Merge pull request #95 from Friz64/scrolling-behaviour

Make scrolling behave like you'd expect it to

1 files changed, 64 insertions, 56 deletions

diff --git a/wgpu/src/renderer/widget/scrollable.rs b/wgpu/src/renderer/widget/scrollable.rs
index 58dc3df9..6ef57185 100644
--- a/wgpu/src/renderer/widget/scrollable.rs
+++ b/wgpu/src/renderer/widget/scrollable.rs
@@ -1,45 +1,58 @@
 use crate::{Primitive, Renderer};
-use iced_native::{
-    scrollable, Background, MouseCursor, Point, Rectangle, Vector,
-};
+use iced_native::{scrollable, Background, MouseCursor, Rectangle, Vector};
 
 const SCROLLBAR_WIDTH: u16 = 10;
 const SCROLLBAR_MARGIN: u16 = 2;
 
-fn scrollbar_bounds(bounds: Rectangle) -> Rectangle {
-    Rectangle {
-        x: bounds.x + bounds.width
-            - f32::from(SCROLLBAR_WIDTH + 2 * SCROLLBAR_MARGIN),
-        y: bounds.y,
-        width: f32::from(SCROLLBAR_WIDTH + 2 * SCROLLBAR_MARGIN),
-        height: bounds.height,
-    }
-}
-
 impl scrollable::Renderer for Renderer {
-    fn is_mouse_over_scrollbar(
+    fn scrollbar(
         &self,
         bounds: Rectangle,
         content_bounds: Rectangle,
-        cursor_position: Point,
-    ) -> bool {
-        content_bounds.height > bounds.height
-            && scrollbar_bounds(bounds).contains(cursor_position)
+        offset: u32,
+    ) -> Option<scrollable::Scrollbar> {
+        if content_bounds.height > bounds.height {
+            let scrollbar_bounds = Rectangle {
+                x: bounds.x + bounds.width
+                    - f32::from(SCROLLBAR_WIDTH + 2 * SCROLLBAR_MARGIN),
+                y: bounds.y,
+                width: f32::from(SCROLLBAR_WIDTH + 2 * SCROLLBAR_MARGIN),
+                height: bounds.height,
+            };
+
+            let ratio = bounds.height / content_bounds.height;
+            let scrollbar_height = bounds.height * ratio;
+            let y_offset = offset as f32 * ratio;
+
+            let scroller_bounds = Rectangle {
+                x: scrollbar_bounds.x + f32::from(SCROLLBAR_MARGIN),
+                y: scrollbar_bounds.y + y_offset,
+                width: scrollbar_bounds.width - f32::from(2 * SCROLLBAR_MARGIN),
+                height: scrollbar_height,
+            };
+
+            Some(scrollable::Scrollbar {
+                bounds: scrollbar_bounds,
+                scroller: scrollable::Scroller {
+                    bounds: scroller_bounds,
+                },
+            })
+        } else {
+            None
+        }
     }
 
     fn draw(
         &mut self,
         state: &scrollable::State,
         bounds: Rectangle,
-        content_bounds: Rectangle,
+        _content_bounds: Rectangle,
         is_mouse_over: bool,
         is_mouse_over_scrollbar: bool,
+        scrollbar: Option<scrollable::Scrollbar>,
         offset: u32,
         (content, mouse_cursor): Self::Output,
     ) -> Self::Output {
-        let is_content_overflowing = content_bounds.height > bounds.height;
-        let scrollbar_bounds = scrollbar_bounds(bounds);
-
         let clip = Primitive::Clip {
             bounds,
             offset: Vector::new(0, offset),
@@ -47,51 +60,46 @@ impl scrollable::Renderer for Renderer {
         };
 
         (
-            if is_content_overflowing
-                && (is_mouse_over || state.is_scrollbar_grabbed())
-            {
-                let ratio = bounds.height / content_bounds.height;
-                let scrollbar_height = bounds.height * ratio;
-                let y_offset = offset as f32 * ratio;
-
-                let scrollbar = Primitive::Quad {
-                    bounds: Rectangle {
-                        x: scrollbar_bounds.x + f32::from(SCROLLBAR_MARGIN),
-                        y: scrollbar_bounds.y + y_offset,
-                        width: scrollbar_bounds.width
-                            - f32::from(2 * SCROLLBAR_MARGIN),
-                        height: scrollbar_height,
-                    },
-                    background: Background::Color([0.0, 0.0, 0.0, 0.7].into()),
-                    border_radius: 5,
-                };
-
-                if is_mouse_over_scrollbar || state.is_scrollbar_grabbed() {
-                    let scrollbar_background = Primitive::Quad {
-                        bounds: Rectangle {
-                            x: scrollbar_bounds.x + f32::from(SCROLLBAR_MARGIN),
-                            width: scrollbar_bounds.width
-                                - f32::from(2 * SCROLLBAR_MARGIN),
-                            ..scrollbar_bounds
-                        },
+            if let Some(scrollbar) = scrollbar {
+                if is_mouse_over || state.is_scroller_grabbed() {
+                    let scroller = Primitive::Quad {
+                        bounds: scrollbar.scroller.bounds,
                         background: Background::Color(
-                            [0.0, 0.0, 0.0, 0.3].into(),
+                            [0.0, 0.0, 0.0, 0.7].into(),
                         ),
                         border_radius: 5,
                     };
 
-                    Primitive::Group {
-                        primitives: vec![clip, scrollbar_background, scrollbar],
+                    if is_mouse_over_scrollbar || state.is_scroller_grabbed() {
+                        let scrollbar = Primitive::Quad {
+                            bounds: Rectangle {
+                                x: scrollbar.bounds.x
+                                    + f32::from(SCROLLBAR_MARGIN),
+                                width: scrollbar.bounds.width
+                                    - f32::from(2 * SCROLLBAR_MARGIN),
+                                ..scrollbar.bounds
+                            },
+                            background: Background::Color(
+                                [0.0, 0.0, 0.0, 0.3].into(),
+                            ),
+                            border_radius: 5,
+                        };
+
+                        Primitive::Group {
+                            primitives: vec![clip, scrollbar, scroller],
+                        }
+                    } else {
+                        Primitive::Group {
+                            primitives: vec![clip, scroller],
+                        }
                     }
                 } else {
-                    Primitive::Group {
-                        primitives: vec![clip, scrollbar],
-                    }
+                    clip
                 }
             } else {
                 clip
             },
-            if is_mouse_over_scrollbar || state.is_scrollbar_grabbed() {
+            if is_mouse_over_scrollbar || state.is_scroller_grabbed() {
                 MouseCursor::Idle
             } else {
                 mouse_cursor