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Usage for Beginners

This section shows the intended usage of the ezdxf package. This is just a brief overview for new ezdxf users, follow the provided links for more detailed information.

First import the package:

import ezdxf

Loading DXF Files

ezdxf supports loading ASCII and binary DXF documents from a file:

doc = ezdxf.readfile(filename)

or from a zip-file:

doc = ezdxf.readzip(zipfilename[, filename])

Which loads the DXF document filename from the zip-file zipfilename or the first DXF file in the zip-file if filename is absent.

It is also possible to read a DXF document from a stream by the :func:`ezdxf.read` function, but this is a more advanced feature, because this requires detection of the file encoding in advance.

This works well with DXF documents from trusted sources like AutoCAD or BricsCAD. For loading DXF documents with minor or major flaws use the :mod:`ezdxf.recover` module.

.. seealso::

    Documentation for :func:`ezdxf.readfile`, :func:`ezdxf.readzip` and
    :func:`ezdxf.read`, for more information about file
    management go to the :ref:`dwgmanagement` section. For loading DXF documents
    with structural errors look at the :mod:`ezdxf.recover` module.

Layouts and Blocks

Layouts are containers for DXF entities like LINE or CIRCLE. The most important layout is the modelspace labeled as "Model" in CAD applications which represents the "world" work space. Paperspace layouts represents plottable sheets which contains often the framing and the tile block of a drawing and VIEWPORT entities as scaled and clipped "windows" into the modelspace.

The modelspace is always present and can not be deleted. The active paperspace is also always present in a new DXF document but can be deleted, in that case another paperspace layout gets the new active paperspace, but you can not delete the last paperspace layout.

Getting the modelspace of a DXF document:

msp = doc.modelspace()

Getting a paperspace layout by the name as shown in the tab of a CAD application:

psp = doc.paperspace("Layout1")

A block is just another kind of entity space, which can be inserted multiple times into other layouts and blocks by the INSERT entity also called block references, this is a very powerful and an important concept of the DXF format.

Getting a block layout by the block name:

blk = doc.blocks.get("NAME")

All these layouts have factory functions to create graphical DXF entities for their entity space, for more information about creating entities see section: Create new DXF Entities

Query DXF Entities

As said in the Layouts and Blocks section, all graphical DXF entities are stored in layouts, all these layouts can be iterated and do support the index operator e.g. layout[-1] returns the last entity.

The main difference between iteration and index access is, that iteration filters destroyed entities, but the index operator returns also destroyed entities until these entities are purged by layout.purge(), more about this topic in section: Delete Entities.

There are two advanced query methods: :meth:`~ezdxf.layouts.BaseLayout.query` and :meth:`~ezdxf.layouts.BaseLayout.groupby`.

Get all lines of layer "MyLayer":

lines = msp.query('LINE[layer=="MyLayer"]')

This returns an :class:`~ezdxf.query.EntityQuery` container, which also provides the same :meth:`query` and :meth:`groupby` methods.

Get all lines categorized by a DXF attribute like color:

all_lines_by_color = msp.query("LINE").groupby("color")
lines_with_color_1 = all_lines_by_color.get(1, [])

The :meth:`groupby` method returns a regular Python :class:`dict` with colors as key and a regular Python :class:`list` of entities as values (not an :class:`~ezdxf.query.EntityQuery` container).

.. seealso::

    For more information go to the :ref:`tut_getting_data`

Examine DXF Entities

Each DXF entity has a :attr:`dxf` namespace attribute, which stores the named DXF attributes, some entity attributes and assets are only available from Python properties or methods outside the :attr:`dxf` namespace like the vertices of the LWPOLYLINE entity. More information about the DXF attributes of each entity can found in the documentation of the :mod:`ezdxf.entities` module.

Get some basic DXF attributes:

layer = entity.dxf.layer  # default is "0"
color = entity.dxf.color  # default is 256 = BYLAYER

Most DXF attributes have a default value, which will be returned if the DXF attribute is not present, for DXF attributes without a default value you can check if the attribute really exist:

entity.dxf.hasattr("true_color")

or use the :meth:`get` method and provide a default value:

entity.dxf.get("true_color", 0)

.. seealso::

    - :ref:`Common graphical DXF attributes`
    - Helper class :class:`ezdxf.gfxattribs.GfxAttribs` for building DXF attribute
      dictionaries.

