The Canvas class is the entry point into CanvasCV. More...

#include <canvas.h>

Inheritance diagram for canvascv::Canvas:

Public Types
typedef std::function< void(Shape *)>	CBCanvasShape
	notification on shapes create/modify/delete from this Canvas instance

Public Member Functions
	Canvas (const std::string &winNameVal, cv::Size sizeVal=cv::Size())
	Canvas. More...

	~Canvas ()
	release all shapes and widgets. Shape callbacks are invoked doe delete.

void	redrawOn (const cv::Mat &src, cv::Mat &dst)
	redrawOn draws the shapes on dst More...

void	redrawOn (cv::Mat &dst)
	redrawOn More...

void	setImage (const cv::Mat &img)
	setImage More...

bool	onMousePress (const cv::Point &pos)
	You should delegate OpenCV mouse callback events to this method - returns true if did something at pos.

void	onMouseRelease (const cv::Point &pos)
	You should delegate OpenCV mouse callback events to this method.

void	onMouseMove (const cv::Point &pos)
	You should delegate OpenCV mouse callback events to this method.

std::shared_ptr< Shape >	createShape (std::string type, const cv::Point &pos=cv::Point(0, 0))
	createShape More...

template<class T >
std::shared_ptr< T >	createShape (const cv::Point &pos=cv::Point(0, 0))
	createShape More...

std::string	getShapeType () const
	get default shape type to draw More...

void	setShapeType (std::string value)
	set default shape type to draw (could be "") More...

void	deleteActive ()
	delete shape currenty selected

void	deleteShape (const std::shared_ptr< Shape > &shape)
	delete specific shape

void	deleteWidget (const std::shared_ptr< Widget > &widget)
	delete specific widget

void	notifyOnShapeCreate (CBCanvasShape cb)
	used to register for notifications on shape creation More...

void	notifyOnShapeModify (CBCanvasShape cb)
	used to register for notifications on shape modification (actually when it is deselected) More...

void	notifyOnShapeDelete (CBCanvasShape cb)
	used to register for notifications on shape deletion More...

void	clearShapes ()
	clear all shapes from Canvas

void	clearWidgets ()
	clear all widgets from Canvas

template<class T >
void	getShapes (std::list< std::shared_ptr< T >> &result)
	getShapes of a specific type More...

std::shared_ptr< Shape >	getShape (int id)
	getShape More...

void	getShapes (const cv::Point &pos, std::list< std::shared_ptr< Shape >> &result)
	getShapes More...

void	disableScreenText ()
	disable the top left text area for manual user messages

void	disableStatusMsg ()
	disable the bottom left text area for auto status messages

void	enableScreenText (cv::Scalar color=Colors::Black, cv::Scalar bgColor=Colors::LightGray, double scale=Consts::DEFAULT_FONT_SCALE, int thickness=Consts::DEFAULT_FONT_THICKNESS, uchar alpha=80, int fontFace=Consts::DEFAULT_FONT)
	enableScreenText enables the top left text area for manual user messages More...

void	enableStatusMsg (cv::Scalar color=Colors::Orange, cv::Scalar bgColor=Colors::LightGray, double scale=Consts::DEFAULT_FONT_SCALE, int thickness=Consts::DEFAULT_FONT_THICKNESS, uchar alpha=80, int fontFace=Consts::DEFAULT_FONT)
	enableStatusMsg enables the bottom left text area for auto status messages More...

void	setDefaultStatusMsg (const std::string &msg)
	set the default status message (active widget and shapes will override it)

std::string	getDefaultStatusMsg () const
	get the default status message (active widget and shapes will override it)

void	setScreenText (const std::string &msg)
	manually set the screen text message. It remains until disabled or changed.

void	setSize (const cv::Size &value)
	set the Canvas size to match the cv::Mat we'll use in redrawOn;

cv::Size	getSize ()
	get the Canvas size

virtual void	addWidget (const std::shared_ptr< Widget > &widget)
	adds the widget to this Layout after removing it from it's previous layout

virtual std::shared_ptr< Widget >	rmvWidget (const std::shared_ptr< Widget > &widget)
	rmvWidget More...

bool	getOn () const
	is redrawOn() on/off?

void	setOn (bool value)
	redrawOn will do nothing if value is 'false'

void	writeShapesToFile (const std::string &filepath) const
	write all the shapes currently in the Canvas to a file

void	readShapesFromFile (const std::string &filepath)
	load all the from a file into the canvas (removing all current shapes in the process)

void	setMouseCallback ()
	utility method to handle mouse events on the associated window

void	imshow (InputArray mat)
	utility method which uses the winName encapsulated in Canvas

int	waitKeyEx (int delay=0)
	waitKeyEx More...

void	applyTheme (bool applyToCanvasText=false)
	applyTheme More...

void	setDirty ()
	while waiting for events the Canvas is redrawn only if it is dirty

Static Public Member Functions
static void	fatal (string errorMsg, int exitStatus)
	fatal More...

