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The Bitmap module

val debug : bool ref

see Swap to set swap file directory

val maximum_live : int ref

val maximum_block_size : int ref

Configuration parameters for image swapping.

You can specify the maximum size of live data by setting maximum_live in words. If the size of live data in heap exceeds maximum_live, then Camlimages library tries to escape part of image buffer into "swap" files. If swapped data are required, they are read back into memory. This swapping is automatically done by the camlimages library. If maximum_live is 0, image swapping is disabled.

Swapped images are separated into block shaped "partitions". maximum_block_size is a maximum size of each partition, also in words. This parameter may affect the swapping performance. There is no theory (yet) how we should specify it. The author of the library propose to have (!maximum_live / 10). If it is larger, each swapping becomes slower. If smaller, more swappings will occur. Too large and too small maximum_block_size, both may make the program slower.

If you use image swapping, you need to explicitly call destroy function of each image format (Rgb24.destroy, image#destroy, etc...) to free the memory and swap files of the needless images.

The defaults are both 0. (i.e. swapping is disabled )

type block;;
type t =
  { bmap_width: int;
    bmap_height: int;
    bytes_per_pixel: int;
    block_size_width: int;
    block_size_height: int;
    blocks_x: int;
    blocks_y: int;
    data: block array array;
    access: int -> int -> string * int };;

Bitmap type. Normal user need not to use these labels.

val create : int -> int -> int -> string option -> t

create width height byte_per_depth initopt creates a bitmap of size width x height, whose depth is byte_per_depth. You can set initopt the value to fill the bitmap

val create_with : int -> int -> int -> string -> t

create_with width height byte_per_depth initdata creates a bitmap whose initial data is initdata.

val destroy : t -> unit

Destroy bitmaps

val get_strip : t -> int -> int -> int -> string

val set_strip : t -> int -> int -> int -> string -> unit

Strip access Here, "strip" means a rectangle region with height 1. get_strip t x y w returns the string reprensentation of strip of t at (x,y)-(x+w-1,y). set_strip t x y w str write str to the strip of t at (x,y)-(x+w-1,y).

val get_scanline : t -> int -> string

val set_scanline : t -> int -> string -> unit

Scanline access get_scanline t y returns the string representation of the scanline of t at y. set_scanline t y str writes str to the scanline of t at y.

val dump : t -> string

Create a string representation of a bitmap. It may easily raise an exception Out_of_memory for large images.

val sub : t -> int -> int -> int -> int -> t

sub dst x y width height returns sub-bitmap of dst, at (x,y)-(x+width-1,y+height-1).

val blit : t -> int -> int -> t -> int -> int -> int -> int -> unit

blit src sx sy dst dx dy width height copies the rectangle region of src at (sx,sy)-(sx+width-1,sy+height-1) to dst, at (dx,dy)-(dx+width-1,dy+height-1)

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