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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

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

Public Functions

boolconvertBinaryDataToQRCode(const uint8_t * data, size_t length)
Convert data to QRCode data and save in the buffer.
boolconvertStringToQRCode(const char * text)
Convert a text to QRCode data and save in the buffer.
virtual voiddraw(const Rect & invalidatedArea) const
Draw this drawable.
uint8_tgetAlpha() const
Gets the current alpha value of the widget.
ECCLevelgetErrorCorrectionLevel() const
Gets the current error correction level.
uint8_tgetQRCodeVersion() const
Gets the current QRCode version.
intgetScale() const
Gets the current scale of the QRCode.
virtual RectgetSolidRect() 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.
voidsetAlpha(uint8_t newAlpha)
Sets the opacity (alpha value).
voidsetBuffers(uint8_t qrBuffer, uint8_t tempBuffer)
Sets the buffers used for QRCode generation.
voidsetColors(colortype colorBlack, colortype colorWhite)
Sets the colors used for the QRCode.
voidsetErrorCorrectionLevel(ECCLevel level)
Sets the desired level of error correction codes.
voidsetQRCodeVersion(uint8_t version)
Sets the version (size) of the QRCode.
voidsetScale(int newScale)
Sets the scale of the QRCode.

Additional inherited members

Public Functions inherited from Widget

virtual voidgetLastChild(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

voidcenter()
Centers the Drawable inside its parent.
voidcenterX()
Center the Drawable horizontally inside its parent.
voidcenterY()
Center the Drawable vertically inside its parent.
virtual voidchildGeometryChanged()
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.
voiddrawToDynamicBitmap(BitmapId id)
Render the Drawable object into a dynamic bitmap.
voidexpand(int margin =0)
Expands the Drawable to have the same size as its parent with a given margin around the edge.
RectgetAbsoluteRect() 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_tgetHeight() const
Gets the height of this Drawable.
virtual voidgetLastChild(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 RectgetSolidRectAbsolute()
Helper function for obtaining the largest solid rect (as implemented by getSolidRect()) expressed in absolute coordinates.
virtual voidgetVisibleRect(Rect & rect) const
Function for finding the visible part of this drawable.
int16_tgetWidth() const
Gets the width of this Drawable.
int16_tgetX() const
Gets the x coordinate of this Drawable, relative to its parent.
int16_tgetY() const
Gets the y coordinate of this Drawable, relative to its parent.
virtual voidhandleClickEvent(const ClickEvent & event)
Defines the event handler interface for ClickEvents.
virtual voidhandleDragEvent(const DragEvent & event)
Defines the event handler interface for DragEvents.
virtual voidhandleGestureEvent(const GestureEvent & event)
Defines the event handler interface for GestureEvents.
virtual voidhandleTickEvent()
Called periodically by the framework if the Drawable instance has subscribed to timer ticks.
virtual voidinvalidate() const
Tell the framework that this entire Drawable needs to be redrawn.
virtual voidinvalidateContent() const
Tell the framework that the contents of the Drawable needs to be redrawn.
virtual voidinvalidateRect(Rect & invalidatedArea) const
Request that a region of this drawable is redrawn.
boolisTouchable() const
Gets whether this Drawable receives touch events or not.
boolisVisible() const
Gets whether this Drawable is visible.
virtual voidmoveRelative(int16_t x, int16_t y)
Moves the drawable.
virtual voidmoveTo(int16_t x, int16_t y)
Moves the drawable.
virtual voidsetHeight(int16_t height)
Sets the height of this drawable.
voidsetPosition(const Drawable & drawable)
Sets the position of the Drawable to the same as the given Drawable.
voidsetPosition(int16_t x, int16_t y, int16_t width, int16_t height)
Sets the size and position of this Drawable, relative to its parent.
voidsetTouchable(bool touch)
Controls whether this Drawable receives touch events or not.
voidsetVisible(bool vis)
Controls whether this Drawable should be visible.
virtual voidsetWidth(int16_t width)
Sets the width of this drawable.
voidsetWidthHeight(const Bitmap & bitmap)
Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates).
voidsetWidthHeight(const Drawable & drawable)
Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates).
voidsetWidthHeight(const Rect & other)
Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates).
voidsetWidthHeight(int16_t width, int16_t height)
Sets the dimensions (width and height) of the Drawable without changing the x and y coordinates).
virtual voidsetX(int16_t x)
Sets the x coordinate of this Drawable, relative to its parent.
voidsetXY(const Drawable & drawable)
Sets the x and y coordinates of this Drawable.
voidsetXY(int16_t x, int16_t y)
Sets the x and y coordinates of this Drawable, relative to its parent.
virtual voidsetY(int16_t y)
Sets the y coordinate of this Drawable, relative to its parent.
virtual voidtranslateRectToAbsolute(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.
Rectrect
The coordinates of this Drawable, relative to its parent.
booltouchable
True if this drawable should receive touch events.
boolvisible
True if this drawable should be drawn.

Public Types Documentation

ECCLevel

ECC levels.

ECC_LOWLow level of ECC (handles around 7% faults)
ECC_MEDMedium level of ECC (handles around 15% faults)
ECC_QUARTILEGood level of ECC (handles around 25% faults)
ECC_HIGHHigh level of ECC (handles around 30% faults)

Public Functions Documentation

convertBinaryDataToQRCode

bool convertBinaryDataToQRCode(const uint8_t *data ,
size_tlength
)

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:
dataThe data to show in the QRCode.
lengthLength 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:
textThe 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:
invalidatedAreaThe 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:

getErrorCorrectionLevel

ECCLevel getErrorCorrectionLevel()const

Gets the current error correction level.

Returns:

The current error correction level.

See also:

getQRCodeVersion

uint8_t getQRCodeVersion()const

Gets the current QRCode version.

Returns:

The current version.

See also:

getScale

int getScale()const

Gets the current scale of the QRCode.

Returns:

The current scale.

See also:

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

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_tnewAlpha)

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:
newAlphaThe 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:
qrBufferBuffer to store the QRcode.
tempBufferScratch buffer used during QRCode generation.

setColors

void setColors(colortypecolorBlack ,
colortypecolorWhite
)

Sets the colors used for the QRCode.

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

Parameters:
colorBlackThe color used for 'black' pixels.
colorWhiteThe color used the 'white' pixels.

setErrorCorrectionLevel

Sets the desired level of error correction codes.

Parameters:
levelThe level of ECC.

setQRCodeVersion

void setQRCodeVersion(uint8_tversion)

Sets the version (size) of the QRCode.

Version is between 1 to 40.

Parameters:
versionThe QRCode version to use.

setScale

void setScale(intnewScale)

Sets the scale of the QRCode.

Each bit will be shown as scale pixels.

Parameters:
newScaleThe scale to use.