Cursor navigation (https://github.com/enso-org/ide/pull/106)

Original commit: 9d1b18d681

gui/lib/core/src/display/render/webgl.rs

@@ -157,7 +157,7 @@ pub fn set_buffer_data(gl_context:&Context, buffer:&WebGlBuffer, data:&[f32]) {
 /// wasm-bindgen examples
 /// (https://rustwasm.github.io/wasm-bindgen/examples/webgl.html)
 fn set_bound_buffer_data(gl_context:&Context, target:u32, data:&[f32]) {
-    let usage      = Context::STATIC_DRAW;
+    let usage = Context::STATIC_DRAW;
     unsafe { // Note [unsafe buffer_data]
         let float_array = Float32Array::view(&data);
         gl_context.buffer_data_with_array_buffer_view(target,&float_array,usage);

gui/lib/core/src/display/shape/text.rs

@@ -20,6 +20,8 @@ use crate::display::render::webgl::Context;
 use crate::display::shape::text::buffer::TextComponentBuffers;
 use crate::display::shape::text::content::TextComponentContent;
 use crate::display::shape::text::cursor::Cursors;
+use crate::display::shape::text::cursor::Step;
+use crate::display::shape::text::cursor::CursorNavigation;
 use crate::display::shape::text::font::FontId;
 use crate::display::shape::text::font::Fonts;
 use crate::display::shape::text::msdf::MsdfTexture;
@@ -134,6 +136,12 @@ impl TextComponent {
         }
     }
 
+    pub fn navigate_cursors(&mut self, step:Step, selecting:bool, fonts:&mut Fonts) {
+        let content        = &mut self.content;
+        let mut navigation = CursorNavigation {content,fonts,selecting};
+        self.cursors.navigate_all_cursors(&mut navigation,&step);
+    }
+
     fn refresh_content_buffers(&mut self, fonts:&mut Fonts) {
         let refresh_info = self.content.refresh_info(fonts);
         self.buffers.refresh(&self.gl_context,refresh_info);
@@ -165,8 +173,7 @@ impl TextComponent {
     }
 
     fn refresh_cursors(&mut self, fonts:&mut Fonts) {
-        let cursors_changed = !self.cursors.dirty_cursors.is_empty();
-        if cursors_changed {
+        if self.cursors.dirty {
             let gl_context = &self.gl_context;
             let content    = &mut self.content;
             self.cursors.update_buffer_data(gl_context,content,fonts);
@@ -209,6 +216,7 @@ impl TextComponent {
     }
 
     fn display_cursors(&self) {
+        let buffer           = self.cursors.buffer.as_ref().unwrap();
         let gl_context       = &self.gl_context;
         let to_scene_matrix  = self.to_scene_matrix();
         let program          = &self.cursors_program;
@@ -216,7 +224,7 @@ impl TextComponent {
 
         gl_context.use_program(Some(&program.gl_program));
         self.cursors_program.set_to_scene_transformation(&to_scene_matrix);
-        self.cursors_program.bind_buffer_to_attribute("position",&self.cursors.buffer);
+        self.cursors_program.bind_buffer_to_attribute("position",buffer);
         gl_context.line_width(2.0);
         gl_context.draw_arrays(WebGl2RenderingContext::LINES,0,vertices_count);
         gl_context.line_width(1.0);

gui/lib/core/src/display/shape/text/content.rs

@@ -82,21 +82,21 @@ pub enum ChangeType {
 
 /// A structure describing a text operation in one place.
 pub struct TextChange {
-    replaced : Range<CharPosition>,
+    replaced : Range<TextLocation>,
     lines    : Vec<Vec<char>>,
 }
 
 impl TextChange {
     /// Creates operation which inserts text at given position.
-    pub fn insert(position:CharPosition, text:&str) -> Self {
+    pub fn insert(at:TextLocation, text:&str) -> Self {
         TextChange {
-            replaced : position..position,
-            lines    : TextComponentContent::split_to_lines(text).map(|s| s.chars().collect_vec()).collect()
+            replaced : at..at,
+            lines    : Self::mk_lines_as_char_vector(text)
         }
     }
 
     /// Creates operation which deletes text at given range.
-    pub fn delete(range:Range<CharPosition>) -> Self {
+    pub fn delete(range:Range<TextLocation>) -> Self {
         TextChange {
             replaced : range,
             lines    : vec![vec![]],
@@ -104,9 +104,9 @@ impl TextChange {
     }
 
