Display Class Reference

Represents a display that can be used to display images. More...

Inheritance diagram for Display:

Public Types
using	WindowClosedHandler = std::function< void(Display &display)>
	Function prototype for window-closed event handlers.
using	NotificationToken = void *
	Represents a registered callback.

Public Member Functions
bool	canRender (const ic4::ImageType &imageType, Error &err=Error::Ignore())
	Checks whether the display can render images of a specified image type.
bool	displayBuffer (const std::shared_ptr< ic4::ImageBuffer > &buffer, Error &err=Error::Default())
	Displays a specific image buffer.
bool	setRenderPosition (DisplayRenderPosition pos, int left=-1, int top=-1, int width=-1, int height=-1, Error &err=Error::Default())
	Configure the image scaling and alignment options for a display.
DisplayStatistics	statistics (Error &err=Error::Default())
	Queries display statistics.
NotificationToken	eventAddWindowClosed (WindowClosedHandler cb, Error &err=Error::Default())
	Registers a new window-closed event handler.
bool	eventRemoveWindowClosed (NotificationToken token, Error &err=Error::Default())
	Unregisters a window-closed event handler.

Static Public Member Functions
static std::shared_ptr< Display >	create (DisplayType type, WindowHandle hParent, Error &err=Error::Default())
	Creates a new display.

Detailed Description

Represents a display that can be used to display images.

To create a display, call Display::create() or ExternalOpenGLDisplay::create().

Display objects are generally used in two distinct ways:

• The display is connected to a data stream when calling Grabber::streamSetup(), automatically displaying all images from the opened device.
• ImageBuffer objects are displayed manually by calling Display::displayBuffer().

Display objects are neither copyable nor movable, and are only handled via std::shared_ptr<Display>.

Note

Some functions, such as Grabber::streamSetup(), takes shared ownership of the display object. The display is kept alive by the Grabber instance even if no external reference to the display object exists.

See also

Display::create

Member Typedef Documentation

NotificationToken

using NotificationToken = void*

Represents a registered callback.

When a callback function is registered using Display::eventAddWindowClosed, a token is returned.

The token can then be used to remove the callback using Display::eventRemoveWindowClosed at a later time.

WindowClosedHandler

using WindowClosedHandler = std::function<void(Display& display)>

Function prototype for window-closed event handlers.

Parameters

[in]

display

The Display on which the event handler was registered.

Member Function Documentation

canRender()

bool canRender ( const ic4::ImageType &  imageType, Error &  err = Error::Ignore()  )

inline

Checks whether the display can render images of a specified image type.

Parameters

[in]	imageType	The image type to check
[out]	err	Reference to an error handler. See Error Handling for details.

Returns

true if the display can render the specified image type, otherwise false.

create()

static std::shared_ptr< Display > create ( DisplayType  type, WindowHandle  hParent, Error &  err = Error::Default()  )

inlinestatic

Creates a new display.

Parameters

[in]	type	The type of display to create
[in]	hParent	Handle to the parent window to embed the display into.
[out]	err	Reference to an error handler. See Error Handling for details.

Returns

The new display, or nullptr if an error occurs.

Warning

This function only works in Windows platforms. For other platforms, use ExternalOpenGLDisplay::create().

displayBuffer()

bool displayBuffer ( const std::shared_ptr< ic4::ImageBuffer > &  buffer, Error &  err = Error::Default()  )

inline

Displays a specific image buffer.

Parameters

[in]	buffer	The buffer to display
[out]	err	Reference to an error handler. See Error Handling for details.

Returns

true on success, otherwise false.

Remarks

When buffer is nullptr, the display is cleared and will no longer display the previous buffer.

eventAddWindowClosed()

NotificationToken eventAddWindowClosed ( WindowClosedHandler  cb, Error &  err = Error::Default()  )

inline

Registers a new window-closed event handler.

Parameters

[in]	cb	Callback function to be called when the display window is closed.
[out]	err	Reference to an error handler. See Error Handling for details.

Returns

A token that can be used to unregister the callback using .\n If an error occurrs, the function returns nullptr.

See also

Display::eventRemoveWindowClosed

eventRemoveWindowClosed()

bool eventRemoveWindowClosed ( NotificationToken  token, Error &  err = Error::Default()  )

inline

Unregisters a window-closed event handler.

Parameters

[in]	token	A token that was returned when registering an event handler using Display::eventAddWindowClosed().
[out]	err	Reference to an error handler. See Error Handling for details.

Returns

true on success, otherwise false.

See also

Display::eventAddWindowClosed

setRenderPosition()

bool setRenderPosition ( DisplayRenderPosition  pos, int  left = -1, int  top = -1, int  width = -1, int  height = -1, Error &  err = Error::Default()  )

inline

Configure the image scaling and alignment options for a display.

Parameters

[in]	pos	The scaling and alignment mode to use
[in]	left	The left coordinate of the target rectangle inside the display window
[in]	top	The top coordinate of the target rectangle inside the display window
[in]	width	The width of the target rectangle inside the display window
[in]	height	The height of the target rectangle inside the display window
[out]	err	Reference to an error handler. See Error Handling for details.

Returns

true on success, otherwise false.

Remarks

The left, top, width and height parameters are ignored unless mode is DisplayRenderPosition::Custom.

A zoom effect can be created by setting width and height to a multiple of the width and height of the image buffer(s) to be displayed. Set left and top to negative values to specifiy the top left corner of the visible image.

statistics()

DisplayStatistics statistics ( Error &  err = Error::Default() )

inline

Queries display statistics.

Parameters

[out]

err

Reference to an error handler. See Error Handling for details.

Returns

A DisplayStatistics structure containing the number of displayed and dropped frames.