SDL  2.0
SDL_stretch.c File Reference
#include "../SDL_internal.h"
#include "SDL_video.h"
#include "SDL_blit.h"
+ Include dependency graph for SDL_stretch.c:

Go to the source code of this file.

Macros

#define DEFINE_COPY_ROW(name, type)
 

Functions

static void copy_row3 (Uint8 *src, int src_w, Uint8 *dst, int dst_w)
 
int SDL_SoftStretch (SDL_Surface *src, const SDL_Rect *srcrect, SDL_Surface *dst, const SDL_Rect *dstrect)
 Perform a fast, low quality, stretch blit between two surfaces of the same pixel format. More...
 

Macro Definition Documentation

◆ DEFINE_COPY_ROW

#define DEFINE_COPY_ROW (   name,
  type 
)
Value:
static void name(type *src, int src_w, type *dst, int dst_w) \
{ \
int i; \
int pos, inc; \
type pixel = 0; \
\
pos = 0x10000; \
inc = (src_w << 16) / dst_w; \
for ( i=dst_w; i>0; --i ) { \
while ( pos >= 0x10000L ) { \
pixel = *src++; \
pos -= 0x10000L; \
} \
*dst++ = pixel; \
pos += inc; \
} \
}
GLenum GLenum dst
GLenum src
GLuint const GLchar * name
return Display return Display Bool Bool int int int return Display XEvent Bool(*) XPointer return Display return Display Drawable _Xconst char unsigned int unsigned int return Display Pixmap Pixmap XColor XColor unsigned int unsigned int return Display _Xconst char char int char return Display Visual unsigned int int int char unsigned int unsigned int in i)
Definition: SDL_x11sym.h:50
GLuint GLuint GLsizei GLenum type
Definition: SDL_opengl.h:1571

Definition at line 151 of file SDL_stretch.c.

Function Documentation

◆ copy_row3()

static void copy_row3 ( Uint8 src,
int  src_w,
Uint8 dst,
int  dst_w 
)
static

Definition at line 177 of file SDL_stretch.c.

References i.

Referenced by SDL_SoftStretch().

178 {
179  int i;
180  int pos, inc;
181  Uint8 pixel[3] = { 0, 0, 0 };
182 
183  pos = 0x10000;
184  inc = (src_w << 16) / dst_w;
185  for (i = dst_w; i > 0; --i) {
186  while (pos >= 0x10000L) {
187  pixel[0] = *src++;
188  pixel[1] = *src++;
189  pixel[2] = *src++;
190  pos -= 0x10000L;
191  }
192  *dst++ = pixel[0];
193  *dst++ = pixel[1];
194  *dst++ = pixel[2];
195  pos += inc;
196  }
197 }
GLenum GLenum dst
GLenum src
uint8_t Uint8
Definition: SDL_stdinc.h:157
return Display return Display Bool Bool int int int return Display XEvent Bool(*) XPointer return Display return Display Drawable _Xconst char unsigned int unsigned int return Display Pixmap Pixmap XColor XColor unsigned int unsigned int return Display _Xconst char char int char return Display Visual unsigned int int int char unsigned int unsigned int in i)
Definition: SDL_x11sym.h:50

◆ SDL_SoftStretch()

int SDL_SoftStretch ( SDL_Surface src,
const SDL_Rect srcrect,
SDL_Surface dst,
const SDL_Rect dstrect 
)

Perform a fast, low quality, stretch blit between two surfaces of the same pixel format.

Note
This function uses a static buffer, and is not thread-safe.

Definition at line 203 of file SDL_stretch.c.

References SDL_PixelFormat::BytesPerPixel, copy_row3(), SDL_Surface::format, SDL_PixelFormat::format, SDL_Rect::h, SDL_Surface::h, NULL, SDL_Surface::pitch, SDL_Surface::pixels, pop, SDL_FALSE, SDL_LockSurface, SDL_MUSTLOCK, SDL_SetError, SDL_TRUE, SDL_UnlockSurface, SDL_Rect::w, SDL_Surface::w, SDL_Rect::x, and SDL_Rect::y.

