lvppCanvasIndexed Class Reference

Construct a canvas which uses INDEXED color rather than FULL color methods. More...

#include <lvpp.h>

Inheritance diagram for lvppCanvasIndexed:

Collaboration diagram for lvppCanvasIndexed:

Public Member Functions
	lvppCanvasIndexed (const char *fName, lv_coord_t x, lv_coord_t y, lv_coord_t w, lv_coord_t h, uint8_t colorDepth, lv_color_t *providedBuffer=nullptr, lv_obj_t *parent=nullptr)
	Construct a new lvpp Canvas Full Color object.
virtual	~lvppCanvasIndexed ()
bool	addColorToIndex (lv_color_t col)
	Add a single color to the indexed color set.
bool	addPaletteToIndex (lv_palette_t pal)
	Add a full palette of color to the indexed color set. This is 10 colors.
void	clearColorIndex ()
	Remove all colors from the indexed color set.
bool	getIndexFromColor (lv_color_t col, lv_color_t &ind)
	Get the Index of a single Color.
void	setbgColor (lv_color_t bgColor)
	Set the background color of the canvas.
void	setbgColorByIndex (lv_color_t bgColorIndex)
	Set the backgrond color from an index color.
void	drawPixel (lv_coord_t x, lv_coord_t y, lv_color_t color)
	Draw a single pixel on to the canvas.
void	drawPixelByIndex (lv_coord_t x, lv_coord_t y, lv_color_t colorIndex)
	Draw a single pixel on to the canvas using an index color.
void	drawLineVert (lv_coord_t x1, lv_coord_t y1, lv_coord_t h, lv_color_t color)
	Draw a verical line on the canvas.
void	drawLineVertByIndex (lv_coord_t x1, lv_coord_t y1, lv_coord_t h, lv_color_t indexCol)
	Draw a verical line on the canvas using an index color.
void	drawLineHoriz (lv_coord_t x1, lv_coord_t y1, lv_coord_t w, lv_color_t color)
	Draw a horizontal line on the canvas.
void	drawLineHorizByIndex (lv_coord_t x1, lv_coord_t y1, lv_coord_t w, lv_color_t indexCol)
	Draw a horizontal line on the canvas using an index color.
void	drawRectWithoutFill (lv_coord_t x1, lv_coord_t y1, lv_coord_t w, lv_coord_t h, lv_color_t borderColor)
	Draw a rectangle on the canvas without filling in the rectangle.
void	drawRectWithoutFillByIndex (lv_coord_t x1, lv_coord_t y1, lv_coord_t w, lv_coord_t h, lv_color_t borderColorInd)
	Draw a rectangle on the canvas without filling in the rectangle using an index color.
void	drawRectWithFill (lv_coord_t x1, lv_coord_t y1, lv_coord_t w, lv_coord_t h, lv_color_t borderColor, lv_color_t fillColor)
	Draw a rectangle on the canvas and fill in the center of the rectangle.
void	drawRectWithFillByIndex (lv_coord_t x1, lv_coord_t y1, lv_coord_t w, lv_coord_t h, lv_color_t borderColorInd, lv_color_t fillColorInd)
	Draw a rectangle on the canvas and fill in the center of the rectangle. This uses index colors.
void	drawCenteredRectWithoutFill (lv_coord_t xBorder, lv_coord_t yBorder, lv_color_t borderColor)
	Draw a centered rectangle on the canvas. Will have xBorder/yBorder around it.
void	drawCenteredRectWithoutFillByIndex (lv_coord_t xBorder, lv_coord_t yBorder, lv_color_t borderColorInd)
	Draw a centered rectangle on the canvas. Will have xBorder/yBorder around it. This uses index colors.
void	drawCenteredRectWithFill (lv_coord_t xBorder, lv_coord_t yBorder, lv_color_t borderColor, lv_color_t fillColor)
	Draw a centered rectangle on the canvas and fill in the rectangle. Will have xBorder/yBorder around it.
void	drawCenteredRectWithFillByIndex (lv_coord_t xBorder, lv_coord_t yBorder, lv_color_t borderColorInd, lv_color_t fillColorInd)
	Draw a centered rectangle on the canvas and fill in the rectangle. Will have xBorder/yBorder around it. This uses index colors.
Public Member Functions inherited from lvppBase
	lvppBase (const char *fName, const char *oType)
	Construct a new lvpp Base object.
	~lvppBase ()
void	createObj (lv_obj_t *o)
	Create the handlers and store the newly created object.
lv_obj_t *	getObj (void)
	Get the Obj object.
lv_obj_t *	getLabelObj (void)
	Get the label object.
virtual void	setSize (lv_coord_t width, lv_coord_t height)
