incorect dimensions with only one of width or height?

[snoyer]

When parsing an SVG with a viewBox but only one of width or height (without passing dimensions to SVG.parse())
the .width and .heigth of the resulting SVG look incorrect:

<svg viewBox="0 0 4 3" width="40"/> <!-- .width = 40.0 .height = 3.0 -->
<svg viewBox="0 0 4 3" height="30"/> <!-- .width = 4.0 .height = 30.0 -->
<svg viewBox="0 0 4 3" width="4in"/> <!-- .width = 384.0 .height = 3.0 -->
<svg viewBox="0 0 4 3" height="3in"/> <!-- .width = 4.0 .height = 288.0 -->

Shouldn't we be able to use the aspect ratio of the viewbox to deduce the missing dimension?

With this PR we get:

<svg viewBox="0 0 4 3" width="40"/> <!-- .width = 40.0 .height = 30.0 -->
<svg viewBox="0 0 4 3" height="30"/> <!-- .width = 40.0 .height = 30.0 -->
<svg viewBox="0 0 4 3" width="4in"/> <!-- .width = 384.0 .height = 288.0 -->
<svg viewBox="0 0 4 3" height="3in"/> <!-- .width = 384.0 .height = 288.0 -->

Could anyone please confirm:

1. whether my assumption is correct
2. how sound the implementation is as I'm not familiar with the intricacies of the parsing/rendering code

Sample code

from io import StringIO
import svgelements


def test(svg_src: str):
    parsed = svgelements.SVG.parse(StringIO(svg_src))
    print(f"{svg_src} <!-- .width = {parsed.width} .height = {parsed.height} -->")


test('<svg viewBox="0 0 4 3" width="40"/>')
test('<svg viewBox="0 0 4 3" height="30"/>')
test('<svg viewBox="0 0 4 3" width="4in"/>')
test('<svg viewBox="0 0 4 3" height="3in"/>')

Summary by Sourcery

Improves SVG parsing by inferring missing dimensions from the viewBox attribute. When an SVG defines a viewBox and either width or height, the missing dimension is calculated based on the viewBox's aspect ratio. Includes new tests to validate the fix.

Bug Fixes:

• Fixes an issue where the height or width of an SVG was not correctly inferred from the viewBox when only one dimension was specified.

Enhancements:

• Infers the missing dimension of an SVG from the viewBox aspect ratio when only one of width or height is provided.

Tests:

• Adds new tests to verify that the width and height of an SVG are correctly inferred from the viewBox when only one dimension is specified.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request addresses an issue where the width and height of an SVG element were not correctly inferred when only one dimension was specified alongside a viewBox. The implementation calculates the missing dimension using the aspect ratio of the viewBox. New test cases have been added to validate the fix.

No diagrams generated as the changes look simple and do not need a visual representation.

File-Level Changes

Change	Details	Files
Implemented logic to deduce missing width or height based on the viewBox aspect ratio when only one dimension is specified.	Added a condition to check if only one of width or height is present and a viewbox exists. Calculates the missing dimension using the aspect ratio derived from the viewBox. Assigns the calculated dimension to the SVG object.	svgelements/svgelements.py
Added new test cases to verify the correct calculation of missing dimensions based on the viewBox.	Created test functions for scenarios where either width or height is missing. Asserts that the calculated width and height match the expected values based on the viewBox aspect ratio.	test/test_viewbox.py

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[sourcery-ai]

Hey @snoyer - I've reviewed your changes - here's some feedback:

Overall Comments:

• The new tests are good, but could you add a test case that uses percentage units for width/height?

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

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