     /// Creates operation which replaces text at given range with given string.
-    pub fn replace(replaced:Range<CharPosition>, text:&str) -> Self {
+    pub fn replace(replaced:Range<TextLocation>, text:&str) -> Self {
         TextChange {replaced,
-            lines : TextComponentContent::split_to_lines(text).map(|s| s.chars().collect_vec()).collect()
+            lines : Self::mk_lines_as_char_vector(text)
         }
     }
 
@@ -123,8 +123,45 @@ impl TextChange {
             ChangeType::Multiline
         }
     }
+
+    fn mk_lines_as_char_vector(text:&str) -> Vec<Vec<char>> {
+        TextComponentContent::split_to_lines(text).map(|s| s.chars().collect_vec()).collect()
+    }
 }
 
+
+
+// ====================
+// === TextLocation ===
+// ====================
+
+/// A position of character in a multiline text.
+#[derive(Copy,Clone,Debug,PartialEq,Eq,PartialOrd,Ord)]
+pub struct TextLocation {
+    pub line   : usize,
+    pub column : usize,
+}
+
+impl TextLocation {
+    /// Create location at begin of given line.
+    pub fn at_line_begin(line_index:usize) -> TextLocation {
+        TextLocation {
+            line   : line_index,
+            column : 0,
+        }
+    }
+
+    /// Create location at begin of the whole document.
+    pub fn at_document_begin() -> TextLocation {
+        TextLocation {
+            line   : 0,
+            column : 0,
+        }
+    }
+}
+
+
+
 // ============================
 // === TextComponentContent ===
 // ============================
@@ -137,13 +174,6 @@ pub struct TextComponentContent {
     pub font        : FontId,
 }
 
-/// A position of character in multiline text.
-#[derive(Copy,Clone,Debug,PartialEq,Eq,PartialOrd,Ord)]
-pub struct CharPosition {
-    pub line   : usize,
-    pub column : usize,
-}
-
 /// References to all needed stuff for generating buffer's data.
 pub struct RefreshInfo<'a, 'b> {
     pub lines            : &'a mut [Line],
@@ -177,7 +207,7 @@ impl TextComponentContent {
     }
 
     /// LineRef structure for line at given index.
-    pub fn line(& mut self, index:usize) -> LineRef {
+    pub fn line(&mut self, index:usize) -> LineRef {
         LineRef {
             line    : &mut self.lines[index],
             line_id : index,
@@ -310,10 +340,10 @@ mod test {
     #[test]
     fn edit_single_line() {
         let text                   = "Line a\nLine b\nLine c";
-        let delete_from            = CharPosition{line:1, column:0};
-        let delete_to              = CharPosition{line:1, column:4};
+        let delete_from            = TextLocation {line:1, column:0};
+        let delete_to              = TextLocation {line:1, column:4};
         let deleted_range          = delete_from..delete_to;
-        let insert                 = TextChange::insert(CharPosition{line:1, column:1}, "ab");
+        let insert                 = TextChange::insert(TextLocation {line:1, column:1}, "ab");
         let delete                 = TextChange::delete(deleted_range.clone());
         let replace                = TextChange::replace(deleted_range, "text");
 
@@ -340,12 +370,12 @@ mod test {
     fn insert_multiple_lines() {
         let text             = "Line a\nLine b\nLine c";
         let inserted         = "Ins a\nIns b";
-        let begin_position   = CharPosition{line:0, column:0};
-        let middle_position  = CharPosition{line:1, column:2};
-        let end_position     = CharPosition{line:2, column:6};
-        let insert_at_begin  = TextChange::insert(begin_position , inserted);
-        let insert_in_middle = TextChange::insert(middle_position, inserted);
-        let insert_at_end    = TextChange::insert(end_position   , inserted);
+        let begin_loc        = TextLocation {line:0, column:0};
+        let middle_loc       = TextLocation {line:1, column:2};
+        let end_loc          = TextLocation {line:2, column:6};
+        let insert_at_begin  = TextChange::insert(begin_loc ,inserted);
+        let insert_in_middle = TextChange::insert(middle_loc,inserted);
+        let insert_at_end    = TextChange::insert(end_loc   ,inserted);
 
         let mut content      = TextComponentContent::new(0,text);
 
