bug(mat-progress-spinner): stroke-width of svg circle not calculated properly for some diameter + strokeWidth values
- Dominant language
- TypeScript
- Stars
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Description
### Is this a regression?
- [ ] Yes, this behavior used to work in the previous version
### The previous version in which this bug was not present was
_No response_
### Description
The `circle` element of the `mat-progress-spinner`'s SVG does not fill up to the whole space of it's container. This only occurs for some combinations of `strokeWidth` and `diameter` inputs and only if the `stokeWidth` is smaller than 10.
E.g. for the values of `diameter=10` and `strokeWidth=5` the circle's `stroke-width` style is calculated to be `20.8333%` which is not filling up to the edge of the SVG container:

If the value of the circle's `stroke-width` is manually set to ~26%, it fits:

### Reproduction
[StackBlitz link](https://stackblitz.com/edit/cxwm1t?file=src%2Fexample%2Fprogress-spinner-configurable-example.html,src%2Fexample%2Fprogress-spinner-configurable-example.html)
Steps to reproduce:
1. Use mat-progress-spinner
2. Set strokeWidth to value < 10
3. Set diameter to e.g. 24
### Expected Behavior
The SVG's `circle` element should fill up the whole space of its container element
### Actual Behavior
The SVG's `circle` element does not fill up the whole space of its container element and leaves some space in between
### Environment
- Angular: 17.0.7
- CDK/Material: 17.0.4
- Browser(s): Chrome
- Operating System (e.g. Windows, macOS, Ubuntu): Ubuntu
Contributor guide
Research direction
Start with the mat-progress-spinner implementation and reproduce the issue using the linked StackBlitz, varying diameter and strokeWidth below 10. Compare the SVG circle's calculated stroke-width with the container bounds for the reported values, then verify that the circle fills its container without leaving a gap.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- angular, typescript
- Domain
- frontend
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100