Create a New DXF File

Create new document for the latest supported DXF version:

doc = ezdxf.new()

Create a new DXF document for a specific DXF version, e.g. for DXF R12:

doc = ezdxf.new("R12")

The :func:`ezdxf.new` function can create some standard resources, such as linetypes and text styles, by setting the argument setup to True:

doc = ezdxf.new(setup=True)

.. seealso::

    - :ref:`tut_simple_drawings`
    - Documentation for :func:`ezdxf.new`, for more information about file
      management go to the :ref:`dwgmanagement` section.

Create New DXF Entities

The factory methods for creating new graphical DXF entities are located in the :class:`~ezdxf.layouts.BaseLayout` class and these factory methods are available for all entity containers:

The usage is simple:

msp = doc.modelspace()
msp.add_line((0, 0), (1, 0), dxfattribs={"layer": "MyLayer"})

A few important/required DXF attributes are explicit method arguments, most additional DXF attributes are gives as a regular Python :class:`dict` object by the keyword only argument :attr:`dxfattribs`. The supported DXF attributes can be found in the documentation of the :mod:`ezdxf.entities` module.

Warning

Do not instantiate DXF entities by yourself and add them to layouts, always use the provided factory methods to create new graphical entities, this is the intended way to use ezdxf.

.. seealso::

    - :ref:`thematic_factory_method_index`
    - :ref:`tut_simple_drawings`
    - :ref:`tut_dxf_primitives`
    - :ref:`tut_lwpolyline`
    - :ref:`tut_text`
    - :ref:`tut_mtext`
    - :ref:`tut_hatch`

Saving DXF Files

Save the DXF document with a new name:

doc.saveas("new_name.dxf")

or with the same name as loaded:

doc.save()

.. seealso::

    Documentation for :func:`ezdxf.document.Drawing.save` and
    :func:`ezdxf.document.Drawing.saveas`, for more information about file
    management go to the :ref:`dwgmanagement` section.

Create New Blocks

The block definitions of a DXF document are managed by the :class:`~ezdxf.sections.blocks.BlocksSection` object:

my_block = doc.blocks.new("MyBlock")

.. seealso::

    :ref:`tut_blocks`

Create Block References

A block reference is just another DXF entity called INSERT. The :class:`~ezdxf.entities.Insert` entity is created by the factory method: :meth:`~ezdxf.layouts.BaseLayout.add_blockref`:

msp.add_blockref("MyBlock", (0, 0))

.. seealso::

    See :ref:`tut_blocks` for more advanced features like using
    :class:`~ezdxf.entities.Attrib` entities.

Create New Layers

A layer is not an entity container, a layer is just another DXF attribute stored in the entity and the entity can inherit some properties from this :class:`~ezdxf.entities.Layer` object. Layer objects are stored in the layer table which is available as attribute doc.layers.

You can create your own layers:

my_layer = doc.layers.add("MyLayer")

The layer object also controls the visibility of entities which references this layer, the on/off state of the layer is unfortunately stored as positive or negative color value which make the raw DXF attribute of layers useless, to change the color of a layer use the property :attr:`Layer.color`

my_layer.color = 1

To change the state of a layer use the provided methods of the :class:`~ezdxf.entities.Layer` object, like :meth:`~ezdxf.entities.Layer.on`, :meth:`~ezdxf.entities.Layer.off`, :meth:`~ezdxf.entities.Layer.freeze` or :meth:`~ezdxf.entities.Layer.thaw`:

my_layer.off()

.. seealso::

    :ref:`layer_concept`

Delete Entities

The safest way to delete entities is to delete the entity from the layout containing that entity:

line = msp.add_line((0, 0), (1, 0))
msp.delete_entity(line)

This removes the entity immediately from the layout and destroys the entity. The property :attr:`~ezdxf.entities.DXFEntity.is_alive` returns False for a destroyed entity and all Python attributes are deleted, so line.dxf.color will raise an :class:`AttributeError` exception, because line does not have a :attr:`~ezdxf.entities.DXFEntity.dxf` attribute anymore.

Ezdxf also supports manually destruction of entities by calling the method :meth:`~ezdxf.entities.DXFEntity.destroy`:

line.destroy()

Manually destroyed entities are not removed immediately from entities containers like :class:`Modelspace` or :class:`EntityQuery`, but iterating such a container will filter destroyed entities automatically, so a for e in msp: ... loop will never yield destroyed entities. The index operator and the :func:`len` function do not filter deleted entities, to avoid getting deleted entities call the :func:`purge` method of the container manually to remove deleted entities.

Further Information