[Rebased] [x11-backend] Retrieve DPI from Xft.dpi XResource (rust-windowing#824)

* [x11-backend] Retrieve DPI from Xft.dpi XResource

* Update CHANGELOG.md

* Update window.rs

* Update CHANGELOG.md

Author: mitchmindtree

CHANGELOG.md

@@ -41,6 +41,7 @@
 - On Windows, fix `CursorMoved(0, 0)` getting dispatched on window focus.
 - On macOS, fix command key event left and right reverse.
 - On FreeBSD, NetBSD, and OpenBSD, fix build of X11 backend.
+- On X11, change DPI scaling factor behavior. First, winit tries to read it from "Xft.dpi" XResource, and uses DPI calculation from xrandr dimensions as fallback behavior.
 
 # Version 0.19.0 (2019-03-06)
 

src/window.rs

@@ -477,7 +477,7 @@ impl Window {
     ///
     /// ## Platform-specific
     ///
-    /// - **X11:** Can be overridden using the `WINIT_HIDPI_FACTOR` environment variable.
+    /// - **X11:** This respects Xft.dpi, and can be overridden using the `WINIT_HIDPI_FACTOR` environment variable.
     /// - **Android:** Always returns 1.0.
     #[inline]
     pub fn get_hidpi_factor(&self) -> f64 {