From d6aa3a67a0fba50869e9b65b5fb6e171e43e5d1b Mon Sep 17 00:00:00 2001
From: ManoloFLTK <41016272+ManoloFLTK@users.noreply.github.com>
Date: Sun, 9 Feb 2020 07:52:20 +0100
Subject: Add screen scaling support to Fl_Cairo_Window under X11 platform.

---
 cairo/Fl_Cairo.cxx | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

(limited to 'cairo')

diff --git a/cairo/Fl_Cairo.cxx b/cairo/Fl_Cairo.cxx
index 41a4e4b6d..de70d33df 100644
--- a/cairo/Fl_Cairo.cxx
+++ b/cairo/Fl_Cairo.cxx
@@ -84,11 +84,20 @@ cairo_t * Fl::cairo_make_current(Fl_Window* wi) {
 
     cairo_state_.window(wi);
 
+  cairo_t * cairo_ctxt;
+#ifndef __APPLE__
+  float scale = Fl::screen_scale(wi->screen_num()); // get the screen scaling factor
+#endif
 #if defined(USE_X11)
-    return Fl::cairo_make_current(0, wi->w(), wi->h());
+  cairo_ctxt = Fl::cairo_make_current(0, wi->w() * scale, wi->h() * scale);
 #else
-    return Fl::cairo_make_current(fl_gc, wi->w(), wi->h());
+  // on macOS, scaling is done before by Fl_Window::make_current(), on Windows, the size is not used
+  cairo_ctxt = Fl::cairo_make_current(fl_gc, wi->w(), wi->h());
+#endif
+#ifndef __APPLE__
+  cairo_scale(cairo_ctxt, scale, scale);
 #endif
+  return cairo_ctxt;
 }
 
 /* 
-- 
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