Fix doubled editor scale for embedded plugin UIs under JUCE 9

[Crandall1]

Problem

Built against JUCE 9, CLAP editors open mis-scaled on Windows and X11 at >100% display scaling in hosts that call set_scale() — the UI renders at twice the size of its frame, so only the upper-left quarter is visible. Manually resizing the window heals it. JUCE 8 builds are unaffected, as are macOS (cocoa never receives set_scale()) and 100% displays.

Cause

JUCE 9 changed peer scaling: every peer now derives its scale factor from the window DPI unconditionally (JUCE 8 gated this on isPerMonitorDPIAwareThread()), and an embedded peer reports its parent window's scale. This wrapper still uses the JUCE 8 model — it applies the host's set_scale() as an editor transform and reports transform-inflated bounds — so the scale is applied twice. (JUCE 9's own plugin wrappers moved scaling into the peer via ComponentPeer::setCustomPlatformScaleFactor() / detail::PluginScaleFactorManager.)

Fix

After addToDesktop() in guiWin32Attach() / guiX11Attach(), pin the peer's platform scale to 1.0 with the JUCE 9 setCustomPlatformScaleFactor() API — restoring the contract this wrapper's sizing model assumes — and push the component bounds to the native window. The push matters: the override alone does not resize the window addToDesktop() created at the native scale, and that stale size otherwise flows back into the component on the first window event, leaving the UI mis-scaled until the user resizes it.

Gated on JUCE_VERSION >= 0x090000; JUCE 8 and earlier paths are untouched.

Testing

Verified on Windows (JUCE 9.0.0, display at >100% scaling): the editor now opens at the correct size and interactive resizing stays correct. The X11 path shares the identical mechanism. macOS is untouched (cocoa attach path), and JUCE 8 builds compile the pre-existing code unchanged.

🤖 Generated with Claude Code

[Crandall1]

Tested fix on Linux. Verified there as well.

[baconpaul]

Thanks chris; I’ll merge this and the. Add a ice 9 ci stage/

‘do we need it on juce 8 if Sid-iawsrethingynalso?

[baconpaul]

Sorry that was mangled

I meant do we need a juce 8 branch for is dpi aware thread branch

[Crandall1]

Best I can tell it will (a) work fine with JUCE 8, and (b) is not necessary for JUCE 8. Anyone on 7 or 6 deserves all the trouble they get.

[baconpaul]

Oh and sudara alreaded added juce 9 to ci. So cool I will merge this once we are green. Thanks!