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180 lines
5.6 KiB
180 lines
5.6 KiB
use crate::ui::{
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component::{Component, Event, EventCtx, Never},
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display::toif::Icon,
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geometry::{Alignment2D, Axis, LinearPlacement, Offset, Rect},
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shape,
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shape::Renderer,
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};
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use super::theme;
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pub struct ScrollBar {
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area: Rect,
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layout: LinearPlacement,
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pub page_count: usize,
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pub active_page: usize,
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}
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impl ScrollBar {
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pub const DOT_SIZE: i16 = 8;
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/// If there's more pages than this value then smaller dots are used at the
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/// beginning/end of the scrollbar to denote the fact.
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const MAX_DOTS: usize = 7;
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/// Center to center.
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const DOT_INTERVAL: i16 = 18;
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pub fn new(axis: Axis) -> Self {
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let layout = LinearPlacement::new(axis);
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Self {
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area: Rect::zero(),
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layout: layout.align_at_center().with_spacing(Self::DOT_INTERVAL),
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page_count: 0,
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active_page: 0,
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}
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}
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pub fn vertical() -> Self {
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Self::new(Axis::Vertical)
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}
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pub fn horizontal() -> Self {
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Self::new(Axis::Horizontal)
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}
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pub fn set_count_and_active_page(&mut self, page_count: usize, active_page: usize) {
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self.page_count = page_count;
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self.active_page = active_page;
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}
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pub fn has_pages(&self) -> bool {
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self.page_count > 1
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}
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pub fn has_next_page(&self) -> bool {
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self.active_page < self.page_count - 1
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}
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pub fn has_previous_page(&self) -> bool {
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self.active_page > 0
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}
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pub fn go_to_next_page(&mut self) {
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self.go_to_relative(1)
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}
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pub fn go_to_previous_page(&mut self) {
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self.go_to_relative(-1)
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}
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pub fn go_to_relative(&mut self, step: isize) {
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self.go_to(
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(self.active_page as isize + step).clamp(0, self.page_count as isize - 1) as usize,
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);
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}
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pub fn go_to(&mut self, active_page: usize) {
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self.active_page = active_page;
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}
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}
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impl Component for ScrollBar {
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type Msg = Never;
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fn event(&mut self, _ctx: &mut EventCtx, _event: Event) -> Option<Self::Msg> {
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None
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}
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fn paint(&mut self) {
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fn dotsize(distance: usize, nhidden: usize) -> Icon {
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match (nhidden.saturating_sub(distance)).min(2 - distance) {
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0 => theme::DOT_INACTIVE,
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1 => theme::DOT_INACTIVE_HALF,
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_ => theme::DOT_INACTIVE_QUARTER,
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}
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}
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// Number of visible dots.
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let num_shown = self.page_count.min(Self::MAX_DOTS);
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// Page indices corresponding to the first (and last) dot.
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let first_shown = self
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.active_page
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.saturating_sub(Self::MAX_DOTS / 2)
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.min(self.page_count.saturating_sub(Self::MAX_DOTS));
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let last_shown = first_shown + num_shown - 1;
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let mut cursor = self.area.center()
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- Offset::on_axis(
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self.layout.axis,
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Self::DOT_INTERVAL * (num_shown.saturating_sub(1) as i16) / 2,
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);
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for i in first_shown..(last_shown + 1) {
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let icon = if i == self.active_page {
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theme::DOT_ACTIVE
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} else if i <= first_shown + 1 {
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let before_first_shown = first_shown;
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dotsize(i - first_shown, before_first_shown)
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} else if i >= last_shown - 1 {
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let after_last_shown = self.page_count - 1 - last_shown;
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dotsize(last_shown - i, after_last_shown)
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} else {
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theme::DOT_INACTIVE
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};
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icon.draw(cursor, Alignment2D::CENTER, theme::FG, theme::BG);
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cursor = cursor + Offset::on_axis(self.layout.axis, Self::DOT_INTERVAL);
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}
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}
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fn render<'s>(&'s self, target: &mut impl Renderer<'s>) {
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fn dotsize(distance: usize, nhidden: usize) -> Icon {
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match (nhidden.saturating_sub(distance)).min(2 - distance) {
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0 => theme::DOT_INACTIVE,
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1 => theme::DOT_INACTIVE_HALF,
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_ => theme::DOT_INACTIVE_QUARTER,
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}
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}
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// Number of visible dots.
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let num_shown = self.page_count.min(Self::MAX_DOTS);
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// Page indices corresponding to the first (and last) dot.
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let first_shown = self
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.active_page
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.saturating_sub(Self::MAX_DOTS / 2)
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.min(self.page_count.saturating_sub(Self::MAX_DOTS));
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let last_shown = first_shown + num_shown - 1;
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let mut cursor = self.area.center()
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- Offset::on_axis(
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self.layout.axis,
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Self::DOT_INTERVAL * (num_shown.saturating_sub(1) as i16) / 2,
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);
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for i in first_shown..(last_shown + 1) {
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let icon = if i == self.active_page {
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theme::DOT_ACTIVE
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} else if i <= first_shown + 1 {
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let before_first_shown = first_shown;
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dotsize(i - first_shown, before_first_shown)
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} else if i >= last_shown - 1 {
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let after_last_shown = self.page_count - 1 - last_shown;
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dotsize(last_shown - i, after_last_shown)
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} else {
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theme::DOT_INACTIVE
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};
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shape::ToifImage::new(cursor, icon.toif)
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.with_align(Alignment2D::CENTER)
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.with_fg(theme::FG)
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.render(target);
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cursor = cursor + Offset::on_axis(self.layout.axis, Self::DOT_INTERVAL);
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}
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}
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fn place(&mut self, bounds: Rect) -> Rect {
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self.area = bounds;
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bounds
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}
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#[cfg(feature = "ui_bounds")]
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fn bounds(&self, sink: &mut dyn FnMut(Rect)) {
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sink(self.area);
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}
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}
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