n_allegro_4.h File Reference

Allegro 4 compatibility layer on top of Allegro 5. More...

#include <stdint.h>
#include <stdio.h>

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Data Structures
struct	BITMAP
	Allegro 4 bitmap. More...
struct	RGB
	palette entry, unused in 32 bit mode More...

Macros
#define	ALLEGRO_ERROR_SIZE   256
	size of the allegro_error buffer
#define	ALLEGTTF_NOSMOOTH   0
	no anti aliasing
#define	ALLEGTTF_REALSMOOTH   2
	anti aliased
#define	ALLEGTTF_TTFSMOOTH   1
	anti aliased
#define	bmp_write15(addr, c)
	write a pixel at addr, only 32 bit bitmaps exist
#define	bmp_write16(addr, c)
	write a pixel at addr, only 32 bit bitmaps exist
#define	bmp_write24(addr, c)
	write a pixel at addr, only 32 bit bitmaps exist
#define	bmp_write32(addr, c)
	write a 32 bit pixel at addr
#define	bmp_write8(addr, c)
	write a pixel at addr, only 32 bit bitmaps exist
#define	BPM_TO_TIMER(x)
	convert beats per minute to timer ticks
#define	BPS_TO_TIMER(x)
	convert beats per second to timer ticks
#define	DIGI_AUTODETECT   -1
	any digital driver
#define	DIGI_NONE   0
	no digital sound
#define	DRAW_MODE_SOLID   0
	drawing mode: plain copy
#define	DRAW_MODE_TRANS   5
	drawing mode: blend with the current blender
#define	END_OF_FUNCTION(x)
	no-op
#define	END_OF_MAIN()
	no-op, Allegro 5 programs need no END_OF_MAIN
#define	END_OF_STATIC_FUNCTION(x)
	no-op
#define	fixtof(x)
	fixed to double
#define	fixtoi(x)
	fixed to int, rounded
#define	ftofix(x)
	double to fixed
#define	GET   4321
	gfx_status() action: read the status (same value as n_common.h's)
#define	get_keyboard   a4_get_keyboard
	the old nilorea name of a4_get_keyboard()
#define	GFX_AUTODETECT   0
	any mode, windowed here
#define	GFX_AUTODETECT_FULLSCREEN   1
	fullscreen
#define	GFX_AUTODETECT_WINDOWED   2
	windowed
#define	GFX_DIRECTX   4
	DirectX fullscreen, mapped to fullscreen.
#define	GFX_DIRECTX_WIN   5
	DirectX windowed, mapped to windowed.
#define	GFX_OPENGL   8
	AllegroGL, windowed.
#define	GFX_OPENGL_FULLSCREEN   7
	AllegroGL fullscreen: screen is shown on allegro_gl_flip() only.
#define	GFX_OPENGL_WINDOWED   6
	AllegroGL windowed: screen is shown on allegro_gl_flip() only.
#define	GFX_SAFE   3
	windowed
#define	GFX_TEXT   -1
	leave graphics mode
#define	GL_COLOR_BUFFER_BIT   0x00004000
	no-op: screen is redrawn whole on every flip
#define	glClear(mask)
	no-op: screen is redrawn whole on every flip
#define	itofix(x)
	int to fixed
#define	KEY_0   27
	key code
#define	KEY_1   28
	key code
#define	KEY_2   29
	key code
#define	KEY_3   30
	key code
#define	KEY_4   31
	key code
#define	KEY_5   32
	key code
#define	KEY_6   33
	key code
#define	KEY_7   34
	key code
#define	KEY_8   35
	key code
#define	KEY_9   36
	key code
#define	KEY_A   1
	key code
#define	KEY_ALT   219
	key code
#define	KEY_ALTGR   220
	key code
#define	KEY_B   2
	key code
#define	KEY_BACKSPACE   63
	key code
#define	KEY_C   3
	key code
#define	KEY_D   4
	key code
#define	KEY_DEL   77
	key code
#define	KEY_DOWN   85
	key code
#define	KEY_E   5
	key code
#define	KEY_END   79
	key code
#define	KEY_ENTER   67
	key code
#define	KEY_ENTER_PAD   91
	key code
#define	KEY_ESC   59
	key code
#define	KEY_F   6
	key code
#define	KEY_F1   47
	key code
#define	KEY_F10   56
	key code
#define	KEY_F11   57
	key code
#define	KEY_F12   58
	key code
#define	KEY_F2   48
	key code
#define	KEY_F3   49
	key code
#define	KEY_F4   50
	key code
#define	KEY_F5   51
	key code
#define	KEY_F6   52
	key code
#define	KEY_F7   53
	key code
#define	KEY_F8   54
	key code
#define	KEY_F9   55
	key code
#define	KEY_G   7
	key code
#define	KEY_H   8
	key code
#define	KEY_HOME   78
	key code
#define	KEY_I   9
	key code
#define	KEY_INSERT   76
	key code
#define	KEY_J   10
	key code
#define	KEY_K   11
	key code
#define	KEY_L   12
	key code
#define	KEY_LCONTROL   217
	key code
#define	KEY_LEFT   82
	key code
#define	KEY_LSHIFT   215
	key code
#define	KEY_M   13
	key code
#define	KEY_MAX   227
	number of entries in key[]
#define	KEY_N   14
	key code
#define	KEY_O   15
	key code
#define	KEY_P   16
	key code
#define	KEY_PGDN   81
	key code
#define	KEY_PGUP   80
	key code
#define	KEY_Q   17
	key code
#define	KEY_R   18
	key code
#define	KEY_RCONTROL   218
	key code
#define	KEY_RIGHT   83
	key code
#define	KEY_RSHIFT   216
	key code
#define	KEY_S   19
	key code
#define	KEY_SPACE   75
	key code
#define	KEY_T   20
	key code
#define	KEY_TAB   64
	key code
#define	KEY_U   21
	key code
#define	KEY_UP   84
	key code
#define	KEY_V   22
	key code
#define	KEY_W   23
	key code
#define	KEY_X   24
	key code
#define	KEY_Y   25
	key code
#define	KEY_Z   26
	key code
#define	LEX_MENU_NORMAL   0
	item state for lexMenuGetBitmap(): normal
#define	LEX_MENU_OVER   1
	item state for lexMenuGetBitmap(): under the pointer
#define	LOCK_FUNCTION(x)
	no-op
#define	LOCK_VARIABLE(x)
	no-op
#define	MIDI_AUTODETECT   -1
	any MIDI driver
#define	MIDI_NONE   0
	no MIDI
#define	MODE_OGL   1
	gfx_status() value: an AllegroGL mode
#define	MODE_STD   0
	gfx_status() value: a non OpenGL mode
#define	MSEC_TO_TIMER(x)
	convert milliseconds to timer ticks
#define	SCREEN_H   (screen ? screen->h : 0)
	screen height
#define	SCREEN_W   (screen ? screen->w : 0)
	screen width
#define	SECS_TO_TIMER(x)
	convert seconds to timer ticks
#define	SET   1234
	gfx_status() action: set the status (same value as n_common.h's)
#define	TIMERS_PER_SECOND   1193181L
	ticks per second of install_int_ex() speeds
#define	U_ASCII   0x41534338
	unicode format id, ignored
#define	U_UTF8   0x55544638
	unicode format id, ignored