	Set the Size object. Most of the time, LVGL does a great job of setting a sane size, but manipulation of things like the text or the font size can cause this to no longer be a good size. It is a common use pattern to instantiate a widget and then use setSize() and align() to place them in your user interface as needed.
void	align (lv_align_t align, lv_coord_t x_ofs, lv_coord_t y_ofs)
	Change the x/y location of the object.
void	setFontSize (uint8_t points)
	Set the Font Size for the object in simple 'points'.
void	setFont (const lv_font_t *pF)
	Set the Font to be used. This is a more complete/complex version of setFontSize(). The fact that the font pointer is required at least means the user knows the font exists.
void	setBGColor (lv_color_t color)
	Set the background color of the object.
void	setColorGradient (lv_color_t col1, lv_color_t col2, lv_grad_dir_t direction)
	Sets a Color Gradient from col1 to col2 in a vertical or horizontal direction. The gradient is place on the indicator for lvppBar, lvppSlider, and lvppArc. The graident is placed on the 'main' area of all other objects.
virtual void	setText (const char *pText)
	Set the Text for the primary text label. For a button, for instance, this is the text on top of the button.
std::string	getText ()
	Get the Text from the object/label and put it in a std::string.
void	setTextAlign (lv_align_t align, lv_coord_t xoff, lv_coord_t yoff)
	Set the Text Alignment. This allows the object's primary label to be moved from its 'center' position.
void	setTextColor (lv_color_t newColor)
	Set the Text Color of the primary label object.
void	setLabelJustificationAlignment (lv_text_align_t _align)
	Set the Label's text alignment (left/right/center)
void	setLabelColorizationEnabled (bool bEnable=true)
	Turn on or off inline text colorization. To use colors inline, simply use #RRGGBB in the text where the R, G, and B are hex values. Be sure to have a space before and after.
virtual void	setAdjText (const char *pText, lv_coord_t x_ofs=-10000, lv_coord_t y_ofs=-10000)
	Set the text for the adjacent text label. This label is not enabled by default. Setting this text will create and enable the adjacent label object. The label's position can be set, optionally, as well.
void	setAdjTextColor (lv_color_t newColor)
	Set the Adjacent text color.
void	setAdjBGColor (lv_color_t color)
	set the background color for the adjacent text
void	setAdjColorGradient (lv_color_t col1, lv_color_t col2, lv_grad_dir_t direction)
	Sets a Color Gradient from col1 to col2 in a vertical or horizontal direction.
void	setAdjFont (const lv_font_t *pF)
	Set the Font to be used for the adjacent text.
void	setAdjJustificationAlignment (lv_text_align_t _align)
	Set the adjacent Label's text alignment (left/right/center)
virtual void	onClicked ()
	Callback that derived objects can use to get notification when the object is clicked.
virtual void	internalOnClicked ()
	Internal version of the onClicked() callback which is used for other derived internal objects in the library.
virtual void	onValueChanged ()
	Callback that derived objects can use to get notification when the value changes of an object.
virtual void	internalOnValueChanged ()
	Internal version of the onValueChanged() callback which is used for other derived internal objects in the library.
void	setFriendlyName (const char *pName)
	Set the Friendly Name of the object. This is the name given in the constructor's fName parameter and is unlikely to be changed. However, it can be via this method.
std::string	getFriendlyName ()
	Get the Friendly Name of the object.
std::string	getObjType ()
	Get the Obj Type.
const char *	whoAmI (void)
	Utility useful for dumping the friendly name and object type if needed.
void	setCallbackOnClicked (std::function< void()> cbF)
	Uses a lambda callback for when an object is clicked.
void	setCallbackOnValueChanged (std::function< void()> cbF)
	Uses a lambda callback for when an object value changes.
virtual void	setNewParent (lv_obj_t *pNewParent)
	Changes the parent object on the fly. Used primarily for lvppScreen::addObject(). Sets parents of adjacent label, value label, and label appropriately.

