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1 /*
2  * Copyright © 2011 Intel Corporation
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice (including the next
12  * paragraph) shall be included in all copies or substantial portions of the
13  * Software.
14  *
15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18  * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
19  * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
20  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
22  * DEALINGS IN THE SOFTWARE.
23  *
24  * Authors:
25  *    Benjamin Franzke <benjaminfranzke@googlemail.com>
26  */
27 
28 #include <stddef.h>
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <string.h>
32 #include <stdint.h>
33 
34 #ifdef MAJOR_IN_MKDEV
35 #include <sys/mkdev.h>
36 #endif
37 #ifdef MAJOR_IN_SYSMACROS
38 #include <sys/sysmacros.h>
39 #endif
40 #include <sys/stat.h>
41 #include <unistd.h>
42 #include <errno.h>
43 
44 #include "gbm.h"
45 #include "gbmint.h"
46 #include "backend.h"
47 
48 /** Returns the file description for the gbm device
49  *
50  * \return The fd that the struct gbm_device was created with
51  */
52 GBM_EXPORT int
gbm_device_get_fd(struct gbm_device * gbm)53 gbm_device_get_fd(struct gbm_device *gbm)
54 {
55    return gbm->fd;
56 }
57 
58 /** Get the backend name for the given gbm device
59  *
60  * \return The backend name string - this belongs to the device and must not
61  * be freed
62  */
63 GBM_EXPORT const char *
gbm_device_get_backend_name(struct gbm_device * gbm)64 gbm_device_get_backend_name(struct gbm_device *gbm)
65 {
66    return gbm->name;
67 }
68 
69 /** Test if a format is supported for a given set of usage flags.
70  *
71  * \param gbm The created buffer manager
72  * \param format The format to test
73  * \param usage A bitmask of the usages to test the format against
74  * \return 1 if the format is supported otherwise 0
75  *
76  * \sa enum gbm_bo_flags for the list of flags that the format can be
77  * tested against
78  *
79  * \sa enum gbm_bo_format for the list of formats
80  */
81 GBM_EXPORT int
gbm_device_is_format_supported(struct gbm_device * gbm,uint32_t format,uint32_t usage)82 gbm_device_is_format_supported(struct gbm_device *gbm,
83                                uint32_t format, uint32_t usage)
84 {
85    return gbm->is_format_supported(gbm, format, usage);
86 }
87 
88 /** Get the number of planes that are required for a given format+modifier
89  *
90  * \param gbm The gbm device returned from gbm_create_device()
91  * \param format The format to query
92  * \param modifier The modifier to query
93  */
94 GBM_EXPORT int
gbm_device_get_format_modifier_plane_count(struct gbm_device * gbm,uint32_t format,uint64_t modifier)95 gbm_device_get_format_modifier_plane_count(struct gbm_device *gbm,
96                                            uint32_t format,
97                                            uint64_t modifier)
98 {
99    return gbm->get_format_modifier_plane_count(gbm, format, modifier);
100 }
101 
102 /** Destroy the gbm device and free all resources associated with it.
103  *
104  * \param gbm The device created using gbm_create_device()
105  */
106 GBM_EXPORT void
gbm_device_destroy(struct gbm_device * gbm)107 gbm_device_destroy(struct gbm_device *gbm)
108 {
109    gbm->refcount--;
110    if (gbm->refcount == 0)
111       gbm->destroy(gbm);
112 }
113 
114 /** Create a gbm device for allocating buffers
115  *
116  * The file descriptor passed in is used by the backend to communicate with
117  * platform for allocating the memory. For allocations using DRI this would be
118  * the file descriptor returned when opening a device such as \c
119  * /dev/dri/card0
120  *
121  * \param fd The file descriptor for a backend specific device
122  * \return The newly created struct gbm_device. The resources associated with
123  * the device should be freed with gbm_device_destroy() when it is no longer
124  * needed. If the creation of the device failed NULL will be returned.
