Screen Class Reference

Manage the FMC CDU display. More...

#include <Screen.h>

Classes
class	ScreenEvent
	Event Data. More...

Public Member Functions
void	initialize (int cols)
	queues an init command the the screen handler. More...
void	clearScreen ()
	queue a screen clear More...
void	drawLine (int line, int col, std::string text, bool spaceErases=true, char color='W', bool smallInBig=false)
	queue a line update to the screen More...
void	mainLoop ()
	the main loop of the screen. More...
void	quitLoop ()
	stop the screen's mainloop More...

Static Public Member Functions
static Screen *	getInstance ()
	returns the singleton intance of a Screen. More...

Static Public Attributes
static int	winWidth = 640
	window width
static int	winHeight = 480
	window height

Protected Types
enum	ScreenEventType : int { init = 0, LineUpdate = 1, clear = 2, quit = 4 }
	enum of possible event types More...

Protected Member Functions
void	doInit (SDL_Event *event)
	implement an "init" action More...
void	doClear ()
	implement a "clear" action More...
void	doDrawLine (SDL_Event *event)
	implement a "lineUpdate" action More...
void	transferBufferToDisplay ()
	transfer buffer to display
SDL_Texture *	generateCharacterTexture (std::string fontPath, int cellWidth, int maxHeight, SDL_Renderer *renderer)
	generate the texture containing all characters for a given cell width and height
TTF_Font *	getFont (std::string fontPath, int maxWidth, int maxHeight, SDL_Renderer *renderer)
	generate a font that fits within a cell's width and height

Protected Attributes
bool	isRunning = false
bool	stopRequested = false
SDL_Window *	window = NULL
	SDL Window.
SDL_Renderer *	renderer = NULL
	SDL renderer.
int	numCols = 0
	current number of columns. More...
int	numRows = 14
	current number of rows. More...
int	cellWidth = 0
	width of a character cell on the screen. More...
int	tallCellHeight = 0
	the height of a tall character. More...
int	shortCellHeight = 0
	the height of a short character. More...
int	winLeftBorder = 0
	left border of the screen. More...
int	winTopBorder = 0
	top border of the screen. More...
int	shortCharVertOffset = 0
	vertical offset for short chars. More...
int	linePos [15]
	screen offsets for each row. More...
SDL_Texture *	tallChars = NULL
	a texture holding pre-generated tall characters
SDL_Texture *	shortChars = NULL
	a texture holding pre-generated short characters
SDL_Texture *	screenBufferTexture = NULL
	ready-composited complete screen texture
Uint32	screenRefreshTimerMs = 10
	How many ms to wait after a line changes before repainting the screen. More...
Uint32	interPollDelayMs = 1
	how long to delay in between polls of the update queue. More...
Uint32	SDLUserEventBase
bool	isx737FMCLegsPage = false

Static Protected Attributes
static Screen *	instance = NULL

Detailed Description

Manage the FMC CDU display.

This is singleton class that manages the screen of the FMC CDU.

It uses SDL2 to render the display.

The class is used by calling submit* methods, which queue activities to be rendered a screen handling thread. This ensures that only one thread is making SDL2 calls at a time.

The class managed a single texture (screenBufferTexture) that holds the current display. All drawing is done onto this texture, which is then rendered to the display in its entirety.

The screen uses truetype fonts, however for performance reasons, it pre-caches the characters used by the FMC into a texture. Whenever a character needs to drawn, a single character is copied to the appropriate position on the screenBufferTexture.

Member Enumeration Documentation

ScreenEventType

enum Screen::ScreenEventType : int

protected

enum of possible event types

Member Function Documentation

clearScreen()

void Screen::clearScreen

(

)

queue a screen clear

This can be called from any thread, and queues a screen clear event. The implementation of this is faster than drawing blanks in every cell.

doClear()

void Screen::doClear ( )

protected

implement a "clear" action

doDrawLine()

void Screen::doDrawLine ( SDL_Event *  event )

protected

implement a "lineUpdate" action

doInit()

void Screen::doInit ( SDL_Event *  event )

protected

implement an "init" action

drawLine()

void Screen::drawLine	(	int	line,
		int	col,
		std::string	text,
		bool	spaceErases = true,
		char	color = 'W',
		bool	smallInBig = false
	)

queue a line update to the screen

This can be called from any thread, and queues a screen update for the main Screen thread. This results in the string "text" being drawn on the screen at the position specified by line/col.

getInstance()

Screen * Screen::getInstance ( )

static

returns the singleton intance of a Screen.

initialize()

void Screen::initialize

(

int

cols

)

queues an init command the the screen handler.

This calculates the screen metrics based on how many columns are required, and regenerates the font textures.

It can be called multiple times, to handle situations where the user switches between FMCs that have a different number of rows and columns.

mainLoop()

void Screen::mainLoop

(

)

the main loop of the screen.

Runs in a loop waiting for SDL events. In then calls the action{event} method to process them.

Note: SDL really doesn't like it when we run this in a separate thread. So main() has to call this and live within it happily ever after.

quitLoop()

void Screen::quitLoop

(

)

stop the screen's mainloop

since the screen's mainLoop is also the main program's mainLoop, this will cause the program to exit gracefully.

Member Data Documentation

cellWidth

int Screen::cellWidth = 0

protected

width of a character cell on the screen.

Calculated by init().

interPollDelayMs

Uint32 Screen::interPollDelayMs = 1

protected

how long to delay in between polls of the update queue.

Too long increases lag, too low increases CPU utilization.

linePos

int Screen::linePos[15]

protected

screen offsets for each row.

numCols

int Screen::numCols = 0

protected

current number of columns.

Set by user via init()

numRows

int Screen::numRows = 14

protected

current number of rows.

Fixed value 8-)

screenRefreshTimerMs

Uint32 Screen::screenRefreshTimerMs = 10

protected

How many ms to wait after a line changes before repainting the screen.

When an entire page changes, we will receive 14 separate messages from ExtPlane. To refresh the entire display for each line creates a laggy display. So it's better to wait a bit and get all the lines in before repainting the screen. Setting this too high however will result in a longer response time, which becomes obvious when a single cell changes (like when typing into the scratchpad).

shortCellHeight

int Screen::shortCellHeight = 0

protected

the height of a short character.

Calculated by init().

shortCharVertOffset

int Screen::shortCharVertOffset = 0

protected

vertical offset for short chars.

In some modes, we display short chars in a tall cell. This controls the vertical offset for the short char within the tall cell.

tallCellHeight

int Screen::tallCellHeight = 0

protected

the height of a tall character.

Calculated by init().

winLeftBorder

int Screen::winLeftBorder = 0

protected

left border of the screen.

Calculated by init() based on the remainder after dividing by the number of columns.

winTopBorder

int Screen::winTopBorder = 0

protected

top border of the screen.

Calculated by init() based on the remainder after dividing by the number of rows.

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

• src/piXPlaneFMCCDU/Screen.h
• src/piXPlaneFMCCDU/Screen.cpp