Typedefs
typedef int32_t	fixed
	16.16 fixed point number

Functions
uint32_t	_a4_pixel_from_color (int color)
	store a colour as it is kept in a bitmap (opaque when its alpha byte is 0)
int	a4_get_keyboard (char *keybuf, int *cur, int flags, int max)
	read the typed keys into keybuf at *cur (printable ASCII, backspace erases), keeping it nul terminated within max bytes; flags is ignored.
void	adjust_sample (const SAMPLE *spl, int vol, int pan, int freq, int loop)
	change the settings of the playing instances of a sample
int	alert (const char *s1, const char *s2, const char *s3, const char *b1, const char *b2, int c1, int c2)
	a box with up to three lines and one or two buttons (b2 may be NULL), chosen with the mouse, the c1 / c2 shortcut keys, Enter (first) or Escape (second): 1 or 2
void	allegro_exit (void)
	shut everything down
void	allegro_gl_flip (void)
	show the screen bitmap
void	allegro_gl_set_allegro_mode (void)
	no-op
void	allegro_gl_unset_allegro_mode (void)
	no-op
int	allegro_init (void)
	init the layer and Allegro 5
void	allegro_message (const char *format,...)
	show a message: a box over the screen, or stderr without a display
int	bitmap_color_depth (BITMAP *bmp)
	always 32
int	bitmap_mask_color (BITMAP *bmp)
	the mask colour, magenta
void	blit (BITMAP *source, BITMAP *dest, int source_x, int source_y, int dest_x, int dest_y, int width, int height)
	copy a rectangle
uintptr_t	bmp_read_line (BITMAP *bmp, int y)
	lock the bitmap and return the address of line y, 32 bit ARGB pixels
void	bmp_select (BITMAP *bmp)
	no-op
void	bmp_unwrite_line (BITMAP *bmp)
	no-op, the bitmap is unlocked when next drawn with the GPU
uintptr_t	bmp_write_line (BITMAP *bmp, int y)
	lock the bitmap and return the address of line y, 32 bit ARGB pixels
void	circle (BITMAP *bmp, int x, int y, int radius, int color)
	draw a circle outline
void	circlefill (BITMAP *bmp, int x, int y, int radius, int color)
	draw a filled circle
void	clear (BITMAP *bmp)
	clear to black
void	clear_bitmap (BITMAP *bmp)
	clear to black
void	clear_keybuf (void)
	empty the readkey() buffer
void	clear_to_color (BITMAP *bmp, int color)
	clear to a colour
BITMAP *	create_bitmap (int width, int height)
	create a w x h bitmap
BITMAP *	create_bitmap_ex (int depth, int width, int height)
	same as create_bitmap(), depth is ignored
BITMAP *	create_video_bitmap (int width, int height)
	same as create_bitmap()
void	destroy_bitmap (BITMAP *bmp)
	free a bitmap
void	destroy_font (FONT *f)
	free a font loaded with load_ttf_font()
void	destroy_midi (MIDI *midi)
	free a MIDI song, stopping it if it plays
void	destroy_sample (SAMPLE *spl)
	free a sample, stopping it
void	draw_sprite (BITMAP *bmp, BITMAP *sprite, int x, int y)
	draw a sprite
void	draw_sprite_h_flip (BITMAP *bmp, BITMAP *sprite, int x, int y)
	draw a sprite mirrored horizontally
void	draw_sprite_v_flip (BITMAP *bmp, BITMAP *sprite, int x, int y)
	draw a sprite mirrored vertically
void	draw_sprite_vh_flip (BITMAP *bmp, BITMAP *sprite, int x, int y)
	draw a sprite mirrored both ways
void	draw_trans_sprite (BITMAP *bmp, BITMAP *sprite, int x, int y)
	draw a sprite with the current blender (set_alpha_blender / set_trans_blender)
void	drawing_mode (int mode, BITMAP *pattern, int x_anchor, int y_anchor)
	set the drawing mode of primitives, pattern arguments are ignored
void	ellipse (BITMAP *bmp, int x, int y, int rx, int ry, int color)
	draw an ellipse outline
void	ellipsefill (BITMAP *bmp, int x, int y, int rx, int ry, int color)
	draw a filled ellipse
void	fill_str (char *str, int c, size_t len)
	fill len bytes of str with c
int	get_color_depth (void)
	return the color depth (always 32)