Additional Inherited Members

Detailed Description

This is conceptually a canvas layer on top of your frame.

It can be turned on and off.
It can show your messages on screen with a semi transparent background.
You can handle mouse and keyboard events:
1. To create/edit/delete shapes on screen for user selections and landmark configuration.
2. To handle widgets you put on the screen for user input.

Examples:: example_add_theme.cpp, example_add_widget.cpp, example_checkboxes.cpp, example_linecrossing.cpp, example_matwidget.cpp, example_msgbox.cpp, example_radiobuttons.cpp, example_selectbox.cpp, example_shapes.cpp, and example_shapes_widgets.cpp.

Constructor & Destructor Documentation

canvascv::Canvas::Canvas	(	const std::string &	winNameVal,
		cv::Size	sizeVal = `cv::Size()`
	)

This class is associated with an OpenCV window of a certain size.

Parameters

winNameVal	is the name of the OpenCV window (it doesn't have to exist yet)
sizeVal	is the size of the OpenCV window

See also: setSize()

Member Function Documentation

void canvascv::Canvas::applyTheme ( bool applyToCanvasText = false )

apply the current theme to all existing widgets and shapes in the canvas

Parameters

applyToCanvasText should be usually false (make it true to affect Status&UserText of Canvas).

std::shared_ptr<Shape> canvascv::Canvas::createShape	(	std::string	type,
		const cv::Point &	pos = `cv::Point(0, 0)`
	)

Create shape by name on the canvas directly from code (instead of by the user using the mouse)

Parameters

type	name of the Shape
pos	shape position

Returns: This method will return a shared_ptr<T> instance, which you don't have to keep since another one is kept by the Canvas in which the shape is placed. Never use delete on a Shape pointer.

Examples:: example_shapes_widgets.cpp.

template<class T >

std::shared_ptr< T > canvascv::Canvas::createShape ( const cv::Point & pos = cv::Point(0,0) )

Create shape by type on the canvas directly from code (instead of by the user using the mouse)

Parameters

pos	shape position

Returns: This method will return a shared_ptr<T> instance, which you don't have to keep since another one is kept by the Canvas in which the shape is placed. Never use delete on a Shape pointer.

void canvascv::Canvas::enableScreenText	(	cv::Scalar	color = `Colors::Black`,
		cv::Scalar	bgColor = `Colors::LightGray`,
		double	scale = `Consts::DEFAULT_FONT_SCALE`,
		int	thickness = `Consts::DEFAULT_FONT_THICKNESS`,
		uchar	alpha = `80`,
		int	fontFace = `Consts::DEFAULT_FONT`
	)

During enable of this feature you can overide some default values. It is safe to call this method again just to change display settings.

Parameters

color	is font color
bgColor	is rect bg color
scale	is font scale
thickness	is font thickness
alpha	is the alpha value of the rect bg [0,255] => [transparent,opaque]
fontFace	is the OpenCV fonr to use

Examples:: example_checkboxes.cpp, example_radiobuttons.cpp, and example_shapes_widgets.cpp.

void canvascv::Canvas::enableStatusMsg	(	cv::Scalar	color = `Colors::Orange`,
		cv::Scalar	bgColor = `Colors::LightGray`,
		double	scale = `Consts::DEFAULT_FONT_SCALE`,
		int	thickness = `Consts::DEFAULT_FONT_THICKNESS`,
		uchar	alpha = `80`,
		int	fontFace = `Consts::DEFAULT_FONT`
	)

During enable of this feature you can overide some default values. It is safe to call this method again just to change display settings.

