LibGUI: Support multiple GTextEditors editing the same GTextDocument

With this patch, you can now assign the same GTextDocument to multiple
GTextEditor widgets via GTextEditor::set_document().

The editors have independent cursors and selection, but all changes
are shared, and immediately propagate to all editors.

This is very unoptimized and will do lots of unnecessary invalidation,
especially line re-wrapping and repainting over and over again.

1 files changed, 53 insertions, 30 deletions

diff --git a/Libraries/LibGUI/GTextEditor.cpp b/Libraries/LibGUI/GTextEditor.cpp
index 20012e4b69..9b991eaff6 100644
--- a/Libraries/LibGUI/GTextEditor.cpp
+++ b/Libraries/LibGUI/GTextEditor.cpp
@@ -19,8 +19,7 @@ GTextEditor::GTextEditor(Type type, GWidget* parent)
     : GScrollableWidget(parent)
     , m_type(type)
 {
-    m_document = GTextDocument::create(this);
-    m_document->register_client(*this);
+    set_document(GTextDocument::create());
     set_frame_shape(FrameShape::Container);
     set_frame_shadow(FrameShadow::Sunken);
     set_frame_thickness(2);
@@ -632,7 +631,7 @@ void GTextEditor::keydown_event(GKeyEvent& event)
 
             // Backspace within line
             for (int i = 0; i < erase_count; ++i) {
-                current_line().remove(m_cursor.column() - 1 - i);
+                current_line().remove(document(), m_cursor.column() - 1 - i);
             }
             update_content_size();
             set_cursor(m_cursor.line(), m_cursor.column() - erase_count);
@@ -643,9 +642,8 @@ void GTextEditor::keydown_event(GKeyEvent& event)
             // Backspace at column 0; merge with previous line
             auto& previous_line = lines()[m_cursor.line() - 1];
             int previous_length = previous_line.length();
-            previous_line.append(current_line().characters(), current_line().length());
-            lines().remove(m_cursor.line());
-            m_line_visual_data.remove(m_cursor.line());
+            previous_line.append(document(), current_line().characters(), current_line().length());
+            document().remove_line(m_cursor.line());
             update_content_size();
             update();
             set_cursor(m_cursor.line() - 1, previous_length);
@@ -678,10 +676,9 @@ void GTextEditor::delete_current_line()
     if (has_selection())
         return delete_selection();
 
-    lines().remove(m_cursor.line());
-    m_line_visual_data.remove(m_cursor.line());
+    document().remove_line(m_cursor.line());
     if (lines().is_empty())
-        document().append_line(make<GTextDocumentLine>());
+        document().append_line(make<GTextDocumentLine>(document()));
 
     update_content_size();
     update();
@@ -697,7 +694,7 @@ void GTextEditor::do_delete()
 
     if (m_cursor.column() < current_line().length()) {
         // Delete within line
-        current_line().remove(m_cursor.column());
+        current_line().remove(document(), m_cursor.column());
         did_change();
         update_cursor();
         return;
@@ -706,9 +703,8 @@ void GTextEditor::do_delete()
         // Delete at end of line; merge with next line
         auto& next_line = lines()[m_cursor.line() + 1];
         int previous_length = current_line().length();
-        current_line().append(next_line.characters(), next_line.length());
-        lines().remove(m_cursor.line() + 1);
-        m_line_visual_data.remove(m_cursor.line() + 1);
+        current_line().append(document(), next_line.characters(), next_line.length());
+        document().remove_line(m_cursor.line() + 1);
         update();
         did_change();
         set_cursor(m_cursor.line(), previous_length);
@@ -743,15 +739,15 @@ void GTextEditor::insert_at_cursor(char ch)
                 if (leading_spaces)
                     new_line_contents = String::repeated(' ', leading_spaces);
             }
-            document().insert_line(m_cursor.line() + (at_tail ? 1 : 0), make<GTextDocumentLine>(new_line_contents));
+            document().insert_line(m_cursor.line() + (at_tail ? 1 : 0), make<GTextDocumentLine>(document(), new_line_contents));
             update();
             did_change();
             set_cursor(m_cursor.line() + 1, lines()[m_cursor.line() + 1].length());
             return;
         }
-        auto new_line = make<GTextDocumentLine>();
-        new_line->append(current_line().characters() + m_cursor.column(), current_line().length() - m_cursor.column());
-        current_line().truncate(m_cursor.column());
+        auto new_line = make<GTextDocumentLine>(document());
+        new_line->append(document(), current_line().characters() + m_cursor.column(), current_line().length() - m_cursor.column());
+        current_line().truncate(document(), m_cursor.column());
         document().insert_line(m_cursor.line() + 1, move(new_line));
         update();
         did_change();
@@ -762,13 +758,13 @@ void GTextEditor::insert_at_cursor(char ch)
         int next_soft_tab_stop = ((m_cursor.column() + m_soft_tab_width) / m_soft_tab_width) * m_soft_tab_width;
         int spaces_to_insert = next_soft_tab_stop - m_cursor.column();
         for (int i = 0; i < spaces_to_insert; ++i) {
-            current_line().insert(m_cursor.column(), ' ');
+            current_line().insert(document(), m_cursor.column(), ' ');
         }
         did_change();
         set_cursor(m_cursor.line(), next_soft_tab_stop);
         return;
     }
-    current_line().insert(m_cursor.column(), ch);
+    current_line().insert(document(), m_cursor.column(), ch);
     did_change();
     set_cursor(m_cursor.line(), m_cursor.column() + 1);
 }
@@ -993,9 +989,8 @@ String GTextEditor::text() const
 
