Xfce Foundation Classes
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Progress Bars


Progress bars are used to show the status of an operation. They are pretty easy to use, as you will see with the code below. But first lets start out with the constructors that create a new progress bar.

ProgressBar();

ProgressBar(Gtk::ProgressBarOrientation orientation);

The 'orientation' argument  can be one of the following values to indicate the direction in which the progress bar moves:
  • PROGRESS_LEFT_TO_RIGHT (the default)
  • PROGRESS_RIGHT_TO_LEFT
  • PROGRESS_BOTTOM_TO_TOP
  • PROGRESS_TOP_TO_BOTTOM
The first constructor takes no arguments and creates a progress bar with the default orientation. You can set the orientation at any time with the following method:

void set_orientation(Gtk::ProgressBarOrientation orientation);

Now that the progress bar has been created and the orientation set we can use it.

void set_fraction(double fraction);

The 'fraction' argument is the amount completed, meaning the amount the progress bar has been filled from 0-100%. This is passed to the method as a real number ranging from 0 to 1.

As well as indicating the amount of progress that has occurred, the progress bar may be set to just indicate that there is some activity. This can be useful in situations where progress cannot be measured against a value range. The following method indicates that some progress has been made.

void pulse();

The step size of the activity indicator is set using the following method:

void set_pulse_step(double fraction);

When not in activity mode, the progress bar can also display a configurable text string within its trough, using the following method:

void set_text(const String& text);

You can turn off the display of the string by calling Gtk::ProgessBar::set_text() again with null as the argument.

The current text setting of a progress bar can be retrieved with the following method:

String get_text() const;

Progress Bars are usually used with timeouts or other such functions to give the illusion of multitasking. All will employ the Gtk::ProgressBar set_fraction() or pulse() methods in the same manner.

ProgessBar Example

Here is an example of a progress bar updated using timeouts. This code also shows you how to reset the progress bar.

The header file for the ProgressBar example is <progressbar.hh>:

#include <xfc/main.hh>
#include <xfc/gtk/progressbar.hh>
#include <xfc/gtk/window.hh>

using namespace Xfc;

class ProgressBarWindow : public Gtk::Window
{
    Gtk::ProgressBar *progress_bar;
    bool activity_mode;

    sigc::connection timeout_connection;

protected:
    bool on_timeout();
    void on_toggle_show_text();
    void on_toggle_activity_mode();
    void on_toggle_orientation();

public:
    ProgressBarWindow();
    ~ProgressBarWindow();
};

and the source file is <progressbar.cc>:

#include "progressbar.hh"
#include <xfc/gtk/alignment.hh>
#include <xfc/gtk/box.hh>
#include <xfc/gtk/checkbutton.hh>
#include <xfc/gtk/separator.hh>
#include <xfc/gtk/table.hh>
#include <xfc/glib/main.hh>

ProgressBarWindow::ProgressBarWindow()
: activity_mode(false)
{
    set_resizable(true);
    set_title("ProgressBar Example");
    set_border_width(0);

    Gtk::VBox *vbox = new Gtk::VBox(false, 5);
    vbox->set_border_width(10);
    add(*vbox);
    vbox->show();

    // Create a centering alignment object
    Gtk::Alignment *align = new Gtk::Alignment(0.5, 0.5);
    vbox->pack_start(*align, false,false, 5);
    align->show();

    // Create the GtkProgressBar
    progress_bar = new Gtk::ProgressBar;
    align->add(*progress_bar);
    progress_bar->show();

    // Add a timer callback to update the value of the progress bar
    timeout_connection = G::timeout_signal.connect(sigc::mem_fun(this, &ProgressBarWindow::on_timeout), 100);

    Gtk::HSeparator *separator = new Gtk::HSeparator;
    vbox->pack_start(*separator, false, false);
    separator->show();

    // Add table: rows, columns, homogeneous = false (by default)
    Gtk::Table *table = new Gtk::Table(2, 2);
    vbox->pack_start(*table, false);
    table->show();

    // Add a check button to select displaying of the trough text
    Gtk::CheckButton *check = new Gtk::CheckButton("Show text");
    table->attach(*check, 0, 1, 0, 1, Gtk::EXPAND | Gtk::FILL, Gtk::EXPAND | Gtk::FILL, 5, 5);
    check->signal_clicked().connect(sigc::mem_fun(this, &ProgressBarWindow::on_toggle_show_text));
    check->show();