125  */
126 GBM_EXPORT struct gbm_device *
gbm_create_device(int fd)127 gbm_create_device(int fd)
128 {
129    struct gbm_device *gbm = NULL;
130    struct stat buf;
131 
132    if (fd < 0 || fstat(fd, &buf) < 0 || !S_ISCHR(buf.st_mode)) {
133       errno = EINVAL;
134       return NULL;
135    }
136 
137    gbm = _gbm_create_device(fd);
138    if (gbm == NULL)
139       return NULL;
140 
141    gbm->dummy = gbm_create_device;
142    gbm->stat = buf;
143    gbm->refcount = 1;
144 
145    return gbm;
146 }
147 
148 /** Get the width of the buffer object
149  *
150  * \param bo The buffer object
151  * \return The width of the allocated buffer object
152  *
153  */
154 GBM_EXPORT uint32_t
gbm_bo_get_width(struct gbm_bo * bo)155 gbm_bo_get_width(struct gbm_bo *bo)
156 {
157    return bo->width;
158 }
159 
160 /** Get the height of the buffer object
161  *
162  * \param bo The buffer object
163  * \return The height of the allocated buffer object
164  */
165 GBM_EXPORT uint32_t
gbm_bo_get_height(struct gbm_bo * bo)166 gbm_bo_get_height(struct gbm_bo *bo)
167 {
168    return bo->height;
169 }
170 
171 /** Get the stride of the buffer object
172  *
173  * This is calculated by the backend when it does the allocation in
174  * gbm_bo_create()
175  *
176  * \param bo The buffer object
177  * \return The stride of the allocated buffer object in bytes
178  */
179 GBM_EXPORT uint32_t
gbm_bo_get_stride(struct gbm_bo * bo)180 gbm_bo_get_stride(struct gbm_bo *bo)
181 {
182    return gbm_bo_get_stride_for_plane(bo, 0);
183 }
184 
185 /** Get the stride for the given plane
186  *
187  * \param bo The buffer object
188  * \param plane for which you want the stride
189  *
190  * \sa gbm_bo_get_stride()
191  */
192 GBM_EXPORT uint32_t
gbm_bo_get_stride_for_plane(struct gbm_bo * bo,int plane)193 gbm_bo_get_stride_for_plane(struct gbm_bo *bo, int plane)
194 {
195    return bo->gbm->bo_get_stride(bo, plane);
196 }
197 
198 /** Get the format of the buffer object
199  *
200  * The format of the pixels in the buffer.
201  *
202  * \param bo The buffer object
203  * \return The format of buffer object, one of the GBM_FORMAT_* codes
204  */
205 GBM_EXPORT uint32_t
gbm_bo_get_format(struct gbm_bo * bo)206 gbm_bo_get_format(struct gbm_bo *bo)
207 {
208    return bo->format;
209 }
210 
211 /** Get the bit-per-pixel of the buffer object's format
212  *
213  * The bits-per-pixel of the buffer object's format.
214  *
215  * Note; The 'in-memory pixel' concept makes no sense for YUV formats
216  * (pixels are the result of the combination of multiple memory sources:
217  * Y, Cb & Cr; usually these are even in separate buffers), so YUV
218  * formats are not supported by this function.
219  *
220  * \param bo The buffer object
221  * \return The number of bits0per-pixel of the buffer object's format.
