First steps with the Final Cut widget toolkit ============================================= How to use the library ---------------------- At the beginning of this introduction to the Final Cut we will start with a small example. The following example creates an empty 30×10 character dialog. **File:** *dialog.cpp* ```cpp #include int main (int argc, char* argv[]) { finalcut::FApplication app(argc, argv); finalcut::FDialog dialog(&app); dialog.setText ("A dialog"); dialog.setGeometry (25, 5, 30, 10); app.setMainWidget(&dialog); dialog.show(); return app.exec(); } ``` *(Note: You can close the dialog with the mouse, Shift+F10 or Ctrl+^)* After entering the source code in *dialog.cpp* you can compile the above program with gcc: ```cpp g++ -O2 -lfinal dialog.cpp -o dialog ``` How it works ------------ ```cpp #include ``` All final cut programs must include the *final.h* header. ```cpp finalcut::FApplication app(argc, argv); ``` This line creates the `finalcut::FApplication` object `app` with the command line arguments `argc` and `argv`. This object manages the application main event loop. It receives keyboard and mouse events and sends them to the target widgets. You must create an application object before you can create a widgets object. The next line ```cpp finalcut::FDialog dialog(&app); ``` creates the `finalcut::FDialog` object `dialog` with the object `app` as parent object. The `finalcut::FDialog` class is the base class for creating dialog windows. ```cpp dialog.setText ("A dialog"); ``` The title bar of the dialog box gets the text "A dialog". ```cpp dialog.setGeometry (25, 5, 30, 10); ``` The dialog window gets a width of 30 and a height of 10 characters. The position of the window in the terminal is at x=25 and y=5 (note: x=1 and y=1 represents the upper left corner). ```cpp app.setMainWidget(&dialog); ``` The `dialog` object was now selected as the main widget for the application. When you close the main widget, the entire application quits. ```cpp dialog.show(); ``` A window or widget is not visible directly after its creation. Only the call of `show()` makes it (and its child objects, if available) visible. ```cpp return app.exec(); ``` The last line calls `exec()` to start the application and return the result to the operating system. The started application enters the main event loop. This loop does not end until the window is not closed. Memory Management ----------------- To create a hierarchy of FObjects (or derived classes/widgets), a new FObject must initialize with its parent object. ```cpp FObject* parent = new FObject(); FObject* child = new FObject(parent); ``` To deallocate the used memory of a parent FObject, the allocated memory of its child objects will also automatically deallocate. An object can also be assigned to another object later via `addChild()`. ```cpp FObject* parent = new FObject(); FObject* child = new FObject(); parent->addChild(child); ``` The child object assignment can also remove at any time with `delChild()`. ```cpp FObject* parent = new FObject(); FObject* child = new FObject(parent); parent->delChild(child); ``` If an FObject with a parent will remove from the hierarchy, the destructor automatically deletes the object assignment from its parent object. If a class object doesn't derive from FObject, you must implement storage deallocation yourself. **File:** *memory.cpp* ```cpp #include using namespace finalcut; int main (int argc, char* argv[]) { FApplication app(argc, argv); // The object dialog is managed by app FDialog* dialog = new FDialog(&app); dialog->setText ("Window Title"); dialog->setGeometry (25, 5, 40, 8); // The object input is managed by dialog FLineEdit* input = new FLineEdit("predefined text", dialog); input->setGeometry(8, 2, 29, 1); input->setLabelText (L"&Input"); // The object label is managed by dialog FLabel* label = new FLabel ( "Lorem ipsum dolor sit amet, consectetur " "adipiscing elit, sed do eiusmod tempor " "incididunt ut labore et dolore magna aliqua." , dialog ); label->setGeometry (2, 4, 36, 1); app.setMainWidget(dialog); dialog->show(); return app.exec(); } ``` *(Note: You can close the window with the mouse, Shift+F10 or Ctrl+^)* After entering the source code in *memory.cpp* you can compile the above program with gcc: ```cpp g++ -O2 -lfinal memory.cpp -o memory ``` Event Processing ---------------- Calling `FApplication::exec()` starts the FINAL CUT main event loop. While the event loop is running, the system constantly checks whether an event has occurred and sends it to the application's currently focused object. The events of the terminal such as keystrokes, mouse actions or resizing the terminal are translated into `FEvent` objects and sent it to the active `FObject`. It is also possible to use `FApplication::sendEvent()` or `FApplication::queueEvent()` to send your own events to an