SpinButton

A SpinButton allows the user to select a value from a range of numeric values. It has an Entry widget with up and down arrow buttons at the side. Clicking the buttons causes the value to 'spin' up and down across the range of possible values. The Entry widget may also be used to enter a value directly.

The value can have an adjustable number of decimal places, and the step size is configurable. SpinButtons have an 'auto-repeat' feature as well: holding down one of the arrows can optionally cause the value to change more quickly the longer the arrow is held down.

SpinButtons use an Adjustment object to hold information about the range of values. These Adjustment attributes are used by the Spin Button like so:

value: value for the Spin Button
lower: lower range value
upper: upper range value
step_increment: value to increment/decrement when pressing mouse button 1 on a button
page_increment: value to increment/decrement when pressing mouse button 2 on a button
page_size: unused

Additionally, mouse button 3 can be used to jump directly to the upper or lower values.

The SpinButton can create a default Adjustment, which you can access via the get_adjustment() method, or you can specify an existing Adjustment in the constructor.

7.3.1. 方法
7.3.2. 示例

The number of decimal places can be altered using the set_digits() method.

You can set the spinbutton's value using the set_value() method, and retrieve it with get_value().

The spin() method 'spins' the SpinButton, as if one of its arrows had been clicked. You need to specify a Gtk::SpinType to specify the direction or new position.

To prevent the user from typing non-numeric characters into the entry box, pass true to the set_numeric() method.

To make the SpinButton 'wrap' between its upper and lower bounds, use the set_wrap() method.

To force it to snap to the nearest step_increment, use set_snap_to_ticks().

You can modify the update policy using the set_update_policy() method, specifying either Gtk::UPDATE_ALWAYS or Gtk::UPDATE_IF_VALID. Gtk::UPDATE_ALWAYS causes the SpinButton to ignore errors encountered while converting the text in the entry box to a numeric value. This setting also therefore allows the SpinButton to accept non-numeric values. You can force an immediate update using the update() method.

参考

Here's an example of a SpinButton in action:

图 7-6 SpinButton

源代码

File: examplewindow.h (For use with gtkmm 3, not gtkmm 2)

#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_snap();
  void on_checkbutton_numeric();
  void on_spinbutton_digits_changed();
  void on_button_close();

  enum enumValueFormats
  {
    VALUE_FORMAT_INT,
    VALUE_FORMAT_FLOAT
  };
  void on_button_getvalue(enumValueFormats display);

  //Child widgets:
  Gtk::Frame m_Frame_NotAccelerated, m_Frame_Accelerated;
  Gtk::Box m_HBox_NotAccelerated, m_HBox_Accelerated,
    m_HBox_Buttons;
  Gtk::Box m_VBox_Main, m_VBox, m_VBox_Day, m_VBox_Month, m_VBox_Year,
    m_VBox_Accelerated, m_VBox_Value, m_VBox_Digits;
  Gtk::Label m_Label_Day, m_Label_Month, m_Label_Year,
    m_Label_Value, m_Label_Digits,
    m_Label_ShowValue;
  Glib::RefPtr<Gtk::Adjustment> m_adjustment_day, m_adjustment_month, m_adjustment_year,
    m_adjustment_value, m_adjustment_digits;
  Gtk::SpinButton m_SpinButton_Day, m_SpinButton_Month, m_SpinButton_Year,
    m_SpinButton_Value, m_SpinButton_Digits;
  Gtk::CheckButton m_CheckButton_Snap, m_CheckButton_Numeric;
  Gtk::Button m_Button_Int, m_Button_Float, m_Button_Close;
};

#endif //GTKMM_EXAMPLEWINDOW_H

File: examplewindow.cc (For use with gtkmm 3, not gtkmm 2)