222  */
223 GBM_EXPORT uint32_t
gbm_bo_get_bpp(struct gbm_bo * bo)224 gbm_bo_get_bpp(struct gbm_bo *bo)
225 {
226    switch (bo->format) {
227       default:
228          return 0;
229       case GBM_FORMAT_C8:
230       case GBM_FORMAT_R8:
231       case GBM_FORMAT_RGB332:
232       case GBM_FORMAT_BGR233:
233          return 8;
234       case GBM_FORMAT_GR88:
235       case GBM_FORMAT_XRGB4444:
236       case GBM_FORMAT_XBGR4444:
237       case GBM_FORMAT_RGBX4444:
238       case GBM_FORMAT_BGRX4444:
239       case GBM_FORMAT_ARGB4444:
240       case GBM_FORMAT_ABGR4444:
241       case GBM_FORMAT_RGBA4444:
242       case GBM_FORMAT_BGRA4444:
243       case GBM_FORMAT_XRGB1555:
244       case GBM_FORMAT_XBGR1555:
245       case GBM_FORMAT_RGBX5551:
246       case GBM_FORMAT_BGRX5551:
247       case GBM_FORMAT_ARGB1555:
248       case GBM_FORMAT_ABGR1555:
249       case GBM_FORMAT_RGBA5551:
250       case GBM_FORMAT_BGRA5551:
251       case GBM_FORMAT_RGB565:
252       case GBM_FORMAT_BGR565:
253          return 16;
254       case GBM_FORMAT_RGB888:
255       case GBM_FORMAT_BGR888:
256          return 24;
257       case GBM_FORMAT_XRGB8888:
258       case GBM_FORMAT_XBGR8888:
259       case GBM_FORMAT_RGBX8888:
260       case GBM_FORMAT_BGRX8888:
261       case GBM_FORMAT_ARGB8888:
262       case GBM_FORMAT_ABGR8888:
263       case GBM_FORMAT_RGBA8888:
264       case GBM_FORMAT_BGRA8888:
265       case GBM_FORMAT_XRGB2101010:
266       case GBM_FORMAT_XBGR2101010:
267       case GBM_FORMAT_RGBX1010102:
268       case GBM_FORMAT_BGRX1010102:
269       case GBM_FORMAT_ARGB2101010:
270       case GBM_FORMAT_ABGR2101010:
271       case GBM_FORMAT_RGBA1010102:
272       case GBM_FORMAT_BGRA1010102:
273          return 32;
274    }
275 }
276 
277 /** Get the offset for the data of the specified plane
278  *
279  * Extra planes, and even the first plane, may have an offset from the start of
280  * the buffer object. This function will provide the offset for the given plane
281  * to be used in various KMS APIs.
282  *
283  * \param bo The buffer object
284  * \return The offset
285  */
286 GBM_EXPORT uint32_t
gbm_bo_get_offset(struct gbm_bo * bo,int plane)287 gbm_bo_get_offset(struct gbm_bo *bo, int plane)
288 {
289    return bo->gbm->bo_get_offset(bo, plane);
290 }
291 
292 /** Get the gbm device used to create the buffer object
293  *
294  * \param bo The buffer object
295  * \return Returns the gbm device with which the buffer object was created
296  */
297 GBM_EXPORT struct gbm_device *
gbm_bo_get_device(struct gbm_bo * bo)298 gbm_bo_get_device(struct gbm_bo *bo)
299 {
300 	return bo->gbm;
301 }
302 
303 /** Get the handle of the buffer object
304  *
305  * This is stored in the platform generic union gbm_bo_handle type. However
306  * the format of this handle is platform specific.
307  *
308  * \param bo The buffer object
309  * \return Returns the handle of the allocated buffer object
310  */
311 GBM_EXPORT union gbm_bo_handle
gbm_bo_get_handle(struct gbm_bo * bo)312 gbm_bo_get_handle(struct gbm_bo *bo)
313 {
314    return bo->handle;
315 }
316 
317 /** Get a DMA-BUF file descriptor for the buffer object
318  *
319  * This function creates a DMA-BUF (also known as PRIME) file descriptor
320  * handle for the buffer object.  Each call to gbm_bo_get_fd() returns a new
321  * file descriptor and the caller is responsible for closing the file
322  * descriptor.
323 
324  * \param bo The buffer object
325  * \return Returns a file descriptor referring to the underlying buffer or -1
326  * if an error occurs.
