1 | /* |
2 | Copyright 2005-2007 Adobe Systems Incorporated |
3 | |
4 | Use, modification and distribution are subject to the Boost Software License, |
5 | Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
6 | http://www.boost.org/LICENSE_1_0.txt). |
7 | |
8 | See http://opensource.adobe.com/gil for most recent version including documentation. |
9 | */ |
10 | |
11 | /*************************************************************************************************/ |
12 | |
13 | #ifndef GIL_IMAGE_VIEW_FACTORY_HPP |
14 | #define GIL_IMAGE_VIEW_FACTORY_HPP |
15 | |
16 | /*! |
17 | /// \file |
18 | /// \brief Methods for constructing image views from raw data or other image views |
19 | /// \author Lubomir Bourdev and Hailin Jin \n |
20 | /// Adobe Systems Incorporated |
21 | /// \date 2005-2007 \n Last updated on March 9, 2007 |
22 | /// Methods for creating shallow image views from raw pixel data or from other image views - |
23 | /// flipping horizontally or vertically, axis-aligned rotation, a subimage, subsampled |
24 | /// or n-th channel image view. Derived image views are shallow copies and are fast to construct. |
25 | */ |
26 | |
27 | #include <cassert> |
28 | #include <cstddef> |
29 | #include "gil_config.hpp" |
30 | #include "metafunctions.hpp" |
31 | #include "gray.hpp" |
32 | #include "color_convert.hpp" |
33 | |
34 | /// \defgroup ImageViewConstructors Image View From Raw Data |
35 | /// \ingroup ImageViewAlgorithm |
36 | /// \brief Methods for constructing image views from raw data and for getting raw data from views |
37 | |
38 | /// \defgroup ImageViewTransformations Image View Transformations |
39 | /// \ingroup ImageViewAlgorithm |
40 | /// \brief Methods for constructing one image view from another |
41 | |
42 | namespace boost { namespace gil { |
43 | struct default_color_converter; |
44 | |
45 | template <typename T> struct dynamic_x_step_type; |
46 | template <typename T> struct dynamic_y_step_type; |
47 | template <typename T> struct transposed_type; |
48 | |
49 | /// \brief Returns the type of a view that has a dynamic step along both X and Y |
50 | /// \ingroup ImageViewTransformations |
51 | template <typename View> |
52 | struct dynamic_xy_step_type : public dynamic_y_step_type<typename dynamic_x_step_type<View>::type> {}; |
53 | |
54 | /// \brief Returns the type of a transposed view that has a dynamic step along both X and Y |
55 | /// \ingroup ImageViewTransformations |
56 | template <typename View> |
57 | struct dynamic_xy_step_transposed_type : public dynamic_xy_step_type<typename transposed_type<View>::type> {}; |
58 | |
59 | |
60 | /// \ingroup ImageViewConstructors |
61 | /// \brief Constructing image views from raw interleaved pixel data |
62 | template <typename Iterator> |
63 | typename type_from_x_iterator<Iterator>::view_t |
64 | interleaved_view(std::size_t width, std::size_t height, |
65 | Iterator pixels, std::ptrdiff_t rowsize_in_bytes) { |
66 | typedef typename type_from_x_iterator<Iterator>::view_t RView; |
67 | return RView(width, height, typename RView::locator(pixels, rowsize_in_bytes)); |
68 | } |
69 | |
70 | /// \ingroup ImageViewConstructors |
71 | /// \brief Constructing image views from raw interleaved pixel data |
72 | template <typename Iterator> |
73 | typename type_from_x_iterator<Iterator>::view_t |
74 | interleaved_view(point2<std::size_t> dim, |
75 | Iterator pixels, std::ptrdiff_t rowsize_in_bytes) { |
76 | typedef typename type_from_x_iterator<Iterator>::view_t RView; |
77 | return RView(dim, typename RView::locator(pixels, rowsize_in_bytes)); |
78 | } |
79 | |
80 | ///////////////////////////// |
81 | // interleaved_view_get_raw_data, planar_view_get_raw_data - return pointers to the raw data (the channels) of a basic homogeneous view. |
82 | ///////////////////////////// |
83 | |
84 | namespace detail { |
