QRCode

touchgfx/widgets/QRCode.hpp

Widget capable of generating and showing a QRCode. This widget uses the QR Code generator library (C). https://www.nayuki.io/page/qr-code-generator-library

Important: The application must allocate buffers and provide these through QRCode::setBuffers.

The QRCode supports framebuffer formats RGB565, RGB888, ARGB8888.

Inherits from: Widget, Drawable

Public Types

enum	ECCLevel { ECC_LOW = 0, ECC_MED = 1, ECC_QUARTILE = 2, ECC_HIGH = 3 }
	ECC levels.

Public Functions

bool	convertBinaryDataToQRCode(const uint8_t * data, size_t length)
	Convert data to QRCode data and save in the buffer.
bool	convertStringToQRCode(const char * text)
	Convert a text to QRCode data and save in the buffer.
virtual void	draw(const Rect & invalidatedArea) const
	Draw this drawable.
uint8_t	getAlpha() const
	Gets the current alpha value of the widget.
ECCLevel	getErrorCorrectionLevel() const
	Gets the current error correction level.
uint8_t	getQRCodeVersion() const
	Gets the current QRCode version.
int	getScale() const
	Gets the current scale of the QRCode.
virtual Rect	getSolidRect() const
	Get (the largest possible) rectangle that is guaranteed to be solid (opaque).
	QRCode()
	Construct a new QRCode using black and white colors with alpha 255.
void	setAlpha(uint8_t newAlpha)
	Sets the opacity (alpha value).
void	setBuffers(uint8_t qrBuffer, uint8_t tempBuffer)
	Sets the buffers used for QRCode generation.
void	setColors(colortype colorBlack, colortype colorWhite)
	Sets the colors used for the QRCode.
void	setErrorCorrectionLevel(ECCLevel level)
	Sets the desired level of error correction codes.
void	setQRCodeVersion(uint8_t version)
	Sets the version (size) of the QRCode.
void	setScale(int newScale)
	Sets the scale of the QRCode.

Additional inherited members

Public Functions inherited from Widget

virtual void	getLastChild(int16_t , int16_t , Drawable ** last)
	Since a Widget is only one Drawable, Widget::getLastChild simply yields itself as result, but only if the Widget isVisible and isTouchable.

