ersa::ui::Canvas Class Reference

#include <canvas.h>

Public Member Functions
virtual	~Canvas ()=default
virtual int	width () const =0
virtual int	height () const =0
virtual void	clear (Color color=Color::Black)=0
virtual void	drawPixel (int x, int y, Color color=Color::White)=0
virtual void	drawLine (int x1, int y1, int x2, int y2, Color color=Color::White)=0
virtual void	drawRect (int x, int y, int w, int h, Color color=Color::White)=0
virtual void	fillRect (int x, int y, int w, int h, Color color=Color::White)=0
virtual void	drawText (int x, int y, const char *text, Color color=Color::White)=0

Detailed Description

Small renderer contract for canvas-oriented watchfaces.

Canvas is intentionally narrower than a vendor graphics library: it exposes logical pixels, primitive geometry, and text while hiding framebuffer and panel details. It is useful for portable watchface code; the fuller display HAL is used when an app needs font selection or refresh-specific behavior.

Constructor & Destructor Documentation

~Canvas()

virtual ersa::ui::Canvas::~Canvas ( )

virtualdefault

Allow concrete canvases to be destroyed through this interface.

Member Function Documentation

clear()

virtual void ersa::ui::Canvas::clear ( Color  color = Color::Black )

pure virtual

Fill the entire canvas; no hardware refresh is implied.

drawLine()

virtual void ersa::ui::Canvas::drawLine ( int  x1, int  y1, int  x2, int  y2, Color  color = Color::White  )

pure virtual

Rasterize a line between logical endpoints.

drawPixel()

virtual void ersa::ui::Canvas::drawPixel ( int  x, int  y, Color  color = Color::White  )

pure virtual

Set one logical pixel, clipping or ignoring coordinates outside bounds.

drawRect()

virtual void ersa::ui::Canvas::drawRect ( int  x, int  y, int  w, int  h, Color  color = Color::White  )

pure virtual

Draw a rectangle outline with the supplied origin and extent.

drawText()

virtual void ersa::ui::Canvas::drawText ( int  x, int  y, const char *  text, Color  color = Color::White  )

pure virtual

Draw text at the backend-defined baseline convention.

fillRect()

virtual void ersa::ui::Canvas::fillRect ( int  x, int  y, int  w, int  h, Color  color = Color::White  )

pure virtual

Fill a rectangle in the framebuffer.

height()

virtual int ersa::ui::Canvas::height ( ) const

pure virtual

Return logical height in pixels for layout calculations.

width()

virtual int ersa::ui::Canvas::width ( ) const

pure virtual

Return logical width in pixels for layout calculations.

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

• include/ersa/ui/canvas.h