Canvas

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 CanvasWidget * _widget, const Rect & invalidatedArea)
	Canvas Constructor.
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).
bool	render(uint8_t customAlpha =255)
	Render the graphical shape drawn using moveTo() and lineTo() with the given Painter.
virtual	~Canvas()
	Finalizes an instance of the Canvas class.

Public Functions Documentation

Canvas

Canvas	(	const CanvasWidget *	_widget ,
		const Rect &	invalidatedArea
		)

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:

_widget	a pointer to the CanvasWidget using this Canvas. Used for getting the canvas dimensions.
invalidatedArea	the are which should be updated.

Note

Locks the framebuffer.

lineTo

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.

See also:

CWRUtil::Q5, lineTo

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.

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.

~Canvas

virtual ~Canvas	(			)

Finalizes an instance of the Canvas class.

Note

Unlocks the framebuffer.