fltk. objectives install and use fltk widgets ◦callbacks handling event ◦system events ◦mouse...

FLTKFLTK

ObjectivesObjectives

Install and Use FLTKWidgets

◦CallbacksHandling event

◦System events◦Mouse events◦Keyboard events

Installing FLTK 1.1Installing FLTK 1.1

Linux◦Package manager

Mac < 10.5◦Mac Ports

*nix◦./configure && make && make install

Visual Studio◦Open fltk-source/visualc/fltk.dsw and build◦In fltk-source copy FL folder to vc/include◦In fltk-source/lib copy all files to vc/lib

Linking Linking

Visual Studio◦Add fltk.lib, wsock32.lib, comctl32.lib,fltkgl.lib,

fltkforms.lib, and fltkimages.lib (or fltkd.lib, etc.) to linker input

*nix◦`fltk-config --use-gl --use-images --use-forms --

cxxflags –ldflags`

WidgetsWidgets

Basic visual building blocks which are combined intoan applications GUI

Common FLTK WidgetsCommon FLTK Widgets

Buttons◦Includes radio buttons and check boxes

Text◦Display and receive strings

Valuators◦Display and receive numbers

Groups◦Containers such as tabs and group boxes◦Also includes windows and OpenGL windows

Hierarchies and PropertiesHierarchies and Properties

Parent Child relationship◦Created widgets are added to current group◦Created group widgets start their own group

Stopped by calling widget->end();◦Can manually add widgets to groups

Get / Set Methods◦Change style, properties, values etc.◦Get: int minimum()◦Set: void minimum(int)

FLTK Hello WorldFLTK Hello World

#include <FL/Fl.H>#include <FL/Fl_Window.H>#include <FL/Fl_Box.H>

intmain(intargc, char **argv){Fl_Window *window = new Fl_Window(300, 180);Fl_Box *box = new Fl_Box(20, 40, 260, 100,

"Hello World");box->box(FL_UP_BOX);window->end();window->show(argc, argv);return Fl::run();

}

FLTK CallbacksFLTK Callbacks

Sets a functions to called when the value of a widget changes◦void functionName(Fl_Widget*, void*)

Called function is passed pointer to the widget that changed and optional pointer to data

Can be activated by keyboard shortcut

Callback DemoCallback Demo

void button_cb(Fl_Widget *widget, void *data){Fl_Button*button = (Fl_Button*)widget; button->label("Thank you");}

intmain(intargc, char **argv){...

Fl_Button *button = new Fl_Button(50, 70, 200, 40, "Click Me");

button->callback(button_cb);...

}

Custom WidgetsCustom Widgets

Subclass an existing widget◦Control widget to get/receive a value◦Composite widget to hold a list of child widgets

and handle them together◦Can also subclass existing widget and change

Custom WidgetCustom Widget

Composite widgetSlider and text boxWhen the value of one changes the other

is updatedWill use slider internally to store data

◦Easier because already has min, max, etc.Improvements

◦Validate text box input

Custom WidgetCustom Widget

Widget is a composition so we will inherit Fl_Group

Class CustomWidget : Fl_Group {Constructor with default FLTK parameterspublic:CustomWidget(intx, inty, intw, inth, char *l =0) : Fl_Group(x, y, w, h, l);

Custom WidgetCustom Widget

Our two widgetsprivate:Fl_Int_Input*input;Fl_Slider*slider;Slider will store our data

◦Current value◦Bounds◦Step size

Custom WidgetCustom Widget

Common slider propertiespublic:int value();void value(intv);

int minimum();void minimum(int min);

int maximum();void maximum(int max);void bounds(int min, int max);

Custom WidgetCustom Widget

Internal callbacksstatic void input_cb(Fl_Widget *w, void *d);

static void slider_cb(Fl_Widget *w, void *d);

void input_cb2();void slider_cb2();

Custom WidgetCustom Widget

Constructor: Layoutintconst in_w = 40;input = new Fl_Int_Input(x, y, in_w,

h);slider = new Fl_Slider(x + in_w, y,w- in_w, h);slider->type(FL_HOR_SLIDER);

Custom WidgetCustom Widget

Constructor: Databounds(1, 100);value(1);Constructor: Callbacksinput->when(FL_WHEN_CHANGED);input->callback(input_cb, this);slider->callback(slider_cb, this);

Custom WidgetCustom Widget

Static callbacksvoid CustomWidget::input_cb(Fl_Widget *w, void *d){((CustomWidget*)d)->input_cb2();

}

void CustomWidget::slider_cb(Fl_Widget *w, void *d){((CustomWidget*)d)->slider_cb2();

}

Custom WidgetCustom Widget

Callbacks: Update the other widgetvoid CustomWidget::input_cb2(){intval;sscanf(input->value(), "%d", &val);slider->value(val);

}

void CustomWidget::slider_cb2(){char val[16];

sprintf(val, "%d", (int)(slider->value() + 0.5));input->value(val);

}

Custom WidgetCustom Widget

PropertiesintCustomWidget::value(){return (int)(slider->value() + 0.5);

}

void CustomWidget::value(intv){slider->value(v);slider_cb2();

}

System EventsSystem Events

Focus events◦Mouse enters/leaves program◦Program gains/loses focus

Clipboard eventsWidget events

◦Activation/deactivation◦Show/hide

Mouse EventsMouse Events

Button pushed downMouse moved while button pressed (drag)Button releaseMouse movedMouse wheel

Keyboard EventsKeyboard Events

Propagate through widgets until handledKey Up/Down

◦Event trigger on both key press and release◦Sent to widget with focus, then parents, then

becomes a shortcutShortcuts

◦Sent to widget under mouse, then parents, then every widget

Custom Widget EventsCustom Widget Events

Override inthandle(int event)◦Return 0 if event unused

Event will continue to be passed around◦Return 1 if event used

Event is consumedSlider responds to left/right keys

◦Expand to include up/down keys

Custom Widget EventsCustom Widget Events

intCustomWidget::handle(int event){if ( event == FL_KEYDOWN ){

if ( Fl::event_key() == FL_Up ){

value(value() + 1);return 1;

}else if ( Fl::event_key() == FL_Down ){

value(value() - 1);return 1;

}}return Fl_Group::handle(event);

}

FLUIDFLUID

GUI to produce FLTK source codeCreates C++ code

◦Compile .fl file into .cxx and .hCan create your entire program

Other FLTK PartsOther FLTK Parts

Premade dialog boxes◦File chooser◦Input◦Color◦Alerts

Images2D drawing functionsThreadsTimers