 void GTextEditor::clear()
 {
-    lines().clear();
-    m_line_visual_data.clear();
-    document().append_line(make<GTextDocumentLine>());
+    document().remove_all_lines();
+    document().append_line(make<GTextDocumentLine>(document()));
     m_selection.clear();
     did_update_selection();
     set_cursor(0, 0);
@@ -1030,8 +1025,7 @@ void GTextEditor::delete_selection()
 
     // First delete all the lines in between the first and last one.
     for (int i = selection.start().line() + 1; i < selection.end().line();) {
-        lines().remove(i);
-        m_line_visual_data.remove(i);
+        document().remove_line(i);
         selection.end().set_line(selection.end().line() - 1);
     }
 
@@ -1040,14 +1034,14 @@ void GTextEditor::delete_selection()
         auto& line = lines()[selection.start().line()];
         bool whole_line_is_selected = selection.start().column() == 0 && selection.end().column() == line.length();
         if (whole_line_is_selected) {
-            line.clear();
+            line.clear(document());
         } else {
             auto before_selection = String(line.characters(), line.length()).substring(0, selection.start().column());
             auto after_selection = String(line.characters(), line.length()).substring(selection.end().column(), line.length() - selection.end().column());
             StringBuilder builder(before_selection.length() + after_selection.length());
             builder.append(before_selection);
             builder.append(after_selection);
-            line.set_text(builder.to_string());
+            line.set_text(document(), builder.to_string());
         }
     } else {
         // Delete across a newline, merging lines.
@@ -1059,13 +1053,12 @@ void GTextEditor::delete_selection()
         StringBuilder builder(before_selection.length() + after_selection.length());
         builder.append(before_selection);
         builder.append(after_selection);
-        first_line.set_text(builder.to_string());
-        lines().remove(selection.end().line());
-        m_line_visual_data.remove(selection.end().line());
+        first_line.set_text(document(), builder.to_string());
+        document().remove_line(selection.end().line());
     }
 
     if (lines().is_empty()) {
-        document().append_line(make<GTextDocumentLine>());
+        document().append_line(make<GTextDocumentLine>(document()));
     }
 
     m_selection.clear();
@@ -1415,20 +1408,50 @@ void GTextEditor::did_change_font()
 void GTextEditor::document_did_append_line()
 {
     m_line_visual_data.append(make<LineVisualData>());
+    recompute_all_visual_lines();
+    update();
 }
 
 void GTextEditor::document_did_remove_line(int line_index)
 {
     m_line_visual_data.remove(line_index);
+    recompute_all_visual_lines();
+    update();
 }
 
 void GTextEditor::document_did_remove_all_lines()
 {
     m_line_visual_data.clear();
+    recompute_all_visual_lines();
+    update();
 }
 
 void GTextEditor::document_did_insert_line(int line_index)
 {
     m_line_visual_data.insert(line_index, make<LineVisualData>());
+    recompute_all_visual_lines();
+    update();
+}
+
+void GTextEditor::document_did_change()
+{
+    recompute_all_visual_lines();
+    update();
 }
 
+void GTextEditor::set_document(GTextDocument& document)
+{
+    if (m_document.ptr() == &document)
+        return;
+    if (m_document)
+        m_document->unregister_client(*this);
+    m_document = document;
+    m_line_visual_data.clear();
+    for (int i = 0; i < m_document->line_count(); ++i) {
+        m_line_visual_data.append(make<LineVisualData>());
+    }
+    m_cursor = { 0, 0 };
+    recompute_all_visual_lines();
+    update();
+    m_document->register_client(*this);
+}