Protected Attributes
uint16_t	maxColorIndexesAllowed
	Number of color indexes available based on the color depth at creation time.
uint8_t	colorIndexesUsed
lv_color_t *	pBuffer
lv_coord_t	width
lv_coord_t	height
Protected Attributes inherited from lvppBase
lv_obj_t *	label
	Primary label.
lv_obj_t *	adjLabel
	For items that have a label 'nearby' (adjacent label)
std::function< void()>	cbOnClicked =nullptr
	Start without a lambda callback.
std::function< void()>	cbOnValueChanged =nullptr
	Start without a lambda callback.
lv_obj_t *	obj
	The LVGL object that was created for this widget.
lv_obj_t *	objParent
	Any parent object (following same principle as LVGL here)
std::string	objType
std::string	friendlyName
lv_style_t	style_obj
	Main style object - unsure if I'm handling all of the style bit correctly.

Additional Inherited Members
Static Public Member Functions inherited from lvppBase
static const char *	getEventName (lv_event_code_t code)
	Get the Event Name from a given event code. Translate it to text, essentially.
static bool	isUnknownCode (lv_event_code_t code)
	Check to see if an event code is valid or not. Utility function.
Protected Member Functions inherited from lvppBase
void	setObjType (const char *pType)
void	baseEventHandler (lv_event_t *event)
	Main event handler loop for all events. This handler makes calls for onClicked() and onValueChanged()
virtual void	eventHandler (lv_event_t *event)
	Any events not handled by baseEventHandler come here. Can be overridden by a derived class.
Static Protected Member Functions inherited from lvppBase
static void	lvCallback (lv_event_t *event)
	Static member to handle all inbound callback events. Used to "route" event handling to the appropriate C++ object.
static void	initEventNames (void)
	One-time initialization of the event names array.
Static Protected Attributes inherited from lvppBase
static bool	bEventNamesInitComplete = false
	Status of the event names table to avoid re-processing.

Detailed Description

Construct a canvas which uses INDEXED color rather than FULL color methods.

Canvas drawing is very powerful in LVGL, but only when a full color canvas is available. In many smaller CPUs, full color isn't an option due to the sheer size of needing to have a buffer which is width * height * 4-bytes plus a bit more. LVGL has some great facilities around drawing rectangles, lines, and labels with really nice options like rounded ends, line thicknesses, and other style attributes. Many of these functions simply do not work in the indexed color world.

The underlying LVGL library allows for pixel drawing using an lv_color_t where the '.full' member is not actually a color but instead is an index based on how many colors are in the indexed color set. For instance, if you've chosen a 4-bit indexed color set, then the indexes would run from 0-15 and it is up to the user to "set up" the indexed color set (palette) prior to using any of those indexed values.

In lvppCanvasIndexed, some of the mystery and intricacy is taken out of the drawing and also the class supports drawing of lines and rectangles in a more limited fashion than the native full color canvas LVGL drawing routines.

To alleviate the complexity of keeping track of which color corresponds to which index value, this class allows the user to utilize either lv_color_t values or index values to do the drawing functions. The internals of the class work out the translation. This is accomplished by the user adding colors and/or palettes to the object through addColorToIndex() and addPaletteToIndex(). These colors are then mapped to index values internally which then allows the user to work in "colors" rather than indexes to colors, if they wish.

