From 37d2840246af43a7141e2a036820fc3dec468f01 Mon Sep 17 00:00:00 2001
From: vaxerski <vaxry@vaxry.net>
Date: Fri, 22 Dec 2023 19:54:05 +0100
Subject: [PATCH] renderer: reject non-clean scales, find nearest clean

---
 src/helpers/Monitor.hpp |  3 ++-
 src/render/Renderer.cpp | 40 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/src/helpers/Monitor.hpp b/src/helpers/Monitor.hpp
index f44e2c16..2b196c96 100644
--- a/src/helpers/Monitor.hpp
+++ b/src/helpers/Monitor.hpp
@@ -40,7 +40,8 @@ class CMonitor {
 
     uint64_t        ID              = -1;
     int             activeWorkspace = -1;
-    float           scale           = 1;
+    float           setScale        = 1; // scale set by cfg
+    float           scale           = 1; // real scale
 
     std::string     szName        = "";
     std::string     szDescription = "";
diff --git a/src/render/Renderer.cpp b/src/render/Renderer.cpp
index 2397849a..b56c275e 100644
--- a/src/render/Renderer.cpp
+++ b/src/render/Renderer.cpp
@@ -1704,7 +1704,7 @@ bool CHyprRenderer::applyMonitorRule(CMonitor* pMonitor, SMonitorRule* pMonitorR
     // Check if the rule isn't already applied
     // TODO: clean this up lol
     if (!force && DELTALESSTHAN(pMonitor->vecPixelSize.x, pMonitorRule->resolution.x, 1) && DELTALESSTHAN(pMonitor->vecPixelSize.y, pMonitorRule->resolution.y, 1) &&
-        DELTALESSTHAN(pMonitor->refreshRate, pMonitorRule->refreshRate, 1) && pMonitor->scale == pMonitorRule->scale &&
+        DELTALESSTHAN(pMonitor->refreshRate, pMonitorRule->refreshRate, 1) && pMonitor->setScale == pMonitorRule->scale &&
         ((DELTALESSTHAN(pMonitor->vecPosition.x, pMonitorRule->offset.x, 1) && DELTALESSTHAN(pMonitor->vecPosition.y, pMonitorRule->offset.y, 1)) ||
          pMonitorRule->offset == Vector2D(-INT32_MAX, -INT32_MAX)) &&
         pMonitor->transform == pMonitorRule->transform && pMonitorRule->enable10bit == pMonitor->enabled10bit &&
@@ -1726,6 +1726,8 @@ bool CHyprRenderer::applyMonitorRule(CMonitor* pMonitor, SMonitorRule* pMonitorR
         pMonitor->scale = DEFAULTSCALE;
     }
 
+    pMonitor->setScale = pMonitor->scale;
+
     wlr_output_set_transform(pMonitor->output, pMonitorRule->transform);
     pMonitor->transform = pMonitorRule->transform;
 
@@ -1942,6 +1944,42 @@ bool CHyprRenderer::applyMonitorRule(CMonitor* pMonitor, SMonitorRule* pMonitorR
 
     pMonitor->vecPixelSize = pMonitor->vecSize;
 
+    Vector2D logicalSize = pMonitor->vecPixelSize / pMonitor->scale;
+    if (logicalSize.x != std::round(logicalSize.x) || logicalSize.y != std::round(logicalSize.y)) {
+        // invalid scale, will produce fractional pixels.
+        // find the nearest valid.
+
+        float searchScale = std::round(pMonitor->scale * 360.0);
+        bool  found       = false;
+
+        for (size_t i = 0; i < 90; ++i) {
+            double   scaleUp   = (searchScale + i) / 360.0;
+            double   scaleDown = (searchScale - i) / 360.0;
+
+            Vector2D logicalUp   = pMonitor->vecPixelSize / scaleUp;
+            Vector2D logicalDown = pMonitor->vecPixelSize / scaleDown;
+
+            if (logicalUp == logicalUp.round()) {
+                found       = true;
+                searchScale = scaleUp;
+                break;
+            }
+            if (logicalDown == logicalDown.round()) {
+                found       = true;
+                searchScale = scaleDown;
+                break;
+            }
+        }
+
+        if (!found) {
+            Debug::log(ERR, "Invalid scale passed to monitor, {} failed to find a clean divisor", pMonitor->scale);
+            g_pConfigManager->addParseError("Invalid scale passed to monitor " + pMonitor->szName + ", failed to find a clean divisor");
+        } else {
+            Debug::log(WARN, "Invalid scale ({}) passed to monitor, adjusting to {}", pMonitor->scale, searchScale);
+            pMonitor->scale = searchScale;
+        }
+    }
+
     // clang-format off
     static const std::array<std::vector<std::pair<std::string, uint32_t>>, 2> formats{
         std::vector<std::pair<std::string, uint32_t>>{ /* 10-bit */