@@ -376,8 +406,8 @@ mod test {
     #[test]
     fn delete_multiple_lines() {
         let text          = "Line a\nLine b\nLine c";
-        let delete_from   = CharPosition{line:0, column:2};
-        let delete_to     = CharPosition{line:2, column:3};
+        let delete_from   = TextLocation {line:0, column:2};
+        let delete_to     = TextLocation {line:2, column:3};
         let deleted_range = delete_from..delete_to;
         let delete        = TextChange::delete(deleted_range);
 

gui/lib/core/src/display/shape/text/cursor.rs

@@ -4,7 +4,7 @@ use crate::prelude::*;
 
 use crate::display::render::webgl::Context;
 use crate::display::render::webgl::set_buffer_data;
-use crate::display::shape::text::content::CharPosition;
+use crate::display::shape::text::content::TextLocation;
 use crate::display::shape::text::content::TextComponentContent;
 use crate::display::shape::text::content::line::LineRef;
 use crate::display::shape::text::buffer::glyph_square::point_to_iterable;
@@ -12,34 +12,33 @@ use crate::display::shape::text::font::Fonts;
 
 use nalgebra::Point2;
 use nalgebra::Translation2;
-use std::collections::HashSet;
 use std::cmp::Ordering;
-use std::iter::once;
 use std::ops::Range;
 use web_sys::WebGlBuffer;
 
 
+
 // ==============
 // === Cursor ===
 // ==============
 
 /// Cursor in TextComponent with its selection
-#[derive(Debug)]
+#[derive(Clone,Debug,Eq,PartialEq)]
 pub struct Cursor {
-    pub position    : CharPosition,
-    pub selected_to : CharPosition,
+    pub position    : TextLocation,
+    pub selected_to : TextLocation,
 }
 
 impl Cursor {
     /// Create a new cursor at given position and without any selection.
-    pub fn new(position:CharPosition) -> Self {
+    pub fn new(position:TextLocation) -> Self {
         Cursor {position,
             selected_to : position
         }
     }
 
     /// Get range of selected text by this cursor.
-    pub fn selection_range(&self) -> Range<CharPosition> {
+    pub fn selection_range(&self) -> Range<TextLocation> {
         match self.position.cmp(&self.selected_to) {
             Ordering::Equal   => self.position..self.position,
             Ordering::Greater => self.selected_to..self.position,
@@ -47,8 +46,19 @@ impl Cursor {
         }
     }
 
+    /// Extend the selection to cover the given range. Cursor itself may be moved, and will be
+    /// on the same side of selection as before.
+    pub fn extend_selection(&mut self, range:&Range<TextLocation>) {
+        let new_start = range.start.min(self.position).min(self.selected_to);
+        let new_end   = range.end.max(self.position).max(self.selected_to);
+        *self = match self.position.cmp(&self.selected_to) {
+            Ordering::Less => Cursor{position:new_start, selected_to:new_end  },
+            _              => Cursor{position:new_end  , selected_to:new_start},
+        }
+    }
+
     /// Check if char at given position is selected.
-    pub fn is_char_selected(&self, position:CharPosition) -> bool {
+    pub fn is_char_selected(&self, position:TextLocation) -> bool {
         self.selection_range().contains(&position)
     }
 
@@ -65,20 +75,156 @@ impl Cursor {
     //  (https://www.freetype.org/freetype2/docs/glyphs/glyphs-3.html#section-1).
     pub fn render_position(&self, content:&mut TextComponentContent, fonts:&mut Fonts)
     -> Point2<f64>{
+        let x = Self::x_position_of_cursor_at(&self.position,content,fonts);
+        let y = self.current_line(content).start_point().y;
+        Point2::new(x,y)
+    }
+
+    fn x_position_of_cursor_at
+    (at:&TextLocation, content:&mut TextComponentContent, fonts:&mut Fonts)
+    -> f64 {
         let font     = fonts.get_render_info(content.font);
-        let mut line = self.current_line(content);
-        if self.position.column > 0 {
-            let char_index = self.position.column - 1;
-            let x          = line.get_char_x_range(char_index,font).end;
-            let y          = line.start_point().y;
-            Point2::new(x.into(),y)
+        let mut line = content.line(at.line);
+        if at.column > 0 {
+            let char_index = at.column - 1;
+            line.get_char_x_range(char_index,font).end.into()
         } else {
-            line.start_point()
+            line.start_point().x
         }
     }
 }
 