Public Functions inherited from Drawable

void	center()
	Centers the Drawable inside its parent.
void	centerX()
	Center the Drawable horizontally inside its parent.
void	centerY()
	Center the Drawable vertically inside its parent.
virtual void	childGeometryChanged()
	This function can be called on parent nodes to signal that the size or position of one or more of its children has changed.
	Drawable()
	Initializes a new instance of the Drawable class.
void	drawToDynamicBitmap(BitmapId id)
	Render the Drawable object into a dynamic bitmap.
void	expand(int margin =0)
	Expands the Drawable to have the same size as its parent with a given margin around the edge.
Rect	getAbsoluteRect() const
	Helper function for obtaining the rectangle this Drawable covers, expressed in absolute coordinates.
virtual Drawable *	getFirstChild()
	Function for obtaining the first child of this drawable if any.
int16_t	getHeight() const
	Gets the height of this Drawable.
virtual void	getLastChild(int16_t x, int16_t y, Drawable ** last) =0
	Function for obtaining the the last child of this drawable that intersects with the specified point.
Drawable *	getNextSibling()
	Gets the next sibling node.
Drawable *	getParent() const
	Returns the parent node.
const Rect &	getRect() const
	Gets the rectangle this Drawable covers, in coordinates relative to its parent.
virtual Rect	getSolidRectAbsolute()
	Helper function for obtaining the largest solid rect (as implemented by getSolidRect()) expressed in absolute coordinates.
virtual void	getVisibleRect(Rect & rect) const
	Function for finding the visible part of this drawable.
int16_t	getWidth() const
	Gets the width of this Drawable.
int16_t	getX() const
	Gets the x coordinate of this Drawable, relative to its parent.
int16_t	getY() const
	Gets the y coordinate of this Drawable, relative to its parent.
virtual void	handleClickEvent(const ClickEvent & event)
	Defines the event handler interface for ClickEvents.
virtual void	handleDragEvent(const DragEvent & event)
	Defines the event handler interface for DragEvents.
virtual void	handleGestureEvent(const GestureEvent & event)
	Defines the event handler interface for GestureEvents.
virtual void	handleTickEvent()
	Called periodically by the framework if the Drawable instance has subscribed to timer ticks.
virtual void	invalidate() const
	Tell the framework that this entire Drawable needs to be redrawn.
virtual void	invalidateContent() const
	Tell the framework that the contents of the Drawable needs to be redrawn.
virtual void	invalidateRect(Rect & invalidatedArea) const
	Request that a region of this drawable is redrawn.
bool	isTouchable() const
	Gets whether this Drawable receives touch events or not.
bool	isVisible() const
	Gets whether this Drawable is visible.
virtual void	moveRelative(int16_t x, int16_t y)
	Moves the drawable.
virtual void	moveTo(int16_t x, int16_t y)
	Moves the drawable.
virtual void	setHeight(int16_t height)
	Sets the height of this drawable.
void	setPosition(const Drawable & drawable)
	Sets the position of the Drawable to the same as the given Drawable.
void	setPosition(int16_t x, int16_t y, int16_t width, int16_t height)
	Sets the size and position of this Drawable, relative to its parent.
void	setTouchable(bool touch)
	Controls whether this Drawable receives touch events or not.
void	setVisible(bool vis)
	Controls whether this Drawable should be visible.
virtual void	setWidth(int16_t width)
	Sets the width of this drawable.
void	setWidthHeight(const Bitmap & bitmap)
	Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates).
void	setWidthHeight(const Drawable & drawable)
	Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates).
void	setWidthHeight(const Rect & other)
	Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates).
void	setWidthHeight(int16_t width, int16_t height)
	Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates).
virtual void	setX(int16_t x)
	Sets the x coordinate of this Drawable, relative to its parent.
void	setXY(const Drawable & drawable)
	Sets the x and y coordinates of this Drawable.
void	setXY(int16_t x, int16_t y)
	Sets the x and y coordinates of this Drawable, relative to its parent.
virtual void	setY(int16_t y)
	Sets the y coordinate of this Drawable, relative to its parent.
virtual void	translateRectToAbsolute(Rect & r) const
	Helper function for converting a region of this Drawable to absolute coordinates.
virtual	~Drawable()
	Finalizes an instance of the Drawable class.

Protected Attributes inherited from Drawable

Drawable *	nextSibling
	Pointer to the next Drawable.
Drawable *	parent
	Pointer to this drawable's parent.
Rect	rect
	The coordinates of this Drawable, relative to its parent.
bool	touchable
	True if this drawable should receive touch events.
bool	visible
	True if this drawable should be drawn.

Public Types Documentation

ECCLevel

enum ECCLevel

ECC levels.

ECC_LOW	Low level of ECC (handles around 7% faults)
ECC_MED	Medium level of ECC (handles around 15% faults)
ECC_QUARTILE	Good level of ECC (handles around 25% faults)
ECC_HIGH	High level of ECC (handles around 30% faults)

Public Functions Documentation

convertBinaryDataToQRCode

bool convertBinaryDataToQRCode	(	const uint8_t *	data ,
		size_t	length
		)

Convert data to QRCode data and save in the buffer.

The function returns false if the encoding of the data does not fit in the QRCode. This depends on the version of the QRCode and the ECCLevel. If the data was not accepted, the QRCodeWidget does not draw anything. User must call invalidate() after changing the data. This function can e.g. be used to store UTF8 encoded strings.

Parameters:

data	The data to show in the QRCode.
length	Length of the data.

Returns:

True if data was converted.

convertStringToQRCode

bool convertStringToQRCode	(	const char *	text	)

Convert a text to QRCode data and save in the buffer.