While it was the original intention to have users utilize only colors in this class, it was revamped to allow drawing by index as well. It is up to the user to keep track of what color is which index. And all of the drawing functions which are draw*Indexed() do take an lv_color_t but this is done in the same manner that LVGL intends it. The ".full" member of that color is actually the index value and not a true color. While I didn't particularly like the type conflict between a real color and an index, I felt it important to lean, again, to being more similar to LVGL concepts than to make my own.

NOTE: If the user tries to draw using an lv_color_t color which is not already defined in the indexed color set via addColorToIndex() or addPaletteToIndex(), the drawing requested will not take place and there will be an LV_LOG_WARN() message created to note that the requested color was not in the indexed color set.

NOTE: The primative drawPixel() is likely 'more expensive' than drawLine() and drawRect() functions for situations where more than a few pixels are to be drawn. This is because the drawing is invalidated after every pixel draw in the primative case while in the case of lines and rects, the invalidation is only done once after all of the pixels are 'laid down' in the drawing area. This is only a performance warning and not a functional one.

Constructor & Destructor Documentation

lvppCanvasIndexed()

lvppCanvasIndexed::lvppCanvasIndexed	(	const char *	fName,
		lv_coord_t	x,
		lv_coord_t	y,
		lv_coord_t	w,
		lv_coord_t	h,
		uint8_t	colorDepth,
		lv_color_t *	providedBuffer = nullptr,
		lv_obj_t *	parent = nullptr
	)

Construct a new lvpp Canvas Full Color object.

Parameters

fName	Internal object name. This is generally used in findObj() or lvppScreen
x,y	Top-left starting point of the canvas on the display.
w,h	Width and height of the canvas referenced from x and y.
colorDepth	How many bits of color depth shall be used for this canvas. Valid values would be 1, 2, 4, or 8. For instance, a 4-bit color depth would have 16 colors available in the indexed color set. NOTE: If the user passes in a providedBuffer, it is incumbent upon that user to ensure this colorDepth and the size of that buffer are not in conflict with each other or bad things could occur.
providedBuffer	If provided, a non-null value will cause the constructor to not allocate its own buffer. This is helpful when a series of screens intend to share a common canvas with no drawing changes between them.
parent	If provided, the parent of the object. This is a real LVGL lv_obj_t pointer

~lvppCanvasIndexed()

lvppCanvasIndexed::~lvppCanvasIndexed ( )

virtual

Member Function Documentation

addColorToIndex()

bool lvppCanvasIndexed::addColorToIndex

(

lv_color_t

col

)

Add a single color to the indexed color set.

Parameters

col	Color to add to the index.

Returns

true If there was room to add a new color or if the color was already in the index.

false If the index is already full based on the indexed color depth of the canvas.

addPaletteToIndex()

bool lvppCanvasIndexed::addPaletteToIndex

(

lv_palette_t

pal

)

Add a full palette of color to the indexed color set. This is 10 colors.

The concept of palette used here is that of LVGL. I felt the palette concept was a powerful one and wanted to support it here, easily. Adding a color palette will effectively add (4) darker palette colors, (1) main palette color, and (5) lighter palette colors. These figures come from the lv_palette_darken(), lv_palette_main() and lv_palette_lighten() functions.

Parameters

pal	Palette (not color) to add to the index. This is generally done by the use of LV_PALETTE_BLUE, LV_PALETTE_TEAL, LV_PALETTE_BROWN, etc.

Returns

true If there was room to add a new color or if the color was already in the index.

false If the index is already full based on the indexed color depth of the canvas.

clearColorIndex()

void lvppCanvasIndexed::clearColorIndex

(

)

Remove all colors from the indexed color set.

drawCenteredRectWithFill()

void lvppCanvasIndexed::drawCenteredRectWithFill	(	lv_coord_t	xBorder,
		lv_coord_t	yBorder,
		lv_color_t	borderColor,
		lv_color_t	fillColor
	)

Draw a centered rectangle on the canvas and fill in the rectangle. Will have xBorder/yBorder around it.

