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use fast function pointers for scaling algorithm selection

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The first implementation used boost function pointers but these
are much slower for many reasons. This commit refactors the system
to use traditional C-style function pointers, which is all that is
actually needed.
This commit is contained in:
Chris Beck 2014-11-28 23:49:20 -05:00
parent 87d5f3b440
commit ee48430f58
3 changed files with 38 additions and 16 deletions
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37
src/image.cpp
View File

@ -174,7 +174,8 @@ int zoom = tile_size;
int cached_zoom = 0;
/** Algorithm choices */
typedef boost::function<surface(const surface &, int, int)> scaling_function;
//typedef boost::function<surface(const surface &, int, int)> scaling_function;
typedef surface(*scaling_function)(const surface &, int, int);
scaling_function scale_to_zoom_func;
scaling_function scale_to_hex_func;
@ -757,33 +758,43 @@ void set_zoom(int amount)
}
}
static surface scale_surface_algorithm(const surface & res, int w, int h, gui2::tadvanced_graphics_options::SCALING_ALGORITHM algo)
// F should be a scaling algorithm without "integral" zoom limitations
template <scaling_function F>
static surface scale_xbrz_helper(const surface & res, int w, int h)
{
int best_integer_zoom = std::min(w / res.get()->w, h / res.get()->h);
int legal_zoom = std::max(std::min(best_integer_zoom, 5), 1);
return F(scale_surface_xbrz(res, legal_zoom), w, h);
}
static scaling_function select_algorithm(gui2::tadvanced_graphics_options::SCALING_ALGORITHM algo)
{
switch (algo)
{
case gui2::tadvanced_graphics_options::LINEAR:
{
return scale_surface(res, w, h);
scaling_function result = &scale_surface;
return result;
}
case gui2::tadvanced_graphics_options::NEAREST_NEIGHBOR:
{
return scale_surface_nn(res, w, h);
scaling_function result = &scale_surface_nn;
return result;
}
case gui2::tadvanced_graphics_options::XBRZ_LIN:
{
int z_factor = std::min(w / res.get()->w, h / res.get()->h);
surface xbrz_temp(scale_surface_xbrz(res, std::max(std::min(z_factor,5),1)));
return scale_surface(xbrz_temp, w, h);
scaling_function result = &scale_xbrz_helper<scale_surface>;
return result;
}
case gui2::tadvanced_graphics_options::XBRZ_NN:
{
int z_factor = std::min(w / res.get()->w, h / res.get()->h);
surface xbrz_temp(scale_surface_xbrz(res, std::max(std::min(z_factor,5),1)));
return scale_surface_nn(xbrz_temp, w, h);
scaling_function result = &scale_xbrz_helper<scale_surface_nn>;
return result;
}
case gui2::tadvanced_graphics_options::LEGACY_LINEAR:
{
return scale_surface_legacy(res, w, h);
scaling_function result = &scale_surface_legacy;
return result;
}
default:
assert(false && "I don't know how to implement this scaling algorithm");
@ -1301,14 +1312,14 @@ bool update_from_preferences()
algo = gui2::tadvanced_graphics_options::string_to_SCALING_ALGORITHM(preferences::get("scale_hex"));
} catch (bad_enum_cast &) {}
scale_to_hex_func = boost::bind(& scale_surface_algorithm, _1, _2, _3, algo);
scale_to_hex_func = select_algorithm(algo);
algo = gui2::tadvanced_graphics_options::LINEAR;
try {
algo = gui2::tadvanced_graphics_options::string_to_SCALING_ALGORITHM(preferences::get("scale_zoom"));
} catch (bad_enum_cast &) {}
scale_to_zoom_func = boost::bind(& scale_surface_algorithm, _1, _2, _3, algo);
scale_to_zoom_func = select_algorithm(algo);
return true;
}

8
src/sdl/utils.cpp
View File

@ -451,6 +451,10 @@ surface scale_surface_nn (const surface & surf, int w, int h)
}
// NOTE: Don't pass this function 0 scaling arguments.
surface scale_surface(const surface &surf, int w, int h) {
return scale_surface(surf, w, h, true);
}
surface scale_surface(const surface &surf, int w, int h, bool optimize)
{
// Since SDL version 1.1.5 0 is transparent, before 255 was transparent.
@ -582,6 +586,10 @@ surface scale_surface(const surface &surf, int w, int h, bool optimize)
}
// NOTE: Don't pass this function 0 scaling arguments.
surface scale_surface_legacy(const surface &surf, int w, int h) {
return scale_surface_legacy(surf, w, h, true);
}
surface scale_surface_legacy(const surface &surf, int w, int h, bool optimize)
{
// Since SDL version 1.1.5 0 is transparent, before 255 was transparent.

9
src/sdl/utils.hpp
View File

@ -191,7 +191,9 @@ surface scale_surface_nn(const surface & surf, int w, int h);
* @retval surf Returned if w == surf->w and h == surf->h
* note this ignores the optimize flag.
*/
surface scale_surface(const surface &surf, int w, int h, bool optimize=true);
surface scale_surface(const surface &surf, int w, int h);
surface scale_surface(const surface &surf, int w, int h, bool optimize /*=true*/);
//commenting out the default parameter so that it is possible to make function pointers to the 3 parameter version
/** Scale a surface (legacy (1.10, 1.12) version)
* @param surf The source surface.
@ -203,8 +205,9 @@ surface scale_surface(const surface &surf, int w, int h, bool optimize=true);
* @retval surf Returned if w == surf->w and h == surf->h
* note this ignores the optimize flag.
*/
surface scale_surface_legacy(const surface &surf, int w, int h, bool optimize=true);
surface scale_surface_legacy(const surface &surf, int w, int h);
surface scale_surface_legacy(const surface &surf, int w, int h, bool optimize /*=true*/);
//commenting out the default parameter so that it is possible to make function pointers to the 3 parameter version
/** Scale a surface using modified nearest neighbour algorithm. Use only if
* preserving sharp edges is a priority (e.g. minimap).