进度条(ProgressBar)

进度条用于显示正在进行的操作的状态。例如，ProgressBar可以用于显示已经有多少任务被完成。

要修改显示的值，请调用set_fraction()方法，向该方法传递一个0.0到1.0之间的double值。

ProgressBar默认是水平且从左向右的，但是你可以使用set_orientation()方法来改变这个行为。

8.4.1. 活动模式
8.4.2. 示例

除了用于表示已经达成的进度，进度条还可以用于表示任务处于活动状态；只需要将进度条的行为模式设置为activity mode即可。在这个模式下，进度条显示一个小矩形，该矩形可以在进度条内前后移动。活动模式在无法确定操作的进度的时候很有用（例如，接受一个长度未知的文件）。

为此，你还需要定时调用pulse()方法。你还可以使用set_pulse_step()方法控制矩形的移动步长。

进度条还可以使用set_text()方法来在其边上显示可配置的文本字符串。

Figure 8-7 进度条(ProgressBar)

源代码

File: examplewindow.h (For use with gtkmm 4)

#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H

#include <gtkmm.h>

class ExampleWindow : public Gtk::Window
{
public:
  ExampleWindow();
  virtual ~ExampleWindow();

protected:
  //Signal handlers:
  void on_checkbutton_text();
  void on_checkbutton_activity();
  void on_checkbutton_inverted();

  bool on_timeout();
  void on_button_close();

  //Child widgets:
  Gtk::Box m_VBox;
  Gtk::Grid m_Grid;
  Gtk::ProgressBar m_ProgressBar;
  Gtk::Separator m_Separator;
  Gtk::CheckButton m_CheckButton_Text, m_CheckButton_Activity, m_CheckButton_Inverted;
  Gtk::Button m_Button_Close;

  sigc::connection m_connection_timeout;
  bool m_bActivityMode;
};

#endif //GTKMM_EXAMPLEWINDOW_H

File: main.cc (For use with gtkmm 4)

#include "examplewindow.h"
#include <gtkmm/application.h>

int main(int argc, char *argv[])
{
  auto app = Gtk::Application::create("org.gtkmm.example");

  //Shows the window and returns when it is closed.
  return app->make_window_and_run<ExampleWindow>(argc, argv);
}

File: examplewindow.cc (For use with gtkmm 4)

#include "examplewindow.h"
#include <iostream>

ExampleWindow::ExampleWindow()
: m_VBox(Gtk::Orientation::VERTICAL, 5),
  m_CheckButton_Text("Show text"),
  m_CheckButton_Activity("Activity mode"),
  m_CheckButton_Inverted("Right to Left"),
  m_Button_Close("Close"),
  m_bActivityMode(false)
{
  set_resizable();
  set_title("Gtk::ProgressBar");

  m_VBox.set_margin(10);
  set_child(m_VBox);

  m_VBox.append(m_ProgressBar);
  m_ProgressBar.set_margin_end(5);
  m_ProgressBar.set_halign(Gtk::Align::CENTER);
  m_ProgressBar.set_valign(Gtk::Align::CENTER);
  m_ProgressBar.set_size_request(100, -1);
  m_ProgressBar.set_text("some text");
  m_ProgressBar.set_show_text(false);

  //Add a timer callback to update the value of the progress bar:
  m_connection_timeout = Glib::signal_timeout().connect(sigc::mem_fun(*this,
              &ExampleWindow::on_timeout), 50 );

  m_VBox.append(m_Separator);
  m_VBox.append(m_Grid);
  m_Grid.set_expand(true);
  m_Grid.set_row_homogeneous(true);

  //Add a check button to select displaying of the trough text:
  m_Grid.attach(m_CheckButton_Text, 0, 0);
  m_CheckButton_Text.set_margin(5);
  m_CheckButton_Text.signal_toggled().connect(sigc::mem_fun(*this,
              &ExampleWindow::on_checkbutton_text) );

  //Add a check button to toggle activity mode:
  m_Grid.attach(m_CheckButton_Activity, 0, 1);
  m_CheckButton_Activity.set_margin(5);
  m_CheckButton_Activity.signal_toggled().connect(sigc::mem_fun(*this,
              &ExampleWindow::on_checkbutton_activity) );

  //Add a check button to select growth from left to right or from right to left:
  m_Grid.attach(m_CheckButton_Inverted, 0, 2);
  m_CheckButton_Inverted.set_margin(5);
  m_CheckButton_Inverted.signal_toggled().connect(sigc::mem_fun(*this,
              &ExampleWindow::on_checkbutton_inverted) );

  //Add a button to exit the program.
  m_VBox.append(m_Button_Close);
  m_Button_Close.signal_clicked().connect(sigc::mem_fun(*this,
              &ExampleWindow::on_button_close) );
  set_default_widget(m_Button_Close);
}

ExampleWindow::~ExampleWindow()
{
}

void ExampleWindow::on_checkbutton_text()
{
  const bool show_text = m_CheckButton_Text.get_active();
  m_ProgressBar.set_show_text(show_text);
}

void ExampleWindow::on_checkbutton_activity()
{
  m_bActivityMode = m_CheckButton_Activity.get_active();

  if(m_bActivityMode)
    m_ProgressBar.pulse();
  else
    m_ProgressBar.set_fraction(0.0);
}

void ExampleWindow::on_checkbutton_inverted()
{
  const bool inverted = m_CheckButton_Inverted.get_active();
  m_ProgressBar.set_inverted(inverted);
}

void ExampleWindow::on_button_close()
{
  hide();
}

/* Update the value of the progress bar so that we get
 * some movement */
bool ExampleWindow::on_timeout()
{
  if(m_bActivityMode)
    m_ProgressBar.pulse();
  else
  {
    double new_val = m_ProgressBar.get_fraction() + 0.01;

    if(new_val > 1.0)
      new_val = 0.0;

    //Set the new value:
    m_ProgressBar.set_fraction(new_val);
  }

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

进度条(ProgressBar)

8.4.1. 活动模式

8.4.2. 示例

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