85 | template <typename View, bool IsMutable> struct channel_pointer_type_impl; |
86 | |
87 | template <typename View> struct channel_pointer_type_impl<View, true> { |
88 | typedef typename channel_type<View>::type* type; |
89 | }; |
90 | template <typename View> struct channel_pointer_type_impl<View, false> { |
91 | typedef const typename channel_type<View>::type* type; |
92 | }; |
93 | |
94 | template <typename View> struct channel_pointer_type |
95 | : public channel_pointer_type_impl<View, view_is_mutable<View>::value> {}; |
96 | } // namespace detail |
97 | |
98 | /// \ingroup ImageViewConstructors |
99 | /// \brief Returns C pointer to the the channels of an interleaved homogeneous view. |
100 | template <typename HomogeneousView> |
101 | typename detail::channel_pointer_type<HomogeneousView>::type interleaved_view_get_raw_data(const HomogeneousView& view) { |
102 | BOOST_STATIC_ASSERT((!is_planar<HomogeneousView>::value && view_is_basic<HomogeneousView>::value)); |
103 | BOOST_STATIC_ASSERT((boost::is_pointer<typename HomogeneousView::x_iterator>::value)); |
104 | |
105 | return &gil::at_c<0>(view(0,0)); |
106 | } |
107 | |
108 | /// \ingroup ImageViewConstructors |
109 | /// \brief Returns C pointer to the the channels of a given color plane of a planar homogeneous view. |
110 | template <typename HomogeneousView> |
111 | typename detail::channel_pointer_type<HomogeneousView>::type planar_view_get_raw_data(const HomogeneousView& view, int plane_index) { |
112 | BOOST_STATIC_ASSERT((is_planar<HomogeneousView>::value && view_is_basic<HomogeneousView>::value)); |
113 | return dynamic_at_c(view.row_begin(0),plane_index); |
114 | } |
115 | |
116 | |
117 | /// \defgroup ImageViewTransformationsColorConvert color_converted_view |
118 | /// \ingroup ImageViewTransformations |
119 | /// \brief Color converted view of another view |
120 | |
121 | /// \ingroup ImageViewTransformationsColorConvert PixelDereferenceAdaptorModel |
122 | /// \brief Function object that given a source pixel, returns it converted to a given color space and channel depth. Models: PixelDereferenceAdaptorConcept |
123 | /// |
124 | /// Useful in constructing a color converted view over a given image view |
125 | template <typename SrcConstRefP, typename DstP, typename CC=default_color_converter > // const_reference to the source pixel and destination pixel value |
126 | class color_convert_deref_fn : public deref_base<color_convert_deref_fn<SrcConstRefP,DstP,CC>, DstP, DstP, const DstP&, SrcConstRefP, DstP, false> { |
127 | private: |
128 | CC _cc; // color-converter |
129 | public: |
130 | color_convert_deref_fn() {} |
131 | color_convert_deref_fn(CC cc_in) : _cc(cc_in) {} |
132 | |
133 | DstP operator()(SrcConstRefP srcP) const { |
134 | DstP dstP; |
135 | _cc(srcP,dstP); |
136 | return dstP; |
137 | } |
138 | }; |
139 | |
140 | namespace detail { |
141 | // Add color converter upon dereferencing |
142 | template <typename SrcView, typename CC, typename DstP, typename SrcP> |
143 | struct _color_converted_view_type { |
144 | private: |
145 | typedef color_convert_deref_fn<typename SrcView::const_t::reference,DstP,CC> deref_t; |
146 | typedef typename SrcView::template add_deref<deref_t> add_ref_t; |
147 | public: |
148 | typedef typename add_ref_t::type type; |
149 | static type make(const SrcView& sv,CC cc) {return add_ref_t::make(sv,deref_t(cc));} |
150 | }; |
151 | |
152 | // If the Src view has the same pixel type as the target, there is no need for color conversion |
153 | template <typename SrcView, typename CC, typename DstP> |
154 | struct _color_converted_view_type<SrcView,CC,DstP,DstP> { |
155 | typedef SrcView type; |
156 | static type make(const SrcView& sv,CC) {return sv;} |
157 | }; |
158 | } // namespace detail |
159 | |
160 | |
161 | /// \brief Returns the type of a view that does color conversion upon dereferencing its pixels |