void	get_mouse_mickeys (int *mickeyx, int *mickeyy)
	movement since the last call
int	geta (int c)
	alpha component, 255 for an opaque colour
int	getb (int c)
	blue component
int	getg (int c)
	green component
int	getpixel (BITMAP *bmp, int x, int y)
	read a pixel, -1 outside the bitmap
int	getr (int c)
	red component
int	gfx_mode (int mode, int w, int h, int v_w, int v_h, int depth, double r, double g, double b, double a)
	set the color depth and the graphics mode in one go, clearing the screen to (r,g,b), components in 0-1 or 0-255; TRUE or FALSE
int	gfx_status (int action, int value)
	with GET, MODE_OGL when the current mode is an AllegroGL one, else MODE_STD
void	hline (BITMAP *bmp, int x1, int y, int x2, int color)
	draw a horizontal line
int	install_allegro_gl (void)
	no-op, the layer always uses Allegro 5's own driver
int	install_int (void(*proc)(void), int speed)
	call proc every speed milliseconds, from the timer thread
int	install_int_ex (void(*proc)(void), long speed)
	call proc every speed timer ticks, from the timer thread
int	install_keyboard (void)
	start the input thread for the keyboard
int	install_mouse (void)
	start the input thread for the mouse
int	install_sound (int digi, int midi, const char *cfg_path)
	start the audio, cfg_path is ignored
int	install_timer (void)
	no-op, timers are always available
int	is_memory_bitmap (BITMAP *bmp)
	always FALSE: pixels are reached through bmp_write_line()
int	keypressed (void)
	TRUE if a key is waiting in the readkey() buffer.
LexMenu *	lexLoadMenuFromFile (const char *file, const char *section)
	load menu section from INI file file, NULL on error
LexMenu *	lexMenuDestroy (LexMenu *menu)
	free a menu, returns NULL
BITMAP *	lexMenuGetBitmap (LexMenu *menu, int item, int state)
	the image of item item in state state, NULL if there is none
int	lexMenuRun (LexMenu *menu, BITMAP *buf)
	run the menu, drawing into buf: the chosen item index, -1 on escape
void	line (BITMAP *bmp, int x1, int y1, int x2, int y2, int color)
	draw a line
BITMAP *	load_bitmap (const char *filename, RGB *pal)
	load a BMP, PCX, TGA, PNG or JPG file, pal is ignored
MIDI *	load_midi (const char *filename)
	load a MIDI file
SAMPLE *	load_sample (const char *filename)
	load a WAV, OGG, FLAC or VOC file
FONT *	load_ttf_font (const char *filename, int points, int smooth)
	load a TrueType font at the given pixel size
FONT *	load_ttf_font_mem (const char *filename, int points, int smooth)
	same as load_ttf_font()
int	makeacol (int r, int g, int b, int a)
	make a colour with alpha
int	makeacol32 (int r, int g, int b, int a)
	make a colour with alpha
int	makecol (int r, int g, int b)
	make an opaque colour
int	makecol32 (int r, int g, int b)
	make an opaque colour
void	masked_blit (BITMAP *source, BITMAP *dest, int source_x, int source_y, int dest_x, int dest_y, int width, int height)
	copy a rectangle, skipping mask colour pixels
void	masked_stretch_blit (BITMAP *source, BITMAP *dest, int source_x, int source_y, int source_w, int source_h, int dest_x, int dest_y, int dest_w, int dest_h)
	copy and scale a rectangle, skipping mask colour pixels
void	midi_pause (void)
	pause the MIDI song
void	midi_resume (void)
	resume the MIDI song
void	pivot_scaled_sprite (BITMAP *bmp, BITMAP *sprite, int x, int y, int cx, int cy, fixed angle, fixed scale)
	rotate and scale a sprite around (cx,cy) in the sprite, drawn at (x,y)
void	pivot_sprite (BITMAP *bmp, BITMAP *sprite, int x, int y, int cx, int cy, fixed angle)
	rotate a sprite around (cx,cy) in the sprite, drawn at (x,y)
int	play_midi (MIDI *midi, int loop)
	play a MIDI song, replacing the current one, NULL stops