object. `FObject`-derived objects process incoming events by reimplementing the virtual method `event()`. The `FObject` itself calls only `onTimer()` or `onUserEvent()` and ignores all other events. The `FObject`-derived class `FWidget` also reimplements the `event()` method to handle further events. `FWidget` calls the `FWidget::onKeyPress` method when you press a key, or the `FWidget::onMouseDown` method when you click a mouse button. ### Event handler reimplementation ### An event in FINAL CUT is an object that inherits from the base class `FEvent`. There are several event types, represented by an enum value. For example, the method `FEvent::type()` returns the type `fc::MouseDown_Event` when you press down a mouse button. Some event types have data that cannot store in an `FEvent` object. For example, a click event of the mouse must store which button it triggered where the mouse pointer was at that time. In classes derived from `FEvent`, such as `FMouseEvent()`, we store this data. Widgets get their events from the `event()` method inherited from FObject. The implementation of `event()` in `FWidget` forwards the most common event types to specific event handlers such as `FMouseEvent()`, `FKeyEvent()` or `FResizeEvent()`. There are many other event types. It is also possible to create own event types and send them to other objects. **The FINAL CUT event types:** ```cpp enum events { None_Event, // invalid event KeyPress_Event, // key pressed KeyUp_Event, // key released KeyDown_Event, // key pressed MouseDown_Event, // mouse button pressed MouseUp_Event, // mouse button released MouseDoubleClick_Event, // mouse button double click MouseWheel_Event, // mouse wheel rolled MouseMove_Event, // mouse move FocusIn_Event, // focus in FocusOut_Event, // focus out ChildFocusIn_Event, // child focus in ChildFocusOut_Event, // child focus out WindowActive_Event, // activate window WindowInactive_Event, // deactivate window WindowRaised_Event, // raise window WindowLowered_Event, // lower window Accelerator_Event, // keyboard accelerator Resize_Event, // terminal resize Show_Event, // widget is shown Hide_Event, // widget is hidden Close_Event, // widget close Timer_Event, // timer event occur User_Event // user defined event }; ``` **File:** *timer.cpp* ```cpp #include using namespace finalcut; class dialogWidget : public FDialog { public: explicit dialogWidget (FWidget* parent = nullptr) : FDialog(parent) { setText ("Dialog"); setGeometry (25, 5, 23, 4); label.setGeometry (1, 1, 10, 1); label.setAlignment (fc::alignRight); value.setGeometry (11, 1, 10, 1); id = addTimer(100); } private: virtual void onTimer (FTimerEvent* ev) { if ( id == ev->getTimerId() && n < 9999999999 ) { value.setNumber(n); value.redraw(); n++; } } FLabel label{"Counter: ", this}; FLabel value{"0", this}; long n{0}; int id{0}; }; int main (int argc, char* argv[]) { FApplication app(argc, argv); dialogWidget dialog(&app); app.setMainWidget(&dialog); dialog.show(); return app.exec(); } ``` *(Note: You can close the window with the mouse, Shift+F10 or Ctrl+^)* After entering the source code in *timer.cpp* you can compile the above program with gcc: ```cpp g++ -O2 -std=c++11 -lfinal timer.cpp -o timer ``` Signals and Callbacks --------------------- The callback mechanism is essential for developing applications with FINAL CUT. Callback routines allow the programmer to connect different objects (which do not need to know each other). Connected objects notify each other when an action occurs in a widget. To uniquely identify a widget action, it uses signal strings. For example, if an `FButton` object gets clicked by a keyboard or mouse, it sends the string "clicked". A signal handler explicitly provided by Widget, in the form of a callback function or a callback method, can react to such a signal. A callback function is always structured as follows: ```cpp void cb_function (FWidget* w, FDataPtr data) {...} ``` The structure of a callback method is the same: ```cpp void classname::cb_methode (FWidget* w, FDataPtr data) {...} ``` We use the `addCallback()` method of the `FWidget` class to connect to other widget objects. For calling functions and static methods: ```cpp void FWidget::addCallback ( const FString& cb_signal , FCallback cb_handler , FDataPtr data ) {...} ``` For calling a member method of a specific instance: ```cpp void FWidget::addCallback ( const FString& cb_signal , FWidget* cb_instance , FMemberCallback cb_handler , FDataPtr data ) {...} ``` There are two macros `F_FUNCTION_CALLBACK` and `F_METHOD_CALLBACK` to avoid having to deal with necessary type conversions. With `delCallback()` you can remove a connection to a signal handler or a widget. Alternatively, you can use `delCallbacks()` to remove all existing callbacks from an object. ### The FINAL CUT widgets emit the following default signals ###
FButton