Parameters

color	is font color
bgColor	is rect bg color
scale	is font scale
thickness	is font thickness
alpha	is the alpha value of the rect bg [0,255] => [transparent,opaque]
fontFace	is the OpenCV fonr to use

Examples:: example_shapes_widgets.cpp.

static void canvascv::Canvas::fatal	(	string	errorMsg,
		int	exitStatus
	)

static

A more elegant way for your app to exit on failures.

A dedicated opencv window with a MsgBox wil show your message.
The error code will be used with _Exit()
The errorMsg will also be written to the standard error
Parameters

errorMsg will be displayed to the user

exitStatus will be used with _Exit()

Examples:: example_add_widget.cpp, example_checkboxes.cpp, example_linecrossing.cpp, example_matwidget.cpp, example_msgbox.cpp, example_radiobuttons.cpp, example_selectbox.cpp, example_shapes.cpp, and example_shapes_widgets.cpp.

std::shared_ptr<Shape> canvascv::Canvas::getShape ( int id )

Parameters

id

Returns: shape with requested id

template<class T >

void canvascv::Canvas::getShapes ( std::list< std::shared_ptr< T >> & result )

Parameters

result will contain alll shapes of the T on return

Note: these are internal shapes used in the canvas, so changing them affects what is drawn on the Canvas.

void canvascv::Canvas::getShapes	(	const cv::Point &	pos,
		std::list< std::shared_ptr< Shape >> &	result
	)

Parameters

pos	is position to search for shapes
result	is all the shapes at pos

std::string canvascv::Canvas::getShapeType ( ) const

inline

Returns: returns the default current shape to create on mouse press

void canvascv::Canvas::notifyOnShapeCreate ( CBCanvasShape cb )

Multiple registrations are allowed.

Parameters

cb	to invoke on shape creation

Examples:: example_shapes_widgets.cpp.

void canvascv::Canvas::notifyOnShapeDelete ( CBCanvasShape cb )

Multiple registrations are allowed.

Parameters

cb	to invoke on shape deletion

void canvascv::Canvas::notifyOnShapeModify ( CBCanvasShape cb )

Multiple registrations are allowed.

Parameters

cb	to invoke on shape modification

void canvascv::Canvas::redrawOn	(	const cv::Mat &	src,
		cv::Mat &	dst
	)

Draws src with shapes and widgets onto dst. src is upgraded to 3 channels if it has 1 channel.

Parameters

src	can be also dst, in which case it is drawn on. src is BGR/BGRA/GRAY.
dst	if different than src, then src is cloned to it and drawn on.

See also: setImage

Examples:: example_shapes_widgets.cpp.

void canvascv::Canvas::redrawOn ( cv::Mat & dst )

A utility method that uses latest Mat used as 'src' in the redrawOn above. This methos is also used internally in waitKeyEx(0)

Parameters

dst	will be used as output.

See also: waitKeyEx

virtual std::shared_ptr<Widget> canvascv::Canvas::rmvWidget ( const std::shared_ptr< Widget > & widget )

virtual

Parameters

widget will be removed from this Layout

Returns: filled shared_ptr to removed widget or empty if not found

Note: Widgets must be in layouts to be displayed correctly.

Implements canvascv::Layout.

Examples:: example_shapes_widgets.cpp.

void canvascv::Canvas::setImage ( const cv::Mat & img )

sets the internal 'latestFrameSrc' used for GUI updates while waitKeyEx(0) is used, or with redrawOn(cv::Mat&)

Parameters

img	will be used to setSize and update internal latestFrameSrc

void canvascv::Canvas::setShapeType ( std::string value )

inline

Parameters

value will be the default current shape to create on mouse press

Examples:: example_linecrossing.cpp, example_shapes.cpp, and example_shapes_widgets.cpp.

int canvascv::Canvas::waitKeyEx ( int delay = 0 )

utility method to handle key strokes - you get the keystroke if a widget/shape didn't consume it.

Parameters

delay in milliseconds. If delay is 0, then the latest image used as input will be the background for internal updates. If you want to change it from a callback, then use setImage.

Returns: the key press or -1 if the timeout reached

See also: setImage

Note: When using widgets with callback on the same image, the delay should be 0. If you're changing frames or using only the polling API of the widgets, then specify a delay of your choice.

Examples:: example_shapes_widgets.cpp.

The documentation for this class was generated from the following file:

CanvasCV-doxygen/src/canvascv/canvas.h

errorMsg	will be displayed to the user
exitStatus	will be used with _Exit()

Public Types

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation