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Merge pull request #95 from Friz64/scrolling-behaviour

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Make scrolling behave like you'd expect it to
This commit is contained in:
Héctor Ramón 2019-12-04 01:14:13 +01:00 • committed by GitHub
commit 6c145bbb23
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GPG key ID: 4AEE18F83AFDEB23
3 changed files with 192 additions and 110 deletions
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9
native/src/renderer/null.rs
View file

@ -61,13 +61,13 @@ impl text::Renderer for Null {
}
impl scrollable::Renderer for Null {
fn is_mouse_over_scrollbar(
fn scrollbar(
&self,
_bounds: Rectangle,
_content_bounds: Rectangle,
_cursor_position: Point,
) -> bool {
false
_offset: u32,
) -> Option<scrollable::Scrollbar> {
None
}
fn draw(
@ -77,6 +77,7 @@ impl scrollable::Renderer for Null {
_content_bounds: Rectangle,
_is_mouse_over: bool,
_is_mouse_over_scrollbar: bool,
_scrollbar: Option<scrollable::Scrollbar>,
_offset: u32,
_content: Self::Output,
) {

173
native/src/widget/scrollable.rs
View file

@ -150,12 +150,6 @@ where
let content = layout.children().next().unwrap();
let content_bounds = content.bounds();
let is_mouse_over_scrollbar = renderer.is_mouse_over_scrollbar(
bounds,
content_bounds,
cursor_position,
);
// TODO: Event capture. Nested scrollables should capture scroll events.
if is_mouse_over {
match event {
@ -174,49 +168,66 @@ where
}
}
if self.state.is_scrollbar_grabbed() || is_mouse_over_scrollbar {
let offset = self.state.offset(bounds, content_bounds);
let scrollbar = renderer.scrollbar(bounds, content_bounds, offset);
let is_mouse_over_scrollbar = scrollbar
.as_ref()
.map(|scrollbar| scrollbar.is_mouse_over(cursor_position))
.unwrap_or(false);
if self.state.is_scroller_grabbed() {
match event {
Event::Mouse(mouse::Event::Input {
button: mouse::Button::Left,
state,
}) => match state {
ButtonState::Pressed => {
self.state.scroll_to(
cursor_position.y / (bounds.y + bounds.height),
bounds,
content_bounds,
);
self.state.scrollbar_grabbed_at = Some(cursor_position);
}
ButtonState::Released => {
self.state.scrollbar_grabbed_at = None;
}
},
state: ButtonState::Released,
}) => {
self.state.scroller_grabbed_at = None;
}
Event::Mouse(mouse::Event::CursorMoved { .. }) => {
if let Some(scrollbar_grabbed_at) =
self.state.scrollbar_grabbed_at
if let (Some(scrollbar), Some(scroller_grabbed_at)) =
(scrollbar, self.state.scroller_grabbed_at)
{
let ratio = content_bounds.height / bounds.height;
let delta = scrollbar_grabbed_at.y - cursor_position.y;
self.state.scroll(
delta * ratio,
self.state.scroll_to(
scrollbar.scroll_percentage(
scroller_grabbed_at,
cursor_position,
),
bounds,
content_bounds,
);
}
}
_ => {}
}
} else if is_mouse_over_scrollbar {
match event {
Event::Mouse(mouse::Event::Input {
button: mouse::Button::Left,
state: ButtonState::Pressed,
}) => {
if let Some(scrollbar) = scrollbar {
if let Some(scroller_grabbed_at) =
scrollbar.grab_scroller(cursor_position)
{
self.state.scroll_to(
scrollbar.scroll_percentage(
scroller_grabbed_at,
cursor_position,
),
bounds,
content_bounds,
);
self.state.scrollbar_grabbed_at = Some(cursor_position);
self.state.scroller_grabbed_at =
Some(scroller_grabbed_at);
}
}
}
_ => {}
}
}
let cursor_position = if is_mouse_over
&& !(is_mouse_over_scrollbar
|| self.state.scrollbar_grabbed_at.is_some())
{
let cursor_position = if is_mouse_over && !is_mouse_over_scrollbar {
Point::new(
cursor_position.x,
cursor_position.y
@ -249,13 +260,13 @@ where
let content_layout = layout.children().next().unwrap();
let content_bounds = content_layout.bounds();
let offset = self.state.offset(bounds, content_bounds);
let scrollbar = renderer.scrollbar(bounds, content_bounds, offset);
let is_mouse_over = bounds.contains(cursor_position);