Parameters

xBorder,yBorder	The border size on each x-side and each y-side of the rectangle
borderColor	Color of the rectangle's border lines.
fillColor	Color to fill in the rectangle.

drawCenteredRectWithFillByIndex()

void lvppCanvasIndexed::drawCenteredRectWithFillByIndex	(	lv_coord_t	xBorder,
		lv_coord_t	yBorder,
		lv_color_t	borderColorInd,
		lv_color_t	fillColorInd
	)

Draw a centered rectangle on the canvas and fill in the rectangle. Will have xBorder/yBorder around it. This uses index colors.

Parameters

xBorder,yBorder	The border size on each x-side and each y-side of the rectangle
borderColorInd	The index of the color to use. This is not a true color but only an index.
fillColorInd	The index of the color to use. This is not a true color but only an index.

drawCenteredRectWithoutFill()

void lvppCanvasIndexed::drawCenteredRectWithoutFill	(	lv_coord_t	xBorder,
		lv_coord_t	yBorder,
		lv_color_t	borderColor
	)

Draw a centered rectangle on the canvas. Will have xBorder/yBorder around it.

Parameters

xBorder,yBorder	The border size on each x-side and each y-side of the rectangle
borderColor	Color of the rectangle's border lines.

drawCenteredRectWithoutFillByIndex()

void lvppCanvasIndexed::drawCenteredRectWithoutFillByIndex	(	lv_coord_t	xBorder,
		lv_coord_t	yBorder,
		lv_color_t	borderColorInd
	)

Draw a centered rectangle on the canvas. Will have xBorder/yBorder around it. This uses index colors.

Parameters

xBorder,yBorder	The border size on each x-side and each y-side of the rectangle
borderColorInd	The index of the color to use. This is not a true color but only an index.

drawLineHoriz()

void lvppCanvasIndexed::drawLineHoriz	(	lv_coord_t	x1,
		lv_coord_t	y1,
		lv_coord_t	w,
		lv_color_t	color
	)

Draw a horizontal line on the canvas.

Parameters

x1,y1	Starting point of the line to be drawn.
w	Width of the line to be drawn.
color	Color of the line to be drawn.

drawLineHorizByIndex()

void lvppCanvasIndexed::drawLineHorizByIndex	(	lv_coord_t	x1,
		lv_coord_t	y1,
		lv_coord_t	w,
		lv_color_t	indexCol
	)

Draw a horizontal line on the canvas using an index color.

Parameters

x1,y1	Starting point of the line to be drawn.
w	Width of the line to be drawn.
indexCol	The index of the color to use. This is not a true color but only an index.

drawLineVert()

void lvppCanvasIndexed::drawLineVert	(	lv_coord_t	x1,
		lv_coord_t	y1,
		lv_coord_t	h,
		lv_color_t	color
	)

Draw a verical line on the canvas.

Parameters

x1,y1	Starting point of the line to be drawn.
h	Height of the line to be drawn.
color	Color of the line to be drawn.

drawLineVertByIndex()

void lvppCanvasIndexed::drawLineVertByIndex	(	lv_coord_t	x1,
		lv_coord_t	y1,
		lv_coord_t	h,
		lv_color_t	indexCol
	)

Draw a verical line on the canvas using an index color.

Parameters

x1,y1	Starting point of the line to be drawn.
h	Height of the line to be drawn.
indexCol	The index of the color to use. This is not a true color but only an index.

drawPixel()

void lvppCanvasIndexed::drawPixel	(	lv_coord_t	x,
		lv_coord_t	y,
		lv_color_t	color
	)

Draw a single pixel on to the canvas.

Parameters

x	X location
y	Y location
color	Color to be drawn.

drawPixelByIndex()

void lvppCanvasIndexed::drawPixelByIndex	(	lv_coord_t	x,
		lv_coord_t	y,
		lv_color_t	colorIndex
	)

Draw a single pixel on to the canvas using an index color.