327  */
328 GBM_EXPORT int
gbm_bo_get_fd(struct gbm_bo * bo)329 gbm_bo_get_fd(struct gbm_bo *bo)
330 {
331    return bo->gbm->bo_get_fd(bo);
332 }
333 
334 /** Get the number of planes for the given bo.
335  *
336  * \param bo The buffer object
337  * \return The number of planes
338  */
339 GBM_EXPORT int
gbm_bo_get_plane_count(struct gbm_bo * bo)340 gbm_bo_get_plane_count(struct gbm_bo *bo)
341 {
342    return bo->gbm->bo_get_planes(bo);
343 }
344 
345 /** Get the handle for the specified plane of the buffer object
346  *
347  * This function gets the handle for any plane associated with the BO. When
348  * dealing with multi-planar formats, or formats which might have implicit
349  * planes based on different underlying hardware it is necessary for the client
350  * to be able to get this information to pass to the DRM.
351  *
352  * \param bo The buffer object
353  * \param plane the plane to get a handle for
354  *
355  * \sa gbm_bo_get_handle()
356  */
357 GBM_EXPORT union gbm_bo_handle
gbm_bo_get_handle_for_plane(struct gbm_bo * bo,int plane)358 gbm_bo_get_handle_for_plane(struct gbm_bo *bo, int plane)
359 {
360    return bo->gbm->bo_get_handle(bo, plane);
361 }
362 
363 /**
364  * Get the chosen modifier for the buffer object
365  *
366  * This function returns the modifier that was chosen for the object. These
367  * properties may be generic, or platform/implementation dependent.
368  *
369  * \param bo The buffer object
370  * \return Returns the selected modifier (chosen by the implementation) for the
371  * BO.
372  * \sa gbm_bo_create_with_modifiers() where possible modifiers are set
373  * \sa gbm_surface_create_with_modifiers() where possible modifiers are set
374  * \sa define DRM_FORMAT_MOD_* in drm_fourcc.h for possible modifiers
375  */
376 GBM_EXPORT uint64_t
gbm_bo_get_modifier(struct gbm_bo * bo)377 gbm_bo_get_modifier(struct gbm_bo *bo)
378 {
379    return bo->gbm->bo_get_modifier(bo);
380 }
381 
382 /** Write data into the buffer object
383  *
384  * If the buffer object was created with the GBM_BO_USE_WRITE flag,
385  * this function can be used to write data into the buffer object.  The
386  * data is copied directly into the object and it's the responsibility
387  * of the caller to make sure the data represents valid pixel data,
388  * according to the width, height, stride and format of the buffer object.
389  *
390  * \param bo The buffer object
391  * \param buf The data to write
392  * \param count The number of bytes to write
393  * \return Returns 0 on success, otherwise -1 is returned an errno set
394  */
395 GBM_EXPORT int
gbm_bo_write(struct gbm_bo * bo,const void * buf,size_t count)396 gbm_bo_write(struct gbm_bo *bo, const void *buf, size_t count)
397 {
398    return bo->gbm->bo_write(bo, buf, count);
399 }
400 
401 /** Set the user data associated with a buffer object
402  *
403  * \param bo The buffer object
404  * \param data The data to associate to the buffer object
405  * \param destroy_user_data A callback (which may be %NULL) that will be
406  * called prior to the buffer destruction
407  */
408 GBM_EXPORT void
gbm_bo_set_user_data(struct gbm_bo * bo,void * data,void (* destroy_user_data)(struct gbm_bo *,void *))409 gbm_bo_set_user_data(struct gbm_bo *bo, void *data,
410 		     void (*destroy_user_data)(struct gbm_bo *, void *))
411 {
412    bo->user_data = data;
413    bo->destroy_user_data = destroy_user_data;
414 }
415 
416 /** Get the user data associated with a buffer object
417  *
418  * \param bo The buffer object
419  * \return Returns the user data associated with the buffer object or %NULL
420  * if no data was associated with it
421  *
422  * \sa gbm_bo_set_user_data()
423  */
424 GBM_EXPORT void *
gbm_bo_get_user_data(struct gbm_bo * bo)425 gbm_bo_get_user_data(struct gbm_bo *bo)
426 {
427    return bo->user_data;
428 }
429 
430 /**
431  * Destroys the given buffer object and frees all resources associated with
432  * it.
