Incorrect scaling of icons in SwitcherRendering on New UI

[AB-xdev]

This problem affects all our plugins.

First discovered in xdev-software/intellij-plugin-openrewriter#19 (complete description)
Tracked upstream by https://youtrack.jetbrains.com/issue/IDEA-354465

Short summary

Steps to reproduce

1. Install a plugin such as OpenRewriter X
2. Enable the "New UI"
3. Open the "Switcher" (Ctrl + Tab) or "Recent Files" (Ctrl + E)

Expected result (correct result):

icon is rendered way to large

Actual result (faulty result):

icon is rendered with expected size, like it was in 2023.2:

Additional information

There seems to be a problem with how the icon scaling is applied inside https://github.com/JetBrains/intellij-community/blob/def6433a5dd9f0a984cbc6e2835d27c97f2cb5f0/platform/platform-impl/src/com/intellij/ide/actions/SwitcherRendering.kt#L113-L119

New versions of IDEA (some time after 2023.2) use CachedImageIcon while 2023.2 used ToolWindowIcon for window.icon.

The scaling of CachedImageIcon seems to be applied incorrectly in this context apparently using the following scheme:

16 (reference width)/13 (incorrect detected width of CachedImageIcon) * 512 (actual width of icon), which results in 630 instead of the expected 16

Applied Counter-Measures/Workarounds

• Fix pluginIcon to a size of 16 so that broken scaling is not invoked
  • like this: <svg width="16" height="16" viewBox="0 0 40 40" style="fill:none" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
• Release new version of plugins ASAP as IDEA 2024.2 will enable "New UI" by default