Provides functions to draw primitives (e.g., lines, shapes) to a rendering context (the MainCanvas). More...

#include <graphics.hpp>

Public Member Functions
void	set_coordinate_system (t_coordinate_system new_coordinate_system)
	Change the current coordinate system. More...

void	set_visible_world (rectangle new_world)
	Set the visible bounds of the world. More...

rectangle	get_visible_world ()
	Get the current visible bounds of the world. More...

rectangle	get_visible_screen ()
	Get the current visible bounds of the screen in pixel coordinates. More...

rectangle	world_to_screen (const rectangle &box)
	Get the screen coordinates (pixel locations) of the world coordinate rectangle box. More...

void	set_color (color new_color)
	Change the color for subsequent draw calls. More...

void	set_color (color new_color, uint_fast8_t alpha)
	Change the color for subsequent draw calls. More...

void	set_color (uint_fast8_t red, uint_fast8_t green, uint_fast8_t blue, uint_fast8_t alpha=255)
	Change the color for subsequent draw calls. More...

void	set_line_cap (line_cap cap)
	Change how line endpoints will be rendered in subsequent draw calls. More...

void	set_line_dash (line_dash dash)
	Change the dash style of the line for subsequent draw calls. More...

void	set_line_width (int width)
	Set the line width. More...

void	set_font_size (double new_size)
	Change the font size. More...

void	format_font (std::string const &family, font_slant slant, font_weight weight)
	Change the font. More...

void	format_font (std::string const &family, font_slant slant, font_weight weight, double new_size)
	Change the font. More...

void	set_text_rotation (double degrees)
	set the rotation_angle at which subsequent text drawing should render. More...

void	set_horiz_justification (justification horiz_just)
	set horizontal justification; used for text and surfaces. More...

void	set_vert_justification (justification vert_just)
	set vertical justification; used for text and surfaces. More...

void	draw_line (point2d start, point2d end)
	Draw a line. More...

void	draw_rectangle (point2d start, point2d end)
	Draw the outline a rectangle. More...

void	draw_rectangle (point2d start, double width, double height)
	Draw the outline of a rectangle. More...

void	draw_rectangle (rectangle r)
	Draw the outline of a rectangle. More...

void	fill_rectangle (point2d start, point2d end)
	Draw a filled in rectangle. More...

void	fill_rectangle (point2d start, double width, double height)
	Draw a filled in rectangle. More...

void	fill_rectangle (rectangle r)
	Draw a filled in rectangle. More...

void	fill_poly (std::vector< point2d > const &points)
	Draw a filled polygon The polygon can have an arbitrary shape and be convex or non-convex, but must be simple (no holes). More...

void	draw_elliptic_arc (point2d center, double radius_x, double radius_y, double start_angle, double extent_angle)
	Draw the outline of an elliptic arc. More...

void	draw_arc (point2d center, double radius, double start_angle, double extent_angle)
	Draw the outline of an arc. More...

void	fill_elliptic_arc (point2d center, double radius_x, double radius_y, double start_angle, double extent_angle)
	Draw a filled in elliptic arc. More...

void	fill_arc (point2d center, double radius, double start_angle, double extent_angle)
	Draw a filled in arc. More...

void	draw_text (point2d point, std::string const &text)
	Draw text justified at the chosen point, according to the current justification. More...

void	draw_text (point2d point, std::string const &text, double bound_x, double bound_y)
	Draw text if it fits in the specified bounds; otherwise not drawn. More...

void	draw_surface (surface *p_surface, point2d anchor_point, double scale_factor=1)
	Draw a surface. More...

	~renderer ()
	Destructor.

Static Public Member Functions
static surface *	load_png (const char *file_path)
	load a png image into a bitmap surface More...

static void	free_surface (surface *surface)
	Free a surface. More...

Protected Types
using	transform_fn = std::function< point2d(point2d)>
	A callback for transforming points from one coordinate system to another.

Protected Member Functions
	renderer (cairo_t cairo, transform_fn transform, camera m_camera, cairo_surface_t *m_surface)
	Constructor. More...

void	update_renderer (cairo_t cairo, cairo_surface_t m_surface)
	Update the renderer when the cairo surface/context changes. More...

Friends
class	canvas

Detailed Description

Provides functions to draw primitives (e.g., lines, shapes) to a rendering context (the MainCanvas).

