How to modify children of `svg::Document`?

[OrangeTux]

I've an SVG file and want to modify it. Among other things, I'd like to do is adding a "id" attribute to certain tags.

My approach is to read the file and create an svg::Parser. Iterate over the parser to create an svg::Document. I'll pass this svg::Document around to functions that modify it. But that doesn't work.

Consider the following code:

let document = svg::Document::new()
    .set("viewBox", (0, 0, 70, 70))

let element: Element = document.get_inner()
for child in element.get_children() {
    child.assign("id", 3);
}

That fails to compile with:

error: the `assign` method cannot be invoked on a trait object
  --> src/bin/optimize.rs:85:15
   |
85 |         child.assign("id", 3);
   |               ^^^^^^
   |
  ::: /home/user/.cargo/registry/src/github.com-1ecc6299db9ec823/svg-0.10.0/src/node/mod.rs:34:15
   |
34 |         Self: Sized,
   |               ----- this has a `Sized` requirement

Even if this would work, how would I know whether the child is a 'line', 'path' or any other tag is?

[IvanUkhov]

Hello, the interface is not designed for modification. But perhaps this is not what you actually want. The example shows that you are trying to construct something from scratch. In such a case, just create each child separately and then append to the parent.

[OrangeTux]

Thanks for the answer @IvanUkhov .

The example shows that you are trying to construct something from scratch. In such a case, just create each child separately and then append to the parent.

My example is reduction of a bigger problem. I want to write a tool that takes an existing SVG and modifies it to make it friendlier to be 'consumed' by a pen plotter.

I read the file using an svg::Parser and turn it into an svg::Document. My idea is to pass this svg::Document down to several functions that modify the svg::Document. Than I'd like to write the modified SVG to disk. But that doesn't seem to be possible as you write:

the interface is not designed for modification.

Thanks for the answer!

[IvanUkhov]

I see. Then indeed it would be difficult to achieve with this crate, unless one is willing to change the approach, such as to parse and augment at the same time. Sorry. I close this one then.