int	play_sample (const SAMPLE *spl, int vol, int pan, int freq, int loop)
	play a sample: vol and pan 0-255, freq 1000 = normal speed
int	poll_keyboard (void)
	no-op, input is updated by a thread
int	poll_mouse (void)
	no-op, input is updated by a thread
void	position_mouse (int x, int y)
	move the mouse pointer
void	putpixel (BITMAP *bmp, int x, int y, int color)
	write a pixel
int	readkey (void)
	wait for a key: (scancode << 8) | ascii
void	rect (BITMAP *bmp, int x1, int y1, int x2, int y2, int color)
	draw a rectangle outline
void	rectfill (BITMAP *bmp, int x1, int y1, int x2, int y2, int color)
	draw a filled rectangle
void	remove_int (void(*proc)(void))
	stop calling proc
void	remove_sound (void)
	stop the audio
void	rest (unsigned int ms)
	sleep ms milliseconds
void	rotate_scaled_sprite (BITMAP *bmp, BITMAP *sprite, int x, int y, fixed angle, fixed scale)
	rotate and scale a sprite around its centre
void	rotate_sprite (BITMAP *bmp, BITMAP *sprite, int x, int y, fixed angle)
	rotate a sprite around its centre, angle in 256ths of a turn, clockwise
int	save_bitmap (const char *filename, BITMAP *bmp, const RGB *pal)
	save a bitmap
void	set_alpha_blender (void)
	blend with the alpha channel of the source colour or sprite
int	set_close_button_callback (void(*proc)(void))
	call proc when the window close button is pressed
void	set_color_depth (int depth)
	set the color depth, only 32 is honoured
int	set_gfx_mode (int card, int w, int h, int v_w, int v_h)
	open a display of w x h pixels, or close it with GFX_TEXT
void	set_trans_blender (int r, int g, int b, int a)
	blend with a constant opacity a (0-255), r, g and b are ignored
void	set_uformat (int type)
	no-op, kept for source compatibility
void	set_volume (int digi_volume, int midi_volume)
	set the volumes (0-255), a negative value leaves one unchanged
void	set_window_title (const char *name)
	set the window title
void	show_mouse (BITMAP *bmp)
	show the system cursor (bmp != NULL) or hide it (NULL)
void	solid_mode (void)
	same as drawing_mode(DRAW_MODE_SOLID, ...)
void	stop_midi (void)
	stop the MIDI song
void	stop_sample (const SAMPLE *spl)
	stop every playing instance of a sample
void	stretch_blit (BITMAP *source, BITMAP *dest, int source_x, int source_y, int source_width, int source_height, int dest_x, int dest_y, int dest_width, int dest_height)
	copy and scale a rectangle
void	stretch_sprite (BITMAP *bmp, BITMAP *sprite, int x, int y, int w, int h)
	draw a sprite scaled to w x h
int	text_height (const FONT *f)
	height of the font in pixels
int	text_length (const FONT *f, const char *str)
	width of str in pixels
void	textout_centre_ex (BITMAP *bmp, const FONT *f, const char *s, int x, int y, int color, int bg)
	draw a string centred on x
void	textout_ex (BITMAP *bmp, const FONT *f, const char *s, int x, int y, int color, int bg)
	draw a string
void	textout_right_ex (BITMAP *bmp, const FONT *f, const char *s, int x, int y, int color, int bg)
	draw a string ending at x
void	textprintf_centre_ex (BITMAP *bmp, const FONT *f, int x, int y, int color, int bg, const char *format,...)
	draw a formatted string centred on x
void	textprintf_ex (BITMAP *bmp, const FONT *f, int x, int y, int color, int bg, const char *format,...)
	draw a formatted string
void	textprintf_right_ex (BITMAP *bmp, const FONT *f, int x, int y, int color, int bg, const char *format,...)
	draw a formatted string ending at x
void	triangle (BITMAP *bmp, int x1, int y1, int x2, int y2, int x3, int y3, int color)
	draw a filled triangle
int	ustricmp (const char *s1, const char *s2)
	case insensitive string compare
void	vline (BITMAP *bmp, int x, int y1, int y2, int color)
	draw a vertical line

