Adds function for fetching ID of a core_graphics::display::CGDisplayMode

This adds a mode_id() function on CGDisplayMode which returns the unique (to that display) integer ID the system uses to identify the display mode. It internally calls down to CGDisplayModeGetIODisplayModeID() in the CoreGraphics framework. The FFI for this function was previously missing and has also been added.

Author: pmj

core-graphics/src/display.rs

@@ -608,6 +608,10 @@ impl CGDisplayMode {
             0
         }
     }
+
+    pub fn mode_id(&self) -> i32 {
+        unsafe { CGDisplayModeGetIODisplayModeID(self.as_ptr()) }
+    }
 }
 
 #[link(name = "CoreGraphics", kind = "framework")]
@@ -686,6 +690,7 @@ extern "C" {
     pub fn CGDisplayModeGetRefreshRate(mode: ::sys::CGDisplayModeRef) -> libc::c_double;
     pub fn CGDisplayModeGetIOFlags(mode: ::sys::CGDisplayModeRef) -> u32;
     pub fn CGDisplayModeCopyPixelEncoding(mode: ::sys::CGDisplayModeRef) -> CFStringRef;
+    pub fn CGDisplayModeGetIODisplayModeID(mode: ::sys::CGDisplayModeRef) -> i32;
 
     pub fn CGDisplayCopyAllDisplayModes(
         display: CGDirectDisplayID,