 
+
+// ==================
+// === Navigation ===
+// ==================
+
+/// An enum representing cursor moving step. The steps are based of possible keystrokes (arrows,
+/// Home, End, Ctrl+Home, etc.)
+#[derive(Debug,Eq,Hash,PartialEq)]
+pub enum Step {Left,Right,Up,Down,LineBegin,LineEnd,DocBegin,DocEnd}
+
+/// A struct for cursor navigation process
+pub struct CursorNavigation<'a,'b> {
+    pub content   : &'a mut TextComponentContent,
+    pub fonts     : &'b mut Fonts,
+    pub selecting : bool
+}
+
+impl<'a,'b> CursorNavigation<'a,'b> {
+    /// Jump cursor directly to given position.
+    pub fn move_cursor_to_position(&self, cursor:&mut Cursor, to:TextLocation) {
+        cursor.position = to;
+        if !self.selecting {
+            cursor.selected_to = to;
+        }
+    }
+
+    /// Move cursor by given step.
+    pub fn move_cursor(&mut self, cursor:&mut Cursor, step:&Step) {
+        let new_position = self.new_position(cursor.position,&step);
+        self.move_cursor_to_position(cursor,new_position);
+    }
+
+    /// Get cursor position at end of given line.
+    pub fn line_end_position(&self, line_index:usize) -> TextLocation {
+        TextLocation {
+            line   : line_index,
+            column : self.content.lines[line_index].len(),
+        }
+    }
+
+    /// Get cursor position at end of whole content
+    pub fn content_end_position(&self) -> TextLocation {
+        TextLocation {
+            column : self.content.lines.last().unwrap().len(),
+            line   : self.content.lines.len() - 1,
+        }
+    }
+
+    /// Get cursor position for the next char from given position. Returns none if at end of
+    /// whole document.
+    pub fn next_char_position(&self, position:&TextLocation) -> Option<TextLocation> {
+        let current_line = &self.content.lines[position.line];
+        let next_column  = Some(position.column + 1).filter(|c| *c <= current_line.len());
+        let next_line    = Some(position.line + 1)  .filter(|l| *l < self.content.lines.len());
+        match (next_column,next_line) {
+            (None         , None      ) => None,
+            (None         , Some(line)) => Some(TextLocation::at_line_begin(line)),
+            (Some(column) , _         ) => Some(TextLocation {column, ..*position})
+        }
+    }
+
+    /// Get cursor position for the previous char from given position. Returns none if at begin of
+    /// whole document.
+    pub fn prev_char_position(&self, position:&TextLocation) -> Option<TextLocation> {
+        let prev_column = position.column.checked_sub(1);
+        let prev_line   = position.line.checked_sub(1);
+        match (prev_column,prev_line) {
+            (None         , None      ) => None,
+            (None         , Some(line)) => Some(self.line_end_position(line)),
+            (Some(column) , _         ) => Some(TextLocation {column, ..*position})
+        }
+    }
+
+    /// Get cursor position one line above the given position, such the new x coordinate of
+    /// displayed cursor on the screen will be nearest the current value.
+    pub fn line_up_position(&mut self, position:&TextLocation) -> Option<TextLocation> {
+        let prev_line = position.line.checked_sub(1);
+        prev_line.map(|line| self.near_same_x_in_another_line(position,line))
+    }
+
+    /// Get cursor position one line behind the given position, such the new x coordinate of
+    /// displayed cursor on the screen will be nearest the current value.
+    pub fn line_down_position(&mut self, position:&TextLocation) -> Option<TextLocation> {
+        let next_line = Some(position.line + 1).filter(|l| *l < self.content.lines.len());
+        next_line.map(|line| self.near_same_x_in_another_line(position,line))
+    }
+
+    /// New position of cursor at `position` after applying `step`.
+    fn new_position(&mut self, position: TextLocation, step:&Step) -> TextLocation {
+        match step {
+            Step::Left      => self.prev_char_position(&position).unwrap_or(position),
+            Step::Right     => self.next_char_position(&position).unwrap_or(position),
+            Step::Up        => self.line_up_position(&position).unwrap_or(position),
+            Step::Down      => self.line_down_position(&position).unwrap_or(position),
+            Step::LineBegin => TextLocation::at_line_begin(position.line),
+            Step::LineEnd   => self.line_end_position(position.line),
+            Step::DocBegin  => TextLocation::at_document_begin(),
+            Step::DocEnd    => self.content_end_position(),
+        }
+    }
+
+    /// Get the cursor position on another line, such that the new x coordinate of
+    /// displayed cursor on the screen will be nearest the current value.
+    fn near_same_x_in_another_line(&mut self, position:&TextLocation, line:usize)
+    -> TextLocation {
+        let x_position = Cursor::x_position_of_cursor_at(position,self.content,self.fonts);
+        let column     = self.column_near_x(line,x_position);
+        TextLocation {line,column}
+    }
+
+    /// Get the column number in given line, so the cursor will be as near as possible the
+    /// `x_position` in _text space_. See `display::shape::text::content::line::Line`
+    /// documentation for details about _text space_.
+    fn column_near_x(&mut self, line_index:usize, x_position:f64) -> usize {
+        let font                    = self.fonts.get_render_info(self.content.font);
+        let mut line                = self.content.line(line_index);
+        let x                       = x_position as f32;
+        let char_at_x               = line.find_char_at_x_position(x,font);
+        let nearer_to_end           = |range:Range<f32>| range.end - x < x - range.start;
+        let mut nearer_to_chars_end = |index| nearer_to_end(line.get_char_x_range(index,font));
+        match char_at_x {
+            Some(index) if nearer_to_chars_end(index) => index + 1,
+            Some(index)                               => index,
+            None                                      => line.len()
+        }
+    }
+}
+
+
+
 // ===============
 // === Cursors ===
 // ===============
@@ -102,9 +248,9 @@ lazy_static! {
 /// a WebGL buffer with vertex positions of all cursors.
 #[derive(Debug)]
 pub struct Cursors {
-    pub cursors       : Vec<Cursor>,
-    pub dirty_cursors : HashSet<usize>,
-    pub buffer        : WebGlBuffer,
+    pub cursors : Vec<Cursor>,
+    pub dirty   : bool,
+    pub buffer  : Option<WebGlBuffer>,
 }
 
