.
Unfortunately there are fonts (even fonts from Adobe) which do not follow this
rule, so I have made this a warning rather than an error.

Remember to hold the control key down when making disjoint selections.

Sadly the direction in which hintmasks apply is backwards from what you would
expect (the hintmask applies to this point an all previous points on the
contour, rather than all subsequent ones).


Active Hints
""""""""""""

This looks just like the hint mask, except you cannot change anything it in. It
shows you what hints are currently selected at this point. If a point has a hint
mask then the two will be identical.


.. _getinfo.Spiro:

Spiro Point Info
----------------

.. image:: /images/spiropointinfo.png
   :align: right

If you are editing in spiro (clothoid) mode rather than Bezier mode, then there
are no control points and the get info dialog is much simpler. Just the location
of the point and the point type.

.. container:: clearer

   ..


.. _getinfo.Anchors:

Anchor Points Info
------------------

.. image:: /images/agetinfo.png
   :align: right

This dialog shows the selected :ref:`anchor point <overview.Anchors>` with the
anchor class, location, type and (for ligatures) the ligature index. You may
change any of these attributes (as long as your changes are reasonable). You may
create new points or delete the current one. As with normal points above you may
step through all the anchor points in your glyph.

In a truetype font you can force the anchor to track a contour point in the
truetype glyph. This point can then be manipulated with truetype instructions to
grid fit it properly with the current rasterization.

Anchor points may also be created with the
:ref:`Point->Add Anchor <pointmenu.AddAnchor>` command.

.. container:: clearer

   ..


.. _getinfo.GetReferenceInfo:

Reference Info
--------------

.. image:: /images/rgetinfo.png
   :align: right

This dialog shows the name of the selected reference, its encoding in the font
and its postscript transformation matrix. You may alter the transformation
matrix if you desire.

.. container:: clearer

   ..

The transformation matrix maps points in the glyph being referred to into their
location in the current glyph:

.. math::

   x_{\mathrm{current}} &= TM_{1,1}\cdot x_{\mathrm{ref}} + TM_{2,1}\cdot y_{\mathrm{ref}} + TM_{3,1} \\
   y_{\mathrm{current}} &= TM_{1,2}\cdot y_{\mathrm{ref}} + TM_{2,2}\cdot y_{\mathrm{ref}} + TM_{3,2}

The Use My Metrics checkbox is useful in truetype fonts where it forces the
metrics (width) of a composite glyph (for exampe acute a) is the same as the
metrics of one of its components (for example a). This is especially important
in fonts containing instructions that might modify a glyph's width.

The Round To Grid checkbox is also used in truetype hints and indicates that the
translation should be rounded to the rasterizer's grid before being applied to
the points of the reference. This means that the grid-fitting done by the
reference's instructions will still be useful in the composite.

In a truetype font a reference may be positioned by matching two points, one in
the base character, and one in the reference itself. In the example at right,
the reference to "acute" will be moved until point 12 in "acute" is at the same
place as point 33 in the base glyph. The glory of this method is that the
truetype instructions associated with the glyphs can move these points around to
an appropriate location for the current pixelsize.

Points in a composite glyph are numbered by counting the points of the first
component, adding 4 (for the 4 phantom (metric) points), then counting the
points in the second composite, adding 4, etc. The first composite is the one
which is drawn first, not the one which is added first. The Base numbering
scheme is from the full composite, while the reference point is numbered by the
current reference. The current reference must be drawn after the base point. You
may use :ref:`Element->Order <elementmenu.Order>` to reorder the references.

(You should probably not set Round To Grid when doing point matching)

The bounding box information is informative only and displays the current
location and size of the reference.

The [Show] button will open a glyph outline view showing the glyph being
referred to.


.. _getinfo.Image:

Image Info
----------

This dialog gives the offset to the lower left corner of the image and the scale
factors applied to the image. Currently you may not alter anything here, it is
purely informational.

See Also:

* :doc:`The font info dialog <fontinfo>`
* :doc:`The glyph info dialog <charinfo>`
