Canvas

touchgfx/widgets/canvas/Canvas.hpp

Class for easy rendering using CanvasWidgetRenderer. The Canvas class will make implementation of a new CanvasWidget very easy. The few simple primitives allows moving a "pen" and drawing the outline of a shape which can then be rendered.

The Canvas class has been optimized to eliminate drawing unnecessary lines outside the currently invalidated rectangle.

Public Functions

	Canvas(const AbstractPainter *const painter, const Rect & canvasAreaAbs, const Rect & invalidatedAreaRel, uint8_t globalAlpha)
	Canvas Constructor.
bool	close()
	Closes the current shape so that the inside can be filled using a Painter.
void	cubicBezierTo(float x0, float y0, float x1, float y1, float x2, float y2, float x, float y)
	Draw a Cubic Bezier curve via x1,y1 and x2,y2 to x3,y3.
Rasterizer::FillingRule	getFillingRule() const
	Gets the filling rule being used when rendering the outline.
virtual void	lineTo(CWRUtil::Q5 x, CWRUtil::Q5 y)
	Draw line from the current (x, y) to the new (x, y) as part of the shape being drawn.
template <typename T > void	lineTo(T x, T y)
	Draw line from the current (x, y) to the new (x, y) as part of the shape being drawn.
void	moveTo(CWRUtil::Q5 x, CWRUtil::Q5 y)
	Move the current pen position to (x, y).
template <typename T > void	moveTo(T x, T y)
	Move the current pen position to (x, y).
void	quadraticBezierTo(float x0, float y0, const float x1, const float y1, const float x, const float y)
	Draw a Quadratic Bezier curve via x1,y1 to x2,y2.
bool	render(uint8_t customAlpha =255)
	Render the graphical shape drawn using moveTo() and lineTo() with the given Painter.
void	setFillingRule(Rasterizer::FillingRule rule)
	Sets the filling rule to be used when rendering the outline.
FORCE_INLINE_FUNCTION bool	wasOutlineTooComplex()
	Determines if we the outline was too complex to draw completely.
virtual	~Canvas()
	Finalizes an instance of the Canvas class.

Public Functions Documentation

Canvas

Canvas	(	const AbstractPainter *const	painter ,
		const Rect &	canvasAreaAbs ,
		const Rect &	invalidatedAreaRel ,
		uint8_t	globalAlpha
		)

Canvas Constructor.

Locks the framebuffer and prepares for drawing only in the allowed area which has been invalidated. The color depth of the LCD is taken into account.

Parameters:

painter	The painter used for drawing in the canvas.
canvasAreaAbs	The canvas dimensions in absolute coordinates.
invalidatedAreaRel	The area which should be updated in relative coordinates to the canvas area.
globalAlpha	The alpha value to use when drawing in the canvas.

Note

Locks the framebuffer.

close

bool close	(			)

Closes the current shape so that the inside can be filled using a Painter.

Returns:

True if there is enough memory to calculate the shape outline, false if there is too little memory.

cubicBezierTo

void cubicBezierTo	(	float	x0 ,
		float	y0 ,
		float	x1 ,
		float	y1 ,
		float	x2 ,
		float	y2 ,
		float	x ,
		float	y
		)

Draw a Cubic Bezier curve via x1,y1 and x2,y2 to x3,y3.

Parameters:

x0	The start x coordinate.
y0	The start y coordinate.
x1	The first 'via' x coordinate.
y1	The first 'via' y coordinate.
x2	The second 'via' x coordinate.
y2	The second 'via' y coordinate.
x	The end x coordinate.
y	The end y coordinate.

getFillingRule

Rasterizer::FillingRule getFillingRule	(			)	const

Gets the filling rule being used when rendering the outline.

Returns:

The filling rule.

See also:

setFillingRule

lineTo

virtual void lineTo	(	CWRUtil::Q5	x ,
		CWRUtil::Q5	y
		)

Draw line from the current (x, y) to the new (x, y) as part of the shape being drawn.

As for moveTo, lineTo commands completely outside the drawing are are discarded.

Parameters:

x	The x coordinate for the pen position in CWRUtil::Q5 format.
y	The y coordinate for the pen position in CWRUtil::Q5 format.

See also:

CWRUtil::Q5, moveTo

lineTo

void lineTo	(	T	x ,
		T	y
		)

Draw line from the current (x, y) to the new (x, y) as part of the shape being drawn.

As for moveTo, lineTo commands completely outside the drawing are are discarded.

Template Parameters:

T	either int or float.

Parameters:

x	The x coordinate for the pen position.
y	The y coordinate for the pen position.

moveTo

void moveTo	(	CWRUtil::Q5	x ,
		CWRUtil::Q5	y
		)

Move the current pen position to (x, y).

If the pen is outside the drawing area, nothing is done, but the coordinates are saved in case the next operation is lineTo a coordinate which is inside (or on the opposite side of) the drawing area.

Parameters:

x	The x coordinate for the pen position in CWRUtil::Q5 format.
y	The y coordinate for the pen position in CWRUtil::Q5 format.

moveTo

void moveTo	(	T	x ,
		T	y
		)

Move the current pen position to (x, y).

If the pen is outside (above or below) the drawing area, nothing is done, but the coordinates are saved in case the next operation is lineTo a coordinate which is inside (or on the opposite side of) the drawing area.

Template Parameters:

T	Either int or float.

Parameters:

x	The x coordinate for the pen position.
y	The y coordinate for the pen position.

quadraticBezierTo

void quadraticBezierTo	(	float	x0 ,
		float	y0 ,
		const float	x1 ,
		const float	y1 ,
		const float	x ,
		const float	y
		)

Draw a Quadratic Bezier curve via x1,y1 to x2,y2.

Parameters:

x0	The start x coordinate.
y0	The start y coordinate.
x1	The 'via' x coordinate.
y1	The 'via' y coordinate.
x	The end x coordinate.
y	The end y coordinate.

render

bool render	(	uint8_t	customAlpha =255	)

Render the graphical shape drawn using moveTo() and lineTo() with the given Painter.

The shape is automatically closed, i.e. a lineTo() is automatically inserted connecting the current pen position with the initial pen position given in the first moveTo() command.

Parameters:

customAlpha	(Optional) Alpha to apply to the entire canvas. Useful if the canvas is part of a more complex container setup that needs to be faded. Default is solid.

Returns:

true if the widget was rendered, false if insufficient memory was available to render the widget.

setFillingRule

void setFillingRule	(	Rasterizer::FillingRule	rule	)

Sets the filling rule to be used when rendering the outline.

Parameters:

rule	The filling rule.

See also:

getFillingRule

wasOutlineTooComplex

FORCE_INLINE_FUNCTION bool wasOutlineTooComplex	(			)

Determines if we the outline was too complex to draw completely.

Returns:

True if it was too complex, false if not.

~Canvas

virtual ~Canvas	(			)

Finalizes an instance of the Canvas class.

Note

Unlocks the framebuffer.