.. _tut_diameter_dimension:

Tutorial for Diameter Dimensions
================================

Please read the :ref:`tut_radius_dimension` before, if you haven't.

This is a repetition of the radius tutorial, just with diameter dimensions.

.. code-block:: Python

    import ezdxf

    # setup=True setups the default dimension styles
    doc = ezdxf.new('R2010', setup=True)

    msp = doc.modelspace()  # add new dimension entities to the modelspace
    msp.add_circle((0, 0), radius=3)  # add a CIRCLE entity, not required
    # add default diameter dimension, measurement text is located outside
    dim = msp.add_diameter_dim(center=(0, 0), radius=3, angle=45, dimstyle='EZ_RADIUS')
    dim.render()
    doc.saveas('diameter_dimension.dxf')

The example above creates a 45 degrees slanted diameter :class:`~ezdxf.entities.Dimension` entity, the default dimension
style ``'EZ_RADIUS'`` (same as for radius dimensions) is defined as 1 drawing unit is 1m in reality, drawing scale 1:100
and the length factor is 100, which creates a measurement text in cm, the default location for the measurement text is
outside of the circle.

The `center` point defines the the center of the circle but there doesn't have to exist a circle entity, `radius`
defines the circle radius and `angle` defines the slope of the dimension line, it is also possible to define the
circle by a measurement point `mpoint` on the circle.

The return value `dim` is **not** a dimension entity, instead a :class:`~ezdxf.entities.DimStyleOverride` object is
returned, the dimension entity is stored as `dim.dimension`.

Placing Measurement Text
------------------------

There are different predefined DIMSTYLES to achieve various text placing locations.

DIMSTYLE ``'EZ_RADIUS'`` settings are: 1 drawing unit is 1m, scale 1:100, length_factor is 100 which creates
measurement text in cm, and a closed filled arrow with size 0.25 is used.

.. note::

    Not all possibles features of DIMSTYLE are supported and especially for diameter dimension there are less
    features supported as for linear dimension because of the lack of good documentation.

.. seealso::

    - Graphical reference of many DIMVARS and some advanced information: :ref:`dimstyle_table_internals`
    - Source code file `standards.py`_ shows how to create your own DIMSTYLES.
    - `dimension_diameter.py`_ for diameter dimension examples.

Default Text Locations Outside
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``'EZ_RADIUS'`` default settings for to place text outside:

=========== ==============================================================================================
tmove       ``1`` to keep dim line with text, this is the best setting for text outside
            to preserve appearance of the DIMENSION entity, if editing afterwards in BricsCAD
            or AutoCAD.
dimtad      ``1`` to place text vertical above the dimension line
=========== ==============================================================================================

.. code-block:: python

    dim = msp.add_diameter_dim(center=(0, 0), radius=2.5, angle=45,
                               dimstyle='EZ_RADIUS')
    dim.render()  # required, but not shown in the following examples

.. image:: gfx/dim_diameter_outside.png

To force text outside horizontal set :attr:`~ezdxf.entities.DimStyle.dxf.dimtoh` to ``1``:

.. code-block:: python

    dim = msp.add_diameter_dim(center=(0, 0), radius=2.5, angle=45,
                              dimstyle='EZ_RADIUS',
                              override={'dimtoh': 1}
                              )
.. image:: gfx/dim_diameter_outside_horiz.png

Default Text Locations Inside
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

DIMSTYLE ``'EZ_RADIUS_INSIDE'`` can be used to place the dimension text inside the circle at a default
location. Default DIMSTYLE settings are: 1 drawing unit is 1m, scale 1:100, length_factor is 100 which creates
measurement text in cm, and a closed filled arrow with size 0.25 is used.

``'EZ_RADIUS_INSIDE'`` default settings:

=========== ==============================================================================================
tmove       ``0`` to keep dim line with text, this is the best setting for text inside
            to preserve appearance of the DIMENSION entity, if editing afterwards in BricsCAD
            or AutoCAD.
dimtix      ``1`` to force text inside
dimatfit    ``0`` to force text inside, required by BricsCAD and AutoCAD
dimtad      ``0`` to center text vertical, BricsCAD and AutoCAD always create vertical centered text,
            `ezdxf` let you choose the vertical placement (above, below, center), but editing the
            DIMENSION in BricsCAD or AutoCAD will reset text to center placement.
=========== ==============================================================================================

.. code-block:: python

    dim = msp.add_diameter_dim(center=(0, 0), radius=2.5, angle=45,
                               dimstyle='EZ_RADIUS_INSIDE'
                               )

.. image:: gfx/dim_diameter_inside.png

To force text inside horizontal set :attr:`~ezdxf.entities.DimStyle.dxf.dimtih` to ``1``:

.. code-block:: python

    dim = msp.add_diameter_dim(center=(0, 0), radius=2.5, angle=45,
                               dimstyle='EZ_RADIUS_INSIDE',
                               override={'dimtih': 1}
                               )

.. image:: gfx/dim_diameter_inside_horiz.png
    :align: center


User Defined Text Locations
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Beside the default location it is always possible to override the text location by a user defined location. This
location also determines the angle of the dimension line and overrides the argument `angle`. For user defined locations
it is not necessary to force text inside (``dimtix=1``), because the location of the text is explicit given,
therefore the DIMSTYLE ``'EZ_RADIUS'`` can be used for all this examples.

User defined location outside of the circle:

.. code-block:: python

    dim = msp.add_diameter_dim(center=(0, 0), radius=2.5, location=(4, 4),
                               dimstyle='EZ_RADIUS'
                              )

.. image:: gfx/dim_diameter_user_outside.png

User defined location outside of the circle and forced horizontal text:

.. code-block:: python

    dim = msp.add_diameter_dim(center=(0, 0), radius=2.5, location=(4, 4),
                               dimstyle='EZ_RADIUS',
                               override={'dimtoh': 1}
                              )

.. image:: gfx/dim_diameter_user_outside_horiz.png

User defined location inside of the circle:

.. code-block:: python

    dim = msp.add_diameter_dim(center=(0, 0), radius=2.5, location=(1, 1),
                               dimstyle='EZ_RADIUS'
                              )

.. image:: gfx/dim_diameter_user_inside.png

User defined location inside of the circle and forced horizontal text:

.. code-block:: python

    dim = msp.add_diameter_dim(center=(0, 0), radius=2.5, location=(1, 1),
                               dimstyle='EZ_RADIUS',
                               override={'dimtih': 1},
                               )

.. image:: gfx/dim_diameter_user_inside_horiz.png

Center Mark/Lines
-----------------

See Radius Dimension Tutorial: :ref:`tut_center_mark`

Overriding Measurement Text
---------------------------

See Linear Dimension Tutorial: :ref:`tut_overriding_measurement_text`

Measurement Text Formatting and Styling
---------------------------------------

See Linear Dimension Tutorial: :ref:`tut_measurement_text_formatting_and_styling`


.. _dimension_diameter.py:  https://github.com/mozman/ezdxf/blob/master/examples/render/dimension_diameter.py
.. _standards.py: https://github.com/mozman/ezdxf/blob/master/src/ezdxf/tools/standards.py