First implementation

1 files changed, 60 insertions, 24 deletions

diff --git a/wgpu/src/renderer/widget/scrollable.rs b/wgpu/src/renderer/widget/scrollable.rs
index 58dc3df9..d069b799 100644
--- a/wgpu/src/renderer/widget/scrollable.rs
+++ b/wgpu/src/renderer/widget/scrollable.rs
@@ -1,12 +1,13 @@
 use crate::{Primitive, Renderer};
 use iced_native::{
-    scrollable, Background, MouseCursor, Point, Rectangle, Vector,
+    scrollable, Background, MouseCursor, Point, Rectangle, ScrollbarGrab,
+    Vector,
 };
 
 const SCROLLBAR_WIDTH: u16 = 10;
 const SCROLLBAR_MARGIN: u16 = 2;
 
-fn scrollbar_bounds(bounds: Rectangle) -> Rectangle {
+fn background_bounds(bounds: Rectangle) -> Rectangle {
     Rectangle {
         x: bounds.x + bounds.width
             - f32::from(SCROLLBAR_WIDTH + 2 * SCROLLBAR_MARGIN),
@@ -16,15 +17,53 @@ fn scrollbar_bounds(bounds: Rectangle) -> Rectangle {
     }
 }
 
+fn scroller_bounds(
+    bounds: Rectangle,
+    content_bounds: Rectangle,
+    background_bounds: Rectangle,
+    offset: u32,
+) -> Rectangle {
+    let ratio = bounds.height / content_bounds.height;
+    let scrollbar_height = bounds.height * ratio;
+    let y_offset = offset as f32 * ratio;
+
+    Rectangle {
+        x: background_bounds.x + f32::from(SCROLLBAR_MARGIN),
+        y: background_bounds.y + y_offset,
+        width: background_bounds.width - f32::from(2 * SCROLLBAR_MARGIN),
+        height: scrollbar_height,
+    }
+}
+
 impl scrollable::Renderer for Renderer {
-    fn is_mouse_over_scrollbar(
+    fn scrollbar_grab(
         &self,
         bounds: Rectangle,
         content_bounds: Rectangle,
+        offset: u32,
         cursor_position: Point,
-    ) -> bool {
-        content_bounds.height > bounds.height
-            && scrollbar_bounds(bounds).contains(cursor_position)
+    ) -> Option<(ScrollbarGrab, Rectangle)> {
+        let background_bounds = background_bounds(bounds);
+        if content_bounds.height > bounds.height
+            && background_bounds.contains(cursor_position)
+        {
+            let scroller_bounds = scroller_bounds(
+                bounds,
+                content_bounds,
+                background_bounds,
+                offset,
+            );
+
+            let scrollbar_grab = if scroller_bounds.contains(cursor_position) {
+                ScrollbarGrab::Scroller
+            } else {
+                ScrollbarGrab::Background
+            };
+
+            Some((scrollbar_grab, scroller_bounds))
+        } else {
+            None
+        }
     }
 
     fn draw(
@@ -38,7 +77,7 @@ impl scrollable::Renderer for Renderer {
         (content, mouse_cursor): Self::Output,
     ) -> Self::Output {
         let is_content_overflowing = content_bounds.height > bounds.height;
-        let scrollbar_bounds = scrollbar_bounds(bounds);
+        let background_bounds = background_bounds(bounds);
 
         let clip = Primitive::Clip {
             bounds,
@@ -48,31 +87,28 @@ impl scrollable::Renderer for Renderer {
 
         (
             if is_content_overflowing
-                && (is_mouse_over || state.is_scrollbar_grabbed())
+                && (is_mouse_over || state.currently_grabbed())
             {
-                let ratio = bounds.height / content_bounds.height;
-                let scrollbar_height = bounds.height * ratio;
-                let y_offset = offset as f32 * ratio;
-
+                let scroller_bounds = scroller_bounds(
+                    bounds,
+                    content_bounds,
+                    background_bounds,
+                    offset,
+                );
                 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,
-                    },
+                    bounds: scroller_bounds,
                     background: Background::Color([0.0, 0.0, 0.0, 0.7].into()),
                     border_radius: 5,
                 };
 
-                if is_mouse_over_scrollbar || state.is_scrollbar_grabbed() {
+                if is_mouse_over_scrollbar || state.currently_grabbed() {
                     let scrollbar_background = Primitive::Quad {
                         bounds: Rectangle {
-                            x: scrollbar_bounds.x + f32::from(SCROLLBAR_MARGIN),
-                            width: scrollbar_bounds.width
+                            x: background_bounds.x
+                                + f32::from(SCROLLBAR_MARGIN),
+                            width: background_bounds.width
                                 - f32::from(2 * SCROLLBAR_MARGIN),
-                            ..scrollbar_bounds
+                            ..background_bounds
                         },
                         background: Background::Color(
                             [0.0, 0.0, 0.0, 0.3].into(),
@@ -91,7 +127,7 @@ impl scrollable::Renderer for Renderer {
             } else {
                 clip
             },
-            if is_mouse_over_scrollbar || state.is_scrollbar_grabbed() {
+            if is_mouse_over_scrollbar || state.currently_grabbed() {
                 MouseCursor::Idle
             } else {
                 mouse_cursor