162 | /// \ingroup ImageViewTransformationsColorConvert |
163 | template <typename SrcView, typename DstP, typename CC=default_color_converter> |
164 | struct color_converted_view_type : public detail::_color_converted_view_type<SrcView, |
165 | CC, |
166 | DstP, |
167 | typename SrcView::value_type> { |
168 | GIL_CLASS_REQUIRE(DstP, boost::gil, MutablePixelConcept)//why does it have to be mutable??? |
169 | }; |
170 | |
171 | |
172 | /// \ingroup ImageViewTransformationsColorConvert |
173 | /// \brief view of a different color space with a user defined color-converter |
174 | template <typename DstP, typename View, typename CC> |
175 | inline typename color_converted_view_type<View,DstP,CC>::type color_converted_view(const View& src,CC cc) { |
176 | return color_converted_view_type<View,DstP,CC>::make(src,cc); |
177 | } |
178 | |
179 | /// \ingroup ImageViewTransformationsColorConvert |
180 | /// \brief overload of generic color_converted_view with the default color-converter |
181 | template <typename DstP, typename View> |
182 | inline typename color_converted_view_type<View,DstP>::type |
183 | color_converted_view(const View& src) { |
184 | return color_converted_view<DstP>(src,default_color_converter()); |
185 | } |
186 | |
187 | /// \defgroup ImageViewTransformationsFlipUD flipped_up_down_view |
188 | /// \ingroup ImageViewTransformations |
189 | /// \brief view of a view flipped up-to-down |
190 | |
191 | /// \ingroup ImageViewTransformationsFlipUD |
192 | template <typename View> |
193 | inline typename dynamic_y_step_type<View>::type flipped_up_down_view(const View& src) { |
194 | typedef typename dynamic_y_step_type<View>::type RView; |
195 | return RView(src.dimensions(),typename RView::xy_locator(src.xy_at(0,src.height()-1),-1)); |
196 | } |
197 | |
198 | /// \defgroup ImageViewTransformationsFlipLR flipped_left_right_view |
199 | /// \ingroup ImageViewTransformations |
200 | /// \brief view of a view flipped left-to-right |
201 | |
202 | /// \ingroup ImageViewTransformationsFlipLR |
203 | template <typename View> |
204 | inline typename dynamic_x_step_type<View>::type flipped_left_right_view(const View& src) { |
205 | typedef typename dynamic_x_step_type<View>::type RView; |
206 | return RView(src.dimensions(),typename RView::xy_locator(src.xy_at(src.width()-1,0),-1,1)); |
207 | } |
208 | |
209 | /// \defgroup ImageViewTransformationsTransposed transposed_view |
210 | /// \ingroup ImageViewTransformations |
211 | /// \brief view of a view transposed |
212 | |
213 | /// \ingroup ImageViewTransformationsTransposed |
214 | template <typename View> |
215 | inline typename dynamic_xy_step_transposed_type<View>::type transposed_view(const View& src) { |
216 | typedef typename dynamic_xy_step_transposed_type<View>::type RView; |
217 | return RView(src.height(),src.width(),typename RView::xy_locator(src.xy_at(0,0),1,1,true)); |
218 | } |
219 | |
220 | /// \defgroup ImageViewTransformations90CW rotated90cw_view |
221 | /// \ingroup ImageViewTransformations |
222 | /// \brief view of a view rotated 90 degrees clockwise |
223 | |
224 | /// \ingroup ImageViewTransformations90CW |
225 | template <typename View> |
226 | inline typename dynamic_xy_step_transposed_type<View>::type rotated90cw_view(const View& src) { |
227 | typedef typename dynamic_xy_step_transposed_type<View>::type RView; |
228 | return RView(src.height(),src.width(),typename RView::xy_locator(src.xy_at(0,src.height()-1),-1,1,true)); |
229 | } |
230 | |
231 | /// \defgroup ImageViewTransformations90CCW rotated90ccw_view |
232 | /// \ingroup ImageViewTransformations |
233 | /// \brief view of a view rotated 90 degrees counter-clockwise |
234 | |
235 | /// \ingroup ImageViewTransformations90CCW |
236 | template <typename View> |
237 | inline typename dynamic_xy_step_transposed_type<View>::type rotated90ccw_view(const View& src) { |
