Rename hidpi_factor to scale_factor (#1334)

* Rename hidpi_factor to scale_factor

* Deprecate WINIT_HIDPI_FACTOR environment variable in favor of WINIT_X11_SCALE_FACTOR

* Rename HiDpiFactorChanged to DpiChanged and update docs

I'm renaming it to DpiChanged instead of ScaleFactorChanged, since I'd
like Winit to expose the raw DPI value at some point in the near future,
and DpiChanged is a more apt name for that purpose.

* Format

* Fix macos and ios again

* Fix bad macos rebase

src/platform_impl/web/event_loop/window_target.rs

@@ -185,7 +185,7 @@ impl<T> WindowTarget<T> {
                     height: raw.height() as u32,
                 };
 
-                backend::window_size().to_physical(backend::hidpi_factor())
+                backend::window_size().to_physical(backend::scale_factor())
             } else {
                 intended_size
             };

src/platform_impl/web/monitor.rs

@@ -5,7 +5,7 @@ use crate::monitor::{MonitorHandle, VideoMode};
 pub struct Handle;
 
 impl Handle {
-    pub fn hidpi_factor(&self) -> f64 {
+    pub fn scale_factor(&self) -> f64 {
         1.0
     }
 

src/platform_impl/web/stdweb/canvas.rs

@@ -213,7 +213,7 @@ impl Canvas {
         self.on_cursor_move = Some(self.add_event(move |event: PointerMoveEvent| {
             handler(
                 event.pointer_id(),
-                event::mouse_position(&event).to_physical(super::hidpi_factor()),
+                event::mouse_position(&event).to_physical(super::scale_factor()),
                 event::mouse_modifiers(&event),
             );
         }));

src/platform_impl/web/stdweb/mod.rs

@@ -41,7 +41,7 @@ pub fn window_size() -> LogicalSize<f64> {
     LogicalSize { width, height }
 }
 
-pub fn hidpi_factor() -> f64 {
+pub fn scale_factor() -> f64 {
     let window = window();
     window.device_pixel_ratio()
 }
@@ -49,10 +49,10 @@ pub fn hidpi_factor() -> f64 {
 pub fn set_canvas_size(raw: &CanvasElement, size: Size) {
     use stdweb::*;
 
-    let hidpi_factor = hidpi_factor();
+    let scale_factor = scale_factor();
 
-    let physical_size = size.to_physical::<u32>(hidpi_factor);
-    let logical_size = size.to_logical::<f64>(hidpi_factor);
+    let physical_size = size.to_physical::<u32>(scale_factor);
+    let logical_size = size.to_logical::<f64>(scale_factor);
 
     raw.set_width(physical_size.width);
     raw.set_height(physical_size.height);

src/platform_impl/web/web_sys/canvas.rs

@@ -221,7 +221,7 @@ impl Canvas {
         self.on_cursor_move = Some(self.add_event("pointermove", move |event: PointerEvent| {
             handler(
                 event.pointer_id(),
-                event::mouse_position(&event).to_physical(super::hidpi_factor()),
+                event::mouse_position(&event).to_physical(super::scale_factor()),
                 event::mouse_modifiers(&event),
             );
         }));

src/platform_impl/web/web_sys/mod.rs

@@ -56,16 +56,16 @@ pub fn window_size() -> LogicalSize<f64> {
     LogicalSize { width, height }
 }
 
-pub fn hidpi_factor() -> f64 {
+pub fn scale_factor() -> f64 {
     let window = web_sys::window().expect("Failed to obtain window");
     window.device_pixel_ratio()
 }
 
 pub fn set_canvas_size(raw: &HtmlCanvasElement, size: Size) {
-    let hidpi_factor = hidpi_factor();
+    let scale_factor = scale_factor();
 
-    let physical_size = size.to_physical::<u32>(hidpi_factor);
-    let logical_size = size.to_logical::<f64>(hidpi_factor);
+    let physical_size = size.to_physical::<u32>(scale_factor);
+    let logical_size = size.to_logical::<f64>(scale_factor);
 
     raw.set_width(physical_size.width);
     raw.set_height(physical_size.height);

src/platform_impl/web/window.rs

@@ -71,7 +71,7 @@ impl Window {
     }
 
     pub fn outer_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
-        Ok(self.canvas.position().to_physical(self.hidpi_factor()))
+        Ok(self.canvas.position().to_physical(self.scale_factor()))
     }
 
     pub fn inner_position(&self) -> Result<PhysicalPosition<i32>, NotSupportedError> {
@@ -80,7 +80,7 @@ impl Window {
     }
 
     pub fn set_outer_position(&self, position: Position) {
-        let position = position.to_logical::<f64>(self.hidpi_factor());
+        let position = position.to_logical::<f64>(self.scale_factor());
 
         self.canvas.set_attribute("position", "fixed");
         self.canvas.set_attribute("left", &position.x.to_string());
@@ -119,8 +119,8 @@ impl Window {
     }
 
     #[inline]
-    pub fn hidpi_factor(&self) -> f64 {
-        super::backend::hidpi_factor()
+    pub fn scale_factor(&self) -> f64 {
+        super::backend::scale_factor()
     }
 
     #[inline]