205 {
206  int src_locked;
207  int dst_locked;
208  int pos, inc;
209  int dst_maxrow;
210  int src_row, dst_row;
211  Uint8 *srcp = NULL;
212  Uint8 *dstp;
213  SDL_Rect full_src;
214  SDL_Rect full_dst;
215 #ifdef USE_ASM_STRETCH
216  SDL_bool use_asm = SDL_TRUE;
217 #ifdef __GNUC__
218  int u1, u2;
219 #endif
220 #endif /* USE_ASM_STRETCH */
221  const int bpp = dst->format->BytesPerPixel;
222 
223  if (src->format->format != dst->format->format) {
224  return SDL_SetError("Only works with same format surfaces");
225  }
226 
227  /* Verify the blit rectangles */
228  if (srcrect) {
229  if ((srcrect->x < 0) || (srcrect->y < 0) ||
230  ((srcrect->x + srcrect->w) > src->w) ||
231  ((srcrect->y + srcrect->h) > src->h)) {
232  return SDL_SetError("Invalid source blit rectangle");
233  }
234  } else {
235  full_src.x = 0;
236  full_src.y = 0;
237  full_src.w = src->w;
238  full_src.h = src->h;
239  srcrect = &full_src;
240  }
241  if (dstrect) {
242  if ((dstrect->x < 0) || (dstrect->y < 0) ||
243  ((dstrect->x + dstrect->w) > dst->w) ||
244  ((dstrect->y + dstrect->h) > dst->h)) {
245  return SDL_SetError("Invalid destination blit rectangle");
246  }
247  } else {
248  full_dst.x = 0;
249  full_dst.y = 0;
250  full_dst.w = dst->w;
251  full_dst.h = dst->h;
252  dstrect = &full_dst;
253  }
254 
255  /* Lock the destination if it's in hardware */
256  dst_locked = 0;
257  if (SDL_MUSTLOCK(dst)) {
258  if (SDL_LockSurface(dst) < 0) {
259  return SDL_SetError("Unable to lock destination surface");
260  }
261  dst_locked = 1;
262  }
263  /* Lock the source if it's in hardware */
264  src_locked = 0;
265  if (SDL_MUSTLOCK(src)) {
266  if (SDL_LockSurface(src) < 0) {
267  if (dst_locked) {
268  SDL_UnlockSurface(dst);
269  }
270  return SDL_SetError("Unable to lock source surface");
271  }
272  src_locked = 1;
273  }
274 
275  /* Set up the data... */
276  pos = 0x10000;
277  inc = (srcrect->h << 16) / dstrect->h;
278  src_row = srcrect->y;
279  dst_row = dstrect->y;
280 
281 #ifdef USE_ASM_STRETCH
282  /* Write the opcodes for this stretch */
283  if ((bpp == 3) || (generate_rowbytes(srcrect->w, dstrect->w, bpp) < 0)) {
284  use_asm = SDL_FALSE;
285  }
286 #endif
287 
288  /* Perform the stretch blit */
289  for (dst_maxrow = dst_row + dstrect->h; dst_row < dst_maxrow; ++dst_row) {
290  dstp = (Uint8 *) dst->pixels + (dst_row * dst->pitch)
291  + (dstrect->x * bpp);
292  while (pos >= 0x10000L) {
293  srcp = (Uint8 *) src->pixels + (src_row * src->pitch)
294  + (srcrect->x * bpp);
295  ++src_row;
296  pos -= 0x10000L;
297  }
298 #ifdef USE_ASM_STRETCH
299  if (use_asm) {
300 #ifdef __GNUC__
301  __asm__ __volatile__("call *%4":"=&D"(u1), "=&S"(u2)
302  :"0"(dstp), "1"(srcp), "r"(copy_row)
303  :"memory");
304 #elif defined(_MSC_VER) || defined(__WATCOMC__)
305  /* *INDENT-OFF* */
306  {
307  void *code = copy_row;
308  __asm {
309  push edi
310  push esi
311  mov edi, dstp
312  mov esi, srcp
313  call dword ptr code
314  pop esi
315  pop edi
316  }
317  }
318  /* *INDENT-ON* */
319 #else
320 #error Need inline assembly for this compiler
321 #endif
322  } else
323 #endif
324  switch (bpp) {
325  case 1:
326  copy_row1(srcp, srcrect->w, dstp, dstrect->w);
327  break;
328  case 2:
329  copy_row2((Uint16 *) srcp, srcrect->w,
330  (Uint16 *) dstp, dstrect->w);
331  break;
332  case 3:
333  copy_row3(srcp, srcrect->w, dstp, dstrect->w);
334  break;
335  case 4:
336  copy_row4((Uint32 *) srcp, srcrect->w,
337  (Uint32 *) dstp, dstrect->w);
338  break;
339  }
340  pos += inc;
341  }
342 
343  /* We need to unlock the surfaces if they're locked */
344  if (dst_locked) {
345  SDL_UnlockSurface(dst);
346  }
347  if (src_locked) {
348  SDL_UnlockSurface(src);
349  }
350  return (0);
351 }
#define SDL_UnlockSurface
Uint8 BytesPerPixel
Definition: SDL_pixels.h:320
GLfixed u1
uint32_t Uint32
Definition: SDL_stdinc.h:181
static void copy_row3(Uint8 *src, int src_w, Uint8 *dst, int dst_w)
Definition: SDL_stretch.c:177
GLfixed GLfixed u2
void * pixels
Definition: SDL_surface.h:75
uint8_t Uint8
Definition: SDL_stdinc.h:157
#define pop
Definition: SDL_qsort.c:192
int x
Definition: SDL_rect.h:66
int w
Definition: SDL_rect.h:67
#define NULL
Definition: begin_code.h:164
SDL_bool
Definition: SDL_stdinc.h:139
SDL_PixelFormat * format
Definition: SDL_surface.h:72
#define SDL_SetError
#define SDL_LockSurface
#define SDL_MUSTLOCK(S)
Definition: SDL_surface.h:61
int h
Definition: SDL_rect.h:67
uint16_t Uint16
Definition: SDL_stdinc.h:169
int y
Definition: SDL_rect.h:66
A rectangle, with the origin at the upper left.
Definition: SDL_rect.h:64