433  *
434  * \param bo The buffer object
435  */
436 GBM_EXPORT void
gbm_bo_destroy(struct gbm_bo * bo)437 gbm_bo_destroy(struct gbm_bo *bo)
438 {
439    if (bo->destroy_user_data)
440       bo->destroy_user_data(bo, bo->user_data);
441 
442    bo->gbm->bo_destroy(bo);
443 }
444 
445 /**
446  * Allocate a buffer object for the given dimensions
447  *
448  * \param gbm The gbm device returned from gbm_create_device()
449  * \param width The width for the buffer
450  * \param height The height for the buffer
451  * \param format The format to use for the buffer
452  * \param usage The union of the usage flags for this buffer
453  *
454  * \return A newly allocated buffer that should be freed with gbm_bo_destroy()
455  * when no longer needed. If an error occurs during allocation %NULL will be
456  * returned and errno set.
457  *
458  * \sa enum gbm_bo_format for the list of formats
459  * \sa enum gbm_bo_flags for the list of usage flags
460  */
461 GBM_EXPORT struct gbm_bo *
gbm_bo_create(struct gbm_device * gbm,uint32_t width,uint32_t height,uint32_t format,uint32_t usage)462 gbm_bo_create(struct gbm_device *gbm,
463               uint32_t width, uint32_t height,
464               uint32_t format, uint32_t usage)
465 {
466    if (width == 0 || height == 0) {
467       errno = EINVAL;
468       return NULL;
469    }
470 
471    return gbm->bo_create(gbm, width, height, format, usage, NULL, 0);
472 }
473 
474 GBM_EXPORT struct gbm_bo *
gbm_bo_create_with_modifiers(struct gbm_device * gbm,uint32_t width,uint32_t height,uint32_t format,const uint64_t * modifiers,const unsigned int count)475 gbm_bo_create_with_modifiers(struct gbm_device *gbm,
476                              uint32_t width, uint32_t height,
477                              uint32_t format,
478                              const uint64_t *modifiers,
479                              const unsigned int count)
480 {
481    if (width == 0 || height == 0) {
482       errno = EINVAL;
483       return NULL;
484    }
485 
486    if ((count && !modifiers) || (modifiers && !count)) {
487       errno = EINVAL;
488       return NULL;
489    }
490 
491    return gbm->bo_create(gbm, width, height, format, 0, modifiers, count);
492 }
493 /**
494  * Create a gbm buffer object from an foreign object
495  *
496  * This function imports a foreign object and creates a new gbm bo for it.
497  * This enabled using the foreign object with a display API such as KMS.
498  * Currently three types of foreign objects are supported, indicated by the type
499  * argument:
500  *
501  *   GBM_BO_IMPORT_WL_BUFFER
502  *   GBM_BO_IMPORT_EGL_IMAGE
503  *   GBM_BO_IMPORT_FD
504  *
505  * The gbm bo shares the underlying pixels but its life-time is
506  * independent of the foreign object.
507  *
508  * \param gbm The gbm device returned from gbm_create_device()
509  * \param type The type of object we're importing
510  * \param buffer Pointer to the external object
511  * \param usage The union of the usage flags for this buffer
512  *
513  * \return A newly allocated buffer object that should be freed with
514  * gbm_bo_destroy() when no longer needed. On error, %NULL is returned
515  * and errno is set.
