bogue 20221002 · OCaml Package

Low-level graphics and colors.

This module is internally used for low-level graphics and a thin layer over Tsdl.

The public API is mainly useful for Color management. There are also some helper functions for drawing into an Sdl_area.

Dependency graph

type canvas

Contains the hardware information for drawing (SDL renderer and window).

type texture = Tsdl.Sdl.texture

Initialization and shutdown

val quit : unit -> unit

Cleanup and quit SDL.

Colors

type rgb = int * int * int

red, green and blue values are integers in the range 0..255

type color = int * int * int * int

r,g,b,a

type fill =

| Pattern of texture
| Solid of color

Predefined colors

val black : rgb

val grey : rgb

val pale_grey : rgb

val dark_grey : rgb

val white : rgb

val red : rgb

val blue : rgb

val green : rgb

val magenta : rgb

val cyan : rgb

val yellow : rgb

val sienna : rgb

val label_color : rgb

val none : color

none = (0,0,0,0) is completely transparent black.

Creating colors

val opaque : rgb -> color

val transp : rgb -> color

val lighter : color -> color

val darker : color -> color

val set_alpha : int -> rgb -> color

val random_color : unit -> color

val find_color : string -> rgb

Convert a string of the form "grey" or "#FE01BC" to a rgb code (r,g,b). Color names are taken from here.

val pale : rgb -> rgb

Using colors

val set_color : Tsdl.Sdl.renderer -> color -> unit

Equivalent to Sdl.set_render_draw_color.

Drawing functions

These functions can be used to draw onto an Sdl_area.t.

val to_pixels : (int * int) -> int * int

Convert BOGUE logical coordinates into hardware pixel coordinates. This takes into account both the Theme SCALE and the high-dpi scaling of some systems (mac OS retina, iOS).

val line : 
  ?thick:int ->
  Tsdl.Sdl.renderer ->
  color:color ->
  x0:int ->
  y0:int ->
  x1:int ->
  y1:int ->
  unit

val rectangle : 
  ?thick:int ->
  Tsdl.Sdl.renderer ->
  color:color ->
  w:int ->
  h:int ->
  x:int ->
  y:int ->
  unit

rectangle renderer ~color ~thick ~w ~h ~x ~y draws a rectangle with given line thickness. The coordinate of the top left corner is (x,y). The size (including the thick line) is (w,h).

val circle : 
  ?thick:int ->
  Tsdl.Sdl.renderer ->
  color:color ->
  radius:int ->
  x:int ->
  y:int ->
  unit

circle renderer ~width ~color ~radius ~x ~y draws a circle with given line thickness, centered at (x,y), with given radius.

Layers

type layer

Layers are used to decide the order of drawing: which graphical elements (layouts) should be below, which should be above. For the most part, you don't have to access them directly.

val use_new_layer : unit -> unit

Use this when you want to switch to a completely different set of layers, typically when you want to draw on another window.

Misc

type align =

| Min
| Center
| Max

val unscale_size : (int * int) -> int * int

Transform a size (W,H) in physical pixels into 'logical' pixels (w,h), which are used for layouts. This is done by dividing by the Theme SCALE variable.

val set_system_cursor : Tsdl.Sdl.System_cursor.t -> unit

Set the mouse cursor to be the standard system cursor. Internally, this first creates an SDL system cursor (or use a previously created one).

package bogue