The Graphps module

module Graphics : sig

Alternate graphics module: PostScript interpretation of Caml machine-independent graphics primitives.

Initializations

val open_ps : string -> unit

Opens the file where the PostScript code corresponding to the Caml drawing is written. At the end of the Caml program, this file will contain a stand alone PostScript file, suitable for direct visualization or printing.

val open_eps : string -> unit

Opens the file where the encapsulated PostScript code corresponding to the Caml drawing is written. At the end of the Caml program, this file will contain an encapsulated PostScript file, suitable for insertion into a TeX file.

val open_graph : string -> unit

Starts the graphics mode. The PostScript drawing initialization is emited. The page is cleared and the current point is set to (0, 0). The string argument is used to pass optional information on the graphics size (using the X Windows geometry convention). If the empty string is given, a sensible default is selected.

val close_graph : unit -> unit

Emits the set of PostScript commands corresponding to the program execution. Closes the PostScript output file if necessary.

val clear_graph : unit -> unit

Clear the PostScript page.

val size_x : unit -> int
val size_y : unit -> int

Returns the size of the graphics page. Coordinates of the page range over 0 .. size_x()-1 and 0 .. size_y()-1. Drawings outside of this rectangle are clipped, without causing an error. The origin (0,0) is at the lower left corner.

Colors

type color = int

A color is specified by its R, G, B components. Each component is in the range 0..255. The three components are packed in an int: 0xRRGGBB, where RR are the two hexadecimal digits for the red component, GG for the green component, BB for the blue component.

val rgb : int -> int -> int -> color

rgb r g b returns the integer encoding the color with red component r, green component g, and blue component b. r, g and b are in the range 0..255.

val set_color : color -> unit

Set the current drawing color.

val black : color
val white : color
val red : color
val green : color
val blue : color
val yellow : color
val cyan : color
val magenta : color

Some predefined colors.

val background : color
val foreground : color

Default background and foreground colors (usually, either black foreground on a white background or white foreground on a black background). clear_graph fills the page with the background color. The initial drawing color is foreground.

Point and line drawing

val plot : x:int -> y:int -> unit

Plot the given point with the current drawing color.

val moveto : x:int -> y:int -> unit

Position the current point.

val rmoveto : dx:int -> dy:int -> unit

rmoveto x y translates the current point of the given vector.

val current_x : unit -> int

Return the abscissa of the current point.

val current_y : unit -> int

Return the ordinate of the current point.

val current_point : unit -> int * int

Return the position of the current point.

val lineto : x:int -> y:int -> unit

Draw a line with endpoints the current point and the given point, and move the current point to the given point.

val rlineto : dx:int -> dy:int -> unit

Draws a line with endpoints the current point and the current point translated of the given vector, and move the current point to this point.

val draw_rect : x:int -> y:int -> w:int -> h:int -> unit

draw_rect x y w h draws the rectangle with lower left corner at x,y, width w and height h. The current point is unchanged.

val draw_arc :
        x:int -> y:int -> rx:int -> ry:int -> start:int -> stop:int -> unit

draw_arc x y rx ry a1 a2 draws an elliptical arc with center x,y, horizontal radius rx, vertical radius ry, from angle a1 to angle a2 (in degrees). The current point is unchanged.

val draw_ellipse : x:int -> y:int -> rx:int -> ry:int -> unit

draw_ellipse x y rx ry draws an ellipse with center x,y, horizontal radius rx and vertical radius ry. The current point is unchanged.

val draw_circle : x:int -> y:int -> r:int -> unit

draw_circle x y r draws a circle with center x,y and radius r. The current point is unchanged.

val draw_poly : (int * int) array -> unit

Draw the given polygon with the current color. The array contains the coordinates of the vertices of the polygon. The current point is unchanged.

val set_line_width : int -> unit

Set the width of points and lines drawn with the functions above.

Text drawing

val draw_char : char -> unit
val draw_string : string -> unit

Draw a character or a character string with lower left corner at current position. After drawing, the current position is set to the lower right corner of the text drawn.

val set_font : string -> unit
val set_text_size : int -> unit

Set the font and character size used for drawing text. The interpretation of the arguments to set_font and set_text_size is implementation-dependent.

val text_size : string -> int * int

Return the dimensions of the given text, if it were drawn with the current font and size.

Filling

val fill_rect : x:int -> y:int -> w:int -> h:int -> unit

fill_rect x y w h fills the rectangle with lower left corner at x,y, width w and height h, with the current color.

val fill_poly : (int * int) array -> unit

Fill the given polygon with the current color. The array contains the coordinates of the vertices of the polygon.

val fill_arc :
        x:int -> y:int -> rx:int -> ry:int -> start:int -> stop:int -> unit

Fill an elliptical pie slice with the current color. The parameters are the same as for draw_arc.

val fill_ellipse : x:int -> y:int -> rx:int -> ry:int -> unit

Fill an ellipse with the current color. The parameters are the same as for draw_ellipse.

val fill_circle : x:int -> y:int -> r:int -> unit

Fill a circle with the current color. The parameters are the same as for draw_circle.

Images

type image

The abstract type for images, in internal representation. Externally, images are represented as matrices of colors. Only here for compatibility: drawing of image is not yet implemented.

val transp : color

In matrices of colors, this color represents a "transparent" point: when drawing the corresponding image, all pixels on the screen corresponding to a transparent pixel in the image will not be modified, while other points will be set to the color of the corresponding point in the image. This allows superimposing an image over an existing background.

end

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