The various set_ functions are sticky; they remain in effect for all graphics drawing calls after them, until overrideen by a later set_ call.

The renderer modifies a cairo_t context based on draw calls. The renderer uses an ezgl::camera object to convert world coordinates into cairo's expected coordinate system.

Constructor & Destructor Documentation

◆ renderer()

ezgl::renderer::renderer	(	cairo_t *	cairo,
		transform_fn	transform,
		camera *	m_camera,
		cairo_surface_t *	m_surface
	)

protected

Constructor.

Parameters

cairo	The cairo graphics state.
transform	The function to use to transform points to cairo's coordinate system.

Member Function Documentation

◆ draw_arc()

void ezgl::renderer::draw_arc	(	point2d	center,
		double	radius,
		double	start_angle,
		double	extent_angle
	)

Draw the outline of an arc.

Parameters

center	The center of the arc, in the current coordinate system
radius	The radius of the arc, in the current coordinate system
start_angle	The starting angle of the arc, in degrees from the positive x axis
extent_angle	The extent angle of the arc, in degrees from the positive x axis

◆ draw_elliptic_arc()

void ezgl::renderer::draw_elliptic_arc	(	point2d	center,
		double	radius_x,
		double	radius_y,
		double	start_angle,
		double	extent_angle
	)

Draw the outline of an elliptic arc.

Parameters

center	The center of the arc, in the current coordinate system
radius_x	The x radius of the elliptic arc, in the current coordinate system
radius_y	The y radius of the elliptic arc.
start_angle	The starting angle of the arc, in degrees from the positive x axis
extent_angle	The extent angle of the arc, in degrees from the positive x axis

◆ draw_line()

void ezgl::renderer::draw_line	(	point2d	start,
		point2d	end
	)

Draw a line.

Parameters

start	The start point of the line, in the current coordinate system
end	The end point of the line

◆ draw_rectangle() [1/3]

void ezgl::renderer::draw_rectangle	(	point2d	start,
		double	width,
		double	height
	)

Draw the outline of a rectangle.

Parameters

start	The lower left corner of the rectangle, in the current coordinate system
width	How wide the rectangle is, in the current coordinate system
height	How high the rectangle is

◆ draw_rectangle() [2/3]

void ezgl::renderer::draw_rectangle	(	point2d	start,
		point2d	end
	)

Draw the outline a rectangle.

Parameters

start	A corner point of the rectangle, in the current coordinate system
end	The diagonally opposite point of the rectangle

◆ draw_rectangle() [3/3]

void ezgl::renderer::draw_rectangle ( rectangle r )

Draw the outline of a rectangle.

Parameters

r	The rectangle

◆ draw_surface()

void ezgl::renderer::draw_surface	(	surface *	p_surface,
		point2d	anchor_point,
		double	scale_factor = `1`
	)

Draw a surface.

Parameters

surface	The surface (bitmap) to draw
anchor_point	The anchor_point point of the drawn surface The surface will be justified at this point accordinate to the current justification.
scale_factor	(optional) The scaling factor of the drawn surface. If specified, the width and height of the surface are each scaled by scale_factor.

◆ draw_text() [1/2]

void ezgl::renderer::draw_text	(	point2d	point,
		std::string const &	text
	)

Draw text justified at the chosen point, according to the current justification.

Parameters

point	The point where the text is drawn, in the current coordinate system
text	The text to draw

◆ draw_text() [2/2]

void ezgl::renderer::draw_text	(	point2d	point,
		std::string const &	text,
		double	bound_x,
		double	bound_y
	)

Draw text if it fits in the specified bounds; otherwise not drawn.

Parameters

point	The point where the text is drawn (justified according to the current justification), in the current coordinate system.
text	The text to draw
bound_x	The maximum allowed width of the text, in the current coordinate system.
bound_y	The maximum allowed height of the text, in the current coordinate system.

◆ fill_arc()

void ezgl::renderer::fill_arc	(	point2d	center,
		double	radius,
		double	start_angle,
		double	extent_angle
	)

Draw a filled in arc.

Parameters

center	The center of the arc, in the current coordinate system
radius	The radius of the arc, in the current coordinate system
start_angle	The starting angle of the arc, in degrees from the positive x axis
extent_angle	The extent angle of the arc, in degrees from the positive x axis

◆ fill_elliptic_arc()

void ezgl::renderer::fill_elliptic_arc	(	point2d	center,
		double	radius_x,
		double	radius_y,
		double	start_angle,
		double	extent_angle
	)

Draw a filled in elliptic arc.

