From 2337214e4e734f7601799aa50b0020c3ff89aede Mon Sep 17 00:00:00 2001
From: ManoloFLTK <41016272+ManoloFLTK@users.noreply.github.com>
Date: Tue, 12 Nov 2024 10:56:19 +0100
Subject: [PATCH]  Fix for Windows and X11: Rounding issues with
 Fl_RGB_Image::draw() (#1120)

---
 FL/Fl_Graphics_Driver.H    | 5 +----
 src/Fl_Graphics_Driver.cxx | 9 +++++++++
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/FL/Fl_Graphics_Driver.H b/FL/Fl_Graphics_Driver.H
index 24246621c..2ac70ba03 100644
--- a/FL/Fl_Graphics_Driver.H
+++ b/FL/Fl_Graphics_Driver.H
@@ -413,10 +413,7 @@ class FL_EXPORT Fl_Scalable_Graphics_Driver : public Fl_Graphics_Driver {
   Fl_Fontsize fontsize_; // scale-independent font size value
 public:
   Fl_Scalable_Graphics_Driver();
-  // This function aims to compute accurately int(x * s) in
-  // presence of rounding errors existing with floating point numbers
-  // and that sometimes differ between 32 and 64 bits.
-  static inline int floor(int x, float s) { return int(x * s + 0.001f); }
+  static int floor(int x, float s);
   inline int floor(int x) { return Fl_Scalable_Graphics_Driver::floor(x, scale()); }
 protected:
   int line_width_;
diff --git a/src/Fl_Graphics_Driver.cxx b/src/Fl_Graphics_Driver.cxx
index 50889bccf..95716530a 100644
--- a/src/Fl_Graphics_Driver.cxx
+++ b/src/Fl_Graphics_Driver.cxx
@@ -759,6 +759,15 @@ void Fl_Scalable_Graphics_Driver::rect(int x, int y, int w, int h)
   }
 }
 
+// This function aims to compute accurately int(x * s) in
+// presence of rounding errors existing with floating point numbers
+// and that sometimes differ between 32 and 64 bits.
+int Fl_Scalable_Graphics_Driver::floor(int x, float s) {
+  if (s == 1) return x;
+  int retval = int(abs(x) * s + 0.001f);
+  return (x >= 0 ? retval : -retval);
+}
+
 void Fl_Scalable_Graphics_Driver::rectf(int x, int y, int w, int h)
 {
   if (w <= 0 || h <= 0) return;