From 55b136e390411fd4af30a16645df7c232dad131c Mon Sep 17 00:00:00 2001
From: Awused <desuwa@desuwa.net>
Date: Thu, 28 May 2026 05:51:15 -0700
Subject: [PATCH] protocols/fractional-scale: track if scale is known and send
 scales eagerly when known (#14798)

---
 src/protocols/FractionalScale.cpp    | 13 +++++++++----
 src/protocols/FractionalScale.hpp    |  1 +
 src/protocols/LayerShell.cpp         |  5 +++++
 src/protocols/core/Subcompositor.cpp | 11 +++++++++++
 4 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/src/protocols/FractionalScale.cpp b/src/protocols/FractionalScale.cpp
index 9bdf59105..9287407ba 100644
--- a/src/protocols/FractionalScale.cpp
+++ b/src/protocols/FractionalScale.cpp
@@ -1,5 +1,6 @@
 #include "FractionalScale.hpp"
 #include <algorithm>
+#include "Compositor.hpp"
 #include "core/Compositor.hpp"
 
 CFractionalScaleProtocol::CFractionalScaleProtocol(const wl_interface* iface, const int& ver, const std::string& name) : IWaylandProtocol(iface, ver, name) {
@@ -44,11 +45,11 @@ void CFractionalScaleProtocol::onGetFractionalScale(CWpFractionalScaleManagerV1*
     PADDON->m_resource->setOnDestroy([this, PADDON](CWpFractionalScaleV1* self) { this->removeAddon(PADDON); });
     PADDON->m_resource->setDestroy([this, PADDON](CWpFractionalScaleV1* self) { this->removeAddon(PADDON); });
 
-    if (std::ranges::find_if(m_surfaceScales, [surface](const auto& e) { return e.first == surface; }) == m_surfaceScales.end())
-        m_surfaceScales.emplace(surface, 1.F);
-
-    if (surface->m_mapped)
+    // send known scale or default 1.0 if surface is already mapped without a known scale
+    if (hasKnownScale(surface))
         PADDON->setScale(m_surfaceScales.at(surface));
+    else if (surface->m_mapped)
+        PADDON->setScale(1.F);
 
     // clean old
     std::erase_if(m_surfaceScales, [](const auto& e) { return e.first.expired(); });
@@ -60,6 +61,10 @@ void CFractionalScaleProtocol::sendScale(SP<CWLSurfaceResource> surf, const floa
         m_addons[surf]->setScale(scale);
 }
 
+bool CFractionalScaleProtocol::hasKnownScale(SP<CWLSurfaceResource> surf) {
+    return m_surfaceScales.contains(surf);
+}
+
 CFractionalScaleAddon::CFractionalScaleAddon(SP<CWpFractionalScaleV1> resource_, SP<CWLSurfaceResource> surf_) : m_resource(resource_), m_surface(surf_) {
     m_resource->setDestroy([this](CWpFractionalScaleV1* self) { PROTO::fractional->removeAddon(this); });
     m_resource->setOnDestroy([this](CWpFractionalScaleV1* self) { PROTO::fractional->removeAddon(this); });
diff --git a/src/protocols/FractionalScale.hpp b/src/protocols/FractionalScale.hpp
index c4aff560e..0596c2acb 100644
--- a/src/protocols/FractionalScale.hpp
+++ b/src/protocols/FractionalScale.hpp
@@ -41,6 +41,7 @@ class CFractionalScaleProtocol : public IWaylandProtocol {
 
     void         onSurfaceDestroy(SP<CWLSurfaceResource> surf);
     void         sendScale(SP<CWLSurfaceResource> surf, const float& scale);
+    bool         hasKnownScale(SP<CWLSurfaceResource> surf);
 
   private:
     void removeAddon(CFractionalScaleAddon*);
diff --git a/src/protocols/LayerShell.cpp b/src/protocols/LayerShell.cpp
index 802226273..2889bf0cc 100644
--- a/src/protocols/LayerShell.cpp
+++ b/src/protocols/LayerShell.cpp
@@ -249,6 +249,11 @@ void CLayerShellProtocol::onGetLayerSurface(CZwlrLayerShellV1* pMgr, uint32_t id
     SURF->m_role = makeShared<CLayerShellRole>(RESOURCE);
     g_pCompositor->m_layers.emplace_back(Desktop::View::CLayerSurface::create(RESOURCE));
 
+    if (PMONITOR) {
+        g_pCompositor->setPreferredScaleForSurface(SURF, PMONITOR->m_scale);
+        g_pCompositor->setPreferredTransformForSurface(SURF, PMONITOR->m_transform);
+    }
+
     LOGM(Log::DEBUG, "New wlr_layer_surface {:x}", (uintptr_t)RESOURCE.get());
 }
 
diff --git a/src/protocols/core/Subcompositor.cpp b/src/protocols/core/Subcompositor.cpp
index d8a3e8608..33db89d91 100644
--- a/src/protocols/core/Subcompositor.cpp
+++ b/src/protocols/core/Subcompositor.cpp
@@ -1,5 +1,7 @@
 #include "Subcompositor.hpp"
 #include "Compositor.hpp"
+#include "protocols/FractionalScale.hpp"
+#include "../../Compositor.hpp"
 #include <algorithm>
 
 CWLSubsurfaceResource::CWLSubsurfaceResource(SP<CWlSubsurface> resource_, SP<CWLSurfaceResource> surface_, SP<CWLSurfaceResource> parent_) :
@@ -197,6 +199,15 @@ CWLSubcompositorResource::CWLSubcompositorResource(SP<CWlSubcompositor> resource
         SURF->m_role     = makeShared<CSubsurfaceRole>(RESOURCE);
         PARENT->m_subsurfaces.emplace_back(RESOURCE);
 
+        if (PROTO::fractional->hasKnownScale(PARENT)) {
+            const auto PARENTSURFACE = Desktop::View::CWLSurface::fromResource(PARENT);
+
+            if (PARENTSURFACE) {
+                g_pCompositor->setPreferredScaleForSurface(SURF, PARENTSURFACE->m_lastScaleFloat);
+                g_pCompositor->setPreferredTransformForSurface(SURF, PARENTSURFACE->m_lastTransform);
+            }
+        }
+
         LOGM(Log::DEBUG, "New wl_subsurface with id {} at {:x}", id, (uintptr_t)RESOURCE.get());
 
         PARENT->m_events.newSubsurface.emit(RESOURCE);