238 | typedef typename dynamic_xy_step_transposed_type<View>::type RView; |
239 | return RView(src.height(),src.width(),typename RView::xy_locator(src.xy_at(src.width()-1,0),1,-1,true)); |
240 | } |
241 | |
242 | /// \defgroup ImageViewTransformations180 rotated180_view |
243 | /// \ingroup ImageViewTransformations |
244 | /// \brief view of a view rotated 180 degrees |
245 | |
246 | /// \ingroup ImageViewTransformations180 |
247 | template <typename View> |
248 | inline typename dynamic_xy_step_type<View>::type rotated180_view(const View& src) { |
249 | typedef typename dynamic_xy_step_type<View>::type RView; |
250 | return RView(src.dimensions(),typename RView::xy_locator(src.xy_at(src.width()-1,src.height()-1),-1,-1)); |
251 | } |
252 | |
253 | /// \defgroup ImageViewTransformationsSubimage subimage_view |
254 | /// \ingroup ImageViewTransformations |
255 | /// \brief view of an axis-aligned rectangular area within an image_view |
256 | |
257 | /// \ingroup ImageViewTransformationsSubimage |
258 | template <typename View> |
259 | inline View subimage_view(const View& src, const typename View::point_t& topleft, const typename View::point_t& dimensions) { |
260 | return View(dimensions,src.xy_at(topleft)); |
261 | } |
262 | |
263 | /// \ingroup ImageViewTransformationsSubimage |
264 | template <typename View> |
265 | inline View subimage_view(const View& src, int xMin, int yMin, int width, int height) { |
266 | return View(width,height,src.xy_at(xMin,yMin)); |
267 | } |
268 | |
269 | /// \defgroup ImageViewTransformationsSubsampled subsampled_view |
270 | /// \ingroup ImageViewTransformations |
271 | /// \brief view of a subsampled version of an image_view, stepping over a number of channels in X and number of rows in Y |
272 | |
273 | /// \ingroup ImageViewTransformationsSubsampled |
274 | template <typename View> |
275 | inline typename dynamic_xy_step_type<View>::type subsampled_view(const View& src, typename View::coord_t xStep, typename View::coord_t yStep) { |
276 | assert(xStep>0 && yStep>0); |
277 | typedef typename dynamic_xy_step_type<View>::type RView; |
278 | return RView((src.width()+(xStep-1))/xStep,(src.height()+(yStep-1))/yStep, |
279 | typename RView::xy_locator(src.xy_at(0,0),xStep,yStep)); |
280 | } |
281 | |
282 | /// \ingroup ImageViewTransformationsSubsampled |
283 | template <typename View> |
284 | inline typename dynamic_xy_step_type<View>::type subsampled_view(const View& src, const typename View::point_t& step) { |
285 | return subsampled_view(src,step.x,step.y); |
286 | } |
287 | |
288 | /// \defgroup ImageViewTransformationsNthChannel nth_channel_view |
289 | /// \ingroup ImageViewTransformations |
290 | /// \brief single-channel (grayscale) view of the N-th channel of a given image_view |
291 | |
292 | namespace detail { |
293 | template <typename View, bool AreChannelsTogether> struct __nth_channel_view_basic; |
294 | |
295 | // nth_channel_view when the channels are not adjacent in memory. This can happen for multi-channel interleaved images |
296 | // or images with a step |
297 | template <typename View> |
298 | struct __nth_channel_view_basic<View,false> { |
299 | typedef typename view_type<typename channel_type<View>::type, gray_layout_t, false, true, view_is_mutable<View>::value>::type type; |
300 | |
301 | static type make(const View& src, int n) { |
302 | typedef typename type::xy_locator locator_t; |
303 | typedef typename type::x_iterator x_iterator_t; |
304 | typedef typename iterator_adaptor_get_base<x_iterator_t>::type x_iterator_base_t; |
305 | x_iterator_t sit(x_iterator_base_t(&(src(0,0)[n])),src.pixels().pixel_size()); |
306 | return type(src.dimensions(),locator_t(sit, src.pixels().row_size())); |
307 | } |
308 | }; |
309 | |
310 | // nth_channel_view when the channels are together in memory (true for simple grayscale or planar images) |
