LibGUI: Store Utf32Views in TextEditor::LineVisualData

Previously this stored the position of each visual line break, meaning
that all the text would always be painted. By storing each visual
line's Utf32View, we can skip over parts of the text, such as for code
folding.

2 files changed, 19 insertions, 13 deletions

diff --git a/Userland/Libraries/LibGUI/TextEditor.cpp b/Userland/Libraries/LibGUI/TextEditor.cpp
index a9f435a6a4..a6c4acac7c 100644
--- a/Userland/Libraries/LibGUI/TextEditor.cpp
+++ b/Userland/Libraries/LibGUI/TextEditor.cpp
@@ -533,7 +533,7 @@ void TextEditor::paint_event(PaintEvent& event)
                 first_visual_line_with_selection = visual_line_containing(line_index, selection.start().column());
 
             if (selection.end().line() > line_index)
-                last_visual_line_with_selection = m_line_visual_data[line_index].visual_line_breaks.size();
+                last_visual_line_with_selection = m_line_visual_data[line_index].visual_lines.size();
             else
                 last_visual_line_with_selection = visual_line_containing(line_index, selection.end().column());
         }
@@ -1891,27 +1891,33 @@ void TextEditor::recompute_visual_lines(size_t line_index)
     size_t line_width_so_far = 0;
 
     auto& visual_data = m_line_visual_data[line_index];
-    visual_data.visual_line_breaks.clear_with_capacity();
+    visual_data.visual_lines.clear_with_capacity();
 
     auto available_width = visible_text_rect_in_inner_coordinates().width();
     auto glyph_spacing = font().glyph_spacing();
 
     auto wrap_visual_lines_anywhere = [&]() {
+        size_t start_of_visual_line = 0;
         for (auto it = line.view().begin(); it != line.view().end(); ++it) {
             auto it_before_computing_glyph_width = it;
             auto glyph_width = font().glyph_or_emoji_width(it);
 
             if (line_width_so_far + glyph_width + glyph_spacing > available_width) {
-                visual_data.visual_line_breaks.append(line.view().iterator_offset(it_before_computing_glyph_width));
+                auto start_of_next_visual_line = line.view().iterator_offset(it_before_computing_glyph_width);
+                visual_data.visual_lines.append(line.view().substring_view(start_of_visual_line, start_of_next_visual_line - start_of_visual_line));
                 line_width_so_far = 0;
+                start_of_visual_line = start_of_next_visual_line;
             }
 
             line_width_so_far += glyph_width + glyph_spacing;
         }
+
+        visual_data.visual_lines.append(line.view().substring_view(start_of_visual_line, line.view().length() - start_of_visual_line));
     };
 
     auto wrap_visual_lines_at_words = [&]() {
         size_t last_boundary = 0;
+        size_t start_of_visual_line = 0;
 
         Unicode::for_each_word_segmentation_boundary(line.view(), [&](auto boundary) {
             if (boundary == 0)
@@ -1921,8 +1927,9 @@ void TextEditor::recompute_visual_lines(size_t line_index)
             auto word_width = font().width(word);
 
             if (line_width_so_far + word_width + glyph_spacing > available_width) {
-                visual_data.visual_line_breaks.append(last_boundary);
+                visual_data.visual_lines.append(line.view().substring_view(start_of_visual_line, last_boundary - start_of_visual_line));
                 line_width_so_far = 0;
+                start_of_visual_line = last_boundary;
             }
 
             line_width_so_far += word_width + glyph_spacing;
@@ -1930,10 +1937,13 @@ void TextEditor::recompute_visual_lines(size_t line_index)
 
             return IterationDecision::Continue;
         });
+
+        visual_data.visual_lines.append(line.view().substring_view(start_of_visual_line, line.view().length() - start_of_visual_line));
     };
 
     switch (wrapping_mode()) {
     case WrappingMode::NoWrap:
+        visual_data.visual_lines.append(line.view());
         break;
     case WrappingMode::WrapAnywhere:
         wrap_visual_lines_anywhere();
@@ -1943,10 +1953,8 @@ void TextEditor::recompute_visual_lines(size_t line_index)
         break;
     }
 
-    visual_data.visual_line_breaks.append(line.length());
-
     if (is_wrapping_enabled())
-        visual_data.visual_rect = { m_horizontal_content_padding, 0, available_width, static_cast<int>(visual_data.visual_line_breaks.size()) * line_height() };
+        visual_data.visual_rect = { m_horizontal_content_padding, 0, available_width, static_cast<int>(visual_data.visual_lines.size()) * line_height() };
     else
         visual_data.visual_rect = { m_horizontal_content_padding, 0, text_width_for_font(line.view(), font()), line_height() };
 }
@@ -1955,14 +1963,12 @@ template<typename Callback>
 void TextEditor::for_each_visual_line(size_t line_index, Callback callback) const
 {
     auto editor_visible_text_rect = visible_text_rect_in_inner_coordinates();
-    size_t start_of_line = 0;
     size_t visual_line_index = 0;
 
     auto& line = document().line(line_index);
     auto& visual_data = m_line_visual_data[line_index];
 
-    for (auto visual_line_break : visual_data.visual_line_breaks) {
-        auto visual_line_view = Utf32View(line.code_points() + start_of_line, visual_line_break - start_of_line);
+    for (auto visual_line_view : visual_data.visual_lines) {
         Gfx::IntRect visual_line_rect {
             visual_data.visual_rect.x(),
             visual_data.visual_rect.y() + ((int)visual_line_index * line_height()),
@@ -1976,9 +1982,9 @@ void TextEditor::for_each_visual_line(size_t line_index, Callback callback) cons
             if (m_icon)
                 visual_line_rect.translate_by(icon_size() + icon_padding(), 0);
         }
-        if (callback(visual_line_rect, visual_line_view, start_of_line, visual_line_index == visual_data.visual_line_breaks.size() - 1) == IterationDecision::Break)
+        size_t start_of_line = visual_line_view.code_points() - line.code_points();
+        if (callback(visual_line_rect, visual_line_view, start_of_line, visual_line_index == visual_data.visual_lines.size() - 1) == IterationDecision::Break)
             break;
-        start_of_line = visual_line_break;
         ++visual_line_index;
     }
 }
diff --git a/Userland/Libraries/LibGUI/TextEditor.h b/Userland/Libraries/LibGUI/TextEditor.h
index 1146a0c1f7..00055ed013 100644
--- a/Userland/Libraries/LibGUI/TextEditor.h
+++ b/Userland/Libraries/LibGUI/TextEditor.h
@@ -423,7 +423,7 @@ private:
     void for_each_visual_line(size_t line_index, Callback) const;
 
     struct LineVisualData {
-        Vector<size_t, 1> visual_line_breaks;
+        Vector<Utf32View> visual_lines;
         Gfx::IntRect visual_rect;
     };