can not rea dxf file with entity type: "AcDbEntity" .

[yanweitong]

When I used this library to read DXF format files, it worked fine most of the time. But recently when I tried to read some DXF files, I couldn't read the content correctly. When I compared the DXF files, I found that the entity inside was of AcDbEntity type. I didn't find the corresponding one in EntityType. Is this the reason?

[brettfo]

Compatibility with other DXF libraries is an ongoing issue. The AcDbEntity you see isn't causing a problem, though. Properties for an entity are commonly grouped under the C++ class that contains those in the AutoCAD source. For example, a line in a DXF file looks like this:

(note, I've added line comments that aren't valid in the DXF, but help explain what's going on)

0              // lines in a DXF file are read in pairs; the first is a code that says what type follows, in this case 0 means start of entity
LINE
100            // this means we're reading properties common to the base entity class
AcDbEntity
8              // code 8 means a layer name follows
WALLS
100            // this means we're now reading properties specific to the line entity
AcDbLine
10             // code 10 means the X coordinate of a primary point; in this case it's really "P1.X"
0
20             // code 20 means the Y coordinate of a primary point; in this case it's really "P1.Y"
0
30             // code 30 means the Z coordinate of a primary point; in this case it's really "P1.Z"
0
11             // code 11 means the X coordinate of a secondary point; in this case it's really "P2.X"
10
21
10
31
0

I didn't label the last few values, but it should be pretty obvious what they are. This snippet defines a line on layer WALLS with a start point of (0, 0, 0) and an end point of (10, 10, 0).