SDL  2.0
SDL_blit_slow.c
Go to the documentation of this file.
1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2018 Sam Lantinga <slouken@libsdl.org>
4 
5  This software is provided 'as-is', without any express or implied
6  warranty. In no event will the authors be held liable for any damages
7  arising from the use of this software.
8 
9  Permission is granted to anyone to use this software for any purpose,
10  including commercial applications, and to alter it and redistribute it
11  freely, subject to the following restrictions:
12 
13  1. The origin of this software must not be misrepresented; you must not
14  claim that you wrote the original software. If you use this software
15  in a product, an acknowledgment in the product documentation would be
16  appreciated but is not required.
17  2. Altered source versions must be plainly marked as such, and must not be
18  misrepresented as being the original software.
19  3. This notice may not be removed or altered from any source distribution.
20 */
21 #include "../SDL_internal.h"
22 
23 #include "SDL_video.h"
24 #include "SDL_blit.h"
25 #include "SDL_blit_slow.h"
26 
27 /* The ONE TRUE BLITTER
28  * This puppy has to handle all the unoptimized cases - yes, it's slow.
29  */
30 void
32 {
33  const int flags = info->flags;
34  const Uint32 modulateR = info->r;
35  const Uint32 modulateG = info->g;
36  const Uint32 modulateB = info->b;
37  const Uint32 modulateA = info->a;
38  Uint32 srcpixel;
39  Uint32 srcR, srcG, srcB, srcA;
40  Uint32 dstpixel;
41  Uint32 dstR, dstG, dstB, dstA;
42  int srcy, srcx;
43  int posy, posx;
44  int incy, incx;
45  SDL_PixelFormat *src_fmt = info->src_fmt;
46  SDL_PixelFormat *dst_fmt = info->dst_fmt;
47  int srcbpp = src_fmt->BytesPerPixel;
48  int dstbpp = dst_fmt->BytesPerPixel;
49  Uint32 rgbmask = ~src_fmt->Amask;
50  Uint32 ckey = info->colorkey & rgbmask;
51 
52  srcy = 0;
53  posy = 0;
54  incy = (info->src_h << 16) / info->dst_h;
55  incx = (info->src_w << 16) / info->dst_w;
56 
57  while (info->dst_h--) {
58  Uint8 *src = 0;
59  Uint8 *dst = (Uint8 *) info->dst;
60  int n = info->dst_w;
61  srcx = -1;
62  posx = 0x10000L;
63  while (posy >= 0x10000L) {
64  ++srcy;
65  posy -= 0x10000L;
66  }
67  while (n--) {
68  if (posx >= 0x10000L) {
69  while (posx >= 0x10000L) {
70  ++srcx;
71  posx -= 0x10000L;
72  }
73  src =
74  (info->src + (srcy * info->src_pitch) + (srcx * srcbpp));
75  }
76  if (src_fmt->Amask) {
77  DISEMBLE_RGBA(src, srcbpp, src_fmt, srcpixel, srcR, srcG,
78  srcB, srcA);
79  } else {
80  DISEMBLE_RGB(src, srcbpp, src_fmt, srcpixel, srcR, srcG,
81  srcB);
82  srcA = 0xFF;
83  }
84  if (flags & SDL_COPY_COLORKEY) {
85  /* srcpixel isn't set for 24 bpp */
86  if (srcbpp == 3) {
87  srcpixel = (srcR << src_fmt->Rshift) |
88  (srcG << src_fmt->Gshift) | (srcB << src_fmt->Bshift);
89  }
90  if ((srcpixel & rgbmask) == ckey) {
91  posx += incx;
92  dst += dstbpp;
93  continue;
94  }
95  }
96  if (dst_fmt->Amask) {
97  DISEMBLE_RGBA(dst, dstbpp, dst_fmt, dstpixel, dstR, dstG,
98  dstB, dstA);
99  } else {
100  DISEMBLE_RGB(dst, dstbpp, dst_fmt, dstpixel, dstR, dstG,
101  dstB);
102  dstA = 0xFF;
103  }
104 
