DIMENSION Text cannot be saved after modification.

[xbdr419]

my code:

import ezdxf
f = 'Before Modification.dxf'
doc = ezdxf.readfile(f)
msp =doc.modelspace()
for e in msp:
if e.dxftype() in ("DIMENSION", "ARC_DIMENSION", "LARGE_RADIAL_DIMENSION"):
e.dxf.text = '6666'
doc.saveas('Modification After.dxf')
————————————————
Hello，I want to modify DIMENSION’s text，when I open new file in autoCAD，The texts is still Before Modification。
As shown below， only one , at bottom left corner is changed.

Modification Before

Modification After

files:
dxf.zip

[mozman]

The DIMENSION entity doesn't work that way! I don't know where to start to explain the problem and I don't have the time now. I will come back in a few days to give more information about this topic.

[mozman]

The DIMENSION entity is very complex and requires an additional anonymous BLOCK that contains the rendering of the dimension as simple DXF entities like LINE, MTEXT and INSERT entities.

The content of that block is what a CAD application displays.

This is the reason why editing the attributes of an exiting DIMENSION entity is not applied immediately.

import ezdxf
from ezdxf.document import Drawing

def update_block(doc: Drawing, block_name: str, value: str):
    block = doc.blocks.get(block_name)
    if block is None:
        return
    mtext = block.query("MTEXT").first
    if mtext is not None:
        mtext.dxf.text = value

def main():
    doc = ezdxf.readfile("dim.dxf")  # see attached zip-file
    msp = doc.modelspace()

    # Just modifying the text doesn't anything
    dim_linear = msp.query("DIMENSION").first
    assert dim_linear is not None
    dim_linear.dxf.text = "200"
    dim_arc = msp.query("ARC_DIMENSION").first
    assert dim_arc is not None
    dim_arc.dxf.text = "90"
    doc.saveas("dim0.dxf")

    # Edit the MTEXT content of the associated BLOCK
    update_block(doc, dim_linear.dxf.geometry, "200")
    update_block(doc, dim_arc.dxf.geometry, "90")

    doc.saveas("dim1.dxf")

if __name__ == '__main__':
    main()

Original dim0.dxf

As soon as you change the dimension in the CAD application, the rendering will be updated and the manual set text is applied.

DIMENSION entity modified by CAD application

You can edit the MTEXT entity in the associated BLOCK.
The name of the BLOCK is stored in the DXF attribute geometry.

Updated MTEXT entity in dim1.dxf

dim.zip

[xbdr419]

Aha！原来如此，Thanks a million!

[xbdr419]

I hava a new questhion, I add some text in DIMENSION . For example ,when I add text "test" in autoCAD, the data shown 'test <>'

I try update it , but it can't Normal display

update_block(doc, dim_linear.dxf.geometry, "200 <>")
update_block(doc, dim_arc.dxf.geometry, "90 <>")

I'm not sure if there's a way to do this，let it Normal display in autoCAD