diff --git a/src/view/scroll.rs b/src/view/scroll.rs index 21720f4..7799f79 100644 --- a/src/view/scroll.rs +++ b/src/view/scroll.rs @@ -1,6 +1,5 @@ use Printer; use std::cmp::{max, min}; - use theme::ColorStyle; use vec::Vec2; @@ -12,10 +11,13 @@ use vec::Vec2; pub struct ScrollBase { /// First line visible pub start_line: usize, + /// Content height pub content_height: usize, + /// Number of lines displayed pub view_height: usize, + /// Padding for the scrollbar /// /// If present, the scrollbar will be shifted @@ -27,6 +29,9 @@ pub struct ScrollBase { /// Blank between the text and the scrollbar. pub right_padding: usize, + + /// Initial position of the cursor when dragging. + pub thumb_grab: usize, } /// Defines the scrolling behaviour on content or size change @@ -54,6 +59,7 @@ impl ScrollBase { view_height: 0, scrollbar_offset: 0, right_padding: 1, + thumb_grab: 0, } } @@ -81,8 +87,8 @@ impl ScrollBase { self.content_height = content_height; if self.scrollable() { - self.start_line = min(self.start_line, - self.content_height - self.view_height); + self.start_line = + min(self.start_line, self.content_height - self.view_height); } else { self.start_line = 0; } @@ -129,11 +135,24 @@ impl ScrollBase { /// Never further than the bottom of the view. pub fn scroll_down(&mut self, n: usize) { if self.scrollable() { - self.start_line = min(self.start_line + n, - self.content_height - self.view_height); + self.start_line = min( + self.start_line + n, + self.content_height - self.view_height, + ); } } + /// Scrolls down until the scrollbar thumb is at the given location. + pub fn scroll_to_thumb(&mut self, thumb_y: usize, thumb_height: usize) { + // The min() is there to stop at the bottom of the content. + // The saturating_sub is there to stop at the bottom of the content. + self.start_line = min( + (1 + self.content_height - self.view_height) * thumb_y + / (self.view_height - thumb_height + 1), + self.content_height - self.view_height, + ); + } + /// Scroll up by the given number of lines. /// /// Never above the top of the view. @@ -143,6 +162,42 @@ impl ScrollBase { } } + /// Starts scrolling from the given cursor position. + pub fn start_drag(&mut self, position: Vec2, width: usize) -> bool { + // First: are we on the correct column? + if position.x != self.scrollbar_x(width) { + return false; + } + + + // Now, did we hit the thumb? Or should we direct-jump? + let height = self.scrollbar_thumb_height(); + let thumb_y = self.scrollbar_thumb_y(height); + + if position.y >= thumb_y && position.y < thumb_y + height { + // Grabbed! + self.thumb_grab = position.y - thumb_y; + } else { + // Just jump a bit... + self.thumb_grab = height / 2; + } + + self.drag(position); + + + true + } + + /// Keeps scrolling by dragging the cursor. + pub fn drag(&mut self, position: Vec2) { + // Our goal is self.scrollbar_thumb_y()+thumb_grab == position.y + // Which means that position.y is the middle of the scrollbar. + let height = self.scrollbar_thumb_height(); + let grab = self.thumb_grab; + self.scroll_to_thumb(position.y.saturating_sub(grab), height); + } + + /// Draws the scroll bar and the content using the given drawer. /// /// `line_drawer` will be called once for each line that needs to be drawn. @@ -168,14 +223,15 @@ impl ScrollBase { /// }); /// ``` pub fn draw(&self, printer: &Printer, line_drawer: F) - where F: Fn(&Printer, usize) + where + F: Fn(&Printer, usize), { if self.view_height == 0 { return; } // Print the content in a sub_printer - let max_y = min(self.view_height, - self.content_height - self.start_line); + let max_y = + min(self.view_height, self.content_height - self.start_line); let w = if self.scrollable() { // We have to remove the bar width and the padding. printer.size.x.saturating_sub(1 + self.right_padding) @@ -186,10 +242,10 @@ impl ScrollBase { for y in 0..max_y { // Y is the actual coordinate of the line. // The item ID is then Y + self.start_line - line_drawer(&printer.sub_printer(Vec2::new(0, y), - Vec2::new(w, 1), - true), - y + self.start_line); + line_drawer( + &printer.sub_printer(Vec2::new(0, y), Vec2::new(w, 1), true), + y + self.start_line, + ); } @@ -199,15 +255,8 @@ impl ScrollBase { // (that way we avoid using floats). // (ratio) * max_height // Where ratio is ({start or end} / content.height) - let height = max(1, - self.view_height * self.view_height / - self.content_height); - // Number of different