Parameters

x	X location
y	Y location
colorIndex	The index of the color to use. This is not a true color but only an index.

drawRectWithFill()

void lvppCanvasIndexed::drawRectWithFill	(	lv_coord_t	x1,
		lv_coord_t	y1,
		lv_coord_t	w,
		lv_coord_t	h,
		lv_color_t	borderColor,
		lv_color_t	fillColor
	)

Draw a rectangle on the canvas and fill in the center of the rectangle.

Parameters

x1,y1	Starting point of the rectangle
w,h	Width and height of the rectangle
borderColor	Color of the rectangle's border lines.
fillColor	Color to fill in the rectangle.

drawRectWithFillByIndex()

void lvppCanvasIndexed::drawRectWithFillByIndex	(	lv_coord_t	x1,
		lv_coord_t	y1,
		lv_coord_t	w,
		lv_coord_t	h,
		lv_color_t	borderColorInd,
		lv_color_t	fillColorInd
	)

Draw a rectangle on the canvas and fill in the center of the rectangle. This uses index colors.

Parameters

x1,y1	Starting point of the rectangle
w,h	Width and height of the rectangle
borderColorInd	The index of the color to use. This is not a true color but only an index.
fillColorInd	The index of the color to use. This is not a true color but only an index.

drawRectWithoutFill()

void lvppCanvasIndexed::drawRectWithoutFill	(	lv_coord_t	x1,
		lv_coord_t	y1,
		lv_coord_t	w,
		lv_coord_t	h,
		lv_color_t	borderColor
	)

Draw a rectangle on the canvas without filling in the rectangle.

Parameters

x1,y1	Starting point of the rectangle
w,h	Width and height of the rectangle
borderColor	Color of the rectangle's border lines.

drawRectWithoutFillByIndex()

void lvppCanvasIndexed::drawRectWithoutFillByIndex	(	lv_coord_t	x1,
		lv_coord_t	y1,
		lv_coord_t	w,
		lv_coord_t	h,
		lv_color_t	borderColorInd
	)

Draw a rectangle on the canvas without filling in the rectangle using an index color.

Parameters

x1,y1	Starting point of the rectangle
w,h	Width and height of the rectangle
borderColorInd	The index of the color to use. This is not a true color but only an index.

getIndexFromColor()

bool lvppCanvasIndexed::getIndexFromColor	(	lv_color_t	col,
		lv_color_t &	ind
	)

Get the Index of a single Color.

Parameters

col	Color being requested for translation
ind	Reference to the index which will be returned (if successful)

Returns

true If the color col is found.

false If the color col is not found in the indexed color set.

setbgColor()

void lvppCanvasIndexed::setbgColor

(

lv_color_t

bgColor

)

Set the background color of the canvas.

Parameters

bgColor

The color to be used in painting the background. This is an lv_color_t from LVGL.

setbgColorByIndex()

void lvppCanvasIndexed::setbgColorByIndex

(

lv_color_t

bgColorIndex

)

Set the backgrond color from an index color.

Parameters

bgColorIndex

The index of the color to use. This is not a true color but only an index.

Member Data Documentation

colorIndexesUsed

uint8_t lvppCanvasIndexed::colorIndexesUsed

protected

How many colors have presently been used in the indexed color set.

height

lv_coord_t lvppCanvasIndexed::height

protected

maxColorIndexesAllowed

uint16_t lvppCanvasIndexed::maxColorIndexesAllowed

protected

Number of color indexes available based on the color depth at creation time.

pBuffer

lv_color_t* lvppCanvasIndexed::pBuffer

protected

Todo:

This use of LV_COLOR_DEPTH is believed to be correct at least for 8 and 16, but is this complete ?

width

lv_coord_t lvppCanvasIndexed::width

protected

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

• src/lvpp.h
• src/lvppCanvas.cpp