311 | template <typename View> |
312 | struct __nth_channel_view_basic<View,true> { |
313 | typedef typename view_type<typename channel_type<View>::type, gray_layout_t, false, false, view_is_mutable<View>::value>::type type; |
314 | static type make(const View& src, int n) { |
315 | typedef typename type::x_iterator x_iterator_t; |
316 | return interleaved_view(src.width(),src.height(),(x_iterator_t)&(src(0,0)[n]), src.pixels().row_size()); |
317 | } |
318 | }; |
319 | |
320 | template <typename View, bool IsBasic> struct __nth_channel_view; |
321 | |
322 | // For basic (memory-based) views dispatch to __nth_channel_view_basic |
323 | template <typename View> struct __nth_channel_view<View,true> { |
324 | private: |
325 | typedef typename View::x_iterator src_x_iterator; |
326 | |
327 | // Determines whether the channels of a given pixel iterator are adjacent in memory. |
328 | // Planar and grayscale iterators have channels adjacent in memory, whereas multi-channel interleaved and iterators with non-fundamental step do not. |
329 | BOOST_STATIC_CONSTANT(bool, adjacent= |
330 | !iterator_is_step<src_x_iterator>::value && |
331 | (is_planar<src_x_iterator>::value || |
332 | num_channels<View>::value==1)); |
333 | public: |
334 | typedef typename __nth_channel_view_basic<View,adjacent>::type type; |
335 | |
336 | static type make(const View& src, int n) { |
337 | return __nth_channel_view_basic<View,adjacent>::make(src,n); |
338 | } |
339 | }; |
340 | |
341 | /// \brief Function object that returns a grayscale reference of the N-th channel of a given reference. Models: PixelDereferenceAdaptorConcept. |
342 | /// \ingroup PixelDereferenceAdaptorModel |
343 | /// |
344 | /// If the input is a pixel value or constant reference, the function object is immutable. Otherwise it is mutable (and returns non-const reference to the n-th channel) |
345 | template <typename SrcP> // SrcP is a reference to PixelConcept (could be pixel value or const/non-const reference) |
346 | // Examples: pixel<T,L>, pixel<T,L>&, const pixel<T,L>&, planar_pixel_reference<T&,L>, planar_pixel_reference<const T&,L> |
347 | struct nth_channel_deref_fn { |
348 | BOOST_STATIC_CONSTANT(bool, is_mutable=pixel_is_reference<SrcP>::value && pixel_reference_is_mutable<SrcP>::value); |
349 | private: |
350 | typedef typename remove_reference<SrcP>::type src_pixel_t; |
351 | typedef typename channel_type<src_pixel_t>::type channel_t; |
352 | typedef typename src_pixel_t::const_reference const_ref_t; |
353 | typedef typename pixel_reference_type<channel_t,gray_layout_t,false,is_mutable>::type ref_t; |
354 | public: |
355 | typedef nth_channel_deref_fn<const_ref_t> const_t; |
356 | typedef typename pixel_value_type<channel_t,gray_layout_t>::type value_type; |
357 | typedef typename pixel_reference_type<channel_t,gray_layout_t,false,false>::type const_reference; |
358 | typedef SrcP argument_type; |
359 | typedef typename mpl::if_c<is_mutable, ref_t, value_type>::type reference; |
360 | typedef reference result_type; |
361 | |
362 | nth_channel_deref_fn(int n=0) : _n(n) {} |
363 | template <typename P> nth_channel_deref_fn(const nth_channel_deref_fn<P>& d) : _n(d._n) {} |
364 | |
365 | int _n; // the channel to use |
366 | |
367 | result_type operator()(argument_type srcP) const { |
368 | return result_type(srcP[_n]); |
369 | } |
370 | }; |
371 | |
372 | template <typename View> struct __nth_channel_view<View,false> { |
373 | private: |
374 | typedef nth_channel_deref_fn<typename View::reference> deref_t; |
375 | typedef typename View::template add_deref<deref_t> AD; |
376 | public: |
377 | typedef typename AD::type type; |
378 | static type make(const View& src, int n) { |
379 | return AD::make(src, deref_t(n)); |
380 | } |
381 | }; |
382 | } // namespace detail |
383 | |
384 | /// \brief Given a source image view type View, returns the type of an image view over a single channel of View |
