64. Drag & Drop

Learn how to get information about files that are dragged and dropped.

64.1 Getting Dropped Files

• You can check if there are files dragged and dropped onto the application window using DragDrop::HasNewFilePaths()
• When this function returns true, you can call DragDrop::GetDroppedFilePaths() to get the list of dropped files as Array<DroppedFilePath> type
• The member variables of DroppedFilePath are as follows:

Code	Description
FilePath path	Absolute path of file or directory
Point pos	Position where it was dropped (scene coordinates)
uint64 timeMillisec	Time point when it was dropped (app runtime measured by Time::GetMillisec())

# include <Siv3D.hpp>

void Main()
{
	while (System::Update())
	{
		if (DragDrop::HasNewFilePaths())
		{
			for (auto&& [path, pos, timeMillisec] : DragDrop::GetDroppedFilePaths())
			{
				Print << U"{} @{} :{}"_fmt(path, pos, timeMillisec);
			}
		}
	}
}

64.2 Disabling File Drop

• To prevent files from being dropped onto the current application window, call DragDrop::AcceptFilePaths(false)

# include <Siv3D.hpp>

void Main()
{
	// Don't accept file path drops
	DragDrop::AcceptFilePaths(false);

	while (System::Update())
	{		
		// Nothing will be dropped since we don't accept them
		if (DragDrop::HasNewFilePaths())
		{
			for (auto&& [path, pos, timeMillisec] : DragDrop::GetDroppedFilePaths())
			{
				Print << U"{} @{} :{}"_fmt(path, pos, timeMillisec);
			}
		}
	}
}

64.3 Getting Dropped Text

• Text (string) drops to the application window are disabled by default
• You can enable text drops by calling DragDrop::AcceptText(true)
• You can check if there's text dragged and dropped onto the application window using DragDrop::HasNewText()
• When this function returns true, you can call DragDrop::GetDroppedText() to get the list of dropped text as Array<DroppedText> type
• The member variables of DroppedText are as follows:

Code	Description
String text	Dropped text
Point pos	Position where it was dropped (scene coordinates)
uint64 timeMillisec	Time point when it was dropped (app runtime measured by Time::GetMillisec())

• You can test text dropping by dragging selected text on a web browser

# include <Siv3D.hpp>

void Main()
{
	DragDrop::AcceptText(true);

	while (System::Update())
	{
		if (DragDrop::HasNewText())
		{
			for (auto&& [text, pos, timeMillisec] : DragDrop::GetDroppedText())
			{
				Print << U"{} @{} :{}"_fmt(text, pos, timeMillisec);
			}
		}
	}
}

64.4 Clearing Dropped Item Information

• Information about dropped items is cleared when you call DragDrop::GetDroppedFilePaths() and DragDrop::GetDroppedText(), but you can also clear it using DragDrop::Clear()

# include <Siv3D.hpp>

void Main()
{
	while (System::Update())
	{		
		if (DragDrop::HasNewFilePaths())
		{
			// Clear dropped item information
			DragDrop::Clear();

			// Nothing will be retrieved since it's been cleared
			for (auto&& [path, pos, timeMillisec] : DragDrop::GetDroppedFilePaths())
			{
				Print << U"{} @{} :{}"_fmt(path, pos, timeMillisec);
			}
		}
	}
}

64.5 Getting Information While Dragging

• To get information about items being dragged over the window, use DragDrop::DragOver()
• This function returns Optional<DragStatus>, or none if there are no items being dragged
• The member variables of DragStatus are as follows:

Code	Description
DragItemType itemType	Type of item being dragged DragItemType::FilePaths or DragItemType::Text
Point cursorPos	Position of cursor while dragging (scene coordinates)

• The following sample code displays an icon on screen when trying to drop files

# include <Siv3D.hpp>

void Main()
{
	Scene::SetBackground(ColorF{ 0.6, 0.8, 0.7 });

	const Texture icon{ 0xf15b_icon, 40 };

	while (System::Update())
	{
		// There's an item being dragged over the window
		if (const auto status = DragDrop::DragOver())
		{
			if (status->itemType == DragItemType::FilePaths)
			{
				// Display icon
				icon.drawAt(status->cursorPos, ColorF{ 0.1 });
			}
		}

		if (DragDrop::HasNewFilePaths())
		{
			for (auto&& [path, pos, timeMillisec] : DragDrop::GetDroppedFilePaths())
			{
				Print << U"{} @{} :{}"_fmt(path, pos, timeMillisec);
			}
		}
	}
}

64.6 Starting a Drag (Windows)

• In the Windows version, you can start dragging files from within the application window
• Call Platform::Windows::DragDrop::MakeDragDrop(file path) to start dragging the specified file path
• You can also specify multiple file paths with an array

# include <Siv3D.hpp>

void Main()
{
	const Texture texture{ U"example/windmill.png" };

	const Rect rect{ 80, 80, texture.size() };

	while (System::Update())
	{
		if (rect.mouseOver())
		{
			Cursor::RequestStyle(CursorStyle::Hand);

			if (MouseL.down())
			{
				Platform::Windows::DragDrop::MakeDragDrop(U"example/windmill.png");
			}
		}

		rect(texture).draw();
	}
}