    // Add a check button to toggle activity mode
    check = new Gtk::CheckButton("Activity mode");
    table->attach(*check, 0, 1, 1, 2, Gtk::EXPAND | Gtk::FILL, Gtk::EXPAND | Gtk::FILL, 5, 5);
    check->signal_clicked().connect(sigc::mem_fun(this, &ProgressBarWindow::on_toggle_activity_mode));
    check->show();

    // Add a check button to toggle orientation
    check = new Gtk::CheckButton("Right to Left");
    table->attach(*check, 0, 1, 2, 3, Gtk::EXPAND | Gtk::FILL, Gtk::EXPAND | Gtk::FILL, 5, 5);
    check->signal_clicked().connect(sigc::mem_fun(this, &ProgressBarWindow::on_toggle_orientation));
    check->show();

    // Add a button to exit the program
    Gtk::Button *button = new Gtk::Button("close");
    button->signal_clicked().connect(sigc::mem_fun(this, &ProgressBarWindow::dispose));
    vbox->pack_start(*button, false, false);

    // This makes it so the button is the default.
    button->set_flags(Gtk::CAN_DEFAULT);

    // This grabs this button to be the default button. Simply hitting the "Enter" key
    // will cause this button to activate.
    button->grab_default();
    button->show();
}

ProgressBarWindow::~ProgressBarWindow()
{
    timeout_connection.disconnect();
}

bool
ProgressBarWindow::on_timeout()
{
    if (activity_mode)
        progress_bar->pulse();
    else
    {
        // Calculate the value of the progress bar using the value range set in the adjustment object
        double new_value = progress_bar->get_fraction() + 0.01;

        if (new_value > 1.0)
            new_value = 0.0;

        // Set the new value
        progress_bar->set_fraction(new_value);
    }

    // As this is a timeout slot, return true so that it continues to get called
    return true;
}

void
ProgressBarWindow::on_toggle_show_text()
{
    // Toggles the text display within the progress bar trough
    String text = progress_bar->get_text();

    if (!text.empty())
        progress_bar->set_text("");
    else
        progress_bar->set_text("some text");
}

void
ProgressBarWindow::on_toggle_activity_mode()
{
    // Toggles the activity mode of the progress bar
    activity_mode = !activity_mode;

    if (activity_mode)
        progress_bar->pulse();
    else
        progress_bar->set_fraction(0.0);
}

void
ProgressBarWindow::on_toggle_orientation()
{
    // Toggles the orientation of the progress bar
    if (progress_bar->get_orientation() == Gtk::PROGRESS_LEFT_TO_RIGHT)
        progress_bar->set_orientation(Gtk::PROGRESS_RIGHT_TO_LEFT);
    else
        progress_bar->set_orientation(Gtk::PROGRESS_LEFT_TO_RIGHT);
}

int main (int argc, char *argv[])
{
    using namespace Main;

    init(&argc, &argv);

    ProgressBarWindow window;
    window.signal_destroy().connect(sigc::ptr_fun(&Xfc::Main::quit));
    window.show();

    run();
    return 0;
}

Compiling ProgressBar

If you compiled and installed XFC yourself, you will find the source code for ProgressBar in the <examples/howto/progressbar> source directory along with a Makefile. If XFC came pre-installed, or you installed it from an RPM package, you will find the source code in the </usr/share/doc/xfcui-X.X/examples/howto/progressbar> subdirectory. In this case you will have to create the Makefile yourself (replace X.X with the version number of the libXFCui library you have installed).

To create a Makefile for ProgressBar, add the following lines to a new text file and save it using the name "Makefile":

CC = g++

CFLAGS = -Wall -O2

progressbar: progressbar.cc progressbar.hh
    $(CC) progressbar.cc -o progressbar $(CFLAGS) `pkg-config xfcui-X.X --cflags --libs`

clean:
    rm -f *.o progressbar


If you cut and paste these lines make sure the whitespace before $(CC) and rm is a tab character. When you compile and run this program you will see the following window appear:



Checking the 'Show text' check button displays the text string 'some text' in the progress bar trough. Checking the right-to-left check button will make the progress bar update from the right side instead of the left. Checking the 'Activity mode' check button will switch the progess bar into action mode. In this mode the progess bar displays a block that moves up and down the trough at a constant rate to indicate that some activity is occuring.


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XFC 4.4