Subject:
Bitblt proposal (was: Re: bogl routines)
From:
Ben Pfaff ####@####.####
Date:
15 May 1999 18:36:50 -0000
Message-Id: <873e0yxjs5.fsf@pfaffben.user.msu.edu>
Greg Haerr ####@####.#### writes:
[...some good points...]
enum
{
BOGL_ROP_NOP,
BOGL_ROP_AND,
BOGL_ROP_OR,
BOGL_ROP_XOR,
};
/* Copy a block of pixels from (SX,SY)-(SX+W,SY+H) in SRC to
(DX,DY)+(DX+W,DY+H) in DEST, applying raster operation ROP. DST
and SRC may be bitmaps created with bogl_create_bitmap(), or they
may be null pointers, representing the screen image. */
void bogl_bitblt (struct bogl_bitmap *dst, int dx, int dy,
struct bogl_bitmap *src, int sx, int sy,
int w, int h, int rop);
/* Dynamically allocate a bitmap of size (W,H). Initialize all the
pixels in the bitmap to background color BG; if BG == -1, leave
them undefined. Returns a pointer to the created bitmap if
successful; otherwise, returns a null pointer. */
struct bogl_bitmap *bogl_create_bitmap (int w, int h, int bg);
Okay, this still leaves masking. We could add a mask parameter, I
suppose:
/* Copy a block of pixels from (SX,SY)-(SX+W,SY+H) in SRC to
(DX,DY)+(DX+W,DY+H) in DEST, applying raster operation ROP. DST
and SRC may be bitmaps created with bogl_create_bitmap(), or they
may be null pointers, representing the screen image. If MASK is
non-null, then it must be a 1-bit-depth mask of size (W,H)
specifying which pixels in SRC should be copied. Each row in MASK
must be padded on the right to a 32-bit multiple in size. */
void bogl_bitblt (struct bogl_bitmap *dst, int dx, int dy,
struct bogl_bitmap *src, int sx, int sy,
int w, int h, int rop, void *mask);
Already I'm saying ``Ugh'' to myself when I think about actually
implementing this. Do we need even more than that?
----------------------------------------------------------------------
An evil thought just occurred to me, actually. With most visuals (not
vga16) we can easily add a `struct bogl_bitmap *' parameter to all the
bogl_*() functions, which could be a bitmap or NULL to represent the
screen. Then we'd be able to support drawing on off-screen bitmaps
just as easily as with the screen.
Comments?
--
"Let others praise ancient times; I am glad I was born in these."
--Ovid (43 BC-18 AD)
