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SDL Area widget.
You can use an Sdl_area widget to draw whatever you want using all the power of the SDL renderer API.
Technically, an Sdl_area widget contains an SDL texture and sets it as a render target.
SDL commands are sent to the Sdl_area using
add (and stored in a command queue). You can also use
add_get in order to get a handle on the command in case you reserve the possibility to remove the command with
Create an empty SDL area. Note that the given size
(width,height) is the logical pixel size of the area. The physical size, to be used for most SDL rendering functions, can be obtained with
val update : t -> unit
Force the area to be re-drawn at the next graphics frame.
val clear : t -> unit
Clear the area (this removes all commands from the render queue).
val add : t -> ?name:string -> (Tsdl.Sdl.renderer -> unit) -> unit
add area ~name f adds the arbitrary command
f to the render queue. The command should be fast, otherwise it will block the UI when the queue is executed. For long drawings, it's better to split them into many commands. If you need the possibility to remove a command later, use
val cache : t -> unit
This will insert a special command in the queue that will save the texture obtained at that point, and clear all previous commands in the queue. Commands added to the queue after the
cache invocation are not removed. Further updates to the area will show the cached texture and then execute the rest of the queue. Use this only for performance reasons when the rendering queue uses a lot of power and/or time.
val clear_cache : t -> unit
Clear the graphics cache generated by the
cache command. It has no effect if no cache was created. Clearing the cache does not restore the commands in the queue that were used to draw it.
Drawing functions and utilities
Shortcuts to some
drawing functions from the
For more sophisticated shapes (and faster rendering), consider using the tsdl_gfx external library or, better, the companion bogue-cairo library.
val drawing_size : t -> int * int
Size in physical pixels of the target SDL texture on which you can draw. You may also use
Tsdl.Sdl.get_renderer_output_size, if used inside the Sdl_area command queue.
val pointer_pos : t -> Tsdl.Sdl.event -> int * int
Position of the pointer (mouse or touchscreen that has generated the event) in physical pixels, with respect to the top-left corner of the Sdl_area. Should be called only after the Sdl_area has been rendered.
Convert BOGUE logical coordinates into pixel coordinates usable for the SDL area. Same as
val draw_line : t -> color:Draw.color -> thick:int -> (int * int) -> (int * int) -> unit
draw_line c ~color ~thick (x1, y1) (x2, y2) draws a line of given
thickness from point
(x1, y1) to point
val draw_rectangle : t -> color:Draw.color -> thick:int -> w:int -> h:int -> (int * int) -> unit
draw_rectangle c ~color ~thick ~w ~h x0 y0 draws a rectangle of the given line thickness inside the box of top-left coordinates
w and height
val fill_rectangle : t -> color:Draw.color -> w:int -> h:int -> (int * int) -> unit
val draw_circle : t -> color:Draw.color -> thick:int -> radius:int -> (int * int) -> unit
draw_circle c ~color ~thick ~radius (x0, y0) draws a circle of the given line
color inside the disc of center coordinates
(x0, y0) and given
An example of
draw_circle is provided by Example #50 (it can be run from the terminal with
boguex 50), which produces the following picture:
The source code for all
boguex examples is here.
val fill_circle : t -> color:Draw.color -> radius:int -> (int * int) -> unit
The command queue can be manipulated. An element of this queue is called a
val add_get : t -> ?name:string -> ?disable:bool -> (Tsdl.Sdl.renderer -> unit) -> draw_element
add, but returns the corresponding
disable is true, the command will not be executed.
val disable : draw_element -> unit
Mark an element for skipping its execution.
val enable : draw_element -> unit
val remove_element : t -> draw_element -> unit
draw_element from the command queue.
val add_element : t -> draw_element -> unit
Append the element to the end of the command queue.
val has_element : t -> draw_element -> bool
Check whether the element belongs to the command queue.
Direct access to the texture
val get_texture : t -> Tsdl.Sdl.texture option
val set_texture : t -> Tsdl.Sdl.texture -> unit