 impl Cursors {
@@ -112,33 +258,92 @@ impl Cursors {
     /// Create empty `Cursors` structure.
     pub fn new(gl_context:&Context) -> Self {
         Cursors {
-            cursors       : Vec::new(),
-            dirty_cursors : HashSet::new(),
-            buffer        : gl_context.create_buffer().unwrap()
+            cursors : Vec::new(),
+            dirty   : false,
+            buffer  : gl_context.create_buffer()
         }
     }
 
-    /// Removes all current cursors and replace them with single cursor without any selection.
-    pub fn set_cursor(&mut self, position:CharPosition) {
-        self.cursors       = vec![Cursor::new(position)];
-        self.dirty_cursors = once(0).collect();
-    }
-
-    /// Add new cursor without selection.
-    pub fn add_cursor(&mut self, position:CharPosition) {
-        let new_index = self.cursors.len();
-        self.cursors.push(Cursor::new(position));
-        self.dirty_cursors.insert(new_index);
-    }
-
     /// Update the cursors' buffer data.
     pub fn update_buffer_data
     (&mut self, gl_context:&Context, content:&mut TextComponentContent, fonts:&mut Fonts) {
         let cursors          = self.cursors.iter();
         let cursors_vertices = cursors.map(|cursor| Self::cursor_vertices(cursor,content,fonts));
         let buffer_data      = cursors_vertices.flatten().collect_vec();
-        set_buffer_data(gl_context,&self.buffer,buffer_data.as_slice());
-        self.dirty_cursors.clear();
+        set_buffer_data(gl_context,self.buffer.as_ref().unwrap(),buffer_data.as_slice());
+        self.dirty = false;
+    }
+
+    /// Removes all current cursors and replace them with single cursor without any selection.
+    pub fn set_cursor(&mut self, position: TextLocation) {
+        self.cursors = vec![Cursor::new(position)];
+        self.dirty   = true;
+    }
+
+    /// Add new cursor without selection.
+    pub fn add_cursor(&mut self, position: TextLocation) {
+        self.cursors.push(Cursor::new(position));
+        self.merge_overlapping_cursors();
+        self.dirty = true;
+    }
+
+    /// Do the navigation step of all cursors.
+    ///
+    /// If after this operation some of the cursors occupies the same position, or their selected
+    /// area overlap, they are irreversibly merged.
+    pub fn navigate_all_cursors(&mut self, navigaton:&mut CursorNavigation, step:&Step) {
+        self.cursors.iter_mut().for_each(|cursor| navigaton.move_cursor(cursor,&step));
+        self.merge_overlapping_cursors();
+        self.dirty = true;
+    }
+
+    /// Number of vertices in cursors' buffer.
+    pub fn vertices_count(&self) -> usize {
+        self.cursors.len() * CURSOR_BASE_LAYOUT_SIZE
+    }
+
+    /// Merge overlapping cursors
+    ///
+    /// This function checks all cursors, and merge each pair where cursors are at the same position
+    /// or their selection overlap.
+    ///
+    /// The merged pair will be replaced with one cursor with selection being a sum of selections of
+    /// removed cursors.
+    fn merge_overlapping_cursors(&mut self) {
+        if !self.cursors.is_empty() {
+            self.cursors.sort_by_key(|c| c.position);
+            let mut i          = 1;
+            while i < self.cursors.len() {
+                let merged = self.merged_selection_range(i - 1,i);
+                match merged {
+                    Some(merged_range) => {
+                        self.cursors[i-1].extend_selection(&merged_range);
+                        self.cursors.remove(i);
+                    },
+                    None => {
+                        i += 1
+                    }
+                };
+            }
+        }
+    }
+
+    /// Checks if two cursors should be merged and returns new selection range after merging if they
+    /// shoukd, and `None` otherwise.
+    fn merged_selection_range(&self, left_cursor_index:usize, right_cursor_index:usize)
+    -> Option<Range<TextLocation>> {
+        let left_cursor_position        = self.cursors[left_cursor_index].position;
+        let left_cursor_range           = self.cursors[left_cursor_index].selection_range();
+        let right_cursor_position       = self.cursors[right_cursor_index].position;
+        let right_cursor_range          = self.cursors[right_cursor_index].selection_range();
+        let are_cursor_at_same_position = left_cursor_position == right_cursor_position;
+        let are_ranges_overlapping      = right_cursor_range.start < left_cursor_range.end;
+        let are_cursors_merged          = are_cursor_at_same_position || are_ranges_overlapping;
+        are_cursors_merged.and_option_from(|| {
+            let new_start = left_cursor_range.start.min(right_cursor_range.start);
+            let new_end   = left_cursor_range.end  .max(right_cursor_range.end  );
+            Some(new_start..new_end)
+        })
     }
 
