QmlDesigner: Synchronize selection with cursor position

We always the select the item that contains the cursor,
so the user can use the property editor.
This even works for non visible items.

Change-Id: I5573e6d9be4b478f764ab6960a3b5742136dcee9
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/qmldesigner/components/texteditor/texteditorwidget.cpp

@@ -26,6 +26,7 @@
 #include "texteditorwidget.h"
 
 #include <texteditorview.h>
+#include <rewriterview.h>
 
 #include <theming.h>
 
@@ -42,12 +43,20 @@ TextEditorWidget::TextEditorWidget(TextEditorView *textEditorView) : QWidget()
     QBoxLayout *layout = new QVBoxLayout(this);
     layout->setMargin(0);
 
+    m_updateSelectionTimer.setSingleShot(true);
+    m_updateSelectionTimer.setInterval(200);
+
+    connect(&m_updateSelectionTimer, &QTimer::timeout, this, &TextEditorWidget::updateSelectionByCursorPosition);
     setStyleSheet(Theming::replaceCssColors(QString::fromUtf8(Utils::FileReader::fetchQrc(QLatin1String(":/qmldesigner/scrollbar.css")))));
 }
 
 void TextEditorWidget::setTextEditor(TextEditor::BaseTextEditor *textEditor) {
     m_textEditor.reset(textEditor);
     layout()->addWidget(textEditor->editorWidget());
+
+
+    connect(textEditor->editorWidget(), &QPlainTextEdit::cursorPositionChanged,
+            &m_updateSelectionTimer, static_cast<void (QTimer::*)()>(&QTimer::start));
 }
 
 QString TextEditorWidget::contextHelpId() const
@@ -55,4 +64,20 @@ QString TextEditorWidget::contextHelpId() const
     return m_textEditorView->contextHelpId();
 }
 
+void TextEditorWidget::updateSelectionByCursorPosition()
+{
+    /* Because of the timer we have to be careful. */
+    if (!m_textEditorView->model())
+        return;
+
+    const int cursorPosition = m_textEditor->editorWidget()->textCursor().position();
+    RewriterView *rewriterView = m_textEditorView->model()->rewriterView();
+
+    if (rewriterView) {
+        ModelNode modelNode = rewriterView->nodeAtTextCursorPosition(cursorPosition);
+        if (modelNode.isValid())
+            m_textEditorView->setSelectedModelNode(modelNode);
+    }
+}
+
 } // namespace QmlDesigner

src/plugins/qmldesigner/components/texteditor/texteditorwidget.h

@@ -27,6 +27,7 @@
 #include <texteditor/texteditor.h>
 
 #include <QWidget>
+#include <QTimer>
 
 #include <memory>
 
@@ -51,8 +52,11 @@ public:
     QString contextHelpId() const;
 
 private:
+    void updateSelectionByCursorPosition();
+
     std::unique_ptr<TextEditor::BaseTextEditor> m_textEditor;
     QPointer<TextEditorView> m_textEditorView;
+    QTimer m_updateSelectionTimer;
 };
 
 } // namespace QmlDesigner