Handle null values from GetKeyName

Author: jayschwa

examples/callbacks.jl

@@ -1,6 +1,6 @@
 import GLFW
 
-window = GLFW.CreateWindow(800, 600, "GLFW Callback Test")
+window = GLFW.CreateWindow(640, 480, "GLFW Callback Test")
 GLFW.MakeContextCurrent(window)
 
 # Window callbacks
@@ -17,12 +17,8 @@ actiontext = Dict(
 	GLFW.REPEAT  => "repeats"
 )
 GLFW.SetKeyCallback(window, (_, key, scancode, action, mods) -> begin
-	char = convert(Char, key)
-	if '!' <= char && char <= '~'
-		println("key '$char' ", actiontext[action])
-	else
-		println("key $key ", actiontext[action])
-	end
+	name = get(GLFW.GetKeyName(key, scancode), "$key")
+	println("key $name ", actiontext[action])
 end)
 
 GLFW.SetCharModsCallback(window, (_, c, mods) -> println("char: $c, mods: $mods"))

src/glfw3.jl

@@ -415,7 +415,16 @@ end
 
 SetInputMode(window::Window, mode::Integer, value::Integer) = ccall( (:glfwSetInputMode, lib), Void, (WindowHandle, Cint, Cint), window, mode, value)
 GetKey(window::Window, key::Integer) = Bool(ccall( (:glfwGetKey, lib), Cint, (WindowHandle, Cint), window, key))
-GetKeyName(key::Integer, scancode::Integer) = unsafe_string(ccall( (:glfwGetKeyName, lib), Cstring, (Cint, Cint), key, scancode))
+
+function GetKeyName(key::Integer, scancode::Integer)
+	ptr = ccall( (:glfwGetKeyName, lib), Cstring, (Cint, Cint), key, scancode)
+	if ptr == C_NULL
+		Nullable{String}()
+	else
+		Nullable(unsafe_string(ptr))
+	end
+end
+
 GetMouseButton(window::Window, button::Integer) = Bool(ccall( (:glfwGetMouseButton, lib), Cint, (WindowHandle, Cint), window, button))
 
 function GetCursorPos(window::Window)