     fn cursor_vertices(cursor:&Cursor, content:&mut TextComponentContent, fonts:&mut Fonts)
@@ -150,8 +355,146 @@ impl Cursors {
         on_position.map(point_to_iterable).flatten().collect()
     }
 
-    /// Number of vertices in cursors' buffer.
-    pub fn vertices_count(&self) -> usize {
-        self.cursors.len() * CURSOR_BASE_LAYOUT_SIZE
+    #[cfg(test)]
+    fn mock(cursors:Vec<Cursor>) -> Self {
+        Cursors{cursors,
+            dirty  : false,
+            buffer : None
+        }
+    }
+}
+
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use Step::*;
+
+    use basegl_core_msdf_sys::test_utils::TestAfterInit;
+    use std::future::Future;
+    use wasm_bindgen_test::wasm_bindgen_test;
+    use wasm_bindgen_test::wasm_bindgen_test_configure;
+    use crate::display::shape::text::cursor::Step::{LineBegin, DocBegin, LineEnd};
+
+    wasm_bindgen_test_configure!(run_in_browser);
+
+    #[wasm_bindgen_test(async)]
+    fn moving_cursors() -> impl Future<Output=()> {
+        TestAfterInit::schedule(||{
+            let text        = "FirstLine.\nSecondLine\nThirdLine";
+            let initial_cursors = vec!
+                [ Cursor::new(TextLocation {line:0, column:0 })
+                , Cursor::new(TextLocation {line:1, column:0 })
+                , Cursor::new(TextLocation {line:1, column:6 })
+                , Cursor::new(TextLocation {line:1, column:10})
+                , Cursor::new(TextLocation {line:2, column:9 })
+                ];
+            let mut expected_positions = HashMap::<Step,Vec<(usize,usize)>>::new();
+            expected_positions.insert(Left,      vec![(0,0),(0,10),(1,5),(1,9),(2,8)]);
+            expected_positions.insert(Right,     vec![(0,1),(1,1),(1,7),(2,0),(2,9)]);
+            expected_positions.insert(Up,        vec![(0,0),(0,6),(0,10),(1,9)]);
+            expected_positions.insert(Down,      vec![(1,0),(2,0),(2,6),(2,9)]);
+            expected_positions.insert(LineBegin, vec![(0,0),(1,0),(2,0)]);
+            expected_positions.insert(LineEnd,   vec![(0,10),(1,10),(2,9)]);
+            expected_positions.insert(DocBegin,  vec![(0,0)]);
+            expected_positions.insert(DocEnd,    vec![(2,9)]);
+
+            let mut fonts      = Fonts::new();
+            let font           = fonts.load_embedded_font("DejaVuSansMono").unwrap();
+            let mut content    = TextComponentContent::new(font,text);
+            let mut navigation = CursorNavigation {
+                content: &mut content,
+                fonts: &mut fonts,
+                selecting: false
+            };
+
+            for step in &[Left,Right,Up,Down,LineBegin,LineEnd,DocBegin,DocEnd] {
+                let mut cursors = Cursors::mock(initial_cursors.clone());
+
+                cursors.navigate_all_cursors(&mut navigation,step);
+                let expected = expected_positions.get(step).unwrap();
+                let current  = cursors.cursors.iter().map(|c| (c.position.line, c.position.column));
+                assert_eq!(expected,&current.collect_vec(), "Error for step {:?}", step);
+            }
+        })
+    }
+
+    #[wasm_bindgen_test(async)]
+    fn moving_without_select() -> impl Future<Output=()> {
+        TestAfterInit::schedule(||{
+            let text              = "FirstLine\nSecondLine";
+            let initial_cursor   = Cursor {
+                position    : TextLocation {line:1, column:0},
+                selected_to : TextLocation {line:0, column:1}
+            };
+            let initial_cursors   = vec![initial_cursor];
+            let new_position      = TextLocation {line:1,column:10};
+
+            let mut fonts      = Fonts::new();
+            let font           = fonts.load_embedded_font("DejaVuSansMono").unwrap();
