GTextEditor: Work on cut/copy/paste operations.

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/48d48679b04

AK/String.cpp

@@ -38,6 +38,8 @@ String String::isolated_copy() const
 
 String String::substring(ssize_t start, ssize_t length) const
 {
+    if (!length)
+        return empty();
     ASSERT(m_impl);
     ASSERT(start + length <= m_impl->length());
     // FIXME: This needs some input bounds checking.

Applications/TextEditor/main.cpp

@@ -8,7 +8,6 @@
 #include <LibGUI/GTextEditor.h>
 #include <LibGUI/GAction.h>
 #include <LibGUI/GFontDatabase.h>
-#include <LibGUI/GClipboard.h>
 #include <AK/StringBuilder.h>
 #include <unistd.h>
 #include <stdio.h>
@@ -80,18 +79,15 @@ int main(int argc, char** argv)
     });
 
     auto cut_action = GAction::create("Cut", { Mod_Ctrl, Key_X }, GraphicsBitmap::load_from_file(GraphicsBitmap::Format::RGBA32, "/res/icons/cut16.rgb", { 16, 16 }), [&] (const GAction&) {
-        dbgprintf("FIXME: Implement Edit/Cut");
+        text_editor->cut();
     });
 
     auto copy_action = GAction::create("Copy", { Mod_Ctrl, Key_C }, GraphicsBitmap::load_from_file(GraphicsBitmap::Format::RGBA32, "/res/icons/copyfile16.rgb", { 16, 16 }), [&] (const GAction&) {
-        auto selected_text = text_editor->selected_text();
-        printf("Copy: \"%s\"\n", selected_text.characters());
-        GClipboard::the().set_data(selected_text);
+        text_editor->copy();
     });
 
     auto paste_action = GAction::create("Paste", { Mod_Ctrl, Key_V }, GraphicsBitmap::load_from_file(GraphicsBitmap::Format::RGBA32, "/res/icons/paste16.rgb", { 16, 16 }), [&] (const GAction&) {
-        auto paste_text = GClipboard::the().data();
-        printf("Paste: \"%s\"\n", paste_text.characters());
+        text_editor->paste();
     });
 
     auto menubar = make<GMenuBar>();

LibGUI/GTextEditor.cpp

@@ -1,6 +1,7 @@
 #include <LibGUI/GTextEditor.h>
 #include <LibGUI/GScrollBar.h>
 #include <LibGUI/GFontDatabase.h>
+#include <LibGUI/GClipboard.h>
 #include <SharedGraphics/Painter.h>
 #include <Kernel/KeyCode.h>
 #include <AK/StringBuilder.h>
@@ -344,6 +345,14 @@ void GTextEditor::keydown_event(GKeyEvent& event)
     return GWidget::keydown_event(event);
 }
 
+void GTextEditor::insert_at_cursor(const String& text)
+{
+    // FIXME: This should obviously not be implemented this way.
+    for (int i = 0; i < text.length(); ++i) {
+        insert_at_cursor(text[i]);
+    }
+}
+
 void GTextEditor::insert_at_cursor(char ch)
 {
     bool at_head = m_cursor.column() == 0;
@@ -449,6 +458,7 @@ void GTextEditor::set_cursor(int line, int column)
 
 void GTextEditor::set_cursor(const GTextPosition& position)
 {
+    ASSERT(!m_lines.is_empty());
     if (m_cursor == position)
         return;
     auto old_cursor_line_rect = line_widget_rect(m_cursor.line());
@@ -596,3 +606,69 @@ String GTextEditor::selected_text() const
 
     return builder.to_string();
 }
+
+void GTextEditor::delete_selection()
+{
+    if (!has_selection())
+        return;
+
+    auto normalized_selection_start = m_selection_start;
+    auto normalized_selection_end = m_cursor;
+    if (m_cursor < m_selection_start)
+        swap(normalized_selection_start, normalized_selection_end);
+
+    for (int i = normalized_selection_start.line(); i <= normalized_selection_end.line();) {
+        auto& line = *m_lines[i];
+        int selection_start_column_on_line = normalized_selection_start.line() == i ? normalized_selection_start.column() : 0;
+        int selection_end_column_on_line = normalized_selection_end.line() == i ? normalized_selection_end.column() : line.length();
+        bool whole_line_is_selected = selection_start_column_on_line == 0 && selection_end_column_on_line == line.length();
+        if (whole_line_is_selected) {
+            m_lines.remove(i);
+            normalized_selection_end.set_line(normalized_selection_end.line() - 1);
+            continue;
+        }
+        auto before_selection = String(line.characters(), line.length()).substring(0, selection_start_column_on_line);
+        auto after_selection = String(line.characters(), line.length()).substring(selection_end_column_on_line, line.length() - selection_end_column_on_line);
+        StringBuilder builder(before_selection.length() + after_selection.length());
+        builder.append(before_selection);
+        builder.append(after_selection);
+        line.set_text(builder.to_string());
+        ++i;
+    }
+
+    if (m_lines.is_empty())
+        m_lines.append(make<Line>());
+
+    m_selection_start = { };
+    set_cursor(normalized_selection_start);
+    update();
+}
+
+void GTextEditor::insert_at_cursor_or_replace_selection(const String& text)
+{
+    if (has_selection())
+        delete_selection();
+    insert_at_cursor(text);
+}
+
+void GTextEditor::cut()
+{
+    auto selected_text = this->selected_text();
+    printf("Cut: \"%s\"\n", selected_text.characters());
+    GClipboard::the().set_data(selected_text);
+    delete_selection();
+}
+
+void GTextEditor::copy()
+{
+    auto selected_text = this->selected_text();
+    printf("Copy: \"%s\"\n", selected_text.characters());
+    GClipboard::the().set_data(selected_text);
+}
+
+void GTextEditor::paste()
+{
+    auto paste_text = GClipboard::the().data();
+    printf("Paste: \"%s\"\n", paste_text.characters());
+    insert_at_cursor_or_replace_selection(paste_text);
+}

LibGUI/GTextEditor.h

@@ -56,6 +56,10 @@ public:
     bool has_selection() const { return m_selection_start.is_valid(); }
     String selected_text() const;
 
+    void cut();
+    void copy();
+    void paste();
+
 private:
     virtual void paint_event(GPaintEvent&) override;
     virtual void resize_event(GResizeEvent&) override;
@@ -98,9 +102,12 @@ private:
     const Line& current_line() const { return *m_lines[m_cursor.line()]; }
     GTextPosition text_position_at(const Point&) const;
     void insert_at_cursor(char);
+    void insert_at_cursor(const String&);
     int ruler_width() const;
     Rect ruler_content_rect(int line) const;
     void toggle_selection_if_needed_for_event(const GKeyEvent&);
+    void insert_at_cursor_or_replace_selection(const String&);
+    void delete_selection();
 
     GScrollBar* m_vertical_scrollbar { nullptr };
     GScrollBar* m_horizontal_scrollbar { nullptr };