Parameters

center	The center of the arc, in pixels.
radius_x	The x radius of the elliptic arc, in the current coordinate sstem.
radius_y	The y radius of the elliptic arc, in the current coordinate system.
start_angle	The starting angle of the arc, in degrees from the positive x axis.
extent_angle	The extent angle of the arc, in degrees from the positive x axis.

◆ fill_poly()

void ezgl::renderer::fill_poly ( std::vector< point2d > const & points )

Draw a filled polygon The polygon can have an arbitrary shape and be convex or non-convex, but must be simple (no holes).

Parameters

points The points to draw, which must be in the current coordinate system (world or screen). The first and last points are connected to close the polygon. There must be at least 2 points.

◆ fill_rectangle() [1/3]

void ezgl::renderer::fill_rectangle	(	point2d	start,
		double	width,
		double	height
	)

Draw a filled in rectangle.

Parameters

start	The lower left corner of the rectangle, the current coordinate system
width	How wide the rectangle is, in the current coordinate system
height	How high the rectangle is

◆ fill_rectangle() [2/3]

void ezgl::renderer::fill_rectangle	(	point2d	start,
		point2d	end
	)

Draw a filled in rectangle.

Parameters

start	One corner of the rectangle, in the current coordinate system
end	The diagonally opposite corner of the rectangle

◆ fill_rectangle() [3/3]

void ezgl::renderer::fill_rectangle ( rectangle r )

Draw a filled in rectangle.

Parameters

r	The rectangle

◆ format_font() [1/2]

void ezgl::renderer::format_font	(	std::string const &	family,
		font_slant	slant,
		font_weight	weight
	)

Change the font.

Parameters

family	The font family to use (e.g., serif). Use an empty string to request the default font.
slant	The slant to use (e.g., italic)
weight	The weight of the font (e.g., bold)

◆ format_font() [2/2]

void ezgl::renderer::format_font	(	std::string const &	family,
		font_slant	slant,
		font_weight	weight,
		double	new_size
	)

Change the font.

Parameters

family	The font family to use (e.g., serif). Use an empty string to request the default font.
slant	The slant to use (e.g., italic)
weight	The weight of the font (e.g., bold)
new_size	The new size text should be drawn at.

◆ free_surface()

static void ezgl::renderer::free_surface ( surface * surface )

static

Free a surface.

Parameters

surface The surface to destroy

◆ get_visible_screen()

rectangle ezgl::renderer::get_visible_screen ( )

Get the current visible bounds of the screen in pixel coordinates.

Returns: A rectangle where rectangle.first is the lower left MainCanvas corner and rectangle.second is the upper right

◆ get_visible_world()

rectangle ezgl::renderer::get_visible_world ( )

Get the current visible bounds of the world.

Returns: A rectangle where rectangle.first is the lower left MainCanvas corner and rectangle.second is the upper right

◆ load_png()

static surface* ezgl::renderer::load_png ( const char * file_path )

static

load a png image into a bitmap surface

Parameters

file_path The path to the png image.

Returns: a pointer to the created surface. This should later be freed using free_surface()

◆ set_color() [1/3]

void ezgl::renderer::set_color ( color new_color )

Change the color for subsequent draw calls.

Parameters

new_color The new color to use.

◆ set_color() [2/3]

void ezgl::renderer::set_color	(	color	new_color,
		uint_fast8_t	alpha
	)

Change the color for subsequent draw calls.

Opaque drawing is about 2x faster than partially transparent.

Parameters

new_color	The new color to use.
alpha	The transparency level. 0 is fully tranparent, 255 is opaque.

◆ set_color() [3/3]

void ezgl::renderer::set_color	(	uint_fast8_t	red,
		uint_fast8_t	green,
		uint_fast8_t	blue,
		uint_fast8_t	alpha = `255`
	)

Change the color for subsequent draw calls.

Opaque drawing is about 2x faster than partially transparent.

Parameters

red	The amount of red to use, between 0 and 255.
green	The amount of green to use, between 0 and 255.
blue	The amount of blue to use, between 0 and 255.
alpha	(optional) The transparency level. 0 is fully transparent, 255 is opaque. Defaults to opaque is not specified.