+            let mut content    = TextComponentContent::new(font,text);
+            let mut navigation = CursorNavigation {
+                content: &mut content,
+                fonts: &mut fonts,
+                selecting: false
+            };
+            let mut cursors    = Cursors::mock(initial_cursors.clone());
+            cursors.navigate_all_cursors(&mut navigation,&LineEnd);
+            assert_eq!(new_position, cursors.cursors.first().unwrap().position);
+            assert_eq!(new_position, cursors.cursors.first().unwrap().selected_to);
+        })
+    }
+
+    #[wasm_bindgen_test(async)]
+    fn moving_with_select() -> impl Future<Output=()> {
+        TestAfterInit::schedule(||{
+            let text              = "FirstLine\nSecondLine";
+            let initial_loc     = TextLocation {line:0,column:1};
+            let initial_cursors = vec![Cursor::new(initial_loc)];
+            let new_loc         = TextLocation {line:0,column:9};
+
+            let mut fonts      = Fonts::new();
+            let font           = fonts.load_embedded_font("DejaVuSansMono").unwrap();
+            let mut content    = TextComponentContent::new(font,text);
+            let mut navigation = CursorNavigation {
+                content: &mut content,
+                fonts: &mut fonts,
+                selecting: true
+            };
+            let mut cursors = Cursors::mock(initial_cursors.clone());
+            cursors.navigate_all_cursors(&mut navigation,&LineEnd);
+            assert_eq!(new_loc    , cursors.cursors.first().unwrap().position);
+            assert_eq!(initial_loc, cursors.cursors.first().unwrap().selected_to);
+        })
+    }
+
+    #[wasm_bindgen_test(async)]
+    fn merging_selection_after_moving() -> impl Future<Output=()> {
+        TestAfterInit::schedule(||{
+            let make_char_loc  = |(line,column):(usize,usize)| TextLocation {line,column};
+            let cursor_on_left = |range:&Range<(usize,usize)>| Cursor {
+                position    : make_char_loc(range.start),
+                selected_to : make_char_loc(range.end)
+            };
+            let cursor_on_right = |range:&Range<(usize,usize)>| Cursor {
+                position    : make_char_loc(range.end),
+                selected_to : make_char_loc(range.start)
+            };
+            merging_selection_after_moving_case(cursor_on_left);
+            merging_selection_after_moving_case(cursor_on_right);
+        })
+    }
+
+    fn merging_selection_after_moving_case<F>(convert:F)
+    where F : FnMut(&Range<(usize,usize)>) -> Cursor + Clone {
+        let ranges           = vec![(1,4)..(1,5), (0,0)..(0,5), (0,2)..(1,0), (1,5)..(2,0)];
+        let expected_ranges  = vec![(0,0)..(1,0), (1,4)..(1,5), (1,5)..(2,0)];
+        let initial_cursors  = ranges.iter().map(convert.clone()).collect_vec();
+        let expected_cursors = expected_ranges.iter().map(convert).collect_vec();
+        let mut cursors      = Cursors::mock(initial_cursors);
+
+        cursors.merge_overlapping_cursors();
+
+        assert_eq!(expected_cursors, cursors.cursors);
     }
 }

gui/lib/core/src/examples/text.rs

@@ -8,11 +8,13 @@ use crate::data::dirty::traits::*;
 
 use nalgebra::Point2;
 use nalgebra::Vector2;
-use crate::display::shape::text::content::CharPosition;
+use crate::display::shape::text::content::TextLocation;
 use crate::display::shape::text::content::TextChange;
-use crate::display::shape::text::{TextComponentBuilder, Color};
+use crate::display::shape::text::TextComponentBuilder;
+use crate::display::shape::text::Color;
 use crate::display::shape::text::TextComponentProperties;
 use crate::system::web::forward_panic_hook_to_console;
+use crate::display::shape::text::cursor::Step::Right;
 
