Implement touchpad scroll

Cargo.lock

@@ -258,15 +258,15 @@ dependencies = [
 
 [[package]]
 name = "async-executor"
-version = "1.7.1"
+version = "1.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0de517d5a758a65a16d18d8f605e7a6beed477444cca270116af40fd3cd59d27"
+checksum = "4b0c4a4f319e45986f347ee47fef8bf5e81c9abc3f6f58dc2391439f30df65f0"
 dependencies = [
- "async-lock 3.1.0",
+ "async-lock 2.8.0",
  "async-task",
  "concurrent-queue",
  "fastrand 2.0.1",
- "futures-lite 2.0.1",
+ "futures-lite 1.13.0",
  "slab",
 ]
 

src/text_box.rs

@@ -533,12 +533,32 @@ where
             }
             Event::Mouse(MouseEvent::WheelScrolled { delta }) => match delta {
                 ScrollDelta::Lines { x, y } => {
-                    editor.action(Action::Scroll {
+                    //TODO: this adjustment is just a guess!
-                        lines: (-y * 6.0) as i32,
+                    state.scroll_pixels = 0.0;
-                    });
+                    let lines = (-y * 6.0) as i32;
+                    if lines != 0 {
+                        editor.action(Action::Scroll { lines });
+                    }
+                    status = Status::Captured;
+                }
+                ScrollDelta::Pixels { x, y } => {
+                    //TODO: this adjustment is just a guess!
+                    state.scroll_pixels -= y * 6.0;
+                    let mut lines = 0;
+                    let metrics = editor.buffer().metrics();
+                    while state.scroll_pixels <= -metrics.line_height {
+                        lines -= 1;
+                        state.scroll_pixels += metrics.line_height;
+                    }
+                    while state.scroll_pixels >= metrics.line_height {
+                        lines += 1;
+                        state.scroll_pixels -= metrics.line_height;
+                    }
+                    if lines != 0 {
+                        editor.action(Action::Scroll { lines });
+                    }
                     status = Status::Captured;
                 }
-                _ => (),
             },
             _ => (),
         }
@@ -566,6 +586,7 @@ pub struct State {
     modifiers: Modifiers,
     dragging: Option<Dragging>,
     scale_factor: Cell<f32>,
+    scroll_pixels: f32,
     scrollbar_rect: Cell<Rectangle<f32>>,
     handle: Mutex<image::Handle>,
 }
@@ -577,6 +598,7 @@ impl State {
             modifiers: Modifiers::empty(),
             dragging: None,
             scale_factor: Cell::new(1.0),
+            scroll_pixels: 0.0,
             scrollbar_rect: Cell::new(Rectangle::default()),
             //TODO: make option!
             handle: Mutex::new(image::Handle::from_pixels(1, 1, vec![0, 0, 0, 0])),