385 | /// \ingroup ImageViewTransformationsNthChannel |
386 | /// |
387 | /// If the channels in the source view are adjacent in memory (such as planar non-step view or single-channel view) then the |
388 | /// return view is a single-channel non-step view. |
389 | /// If the channels are non-adjacent (interleaved and/or step view) then the return view is a single-channel step view. |
390 | template <typename View> |
391 | struct nth_channel_view_type { |
392 | private: |
393 | GIL_CLASS_REQUIRE(View, boost::gil, ImageViewConcept) |
394 | typedef detail::__nth_channel_view<View,view_is_basic<View>::value> VB; |
395 | public: |
396 | typedef typename VB::type type; |
397 | static type make(const View& src, int n) { return VB::make(src,n); } |
398 | }; |
399 | |
400 | |
401 | /// \ingroup ImageViewTransformationsNthChannel |
402 | template <typename View> |
403 | typename nth_channel_view_type<View>::type nth_channel_view(const View& src, int n) { |
404 | return nth_channel_view_type<View>::make(src,n); |
405 | } |
406 | |
407 | |
408 | |
409 | |
410 | |
411 | |
412 | |
413 | /// \defgroup ImageViewTransformationsKthChannel kth_channel_view |
414 | /// \ingroup ImageViewTransformations |
415 | /// \brief single-channel (grayscale) view of the K-th channel of a given image_view. The channel index is a template parameter |
416 | |
417 | namespace detail { |
418 | template <int K, typename View, bool AreChannelsTogether> struct __kth_channel_view_basic; |
419 | |
420 | // kth_channel_view when the channels are not adjacent in memory. This can happen for multi-channel interleaved images |
421 | // or images with a step |
422 | template <int K, typename View> |
423 | struct __kth_channel_view_basic<K,View,false> { |
424 | private: |
425 | typedef typename kth_element_type<typename View::value_type,K>::type channel_t; |
426 | public: |
427 | typedef typename view_type<channel_t, gray_layout_t, false, true, view_is_mutable<View>::value>::type type; |
428 | |
429 | static type make(const View& src) { |
430 | typedef typename type::xy_locator locator_t; |
431 | typedef typename type::x_iterator x_iterator_t; |
432 | typedef typename iterator_adaptor_get_base<x_iterator_t>::type x_iterator_base_t; |
433 | x_iterator_t sit(x_iterator_base_t(&gil::at_c<K>(src(0,0))),src.pixels().pixel_size()); |
434 | return type(src.dimensions(),locator_t(sit, src.pixels().row_size())); |
435 | } |
436 | }; |
437 | |
438 | // kth_channel_view when the channels are together in memory (true for simple grayscale or planar images) |
439 | template <int K, typename View> |
440 | struct __kth_channel_view_basic<K,View,true> { |
441 | private: |
442 | typedef typename kth_element_type<typename View::value_type, K>::type channel_t; |
443 | public: |
444 | typedef typename view_type<channel_t, gray_layout_t, false, false, view_is_mutable<View>::value>::type type; |
445 | static type make(const View& src) { |
446 | typedef typename type::x_iterator x_iterator_t; |
447 | return interleaved_view(src.width(),src.height(),(x_iterator_t)&gil::at_c<K>(src(0,0)), src.pixels().row_size()); |
448 | } |
449 | }; |
450 | |
451 | template <int K, typename View, bool IsBasic> struct __kth_channel_view; |
452 | |
453 | // For basic (memory-based) views dispatch to __kth_channel_view_basic |
454 | template <int K, typename View> struct __kth_channel_view<K,View,true> { |
455 | private: |
456 | typedef typename View::x_iterator src_x_iterator; |
457 | |
458 | // Determines whether the channels of a given pixel iterator are adjacent in memory. |
459 | // Planar and grayscale iterators have channels adjacent in memory, whereas multi-channel interleaved and iterators with non-fundamental step do not. |
460 | BOOST_STATIC_CONSTANT(bool, adjacent= |
461 | !iterator_is_step<src_x_iterator>::value && |