let is_mouse_over_scrollbar = renderer.is_mouse_over_scrollbar(
bounds,
content_bounds,
cursor_position,
);
let is_mouse_over_scrollbar = scrollbar
.as_ref()
.map(|scrollbar| scrollbar.is_mouse_over(cursor_position))
.unwrap_or(false);
let content = {
let cursor_position = if is_mouse_over && !is_mouse_over_scrollbar {
@ -274,6 +285,7 @@ where
content_layout.bounds(),
is_mouse_over,
is_mouse_over_scrollbar,
scrollbar,
offset,
content,
)
@ -294,7 +306,7 @@ where
/// [`Scrollable`]: struct.Scrollable.html
#[derive(Debug, Clone, Copy, Default)]
pub struct State {
scrollbar_grabbed_at: Option<Point>,
scroller_grabbed_at: Option<f32>,
offset: f32,
}
@ -356,12 +368,68 @@ impl State {
self.offset.min(hidden_content as f32) as u32
}
/// Returns whether the scrollbar is currently grabbed or not.
pub fn is_scrollbar_grabbed(&self) -> bool {
self.scrollbar_grabbed_at.is_some()
/// Returns whether the scroller is currently grabbed or not.
pub fn is_scroller_grabbed(&self) -> bool {
self.scroller_grabbed_at.is_some()
}
}
/// The scrollbar of a [`Scrollable`].
///
/// [`Scrollable`]: struct.Scrollable.html
#[derive(Debug)]
pub struct Scrollbar {
/// The bounds of the [`Scrollbar`].
///
/// [`Scrollbar`]: struct.Scrollbar.html
pub bounds: Rectangle,
/// The bounds of the [`Scroller`].
///
/// [`Scroller`]: struct.Scroller.html
pub scroller: Scroller,
}
impl Scrollbar {
fn is_mouse_over(&self, cursor_position: Point) -> bool {
self.bounds.contains(cursor_position)
}
fn grab_scroller(&self, cursor_position: Point) -> Option<f32> {
if self.bounds.contains(cursor_position) {
Some(if self.scroller.bounds.contains(cursor_position) {
(cursor_position.y - self.scroller.bounds.y)
/ self.scroller.bounds.height
} else {
0.5
})
} else {
None
}
}
fn scroll_percentage(
&self,
grabbed_at: f32,
cursor_position: Point,
) -> f32 {
(cursor_position.y + self.bounds.y
- self.scroller.bounds.height * grabbed_at)
/ (self.bounds.height - self.scroller.bounds.height)
}
}
/// The handle of a [`Scrollbar`].
///
/// [`Scrollbar`]: struct.Scrollbar.html
#[derive(Debug, Clone, Copy)]
pub struct Scroller {
/// The bounds of the [`Scroller`].
///
/// [`Scroller`]: struct.Scrollbar.html
pub bounds: Rectangle,
}
/// The renderer of a [`Scrollable`].
///
/// Your [renderer] will need to implement this trait before being
@ -370,27 +438,31 @@ impl State {
/// [`Scrollable`]: struct.Scrollable.html
/// [renderer]: ../../renderer/index.html
pub trait Renderer: crate::Renderer + Sized {
/// Returns whether the mouse is over the scrollbar given the bounds of
/// the [`Scrollable`] and its contents.
/// Returns the [`Scrollbar`] given the bounds and content bounds of a
/// [`Scrollable`].
///
/// [`Scrollbar`]: struct.Scrollbar.html
/// [`Scrollable`]: struct.Scrollable.html
fn is_mouse_over_scrollbar(
fn scrollbar(
&self,
bounds: Rectangle,
content_bounds: Rectangle,
cursor_position: Point,
) -> bool;
offset: u32,
) -> Option<Scrollbar>;
/// Draws the [`Scrollable`].
///
/// It receives:
/// - the [`State`] of the [`Scrollable`]
/// - the bounds of the [`Scrollable`]
/// - the bounds of the [`Scrollable`] widget
/// - the bounds of the [`Scrollable`] content
/// - whether the mouse is over the [`Scrollable`] or not
/// - whether the mouse is over the scrollbar or not
/// - whether the mouse is over the [`Scrollbar`] or not
/// - a optional [`Scrollbar`] to be rendered
/// - the scrolling offset
/// - the drawn content
///
/// [`Scrollbar`]: struct.Scrollbar.html
/// [`Scrollable`]: struct.Scrollable.html
/// [`State`]: struct.State.html
fn draw(
@ -400,6 +472,7 @@ pub trait Renderer: crate::Renderer + Sized {
content_bounds: Rectangle,
is_mouse_over: bool,
is_mouse_over_scrollbar: bool,
scrollbar: Option<Scrollbar>,
offset: u32,
content: Self::Output,
) -> Self::Output;