 #[wasm_bindgen]
 #[allow(dead_code)]
@@ -38,7 +40,7 @@ pub fn run_example_text() {
                     color: Color { r: 0.0, g: 0.8, b: 0.0, a: 1.0 },
                 }
             }.build();
-            text_component.cursors.add_cursor(CharPosition { line: 0, column: 0 });
+            text_component.cursors.add_cursor(TextLocation { line: 0, column: 0 });
             workspace.text_components.push(text_component);
             world.workspace_dirty.set();
         }
@@ -71,10 +73,11 @@ fn animate_text_component
 ( world:&World
 , typed_chars:&mut Vec<CharToPush>
 , start_scrolling:f64) {
-    let mut world   = world.rc.borrow_mut();
-    let workspace   = &mut world.workspace;
-    let editor      = workspace.text_components.first_mut().unwrap();
-    let now         = js_sys::Date::now();
+    let world : &mut WorldData = &mut world.rc.borrow_mut();
+    let workspace              = &mut world.workspace;
+    let editor                 = workspace.text_components.first_mut().unwrap();
+    let fonts                  = &mut world.fonts;
+    let now                    = js_sys::Date::now();
 
     let to_type_now = typed_chars.drain_filter(|ch| ch.time <= now);
     for ch in to_type_now {
@@ -82,12 +85,7 @@ fn animate_text_component
         let string = ch.a_char.to_string();
         let change = TextChange::insert(cursor.position, string.as_str());
         editor.content.make_change(change);
-        let new_cursor_position = CharPosition {
-            line: editor.content.lines.len()-1,
-            column : editor.content.lines.last().unwrap().len(),
-        };
-        cursor.position = new_cursor_position;
-        editor.cursors.dirty_cursors.insert(0);
+        editor.navigate_cursors(Right,false,fonts);
     }
     if start_scrolling <= js_sys::Date::now() {
         editor.scroll(Vector2::new(0.0, -0.01));

gui/lib/core/tests/text.rs

@@ -76,7 +76,7 @@ mod tests {
     use super::WorldTest;
     use basegl::display::shape::text::Color;
     use basegl::display::shape::text::content::TextChange;
-    use basegl::display::shape::text::content::CharPosition;
+    use basegl::display::shape::text::content::TextLocation;
     use basegl::display::shape::text::TextComponentBuilder;
     use basegl::display::world::WorldData;
     use basegl::display::shape::text::TextComponentProperties;
@@ -185,8 +185,8 @@ mod tests {
                     for _ in 0..20 {
                         let workspace      = &mut world.workspace;
                         let text_component = &mut workspace.text_components[0];
-                        let replace_from   = CharPosition{line:1, column:2};
-                        let replace_to     = CharPosition{line:1, column:3};
+                        let replace_from   = TextLocation {line:1, column:2};
+                        let replace_to     = TextLocation {line:1, column:3};
                         let replaced_range = replace_from..replace_to;
                         let change         = TextChange::replace(replaced_range, "abc");
                         text_component.content.make_change(change);
@@ -208,8 +208,8 @@ mod tests {
                     let world : &mut WorldData = &mut world_test.world_ptr.borrow_mut();
                     let workspace      = &mut world.workspace;
                     let text_component = &mut workspace.text_components[0];
-                    let position       = CharPosition{line:1, column:0};
-                    let change         = TextChange::insert(position, TEST_TEXT);
+                    let location       = TextLocation {line:1, column:0};
+                    let change         = TextChange::insert(location,TEST_TEXT);
                     text_component.content.make_change(change);
                     world.workspace_dirty.set();
                     world.update();
@@ -256,10 +256,10 @@ mod tests {
                 text: text.clone()
             };
             let mut text_component = builder.build();
-            let cursor_position_1  = CharPosition{line:0, column: 10};
-            let cursor_position_2  = CharPosition{line:1, column: 6};
-            text_component.cursors.add_cursor(cursor_position_1);
-            text_component.cursors.add_cursor(cursor_position_2);
+            let cursor_loc_1       = TextLocation {line:0, column: 10};
+            let cursor_loc_2       = TextLocation {line:1, column: 6};
+            text_component.cursors.add_cursor(cursor_loc_1);
+            text_component.cursors.add_cursor(cursor_loc_2);
             workspace.text_components.push(text_component);
         }
         world.workspace_dirty.set();