105  if (flags & SDL_COPY_MODULATE_COLOR) {
106  srcR = (srcR * modulateR) / 255;
107  srcG = (srcG * modulateG) / 255;
108  srcB = (srcB * modulateB) / 255;
109  }
110  if (flags & SDL_COPY_MODULATE_ALPHA) {
111  srcA = (srcA * modulateA) / 255;
112  }
113  if (flags & (SDL_COPY_BLEND | SDL_COPY_ADD)) {
114  /* This goes away if we ever use premultiplied alpha */
115  if (srcA < 255) {
116  srcR = (srcR * srcA) / 255;
117  srcG = (srcG * srcA) / 255;
118  srcB = (srcB * srcA) / 255;
119  }
120  }
121  switch (flags & (SDL_COPY_BLEND | SDL_COPY_ADD | SDL_COPY_MOD)) {
122  case 0:
123  dstR = srcR;
124  dstG = srcG;
125  dstB = srcB;
126  dstA = srcA;
127  break;
128  case SDL_COPY_BLEND:
129  dstR = srcR + ((255 - srcA) * dstR) / 255;
130  dstG = srcG + ((255 - srcA) * dstG) / 255;
131  dstB = srcB + ((255 - srcA) * dstB) / 255;
132  dstA = srcA + ((255 - srcA) * dstA) / 255;
133  break;
134  case SDL_COPY_ADD:
135  dstR = srcR + dstR;
136  if (dstR > 255)
137  dstR = 255;
138  dstG = srcG + dstG;
139  if (dstG > 255)
140  dstG = 255;
141  dstB = srcB + dstB;
142  if (dstB > 255)
143  dstB = 255;
144  break;
145  case SDL_COPY_MOD:
146  dstR = (srcR * dstR) / 255;
147  dstG = (srcG * dstG) / 255;
148  dstB = (srcB * dstB) / 255;
149  break;
150  }
151  if (dst_fmt->Amask) {
152  ASSEMBLE_RGBA(dst, dstbpp, dst_fmt, dstR, dstG, dstB, dstA);
153  } else {
154  ASSEMBLE_RGB(dst, dstbpp, dst_fmt, dstR, dstG, dstB);
155  }
156  posx += incx;
157  dst += dstbpp;
158  }
159  posy += incy;
160  info->dst += info->dst_pitch;
161  }
162 }
163 
164 /* vi: set ts=4 sw=4 expandtab: */
Uint8 r
Definition: SDL_blit.h:70
#define SDL_COPY_MODULATE_COLOR
Definition: SDL_blit.h:34
Uint32 srcG
Definition: SDL_blit_N.c:2471
Uint32 srcB
Definition: SDL_blit_N.c:2471
Uint8 b
Definition: SDL_blit.h:70
#define SDL_COPY_COLORKEY
Definition: SDL_blit.h:39
GLenum GLenum dst
Uint32 dstB
Definition: SDL_blit_N.c:2473
Uint32 dstR
Definition: SDL_blit_N.c:2473
Uint8 BytesPerPixel
Definition: SDL_pixels.h:320
Uint8 g
Definition: SDL_blit.h:70
#define SDL_COPY_MOD
Definition: SDL_blit.h:38
SDL_PixelFormat * src_fmt
Definition: SDL_blit.h:65
void SDL_Blit_Slow(SDL_BlitInfo *info)
Definition: SDL_blit_slow.c:31
#define ASSEMBLE_RGBA(buf, bpp, fmt, r, g, b, a)
Definition: SDL_blit.h:402
int dst_pitch
Definition: SDL_blit.h:63
uint32_t Uint32
Definition: SDL_stdinc.h:181
GLenum src
#define SDL_COPY_ADD
Definition: SDL_blit.h:37
Uint32 colorkey
Definition: SDL_blit.h:69
Uint8 * dst
Definition: SDL_blit.h:61
Uint32 srcR
Definition: SDL_blit_N.c:2471
#define DISEMBLE_RGBA(buf, bpp, fmt, Pixel, r, g, b, a)
Definition: SDL_blit.h:353
Uint32 dstG
Definition: SDL_blit_N.c:2473
uint8_t Uint8
Definition: SDL_stdinc.h:157
#define ASSEMBLE_RGB(buf, bpp, fmt, r, g, b)
Definition: SDL_blit.h:261
Uint8 * src
Definition: SDL_blit.h:57
SDL_PixelFormat * dst_fmt
Definition: SDL_blit.h:66
int src_pitch
Definition: SDL_blit.h:59
GLbitfield flags
#define SDL_COPY_MODULATE_ALPHA
Definition: SDL_blit.h:35
GLdouble n
#define DISEMBLE_RGB(buf, bpp, fmt, Pixel, r, g, b)
Definition: SDL_blit.h:177
#define SDL_COPY_BLEND
Definition: SDL_blit.h:36
Uint8 a
Definition: SDL_blit.h:70