From 398718a3c80856b49422dc61169fe7b40189ee7d Mon Sep 17 00:00:00 2001
From: Patrick Walton <pcwalton@mimiga.net>
Date: Tue, 12 Feb 2019 12:49:35 -0800
Subject: [PATCH] Allow the rotation slider to be dragged

---
 demo/src/main.rs |  5 +++++
 demo/src/ui.rs   | 14 +++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/demo/src/main.rs b/demo/src/main.rs
index c5b5c68d..b7a21abf 100644
--- a/demo/src/main.rs
+++ b/demo/src/main.rs
@@ -247,6 +247,11 @@ impl DemoApp {
                     self.camera_pitch -= yrel as f32 * MOUSELOOK_ROTATION_SPEED;
                     self.dirty = true;
                 }
+                Event::MouseMotion { x, y, mousestate, .. } if mousestate.left() => {
+                    let point = Point2DI32::new(x, y).scale(self.scale_factor as i32);
+                    ui_event = UIEvent::MouseDragged(point);
+                    self.dirty = true;
+                }
                 Event::KeyDown { keycode: Some(Keycode::W), .. } => {
                     self.camera_velocity.set_z(-CAMERA_VELOCITY);
                     self.dirty = true;
diff --git a/demo/src/ui.rs b/demo/src/ui.rs
index 5cd40997..afbb1075 100644
--- a/demo/src/ui.rs
+++ b/demo/src/ui.rs
@@ -178,7 +178,7 @@ impl DemoUI {
         let (widget_x, widget_y) = (ROTATE_PANEL_X + PADDING, rotate_panel_y + PADDING);
         let widget_rect = RectI32::new(Point2DI32::new(widget_x, widget_y),
                                        Point2DI32::new(SLIDER_WIDTH, SLIDER_KNOB_HEIGHT));
-        if let Some(position) = event.handle_mouse_down_in_rect(widget_rect) {
+        if let Some(position) = event.handle_mouse_down_or_dragged_in_rect(widget_rect) {
             self.rotation = position.x();
         }
 
@@ -267,6 +267,7 @@ impl DemoUI {
 pub enum UIEvent {
     None,
     MouseDown(Point2DI32),
+    MouseDragged(Point2DI32),
 }
 
 impl UIEvent {
@@ -283,4 +284,15 @@ impl UIEvent {
         }
         None
     }
+
+    fn handle_mouse_down_or_dragged_in_rect(&mut self, rect: RectI32) -> Option<Point2DI32> {
+        match *self {
+            UIEvent::MouseDown(point) |
+                    UIEvent::MouseDragged(point) if rect.contains_point(point) => {
+                *self = UIEvent::None;
+                Some(point - rect.origin())
+            }
+            _ => None,
+        }
+    }
 }