The function returns false if the encoding of the string does not fit in the QRCode. This depends on the version of the QRCode and the ECCLevel. If the text was not accepted, the QRCodeWidget does not draw anything. User must call invalidate() after changing the data.

Parameters:

text	The text to show in the QRCode.

Returns:

True if data was converted.

draw

virtual void draw	(	const Rect &	invalidatedArea	)

Draw this drawable.

It is a requirement that the draw implementation does not draw outside the region specified by invalidatedArea.

Parameters:

invalidatedArea	The sub-region of this drawable that needs to be redrawn, expressed in coordinates relative to its parent (e.g. for a complete redraw, invalidatedArea will be (0, 0, width, height).

Reimplements: touchgfx::Drawable::draw

getAlpha

uint8_t getAlpha	(			)	const

Gets the current alpha value of the widget.

The alpha value is in range 255 (solid) to 0 (invisible).

Returns:

The current alpha value.

See also:

setAlpha

getErrorCorrectionLevel

ECCLevel getErrorCorrectionLevel	(			)	const

Gets the current error correction level.

Returns:

The current error correction level.

See also:

setErrorCorrectionLevel

getQRCodeVersion

uint8_t getQRCodeVersion	(			)	const

Gets the current QRCode version.

Returns:

The current version.

See also:

setQRCodeVersion

getScale

int getScale	(			)	const

Gets the current scale of the QRCode.

Returns:

The current scale.

See also:

setScale

getSolidRect

virtual Rect getSolidRect	(			)	const

Get (the largest possible) rectangle that is guaranteed to be solid (opaque).

This information is important, as any Drawable underneath the solid area does not need to be drawn.

Returns:

The solid rectangle part of the Drawable.

Note

The rectangle returned must be relative to upper left corner of the Drawable, meaning that a completely solid widget should return the full size Rect(0, 0, getWidth(), getHeight()). If no area can be guaranteed to be solid, an empty Rect must be returned. Failing to return the correct rectangle may result in errors on the display.

Reimplements: touchgfx::Drawable::getSolidRect

QRCode

QRCode	(			)

Construct a new QRCode using black and white colors with alpha 255.

The user must supply buffers and set the scale and QR version as wanted.

setAlpha

void setAlpha	(	uint8_t	newAlpha	)

Sets the opacity (alpha value).

This can be used to fade it away by gradually decreasing the alpha value from 255 (solid) to 0 (invisible).

Parameters:

newAlpha	The new alpha value. 255=solid, 0=invisible.

Note

The user code must call invalidate() in order to update the display.

setBuffers

void setBuffers	(	uint8_t *	qrBuffer ,
		uint8_t *	tempBuffer
		)

Sets the buffers used for QRCode generation.

The length of the buffers must match the version of the QRCode used. Use the above macro QRCODE_BUFFER_SIZE(version) when allocating buffers. The qrBuffer is holding the QRCode bit-stream. The tempBuffer is only used during QRCode generation. It can be used for other purposes afterwards and shared between Widgets.

Parameters:

qrBuffer	Buffer to store the QRcode.
tempBuffer	Scratch buffer used during QRCode generation.

setColors

void setColors	(	colortype	colorBlack ,
		colortype	colorWhite
		)

Sets the colors used for the QRCode.

Black and White is traditionally used, but other colors will also work.

Parameters:

colorBlack	The color used for 'black' pixels.
colorWhite	The color used the 'white' pixels.

setErrorCorrectionLevel

void setErrorCorrectionLevel	(	ECCLevel	level	)

Sets the desired level of error correction codes.

Parameters:

level	The level of ECC.

setQRCodeVersion

void setQRCodeVersion	(	uint8_t	version	)

Sets the version (size) of the QRCode.

Version is between 1 to 40.

Parameters:

version	The QRCode version to use.

setScale

void setScale	(	int	newScale	)

Sets the scale of the QRCode.

Each bit will be shown as scale pixels.

Parameters:

newScale	The scale to use.