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

ExampleWindow::ExampleWindow()
:
  m_Frame_NotAccelerated("Not accelerated"),
  m_Frame_Accelerated("Accelerated"),
  m_VBox_Main(Gtk::ORIENTATION_VERTICAL, 5),
  m_VBox(Gtk::ORIENTATION_VERTICAL),
  m_VBox_Day(Gtk::ORIENTATION_VERTICAL),
  m_VBox_Month(Gtk::ORIENTATION_VERTICAL),
  m_VBox_Year(Gtk::ORIENTATION_VERTICAL),
  m_VBox_Accelerated(Gtk::ORIENTATION_VERTICAL),
  m_VBox_Value(Gtk::ORIENTATION_VERTICAL),
  m_VBox_Digits(Gtk::ORIENTATION_VERTICAL),
  m_Label_Day("Day: "),
  m_Label_Month("Month: "),
  m_Label_Year("Year: "),
  m_Label_Value("Value: "),
  m_Label_Digits("Digits: "),
  m_adjustment_day( Gtk::Adjustment::create(1.0, 1.0, 31.0, 1.0, 5.0, 0.0) ),
  m_adjustment_month( Gtk::Adjustment::create(1.0, 1.0, 12.0, 1.0, 5.0, 0.0) ),
  m_adjustment_year( Gtk::Adjustment::create(2012.0, 1.0, 2200.0, 1.0, 100.0, 0.0) ),
  m_adjustment_value( Gtk::Adjustment::create(0.0, -10000.0, 10000.0, 0.5, 100.0, 0.0) ),
  m_adjustment_digits( Gtk::Adjustment::create(2.0, 1.0, 5.0, 1.0, 1.0, 0.0) ),
  m_SpinButton_Day(m_adjustment_day),
  m_SpinButton_Month(m_adjustment_month),
  m_SpinButton_Year(m_adjustment_year),
  m_SpinButton_Value(m_adjustment_value, 1.0, 2),
  m_SpinButton_Digits(m_adjustment_digits),
  m_CheckButton_Snap("Snap to 0.5-ticks"),
  m_CheckButton_Numeric("Numeric only input mode"),
  m_Button_Int("Value as Int"),
  m_Button_Float("Value as Float"),
  m_Button_Close("Close")
{
  set_title("SpinButton");

  m_VBox_Main.set_border_width(10);
  add(m_VBox_Main);

  m_VBox_Main.pack_start(m_Frame_NotAccelerated);

  m_VBox.set_border_width(5);
  m_Frame_NotAccelerated.add(m_VBox);

  /* Day, month, year spinners */

  m_VBox.pack_start(m_HBox_NotAccelerated, Gtk::PACK_EXPAND_WIDGET, 5);

  m_Label_Day.set_alignment(Gtk::ALIGN_START);
  m_VBox_Day.pack_start(m_Label_Day);

  m_SpinButton_Day.set_wrap();

  m_VBox_Day.pack_start(m_SpinButton_Day);

  m_HBox_NotAccelerated.pack_start(m_VBox_Day, Gtk::PACK_EXPAND_WIDGET, 5);

  m_Label_Month.set_alignment(Gtk::ALIGN_START);
  m_VBox_Month.pack_start(m_Label_Month);

  m_SpinButton_Month.set_wrap();
  m_VBox_Month.pack_start(m_SpinButton_Month);

  m_HBox_NotAccelerated.pack_start(m_VBox_Month, Gtk::PACK_EXPAND_WIDGET, 5);

  m_Label_Year.set_alignment(Gtk::ALIGN_START);
  m_VBox_Year.pack_start(m_Label_Year);

  m_SpinButton_Year.set_wrap();
  m_SpinButton_Year.set_size_request(55, -1);
  m_VBox_Year.pack_start(m_SpinButton_Year);

  m_HBox_NotAccelerated.pack_start(m_VBox_Year, Gtk::PACK_EXPAND_WIDGET, 5);

