# \[Windows\] DPI scaling broken in JUCE 8.0.13 for some DAWs (renoise)

**URL:** <https://forum.juce.com/t/windows-dpi-scaling-broken-in-juce-8-0-13-for-some-daws-renoise/68923>\
**Category:** Windows\
**Created:** [June 1, 2026, 2:05am UTC](https://forum.juce.com/t/windows-dpi-scaling-broken-in-juce-8-0-13-for-some-daws-renoise/68923 "2026-06-01T02:05:39Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![emezeske](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.juce.com/emezeske/32/15528_2.png) [@emezeske](https://forum.juce.com/u/emezeske)\
**Post date:** [June 1, 2026, 2:05am UTC](https://forum.juce.com/t/windows-dpi-scaling-broken-in-juce-8-0-13-for-some-daws-renoise/68923/1 "2026-06-01T02:05:39Z")

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PR to fix:

> <https://github.com/juce-framework/JUCE/pull/1664>
>
> \# Fix double-scaled plug-in editors on Windows in hosts that send a redundant co…ntent scale
> 
> \## The problem
> 
> On a high-DPI Windows display the plug-in UI has to be drawn bigger (e.g. 1.25x at 125%). There are \*\*two independent ways\*\* a plug-in can be told to do that:
> 
> 1. \*\*The OS way\*\*: the window is marked per-monitor DPI-aware, and Windows scales it.
> 2. \*\*The host way\*\*: the host calls \`IPlugViewContentScaleSupport::setContentScaleFactor(...)\`.
> 
> Some hosts do \*\*both at once for the same factor\*\*: the window is DPI-aware \*and\* the host also sends a content scale equal to the monitor's DPI. When that happens, if the desktop scaling is e.g. 1.25 JUCE applies the 1.25 twice and the editor renders at ~1.56x.
> 
> I observed this in Renoise, where the plugin window is too large and scaled up too much.
> 
> \## Why it works in most hosts but breaks in Renoise
> 
> Most hosts pick \*\*one\*\* mechanism: per-monitor-aware hosts (Reaper, Cubase, etc.) rely on the OS and send no content scale (or 1.0). \*\*Renoise\*\* (and \*\*Tracktion Waveform\*\*) are DPI-aware \*and\* call \`setContentScaleFactor\` with a factor equal to the monitor DPI, so the same scale is counted twice. It is not a Renoise-specific bug; it is any host that supplies a content scale a DPI-aware window does not need.
> 
> \## Why old JUCE worked and 8.0.13 broke it
> 
> This regressed in \*\*\`fcf1971122\` ("Plugin Client: Change scaling mechanism on Linux/Windows plugins")\*\*, which changed \*how\* the host content scale is applied:
> 
> \- \*\*Before 8.0.13:\*\* the host content scale was applied as a \*\*top-level \`AffineTransform\`\*\* on the editor, independent of the window's OS/peer DPI scaling. The two lived in separate channels and did \*\*not\*\* stack, so a redundant host scale was harmless.
> \- \*\*In 8.0.13:\*\* the host content scale is applied as the window's \*\*platform scale\*\* (\`ComponentPeer::setCustomPlatformScaleFactor\`), and \`convertToHostBounds\` now multiplies by \`desktopScale \* platformScale\`. The host scale and the window's own DPI scaling now occupy the \*\*same channel\*\*, so a host scale that equals the DPI gets multiplied in on top of it, leading to double-scaling.
> 
> \## The fix
> 
> In \`JuceVST3Editor::setContentScaleFactor\`, ignore any content scale that is \*\*at or below the window's own DPI scale\*\* (\`getScaleFactorForWindow\`). The OS already applies that much to a DPI-aware window, so such a factor carries no new information; only a factor that \*\*exceeds\*\* the window's DPI represents extra scaling the host actually wants.
> 
> This is correct in every case:
> 
> \- \*\*DPI-aware window, redundant scale (Renoise / Waveform):\*\* ignored: the OS's single DPI scaling stands.
> \- \*\*DPI-unaware window:\*\* \`getScaleFactorForWindow\` returns 1.0, so a real host scale (\> 1.0) is never mistaken for redundant and is still applied.
> \- \*\*Cubase 10 integer-scale workaround\*\* (the existing block right below): its integer factor never equals the fractional window DPI, so that path is untouched.
> \- \*\*Genuine host zoom beyond the monitor DPI:\*\* a factor greater than the window scale is still honored.
> 
> It restores the pre-8.0.13 result (a single DPI scaling) without reverting the new mechanism, and is a no-op for any host that was not already sending a redundant content scale.

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**Author:** ![fuo](https://avatars.discourse-cdn.com/v4/letter/f/ba8739/32.png) [@fuo](https://forum.juce.com/u/fuo)\
**Post date:** [June 11, 2026, 2:59pm UTC](https://forum.juce.com/t/windows-dpi-scaling-broken-in-juce-8-0-13-for-some-daws-renoise/68923/2 "2026-06-11T14:59:49Z")

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> [@JUCE 8.0.13 released](https://forum.juce.com/t/juce-8-0-13-released/68851/26):
>
> Found an issue introduced with this patch: in PluginDoctor when showing the plugin UI the window is too big for a fraction of a second (eg twice as big when DPI scale is 200%).