5. Application Basics

Learn the basic operations of Siv3D applications.

5.1 Exit the Program and Close the Window

• You can exit the running program with any of the following operations (see Tutorial 3.5):
  1. Press the window close button
  2. Press the Esc key
  3. Call System::Exit() in the program
• When the program exits, the window is also closed
• For how to customize exit operations, see Tutorial 5.6

5.2 Save Screenshots

• While the program is running, save screenshots with any of the following shortcut keys:
  • Press Print Screen
  • Press F12 (not available during Visual Studio debugging as F12 is assigned to another function)
• The screenshot save location varies by OS

OS	Save Location
Windows	Screenshot folder in the same directory as the executable file
macOS	Screenshot folder within the Pictures folder
Linux	Screenshot folder in the same directory as the executable file

• Depending on your computer settings, the Print Screen key may be associated with other applications (OneDrive or Dropbox), and screenshots may not be saved to the above location

Recording screens on Windows

• Windows 10 and 11 have built-in screen recording functionality
• For details, see Xbox Game Bar

5.3 Change Screenshot Shortcut Keys

• To change the shortcut keys for saving screenshots in the current Siv3D app, use ScreenCapture::SetShortcutKeys({ list of keys })

Change Screenshot Shortcut Keys

# include <Siv3D.hpp>

void Main()
{
	// Set to save screenshots only when [A] key is pressed
	ScreenCapture::SetShortcutKeys({ KeyA });

	while (System::Update())
	{
		Circle{ 400, 300, 100 }.draw();
	}
}

• You can also specify multiple keys

Change Screenshot Shortcut Keys

# include <Siv3D.hpp>

void Main()
{
	// Set to save screenshots only when [PrintScreen] or [P] key is pressed
	ScreenCapture::SetShortcutKeys({ KeyPrintScreen, KeyP });

	while (System::Update())
	{
		Circle{ 400, 300, 100 }.draw();
	}
}

5.4 Display License Information

• While the program is running, display license information using any of the following methods:
  • Press F1
  • Call LicenseManager::ShowInBrowser()
• License information related to Siv3D will be displayed in a web browser

Add License Information

• You can use LicenseManager::AddLicense() to add new items at the beginning of the license information

Add License Information

# include <Siv3D.hpp>

void Main()
{
	LicenseManager::AddLicense({
		.title = U"My game",
		.copyright = U"(C) 2025 My name",
		.text = U"License" });

	while (System::Update())
	{

	}
}

5.5 Full Screen with Key Operation (Windows Only)

• On Windows, you can make the window full screen with the following key operation:
  • Press Alt+Enter
  • Press Alt+Enter again to return to windowed display
• This is convenient when displaying games or giving presentations

5.6 Change Exit Operations

• System::Update() returns false thereafter when special user actions to exit the application are performed
• Exit operation user actions can be changed by passing UserAction flags to System::SetTerminationTriggers()
  • When setting multiple user actions, use the bitwise OR operator |
• By default, the following 2 user actions are set as exit operations:

User Action	Description
UserAction::CloseButtonClicked	Press the window close button
UserAction::EscapeKeyDown	Press Esc

5.6.1 Prevent Exit with Esc

• To prevent exiting when Esc is pressed, do the following:

# include <Siv3D.hpp>

void Main()
{
	// Set only window close user action as exit operation
	System::SetTerminationTriggers(UserAction::CloseButtonClicked);

	while (System::Update())
	{

	}
}

5.6.2 Exit Only by Program

• When only UserAction::NoAction is passed to System::SetTerminationTriggers(), the window close button and Esc key are no longer considered exit operations
• In this case, the application will not exit unless System::Exit() is called or return is used in Main()

# include <Siv3D.hpp>

void Main()
{
	// Don't set exit operations
	System::SetTerminationTriggers(UserAction::NoAction);

	while (System::Update())
	{
		// If 5 seconds have passed since program start
		if (5.0 <= Scene::Time())
		{
			System::Exit();
		}
	}
}

5.6.3 Return to Default Exit Operations

• To return exit operations to default settings (window close operation, Esc key operation), pass UserAction::Default to System::SetTerminationTriggers()
• UserAction::Default is the same as (UserAction::CloseButtonClicked | UserAction::EscapeKeyDown)

# include <Siv3D.hpp>

void Main()
{
	// Don't set exit operations
	System::SetTerminationTriggers(UserAction::NoAction);

	// Return to default exit operations
	System::SetTerminationTriggers(UserAction::Default);

	while (System::Update())
	{

	}
}

Review Checklist

• Learned that screenshots are saved with Print Screen or F12
• Learned how to change screenshot shortcut keys
• Learned how to display license information
• Learned that on Windows you can make the window full screen with Alt+Enter
• Learned that program exit operations can be customized