possible positions - let steps = self.view_height - height + 1; - - // Now - let start = steps * self.start_line / - (1 + self.content_height - self.view_height); + let height = self.scrollbar_thumb_height(); + let start = self.scrollbar_thumb_y(height); let color = if printer.focused { ColorStyle::Highlight @@ -215,12 +264,34 @@ impl ScrollBase { ColorStyle::HighlightInactive }; - // TODO: use 1 instead of 2 - let scrollbar_x = printer.size.x.saturating_sub(1 + self.scrollbar_offset); + let scrollbar_x = self.scrollbar_x(printer.size.x); + + // The background printer.print_vline((scrollbar_x, 0), printer.size.y, "|"); + + // The scrollbar thumb printer.with_color(color, |printer| { printer.print_vline((scrollbar_x, start), height, "▒"); }); } } + + /// Returns the X position of the scrollbar, given the size available. + /// + /// Note that this does not depend whether or + /// not a scrollbar will actually be present. + pub fn scrollbar_x(&self, total_size: usize) -> usize { + total_size.saturating_sub(1 + self.scrollbar_offset) + } + + /// Returns the height of the scrollbar thumb. + pub fn scrollbar_thumb_height(&self) -> usize { + max(1, self.view_height * self.view_height / self.content_height) + } + + /// Returns the y position of the scrollbar thumb. + pub fn scrollbar_thumb_y(&self, scrollbar_thumb_height: usize) -> usize { + let steps = self.view_height - scrollbar_thumb_height + 1; + steps * self.start_line / (1 + self.content_height - self.view_height) + } } diff --git a/src/views/text_view.rs b/src/views/text_view.rs index 63d53da..e8a4c2b 100644 --- a/src/views/text_view.rs +++ b/src/views/text_view.rs @@ -4,12 +4,10 @@ use XY; use align::*; use direction::Direction; use event::*; - use unicode_width::UnicodeWidthStr; - use utils::{LinesIterator, Row}; use vec::Vec2; -use view::{SizeCache, View, ScrollBase, ScrollStrategy}; +use view::{ScrollBase, ScrollStrategy, SizeCache, View}; /// A simple view showing a fixed text pub struct TextView { @@ -181,9 +179,9 @@ impl TextView { // First attempt: naively hope that we won't need a scrollbar_width // (This means we try to use the entire available width for text). - self.rows = LinesIterator::new(strip_last_newline(&self.content), - size.x) - .collect(); + self.rows = + LinesIterator::new(strip_last_newline(&self.content), size.x) + .collect(); // Width taken by the scrollbar. Without a scrollbar, it's 0. let mut scrollbar_width = 0; @@ -241,11 +239,10 @@ impl TextView { impl View for TextView { fn draw(&self, printer: &Printer) { - let h = self.rows.len(); + // If the content is smaller than the view, align it somewhere. let offset = self.align.v.get_offset(h, printer.size.y); - let printer = - &printer.sub_printer(Vec2::new(0, offset), printer.size, true); + let printer = &printer.offset((0, offset), true); self.scrollbase.draw(printer, |printer, i| { let row = &self.rows[i]; @@ -261,14 +258,56 @@ impl View for TextView { return EventResult::Ignored; } + // We know we are scrollable, otherwise the event would just be ignored. match event { Event::Key(Key::Home) => self.scrollbase.scroll_top(), Event::Key(Key::End) => self.scrollbase.scroll_bottom(), Event::Key(Key::Up) if self.scrollbase.can_scroll_up() => { self.scrollbase.scroll_up(1) } - Event::Key(Key::Down) if self.scrollbase - .can_scroll_down() => self.scrollbase.scroll_down(1), + Event::Key(Key::Down) if self.scrollbase.can_scroll_down() => { + self.scrollbase.scroll_down(1) + } + Event::Mouse { + event: MouseEvent::WheelDown, + position: _, + offset: _, + } if self.scrollbase.can_scroll_down() => + { + self.scrollbase.scroll_down(5) + } + Event::Mouse { + event: MouseEvent::WheelUp, + position: _, + offset: _, + } if self.scrollbase.can_scroll_up() => + { + self.scrollbase.scroll_up(5) + } + Event::Mouse { + event: MouseEvent::Press(MouseButton::Left), + position, + offset, + } if position + .checked_sub(offset) + .and_then(|position| { + self.width.map( + |width| self.scrollbase.start_drag(position, width), + ) + }) + .unwrap_or(false) => + { + // Start scroll drag at the given position + } + Event::Mouse { + event: MouseEvent::Hold(MouseButton::Left), + position, + offset, + } => { + position + .checked_sub(offset) + .map(|position| self.scrollbase.drag(position)); + } Event::Key(Key::PageDown) => self.scrollbase.scroll_down(10), Event::Key(Key::PageUp) => self.scrollbase.scroll_up(10), _ => return EventResult::Ignored,