1 files changed, 129 insertions, 0 deletions
diff --git a/wgpu/src/renderer/widget/scrollable.rs b/wgpu/src/renderer/widget/scrollable.rs
new file mode 100644
index 00000000..72d77cc8
--- /dev/null
+++ b/wgpu/src/renderer/widget/scrollable.rs
@@ -0,0 +1,129 @@
+use crate::{Primitive, Renderer};
+use iced_native::{
+    scrollable, Background, Color, Layout, MouseCursor, Point, Rectangle,
+    Scrollable, Widget,
+};
+
+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(
+        &self,
+        bounds: Rectangle,
+        content_bounds: Rectangle,
+        cursor_position: Point,
+    ) -> bool {
+        content_bounds.height > bounds.height
+            && scrollbar_bounds(bounds).contains(cursor_position)
+    }
+
+    fn draw<Message>(
+        &mut self,
+        scrollable: &Scrollable<'_, Message, Self>,
+        bounds: Rectangle,
+        content: Layout<'_>,
+        cursor_position: Point,
+    ) -> Self::Output {
+        let is_mouse_over = bounds.contains(cursor_position);
+        let content_bounds = content.bounds();
+
+        let offset = scrollable.state.offset(bounds, content_bounds);
+        let is_content_overflowing = content_bounds.height > bounds.height;
+        let scrollbar_bounds = scrollbar_bounds(bounds);
+        let is_mouse_over_scrollbar = self.is_mouse_over_scrollbar(
+            bounds,
+            content_bounds,
+            cursor_position,
+        );
+
+        let cursor_position = if is_mouse_over && !is_mouse_over_scrollbar {
+            Point::new(cursor_position.x, cursor_position.y + offset as f32)
+        } else {
+            Point::new(cursor_position.x, -1.0)
+        };
+
+        let (content, mouse_cursor) =
+            scrollable.content.draw(self, content, cursor_position);
+
+        let clip = Primitive::Clip {
+            bounds,
+            offset,
+            content: Box::new(content),
+        };
+
+        (
+            if is_content_overflowing
+                && (is_mouse_over || scrollable.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(Color {
+                        r: 0.0,
+                        g: 0.0,
+                        b: 0.0,
+                        a: 0.7,
+                    }),
+                    border_radius: 5,
+                };
+
+                if is_mouse_over_scrollbar
+                    || scrollable.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
+                        },
+                        background: Background::Color(Color {
+                            r: 0.0,
+                            g: 0.0,
+                            b: 0.0,
+                            a: 0.3,
+                        }),
+                        border_radius: 5,
+                    };
+
+                    Primitive::Group {
+                        primitives: vec![clip, scrollbar_background, scrollbar],
+                    }
+                } else {
+                    Primitive::Group {
+                        primitives: vec![clip, scrollbar],
+                    }
+                }
+            } else {
+                clip
+            },
+            if is_mouse_over_scrollbar
+                || scrollable.state.is_scrollbar_grabbed()
+            {
+                MouseCursor::Idle
+            } else {
+                mouse_cursor
+            },
+        )
+    }
+}