Drawings and model.py

A drawing, a .dxcdrg file, is a sheet drawn from a part or assembly file: its standard views, dimensions, hole callouts and parts list, the views and annotations of any plugin, and a title block. The window opens one in a tab of its own, and dxcad drawing FILE.dxcdrg --output sheet.pdf writes it as a PDF or a DXF. Every time a drawing is drawn it is drawn from its model as the model is now, so a drawing follows every change to the part.

A drawing of an assembly may hold a sheet for each of its parts as well: Drawing > Add Part Sheets... lists the parts and sub-assemblies with a tick box each, and every one ticked gets a sheet of its own, drawn alone in the sheet's four views, its name, part number and material in the title block. The sheets are tabs along the bottom of the drawing and are kept in its file, under "sheets"; dxcad drawing and Export Drawing write one sheet, the drawing's own from the command line and the one in front from the window.

This page is for a plugin that extends drawings, and for a model that uses what such a plugin adds.

Drawing functions

A plugin may add functions to the model language that work on a drawing:

def label(drawing, part, words):
    """Put a note with `words` on `part` in the front view."""
    notes = drawing.annotations("myplugin")
    notes.append(
        {"kind": "myplugin.note", "view": "front", "ref": {"part": part},
         "data": {"text": words}}
    )
    drawing.set_annotations("myplugin", notes)


def register(registry):
    registry.drawing_function("label", label)

A model.py then calls label("plate", "DEBURR ALL EDGES") after the parts, as it calls any other name of the model language. When the model is run for its parts, by Run Script, dxcad run or the agent door, the call does nothing. When a drawing of the model is drawn, on screen or for an export, the model is run once more for the drawing, and each drawing function it called is called with the drawing being drawn, label(drawing, "plate", "DEBURR ALL EDGES"), in the order the model called them. What they add is drawn on the sheet each time the drawing is drawn; it is the model's, so the drawing file itself is not changed by it.

A model that fails when it is run for the drawing, and a drawing function that raises, are said among the sheet's warnings, on the window's status bar and on dxcad drawing's stderr; the rest of the sheet is drawn as usual.

The drawing a plugin is handed

A drawing function, and a plugin's MCP tool registered with drawing=True, are handed the drawing as an object with three calls:

Call	What it does
drawing.annotations(plugin)	The plugin's annotation records on the drawing, each {"kind", "view", "ref", "data"}, as copies.
drawing.set_annotations(plugin, records)	Puts records in place of the plugin's annotations. In the window this is one undo step.
drawing.scale(view)	A view's scale as drawn over true, 0.5 for 1 : 2: a standard view by name ("front", "top", "right", "iso"), or a plugin's view as (plugin, index). None for a view the drawing has not got.

A tool registered with registry.tool(..., drawing=True) is called as call(document, arguments, drawing). Called from the window, over dxcad serve --window, it is handed the drawing tab in front, and what it changes is one undo step with the rest of the call. It may also be called with a "drawing" argument naming a .dxcdrg file, from the server's directory like every path a tool is given; it is then handed that file, and set_annotations writes the file again. With neither, the call is answered with an error saying so. The argument is added to the tool's schema for it.

DX-CAD adds no tool or function of its own that suggests dimensions or balloons: it hands plugins the drawing, and what they place there is theirs.

Where the user adds a view

So a message can name the place (item 862): a standard view is added with Drawing > Add View..., or right-click on the sheet > Add View...; a new drawing's first four views come with File > New Drawing; and a plugin's view, such as a detail or a section, with its sheet tool on the right-click menu of the sheet and on the plugin's own menu, the menu bar's menu named after the plugin. Plugins says each in full.