"clicked"
FCheckMenuItem
"clicked"
"toggled"
FLineEdit
"activate"
"changed"
FListBox
"clicked"
"row-changed"
"row-selected"
FListView
"clicked"
"row-changed"
FMenu
"activate"
FMenuItem
"activate"
"clicked"
"deactivate"
FRadioMenuItem
"clicked"
"toggled"
FScrollbar
"change-value"
FStatusBar
"activate"
FTextView
"changed"
FToggleButton
"clicked"
"toggled"
  ### Example of a callback function: ### **File:** *callback-function.cpp* ```cpp #include using namespace finalcut; void cb_changeText (FWidget* w, FDataPtr data) { FButton& button = *(static_cast(w)); FLabel& label = *(static_cast(data)); label.clear(); label << "The " << button.getClassName() << " was pressed"; label.redraw(); } int main (int argc, char* argv[]) { FApplication app(argc, argv); FDialog dialog(&app); dialog.setText ("A dialog with callback function"); dialog.setGeometry (25, 5, 45, 9); FLabel label (&dialog); label = "The button has never been pressed before"; label.setGeometry (2, 2, 41, 1); FButton button (&dialog); // Character follows '&' will be used as the accelerator key button = "&Click me"; button.setGeometry (15, 5, 14, 1); // Connect the button signal "clicked" with the callback function button.addCallback ( "clicked", F_FUNCTION_CALLBACK (&cb_changeText), &label ); app.setMainWidget(&dialog); dialog.show(); return app.exec(); } ``` *(Note: You can close the dialog with the mouse, Shift+F10 or Ctrl+^)* After entering the source code in *callback-function.cpp* you can compile the above program with gcc: ```cpp g++ -O2 -lfinal callback-function.cpp -o callback-function ```   ### Example of a callback method: ### **File:** *callback-method.cpp* ```cpp #include using namespace finalcut; class dialogWidget : public FDialog { public: explicit dialogWidget (FWidget* parent = nullptr) : FDialog(parent) { setText ("Callback method"); setGeometry (25, 5, 25, 7); button.setGeometry (7, 3, 10, 1); // Connect the button signal "clicked" with the callback method button.addCallback ( "clicked", F_METHOD_CALLBACK (this, &FApplication::cb_exitApp), nullptr ); } private: FButton button{"&Quit", this}; }; int main (int argc, char* argv[]) { FApplication app(argc, argv); dialogWidget dialog(&app); app.setMainWidget(&dialog); dialog.show(); return app.exec(); } ``` *(Note: You can close the window with the mouse, Shift+F10 or Ctrl+^)* After entering the source code in *callback-method.cpp* you can compile the above program with gcc: ```cpp g++ -O2 -std=c++11 -lfinal callback-method.cpp -o callback-method ```   ### Send custom signals ### You can use the `emitCallback()` method to generate a user-defined signal. You can connect this signal later with the method `addCallback()` to a self-defined routine. **File:** *emit-signal.cpp* ```cpp #include using namespace finalcut; class dialogWidget : public FDialog { public: explicit dialogWidget (FWidget* parent = nullptr) : FDialog(parent) { setGeometry (25, 5, 22, 7); setText ("Emit signal"); label.setGeometry (8, 1, 5, 1); label.setAlignment (fc::alignRight); label.setForegroundColor (fc::Black); plus.setGeometry (3, 3, 5, 1); minus.setGeometry (13, 3, 5, 1); plus.setNoUnderline(); minus.setNoUnderline(); // Connect the button signal "clicked" with the callback method plus.addCallback ( "clicked", F_METHOD_CALLBACK (this, &dialogWidget::cb_plus) ); minus.addCallback ( "clicked", F_METHOD_CALLBACK (this, &dialogWidget::cb_minus) ); // Connect own signals addCallback ( "hot", F_METHOD_CALLBACK (this, &dialogWidget::cb_set_red) ); addCallback ( "regular", F_METHOD_CALLBACK (this, &dialogWidget::cb_set_black) ); addCallback ( "cold", F_METHOD_CALLBACK (this, &dialogWidget::cb_set_blue) ); } private: void cb_plus (FWidget*, FDataPtr) { if ( t < 100 ) t++; if ( t == 30 ) emitCallback("hot"); else if ( t == 1 ) emitCallback("regular"); setTemperature(); } void cb_minus (FWidget*, FDataPtr) { if ( t > -99 ) t--; if ( t == 0 ) emitCallback("cold"); else if ( t == 29 ) emitCallback("regular"); setTemperature(); } void cb_set_blue (FWidget*, FDataPtr) { label.setForegroundColor (fc::Blue); } void cb_set_black (FWidget*, FDataPtr) { label.setForegroundColor (fc::Black); } void cb_set_red (FWidget*, FDataPtr) { label.setForegroundColor (fc::Red); } void setTemperature() { label.clear(); label << t << "°C"; label.redraw(); } int t = 20; FLabel label{FString() << t << "°C", this}; FButton plus {"&+", this}; FButton minus {"&-", this}; }; int main (int argc, char* argv[]) { FApplication app(argc, argv); dialogWidget dialog(&app); app.setMainWidget(&dialog); dialog.show(); return app.exec(); } ``` *(Note: You can close the window with the mouse, Shift+F10 or Ctrl+^)* After entering the source code in *emit-signal.cpp* you can compile the above program with gcc: ```cpp g++ -O2 -std=c++11 -lfinal emit-signal.cpp -o emit-signal ``` The FINAL CUT widgets emit the following default signals: