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#include "scroller.h"
#include "SFont.h"
#include <assert.h>
#define SCROLLER_GAP 45.0
Scroller_t *init_scroller(const char *stext, Sint16 pos, float defspeed, Uint16 visiwidth) {
int text_scroller_width;
Scroller_t *scroller = calloc(1, sizeof(Scroller_t));
SDL_Surface *surf = NULL;
if(scroller) {
scroller->position = -((float)visiwidth) - SCROLLER_GAP;
scroller->speed = defspeed;
scroller->y = pos;
text_scroller_width = SFont_wide(stext);
#ifdef DEBUG
printf("Text scroller surface has a width of %d pixels.\n", text_scroller_width);
#endif
/*
* Just create a surface, no special needs, etc. Therefore we use
* a simple 2-bit surface, give it a colorkey for transparency and
* convert it to the display format.
*/
if((surf = SDL_CreateRGBSurface(SDL_SWSURFACE, text_scroller_width, 36, 2, 0, 0, 0, 0)) != NULL) {
SDL_SetColorKey(surf, SDL_SRCCOLORKEY, 0); //Set black (default fill?) to transparent
scroller->playfield = SDL_DisplayFormat(surf); //Convert to display format (no problems with rgbamask, etc.)
if(scroller->playfield == NULL) goto on_error;
SDL_FreeSurface(surf);
surf = NULL;
PutString(scroller->playfield, 0, 0, stext);
} else goto on_error;
}
return scroller;
on_error:
if(surf != NULL) SDL_FreeSurface(surf);
if(scroller != NULL) free(scroller);
return NULL;
}
void destroy_scroller(Scroller_t *scroller) {
SDL_FreeSurface(scroller->playfield);
free(scroller);
}
void update_and_draw_scroller(Scroller_t *scroller, SDL_Surface *target, float speed) {
SDL_Rect r = { 0, scroller->y, 0, 0 };
assert(scroller != NULL);
assert(target != NULL);
scroller->position += scroller->speed * speed;
if(scroller->position <= -target->w) {
} else if(scroller->position <= 0) {
r.w = target->w + scroller->position;
r.x = -scroller->position;
SDL_BlitSurface(scroller->playfield, NULL, target, &r);
} else if(scroller->position > scroller->playfield->w){
scroller->position = -target->w - SCROLLER_GAP;
} else {
SDL_Rect src = { scroller->position, 0, target->w, scroller->playfield->h };
r.w = target->w;
r.x = 0;
SDL_BlitSurface(scroller->playfield, &src, target, &r);
}
}
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