nerdcruft/libcruft-util
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image: add basic buffer class

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This commit is contained in:
Danny Robson 2015-02-04 15:59:06 +11:00
parent 1db9057c95
commit b542062cc4
2 changed files with 157 additions and 6 deletions
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122
image.cpp
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@ -14,7 +14,7 @@
* You should have received a copy of the GNU General Public License
* along with libgim. If not, see <http://www.gnu.org/licenses/>.
*
* Copyright 2011-2014 Danny Robson <danny@nerdcruft.net>
* Copyright 2011-2015 Danny Robson <danny@nerdcruft.net>
*/
@ -26,6 +26,121 @@
#include <fstream>
//-----------------------------------------------------------------------------
template <typename T>
util::image::buffer<T>::buffer (size_t _w, size_t _h, size_t _s):
w (_w),
h (_h),
s (_s),
data (std::make_unique<T[]> (_w * _s))
{
CHECK_NEQ (w * h, 0);
CHECK_GE (s, w);
}
//-----------------------------------------------------------------------------
template <typename T>
util::image::buffer<T>::buffer (size_t _w, size_t _h):
buffer<T> (_w, _h, _w)
{ ; }
//-----------------------------------------------------------------------------
template <typename T>
util::image::buffer<T>::buffer (size_t _w,
size_t _h,
size_t _s,
std::unique_ptr<T[]> &&_data):
w (_w),
h (_h),
s (_s),
data (std::move (_data))
{
CHECK_NEQ (w * h, 0);
CHECK_GE (s, w);
}
//-----------------------------------------------------------------------------
template <typename T>
template <typename U>
util::image::buffer<U>
util::image::buffer<T>::alloc (void) const
{
return buffer<U> (w, h, s);
}
//-----------------------------------------------------------------------------
template <typename T>
void
util::image::buffer<T>::fill (const T v)
{
std::fill (data.get (), data.get () + w * s, v);
}
//-----------------------------------------------------------------------------
template <typename T, typename U>
static U
rescale (T v)
{
return v * sizeof (U) / sizeof (T);
}
//-----------------------------------------------------------------------------
template <typename T>
template <typename U>
util::image::buffer<U>
util::image::buffer<T>::clone (void) const
{
auto out = alloc<U> ();
std::transform (data.get (),
data.get () + w * s,
out.data.get (),
[] (auto v) {
return rescale<T,U> (v);
});
return out;
}
//-----------------------------------------------------------------------------
template <typename T>
util::image::buffer<T>
util::image::buffer<T>::downsample (unsigned factor)
{
CHECK_GT (factor, 1);
size_t w_ = w / factor;
size_t h_ = h / factor;
size_t s_ = w_;
CHECK_NEQ (w_, 0);
CHECK_NEQ (h_, 0);
buffer out { w_, h_, s_, std::make_unique<T[]> (w_ * h_) };
// Do a really shitty nearest neighbour average in src-space.
for (size_t y = 0; y < out.h; ++y)
for (size_t x = 0; x < out.w; ++x) {
size_t src00 = ((y * factor) + 0) * s + (x * factor) + 0;
size_t src01 = ((y * factor) + 0) * s + (x * factor) + 1;
size_t src10 = ((y * factor) + 1) * s + (x * factor) + 0;
size_t src11 = ((y * factor) + 1) * s + (x * factor) + 1;
size_t dst_offset = y * out.s + x;
out.data[dst_offset] = (src00 + src01 + src10 + src11) / 4;
}
return out;
}
//-----------------------------------------------------------------------------
static void
write_netpbm (const uint8_t *restrict pixels,
@ -82,3 +197,8 @@ util::ppm::write (const uint8_t *restrict pixels,
static const char MAGIC[] = "P6";
write_netpbm (pixels, width, height, stride, path, MAGIC);
}
//-----------------------------------------------------------------------------
template struct util::image::buffer<uint8_t>;
template util::image::buffer<uint8_t> util::image::buffer<uint8_t>::alloc (void) const;

33
image.hpp
View File

@ -14,7 +14,7 @@
* You should have received a copy of the GNU General Public License
* along with libgim. If not, see <http://www.gnu.org/licenses/>.
*
* Copyright 2011-2014 Danny Robson <danny@nerdcruft.net>
* Copyright 2011-2015 Danny Robson <danny@nerdcruft.net>
*/
#ifndef __UTIL_IMAGE_HPP
@ -22,9 +22,40 @@
#include <cstdint>
#include <cstdlib>
#include <memory>
#include <boost/filesystem/path.hpp>
namespace util {
namespace image {
template <typename T>
struct buffer {
buffer (size_t w, size_t h);
buffer (size_t w, size_t h, size_t s);
buffer (size_t w, size_t h, size_t s, std::unique_ptr<T[]> &&data);
buffer (const buffer<T>&) = delete;
buffer (buffer<T> &&) = default;
void fill (T);
template <typename U>
buffer<U> alloc (void) const;
template <typename U>
buffer<U> clone (void) const;
buffer<T> downsample (unsigned factor);
size_t w;
size_t h;
size_t s;
std::unique_ptr<T[]> data;
};
}
struct pgm {
static void write (const uint8_t *restrict pixels,
size_t width,