◆ set_coordinate_system()

void ezgl::renderer::set_coordinate_system ( t_coordinate_system new_coordinate_system )

Change the current coordinate system.

Parameters

new_coordinate_system The drawing coordinate system SCREEN or WORLD

◆ set_font_size()

void ezgl::renderer::set_font_size ( double new_size )

Change the font size.

Parameters

new_size The size text should be drawn at, in points. A point is 1/72 of an inch. Text sizes do not scale as graphics are zoomed in and out; they are always drawn at the chosen point size.

◆ set_horiz_justification()

void ezgl::renderer::set_horiz_justification ( justification horiz_just )

set horizontal justification; used for text and surfaces.

Parameters

horiz_just Options: center, left and right justification.

◆ set_line_cap()

void ezgl::renderer::set_line_cap ( line_cap cap )

Change how line endpoints will be rendered in subsequent draw calls.

Parameters

cap	The line_cap style

◆ set_line_dash()

void ezgl::renderer::set_line_dash ( line_dash dash )

Change the dash style of the line for subsequent draw calls.

Parameters

dash	The line_dash style

◆ set_line_width()

void ezgl::renderer::set_line_width ( int width )

Set the line width.

Parameters

width The width in pixels. A value of 0 is still one pixel wide but about 100x faster to draw than other line widths as small accuracy shortcuts are allowed. Line widths are in pixels (i.e. screen coordinates) and do not scale as graphics are zoomed in or out.

◆ set_text_rotation()

void ezgl::renderer::set_text_rotation ( double degrees )

set the rotation_angle at which subsequent text drawing should render.

Parameters

degrees The angle by which the text should rotate, in degrees from the x-axis.

◆ set_vert_justification()

void ezgl::renderer::set_vert_justification ( justification vert_just )

set vertical justification; used for text and surfaces.

Parameters

vert_just Options: center, top and bottom justification.

◆ set_visible_world()

void ezgl::renderer::set_visible_world ( rectangle new_world )

Set the visible bounds of the world.

The function preserves the aspect ratio of the new world so that a single x-unit and a single y-unit map to the same distance on screen. It does this by expanding the new_world in either the x- or y-direction so it matches the MainCanvas aspect ratio.

Parameters

new_world The new visible bounds of the world. new_world.first is the lower left corner of the MainCanvas, and new_world.second is the upper right.

◆ update_renderer()

void ezgl::renderer::update_renderer	(	cairo_t *	cairo,
		cairo_surface_t *	m_surface
	)

protected

Update the renderer when the cairo surface/context changes.

Parameters

cairo	The new cairo graphics state
m_surface	The new cairo surface

◆ world_to_screen()

rectangle ezgl::renderer::world_to_screen ( const rectangle & box )

Get the screen coordinates (pixel locations) of the world coordinate rectangle box.

Parameters

box	A rectangle in world coordinates

Returns: The corresponding rectangle in screen coordinates

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

graphics.hpp

Public Member Functions

Static Public Member Functions

Protected Types

Protected Member Functions

Friends

Detailed Description

Constructor & Destructor Documentation

◆ renderer()

Member Function Documentation

◆ draw_arc()

◆ draw_elliptic_arc()

◆ draw_line()

◆ draw_rectangle() [1/3]

◆ draw_rectangle() [2/3]

◆ draw_rectangle() [3/3]

◆ draw_surface()

◆ draw_text() [1/2]

◆ draw_text() [2/2]

◆ fill_arc()

◆ fill_elliptic_arc()

◆ fill_poly()

◆ fill_rectangle() [1/3]

◆ fill_rectangle() [2/3]

◆ fill_rectangle() [3/3]

◆ format_font() [1/2]

◆ format_font() [2/2]

◆ free_surface()

◆ get_visible_screen()

◆ get_visible_world()

◆ load_png()

◆ set_color() [1/3]

◆ set_color() [2/3]

◆ set_color() [3/3]

◆ set_coordinate_system()

◆ set_font_size()

◆ set_horiz_justification()

◆ set_line_cap()

◆ set_line_dash()

◆ set_line_width()

◆ set_text_rotation()

◆ set_vert_justification()

◆ set_visible_world()

◆ update_renderer()

◆ world_to_screen()