[cpp] Add Qt Desginer widget plugin examples

cpp/qt/designer-plugin-collection/textview.h

@@ -0,0 +1,44 @@
+/*##############################################################################
+## Author: Shaun Reed                                                         ##
+## Legal: All Content (c) 2022 Shaun Reed, all rights reserved                ##
+## About: Text viewer for signals and slots examples                          ##
+##                                                                            ##
+## Contact: shaunrd0@gmail.com  | URL: www.shaunreed.com | GitHub: shaunrd0   ##
+################################################################################
+*/
+
+#ifndef KLIPS_TEXTVIEW_H
+#define KLIPS_TEXTVIEW_H
+
+#include "widget-plugin-library_export.h"
+#include <QPlainTextEdit>
+
+class WIDGET_PLUGIN_LIBRARY_EXPORT TextView : public QPlainTextEdit {
+  Q_OBJECT
+
+public:
+  explicit TextView(QWidget *parent = nullptr) : QPlainTextEdit(parent) {
+    appendPlainText("This is an example of a custom QTextView widget.");
+  }
+
+  ~TextView() = default;
+
+  QString includeFile() const { return QStringLiteral("text-view.h"); };
+public:
+signals:
+  void sendTest();
+
+private:
+signals:
+  void sentTestPrivate();
+
+public slots:
+  void test() { appendPlainText("Test signal received by TextView."); }
+
+  void testArgs(const QString &message) { appendPlainText(message); }
+
+private slots:
+  void testPrivate() {}
+};
+
+#endif // KLIPS_TEXTVIEW_H