  //Accelerated:
  m_VBox_Main.pack_start(m_Frame_Accelerated);

  m_VBox_Accelerated.set_border_width(5);
  m_Frame_Accelerated.add(m_VBox_Accelerated);

  m_VBox_Accelerated.pack_start(m_HBox_Accelerated, Gtk::PACK_EXPAND_WIDGET, 5);

  m_HBox_Accelerated.pack_start(m_VBox_Value, Gtk::PACK_EXPAND_WIDGET, 5);

  m_Label_Value.set_alignment(Gtk::ALIGN_START);
  m_VBox_Value.pack_start(m_Label_Value);

  m_SpinButton_Value.set_wrap();
  m_SpinButton_Value.set_size_request(100, -1);
  m_VBox_Value.pack_start(m_SpinButton_Value);

  m_HBox_Accelerated.pack_start(m_VBox_Digits, Gtk::PACK_EXPAND_WIDGET, 5);

  m_Label_Digits.set_alignment(Gtk::ALIGN_START);
  m_VBox_Digits.pack_start(m_Label_Digits);

  m_SpinButton_Digits.set_wrap();
  m_adjustment_digits->signal_value_changed().connect( sigc::mem_fun(*this,
              &ExampleWindow::on_spinbutton_digits_changed) );

  m_VBox_Digits.pack_start(m_SpinButton_Digits);


  //CheckButtons:
  m_VBox_Accelerated.pack_start(m_CheckButton_Snap);
  m_CheckButton_Snap.set_active();
  m_CheckButton_Snap.signal_clicked().connect( sigc::mem_fun(*this,
              &ExampleWindow::on_checkbutton_snap) );

  m_VBox_Accelerated.pack_start(m_CheckButton_Numeric);
  m_CheckButton_Numeric.set_active();
  m_CheckButton_Numeric.signal_clicked().connect( sigc::mem_fun(*this,
              &ExampleWindow::on_checkbutton_numeric) );


  //Buttons:
  m_VBox_Accelerated.pack_start (m_HBox_Buttons, Gtk::PACK_SHRINK, 5);

  m_Button_Int.signal_clicked().connect( sigc::bind( sigc::mem_fun(*this,
                  &ExampleWindow::on_button_getvalue), VALUE_FORMAT_INT) );
  m_HBox_Buttons.pack_start(m_Button_Int, Gtk::PACK_EXPAND_WIDGET, 5);

  m_Button_Float.signal_clicked().connect( sigc::bind( sigc::mem_fun(*this,
                  &ExampleWindow::on_button_getvalue), VALUE_FORMAT_FLOAT) );
  m_HBox_Buttons.pack_start(m_Button_Float, Gtk::PACK_EXPAND_WIDGET, 5);

  m_VBox_Accelerated.pack_start(m_Label_ShowValue);
  m_Label_ShowValue.set_text("0");

  //Close button:
  m_Button_Close.signal_clicked().connect( sigc::mem_fun(*this,
              &ExampleWindow::on_button_close) );
  m_VBox_Main.pack_start(m_Button_Close, Gtk::PACK_SHRINK);

  show_all_children();
}

ExampleWindow::~ExampleWindow()
{
}


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

void ExampleWindow::on_checkbutton_snap()
{
  m_SpinButton_Value.set_snap_to_ticks( m_CheckButton_Snap.get_active() );
}

void ExampleWindow::on_checkbutton_numeric()
{
  m_SpinButton_Value.set_numeric( m_CheckButton_Numeric.get_active() );
}

void ExampleWindow::on_spinbutton_digits_changed()
{
  m_SpinButton_Value.set_digits( m_SpinButton_Digits.get_value_as_int() );
}

void ExampleWindow::on_button_getvalue(enumValueFormats display)
{
  gchar buf[32];

  if (display == VALUE_FORMAT_INT)
    sprintf (buf, "%d", m_SpinButton_Value.get_value_as_int());
  else
    sprintf (buf, "%0.*f", m_SpinButton_Value.get_digits(),
            m_SpinButton_Value.get_value());

  m_Label_ShowValue.set_text(buf);
}

File: main.cc (For use with gtkmm 3, not gtkmm 2)

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

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

  ExampleWindow window;

  //Shows the window and returns when it is closed.
  return app->run(window);
}

SpinButton

7.3.1. 方法

7.3.2. 示例

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