[gnome-shell/gnome-3-10] layout: Set high dpi scaling factor

[Adel Gadllah <agadllah src gnome org>]

commit 470889f1c303f96493c218949a52756910b5a53c
Author: Adel Gadllah <adel gadllah gmail com>
Date:   Wed Feb 12 17:40:01 2014 +0100

    layout: Set high dpi scaling factor
    
    Set the scaling factor when the dpi is above the hidpi threshold.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=705410

 js/ui/layout.js |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)
---
diff --git a/js/ui/layout.js b/js/ui/layout.js
index 17073a6..ab03f51 100644
--- a/js/ui/layout.js
+++ b/js/ui/layout.js
@@ -31,6 +31,9 @@ const MESSAGE_TRAY_PRESSURE_TIMEOUT = 1000; // ms
 const HOT_CORNER_PRESSURE_THRESHOLD = 100; // pixels
 const HOT_CORNER_PRESSURE_TIMEOUT = 1000; // ms
 
+// We scale up when the dpi is higher then this (same value used by gsd)
+const HIGH_DPI_LIMIT = 192;
+
 function isPopupMetaWindow(actor) {
     switch(actor.meta_window.get_window_type()) {
     case Meta.WindowType.DROPDOWN_MENU:
@@ -484,8 +487,19 @@ const LayoutManager = new Lang.Class({
         return false;
     },
 
+    _updateScaling: function() {
+        let primary = this.monitors[this.primaryIndex];
+        let dpi_x = primary.width / (global.gdk_screen.get_monitor_width_mm(this.primaryIndex) / 25.4);
+        let dpi_y = primary.height / (global.gdk_screen.get_monitor_height_mm(this.primaryIndex) / 25.4);
+        if (dpi_x > HIGH_DPI_LIMIT && dpi_y > HIGH_DPI_LIMIT)
+            St.ThemeContext.get_for_stage(global.stage).scale_factor = 2;
+        else
+            St.ThemeContext.get_for_stage(global.stage).scale_factor = 1;
+    },
+
     _monitorsChanged: function() {
         this._updateMonitors();
+        this._updateScaling();
         this._updateBoxes();
         this._updateTrayBarrier();
         this._updateHotCorners();