462 | (is_planar<src_x_iterator>::value || |
463 | num_channels<View>::value==1)); |
464 | public: |
465 | typedef typename __kth_channel_view_basic<K,View,adjacent>::type type; |
466 | |
467 | static type make(const View& src) { |
468 | return __kth_channel_view_basic<K,View,adjacent>::make(src); |
469 | } |
470 | }; |
471 | |
472 | /// \brief Function object that returns a grayscale reference of the K-th channel (specified as a template parameter) of a given reference. Models: PixelDereferenceAdaptorConcept. |
473 | /// \ingroup PixelDereferenceAdaptorModel |
474 | /// |
475 | /// If the input is a pixel value or constant reference, the function object is immutable. Otherwise it is mutable (and returns non-const reference to the k-th channel) |
476 | template <int K, typename SrcP> // SrcP is a reference to PixelConcept (could be pixel value or const/non-const reference) |
477 | // Examples: pixel<T,L>, pixel<T,L>&, const pixel<T,L>&, planar_pixel_reference<T&,L>, planar_pixel_reference<const T&,L> |
478 | struct kth_channel_deref_fn { |
479 | BOOST_STATIC_CONSTANT(bool, is_mutable=pixel_is_reference<SrcP>::value && pixel_reference_is_mutable<SrcP>::value); |
480 | private: |
481 | typedef typename remove_reference<SrcP>::type src_pixel_t; |
482 | typedef typename kth_element_type<src_pixel_t, K>::type channel_t; |
483 | typedef typename src_pixel_t::const_reference const_ref_t; |
484 | typedef typename pixel_reference_type<channel_t,gray_layout_t,false,is_mutable>::type ref_t; |
485 | public: |
486 | typedef kth_channel_deref_fn<K,const_ref_t> const_t; |
487 | typedef typename pixel_value_type<channel_t,gray_layout_t>::type value_type; |
488 | typedef typename pixel_reference_type<channel_t,gray_layout_t,false,false>::type const_reference; |
489 | typedef SrcP argument_type; |
490 | typedef typename mpl::if_c<is_mutable, ref_t, value_type>::type reference; |
491 | typedef reference result_type; |
492 | |
493 | kth_channel_deref_fn() {} |
494 | template <typename P> kth_channel_deref_fn(const kth_channel_deref_fn<K,P>&) {} |
495 | |
496 | result_type operator()(argument_type srcP) const { |
497 | return result_type(gil::at_c<K>(srcP)); |
498 | } |
499 | }; |
500 | |
501 | template <int K, typename View> struct __kth_channel_view<K,View,false> { |
502 | private: |
503 | typedef kth_channel_deref_fn<K,typename View::reference> deref_t; |
504 | typedef typename View::template add_deref<deref_t> AD; |
505 | public: |
506 | typedef typename AD::type type; |
507 | static type make(const View& src) { |
508 | return AD::make(src, deref_t()); |
509 | } |
510 | }; |
511 | } // namespace detail |
512 | |
513 | /// \brief Given a source image view type View, returns the type of an image view over a given channel of View. |
514 | /// \ingroup ImageViewTransformationsKthChannel |
515 | /// |
516 | /// If the channels in the source view are adjacent in memory (such as planar non-step view or single-channel view) then the |
517 | /// return view is a single-channel non-step view. |
518 | /// If the channels are non-adjacent (interleaved and/or step view) then the return view is a single-channel step view. |
519 | template <int K, typename View> |
520 | struct kth_channel_view_type { |
521 | private: |
522 | GIL_CLASS_REQUIRE(View, boost::gil, ImageViewConcept) |
523 | typedef detail::__kth_channel_view<K,View,view_is_basic<View>::value> VB; |
524 | public: |
525 | typedef typename VB::type type; |
526 | static type make(const View& src) { return VB::make(src); } |
527 | }; |
528 | |
529 | /// \ingroup ImageViewTransformationsKthChannel |
530 | template <int K, typename View> |
531 | typename kth_channel_view_type<K,View>::type kth_channel_view(const View& src) { |
532 | return kth_channel_view_type<K,View>::make(src); |
533 | } |
534 | |
535 | } } // namespace boost::gil |
536 | |
537 | #endif |
538 | |