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Handle pixel scaling when creating the cursors

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Nick Briggs
2021-12-06 19:21:10 -08:00
parent a5923f42f9
commit 7048f7dd8d
1 changed files with 57 additions and 19 deletions
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76
src/sdl.c
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@@ -248,6 +248,26 @@ struct CachedCursor {
SDL_Cursor *cursor;
} *sdl_cursorlist = NULL;
/*
* given a 16-bit value and a repeat count modify an array
* of bytes to contain the same bit pattern with each bit
* repeated "reps" times consecutively in the output
*/
static void replicate_bits(int bits, int reps, Uint8 *out) {
int dbyte = 0;
int dbit = 7;
for (int ibit = 15; ibit >= 0; --ibit) {
for (int r = 0; r < reps; r++) {
if (bits & (1 << ibit))
out[dbyte] |= 1 << dbit;
if (--dbit < 0) {
dbyte++;
dbit = 7;
}
}
}
}
static int cursor_equal_p(DLword *a, DLword *b) {
for (int i = 0; i < CURSORHEIGHT; i++)
if (a[i] != b[i]) return FALSE;
@@ -261,34 +281,52 @@ static int cursor_equal_p(DLword *a, DLword *b) {
static SDL_Cursor *sdl_getOrAllocateCursor(DLword cursor[16], int hot_x, int hot_y) {
hot_x = 0;
hot_y = 0;
Uint8 sdl_cursor_data[32];
/* try to find the cursor by checking the full bitmap */
struct CachedCursor *pclp = NULL;
struct CachedCursor *clp = sdl_cursorlist;
SDL_Cursor *c;
while (clp != NULL) {
if (cursor_equal_p(clp->EmCursorBitMap, cursor) == TRUE) break;
if (cursor_equal_p(clp->EmCursorBitMap, cursor) == TRUE) {
/* if it's in the first two elements of the list, leave the order alone.
* There is a high probability of flipping back and forth between two
*/
if (clp == sdl_cursorlist || pclp == sdl_cursorlist) {
return clp->cursor;
}
/* otherwise unlink the found item and reinsert at the front */
pclp->next = clp->next;
clp->next = sdl_cursorlist;
sdl_cursorlist = clp;
return clp->cursor;
}
pclp = clp;
clp = clp->next;
}
if (clp == NULL) { /* it isn't there, push on a new one to the front of the list */
clp = (struct CachedCursor *)malloc(sizeof(struct CachedCursor));
memcpy(clp->EmCursorBitMap, cursor, sizeof(clp->EmCursorBitMap));
/* It isn't there, so build a new one */
clp = (struct CachedCursor *)malloc(sizeof(struct CachedCursor));
memcpy(clp->EmCursorBitMap, cursor, sizeof(clp->EmCursorBitMap));
/* no scaling is an easy case, scale > 1 is harder */
if (sdl_pixelscale == 1) {
Uint8 sdl_cursor_data[32];
for (int i = 0; i < 32; i++) sdl_cursor_data[i] = GETBYTE(((Uint8 *)cursor) + i);
SDL_Cursor *c = SDL_CreateCursor(sdl_cursor_data, sdl_cursor_data, 16, 16, hot_x, hot_y);
if (c == NULL) printf("ERROR creating cursor: %s\n", SDL_GetError());
clp->cursor = c;
clp->next = sdl_cursorlist;
sdl_cursorlist = clp;
return clp->cursor;
c = SDL_CreateCursor(sdl_cursor_data, sdl_cursor_data, 16, 16, hot_x, hot_y);
} else {
Uint8 *sdl_cursor_data = calloc(sdl_pixelscale * sdl_pixelscale, 32);
/* fill in the cursor data expanded */
for (int i = 0; i < 32; i += 2) {
int v = GETBYTE(((Uint8 *)cursor) + i) << 8 | GETBYTE(((Uint8 *)cursor) + i + 1);
int db = i * sdl_pixelscale * sdl_pixelscale;
/* spread the bits out for the first copy of the row */
replicate_bits(v, sdl_pixelscale, &sdl_cursor_data[db]);
/* and then copy the replicated bits for the copies of the row */
for (int j = 1; j < sdl_pixelscale; j++) {
memcpy(&sdl_cursor_data[db + (j * 2 * sdl_pixelscale)], &sdl_cursor_data[db], 2 * sdl_pixelscale);
}
}
c = SDL_CreateCursor(sdl_cursor_data, sdl_cursor_data, 16 * sdl_pixelscale, 16 * sdl_pixelscale, hot_x, hot_y);
}
/* if it's in the first two elements of the list, leave the order alone.
* There is a high probability of flipping back and forth between two
*/
if (clp == sdl_cursorlist || pclp == sdl_cursorlist) {
return clp->cursor;
}
/* otherwise unlink the found item and reinsert at the front */
pclp->next = clp->next;
if (c == NULL) printf("ERROR creating cursor: %s\n", SDL_GetError());
clp->cursor = c;
clp->next = sdl_cursorlist;
sdl_cursorlist = clp;
return clp->cursor;