fix wrapping text selection

src/core/text/edit.rs

@@ -1,7 +1,7 @@
 use std::ops::{Deref, DerefMut};
 
 use crate::prelude::*;
-use cosmic_text::{Affinity, Attrs, Cursor, FontSystem, Motion};
+use cosmic_text::{Affinity, Attrs, Cursor, FontSystem, LayoutRun, Motion};
 use unicode_segmentation::UnicodeSegmentation;
 use winit::{
     event::KeyEvent,
@@ -53,38 +53,16 @@ impl Widget for TextEdit {
             TextSelection::Span { start, end } => {
                 let (start, end) = sort_cursors(*start, *end);
                 let line_height = self.attrs.line_height;
-                let mut highlight = |offset, width: f32| {
+                for (top_left, width) in iter_layout_lines(&self.buf, &start, &end) {
                     painter.primitive_within(
                         RectPrimitive::color(Color::SKY),
                         vec2(width, line_height)
                             .align(Align::TOP_LEFT)
-                            .offset(offset)
+                            .offset(top_left)
                             .within(&region),
                     );
-                };
-                if let (Some(start_offset), Some(end_offset)) =
-                    (cursor_pos(&start, &self.buf), cursor_pos(&end, &self.buf))
-                {
-                    let mut iter = self.buf.layout_runs().skip(start.line);
-                    if start.line == end.line {
-                        highlight(start_offset, end_offset.x - start_offset.x);
-                    } else {
-                        let first = iter.next().unwrap();
-                        highlight(start_offset, first.line_w - start_offset.x);
-                        for i in (start.line + 1)..end.line {
-                            let line = iter.next().unwrap();
-                            let offset = vec2(0.0, i as f32 * line_height);
-                            highlight(offset, line.line_w);
                 }
-                        let offset = vec2(0.0, end.line as f32 * line_height);
-                        highlight(offset, end_offset.x);
-                    }
-                    // painter.primitive_within(
-                    //     RectPrimitive::color(Color::WHITE),
-                    //     size.align(Align::TOP_LEFT)
-                    //         .offset(end_offset)
-                    //         .within(&region),
-                    // );
+                if let Some(end_offset) = cursor_pos(&end, &self.buf) {
                     let size = vec2(1, self.attrs.line_height);
                     painter.primitive_within(
                         RectPrimitive::color(Color::WHITE),
@@ -106,7 +84,67 @@ impl Widget for TextEdit {
     }
 }
 
+/// provides top left + width
+fn iter_layout_lines(
+    buf: &TextBuffer,
+    start: &Cursor,
+    end: &Cursor,
+) -> impl Iterator<Item = (Vec2, f32)> {
+    gen {
+        let mut iter = buf.layout_runs();
+        for line in iter.by_ref() {
+            if line.line_i == start.line
+                && let Some(start_x) = index_x(&line, start.index)
+            {
+                if start.line == end.line
+                    && let Some(end_x) = index_x(&line, end.index)
+                {
+                    yield (vec2(start_x, line.line_top), end_x - start_x);
+                    return;
+                }
+                yield (vec2(start_x, line.line_top), line.line_w - start_x);
+                break;
+            }
+        }
+        for line in iter {
+            if line.line_i == end.line
+                && let Some(end_x) = index_x(&line, end.index)
+            {
+                yield (vec2(0.0, line.line_top), end_x);
+                return;
+            }
+            yield (vec2(0.0, line.line_top), line.line_w);
+        }
+    }
+}
+
 /// copied & modified from fn found in Editor in cosmic_text
+/// returns x pos of a (non layout) index within an layout run
+fn index_x(run: &LayoutRun, index: usize) -> Option<f32> {
+    for glyph in run.glyphs.iter() {
+        if index == glyph.start {
+            return Some(glyph.x);
+        } else if index > glyph.start && index < glyph.end {
+            // Guess x offset based on characters
+            let mut before = 0;
+            let mut total = 0;
+
+            let cluster = &run.text[glyph.start..glyph.end];
+            for (i, _) in cluster.grapheme_indices(true) {
+                if glyph.start + i < index {
+                    before += 1;
+                }
+                total += 1;
+            }
+
+            let offset = glyph.w * (before as f32) / (total as f32);
+            return Some(glyph.x + offset);
+        }
+    }
+    None
+}
+
+/// returns top of line segment where cursor should visually select
 fn cursor_pos(cursor: &Cursor, buf: &TextBuffer) -> Option<Vec2> {
     let mut prev = None;
     for run in buf
@@ -115,25 +153,8 @@ fn cursor_pos(cursor: &Cursor, buf: &TextBuffer) -> Option<Vec2> {
         .take_while(|r| r.line_i == cursor.line)
     {
         prev = Some(vec2(run.line_w, run.line_top));
-        for glyph in run.glyphs.iter() {
-            if cursor.index == glyph.start {
-                return Some(vec2(glyph.x, run.line_top));
-            } else if cursor.index > glyph.start && cursor.index < glyph.end {
-                // Guess x offset based on characters
-                let mut before = 0;
-                let mut total = 0;
-
-                let cluster = &run.text[glyph.start..glyph.end];
-                for (i, _) in cluster.grapheme_indices(true) {
-                    if glyph.start + i < cursor.index {
-                        before += 1;
-                    }
-                    total += 1;
-                }
-
-                let offset = glyph.w * (before as f32) / (total as f32);
-                return Some(vec2(glyph.x + offset, run.line_top));
-            }
+        if let Some(pos) = index_x(&run, cursor.index) {
+            return Some(vec2(pos, run.line_top));
         }
     }
     prev

src/lib.rs

@@ -8,6 +8,7 @@
 #![feature(const_cmp)]
 #![feature(const_destruct)]
 #![feature(portable_simd)]
+#![feature(gen_blocks)]
 
 pub mod core;
 pub mod layout;