From 7e1c70964d54b2bdc33aad316b310570ede1fdcc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Robert=20G=C3=BCnzler?= <r@gnzler.io>
Date: Mon, 22 Jan 2018 18:07:51 +0000
Subject: [PATCH] [macOS] Move the window if there is no title bar (#382)

* macOS: Move the window if there is no title bar

On macOS by default windows can only be moved by clicking and
dragging on the titlebar, if we spawn a window without one we
need to set the `movableByWindowBackground` property.

Partial fix for #368

* macOS: Make moveByWindowBackground optional

Implements setting the property via WindowBuilderExt:

    WindowBuilder::new()
        .with_decorations(false)
        .with_movable_by_window_background(true)

* Update CHANGELOG
---
 CHANGELOG.md                 |  1 +
 src/os/macos.rs              |  8 ++++++++
 src/platform/macos/window.rs | 12 ++++++++++--
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 734814eb..0b7282bc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,6 @@
 # Unreleased
 
+- Added method `os::macos::WindowBuilderExt::with_movable_by_window_background(bool)` that allows to move a window without a titlebar - `with_decorations(false)`
 - Implement `Window::set_fullscreen`, `Window::set_maximized` and `Window::set_decorations` for Wayland.
 
 # Version 0.10.0 (2017-12-27)
diff --git a/src/os/macos.rs b/src/os/macos.rs
index b3cd0289..5a6ef1bb 100755
--- a/src/os/macos.rs
+++ b/src/os/macos.rs
@@ -63,6 +63,7 @@ impl From<ActivationPolicy> for NSApplicationActivationPolicy {
 /// Additional methods on `WindowBuilder` that are specific to MacOS.
 pub trait WindowBuilderExt {
     fn with_activation_policy(self, activation_policy: ActivationPolicy) -> WindowBuilder;
+    fn with_movable_by_window_background(self, movable_by_window_background: bool) -> WindowBuilder;
 }
 
 impl WindowBuilderExt for WindowBuilder {
@@ -72,6 +73,13 @@ impl WindowBuilderExt for WindowBuilder {
         self.platform_specific.activation_policy = activation_policy;
         self
     }
+
+    /// Enables click-and-drag behavior for the entire window, not just the titlebar
+    #[inline]
+    fn with_movable_by_window_background(mut self, movable_by_window_background: bool) -> WindowBuilder {
+        self.platform_specific.movable_by_window_background = movable_by_window_background;
+        self
+    }
 }
 
 /// Additional methods on `MonitorId` that are specific to MacOS.
diff --git a/src/platform/macos/window.rs b/src/platform/macos/window.rs
index 1eb41235..8c1e5842 100644
--- a/src/platform/macos/window.rs
+++ b/src/platform/macos/window.rs
@@ -254,6 +254,7 @@ impl Drop for WindowDelegate {
 #[derive(Clone, Default)]
 pub struct PlatformSpecificWindowBuilderAttributes {
     pub activation_policy: ActivationPolicy,
+    pub movable_by_window_background: bool,
 }
 
 pub struct Window2 {
@@ -312,7 +313,7 @@ impl Window2 {
             None      => { return Err(OsError(format!("Couldn't create NSApplication"))); },
         };
 
-        let window = match Window2::create_window(win_attribs)
+        let window = match Window2::create_window(win_attribs, pl_attribs)
         {
             Some(window) => window,
             None         => { return Err(OsError(format!("Couldn't create NSWindow"))); },
@@ -381,7 +382,10 @@ impl Window2 {
         }
     }
 
-    fn create_window(attrs: &WindowAttributes) -> Option<IdRef> {
+    fn create_window(
+        attrs: &WindowAttributes,
+        pl_attrs: &PlatformSpecificWindowBuilderAttributes)
+        -> Option<IdRef> {
         unsafe {
             let screen = match attrs.fullscreen {
                 Some(ref monitor_id) => {
@@ -449,6 +453,10 @@ impl Window2 {
                     window.setTitlebarAppearsTransparent_(YES);
                 }
 
+                if pl_attrs.movable_by_window_background {
+                    window.setMovableByWindowBackground_(YES);
+                }
+
                 if screen.is_some() {
                     window.setLevel_(appkit::NSMainMenuWindowLevel as i64 + 1);
                 }