Variables
char	allegro_error [256]
	last error message, as in Allegro 4
FONT *	font
	the default 8x8 font, valid after allegro_init()
volatile char	key [227]
	TRUE while the key is held.
volatile int	key_shifts
	modifier flags, unused
volatile int	mouse_b
	button flags: 1 left, 2 right, 4 middle
volatile int	mouse_x
	mouse x in screen coordinates
volatile int	mouse_y
	mouse y in screen coordinates
volatile int	mouse_z
	mouse wheel position
BITMAP *	screen
	the screen, valid after set_gfx_mode()

Detailed Description

Allegro 4 compatibility layer on top of Allegro 5.

Lets old Allegro 4 / AllegroGL / AllegTTF programs build and run on Allegro 5 with their drawing, input, timer and sound calls unchanged: replace the <allegro.h>, <alleggl.h>, <winalleg.h> and "allegttf.h" includes with this header and link the program with nilorea.

This header deliberately exposes Allegro 4 names (BITMAP, screen, key, clear(), line(), rest(), font, ...) at global scope, which is the whole point of it and also why it is NOT included by nilorea.h: include it only from a program that wants the Allegro 4 API. It does not include any Allegro 5 header, so a translation unit sees one API only.

Model:

• Only 32 bit colour is supported. Colours are Allegro 4 style ints, 0xAARRGGBB, where an alpha byte of 0 (what makecol() produces) means opaque, as in Allegro 4 where the alpha byte of makecol() is unused.
• The mask colour is magenta (makecol(255,0,255)). Masked draws (draw_sprite, masked_blit, rotate_sprite, ...) use a cached copy of the sprite with the mask colour turned transparent, rebuilt only after the sprite changed.
• screen is an off screen bitmap. It is shown on allegro_gl_flip(), or right after a draw to it when the mode is not an OpenGL one (Allegro 4 showed screen drawing immediately).
• key[], mouse_x, mouse_y, mouse_b and the readkey() buffer are kept up to date by a background thread, like Allegro 4's interrupts.
• install_int() callbacks run on a timer thread: they must not draw.
• Drawing must happen on the thread that called set_gfx_mode().
• MIDI is played through libfluidsynth, loaded at run time, with the first General MIDI soundfont found (or $NILOREA_SOUNDFONT). Without either, MIDI calls succeed and stay silent.
• File names are resolved case insensitively and with '\' accepted as a separator, since most Allegro 4 games were written on Windows.
• lexLoadMenuFromFile() / lexMenuRun() re-implement the old nilorea INI driven menu module used by some of those games: a [menu] section with bg= and item0= ... itemN=, and a [menu.item] section per item with x, y, h_align (left/center/right: the part of the image at x), v_align (bottom/middle/top: the side of y the image hangs, so bottom makes y the top edge), image and an optional click sound.

  Author

  Castagnier Mickael

  Version

  1.0

  Date

  08/10/2026

Definition in file n_allegro_4.h.