516  *
517  * \sa enum gbm_bo_flags for the list of usage flags
518  */
519 GBM_EXPORT struct gbm_bo *
gbm_bo_import(struct gbm_device * gbm,uint32_t type,void * buffer,uint32_t usage)520 gbm_bo_import(struct gbm_device *gbm,
521               uint32_t type, void *buffer, uint32_t usage)
522 {
523    return gbm->bo_import(gbm, type, buffer, usage);
524 }
525 
526 /**
527  * Map a region of a gbm buffer object for cpu access
528  *
529  * This function maps a region of a gbm bo for cpu read and/or write
530  * access.
531  *
532  * \param bo The buffer object
533  * \param x The X (top left origin) starting position of the mapped region for
534  * the buffer
535  * \param y The Y (top left origin) starting position of the mapped region for
536  * the buffer
537  * \param width The width of the mapped region for the buffer
538  * \param height The height of the mapped region for the buffer
539  * \param flags The union of the GBM_BO_TRANSFER_* flags for this buffer
540  * \param stride Ptr for returned stride in bytes of the mapped region
541  * \param map_data Returned opaque ptr for the mapped region
542  *
543  * \return Address of the mapped buffer that should be unmapped with
544  * gbm_bo_unmap() when no longer needed. On error, %NULL is returned
545  * and errno is set.
546  *
547  * \sa enum gbm_bo_transfer_flags for the list of flags
548  */
549 GBM_EXPORT void *
gbm_bo_map(struct gbm_bo * bo,uint32_t x,uint32_t y,uint32_t width,uint32_t height,uint32_t flags,uint32_t * stride,void ** map_data)550 gbm_bo_map(struct gbm_bo *bo,
551               uint32_t x, uint32_t y,
552               uint32_t width, uint32_t height,
553               uint32_t flags, uint32_t *stride, void **map_data)
554 {
555    if (!bo || width == 0 || height == 0 || !stride || !map_data) {
556       errno = EINVAL;
557       return NULL;
558    }
559 
560    return bo->gbm->bo_map(bo, x, y, width, height,
561                           flags, stride, map_data);
562 }
563 
564 /**
565  * Unmap a previously mapped region of a gbm buffer object
566  *
567  * This function unmaps a region of a gbm bo for cpu read and/or write
568  * access.
569  *
570  * \param bo The buffer object
571  * \param map_data opaque ptr returned from prior gbm_bo_map
572  */
573 GBM_EXPORT void
gbm_bo_unmap(struct gbm_bo * bo,void * map_data)574 gbm_bo_unmap(struct gbm_bo *bo, void *map_data)
575 {
576    bo->gbm->bo_unmap(bo, map_data);
577 }
578 
579 /**
580  * Allocate a surface object
581  *
582  * \param gbm The gbm device returned from gbm_create_device()
583  * \param width The width for the surface
584  * \param height The height for the surface
585  * \param format The format to use for the surface
586  *
587  * \return A newly allocated surface that should be freed with
588  * gbm_surface_destroy() when no longer needed. If an error occurs
589  * during allocation %NULL will be returned.
590  *
591  * \sa enum gbm_bo_format for the list of formats
592  */
593 GBM_EXPORT struct gbm_surface *
gbm_surface_create(struct gbm_device * gbm,uint32_t width,uint32_t height,uint32_t format,uint32_t flags)594 gbm_surface_create(struct gbm_device *gbm,
595                    uint32_t width, uint32_t height,
596 		   uint32_t format, uint32_t flags)
597 {
598    return gbm->surface_create(gbm, width, height, format, flags, NULL, 0);
599 }
600 
601 GBM_EXPORT struct gbm_surface *
gbm_surface_create_with_modifiers(struct gbm_device * gbm,uint32_t width,uint32_t height,uint32_t format,const uint64_t * modifiers,const unsigned int count)602 gbm_surface_create_with_modifiers(struct gbm_device *gbm,
603                                   uint32_t width, uint32_t height,
604                                   uint32_t format,
605                                   const uint64_t *modifiers,
606                                   const unsigned int count)
607 {
608    if ((count && !modifiers) || (modifiers && !count)) {
609       errno = EINVAL;
610       return NULL;
611    }
612 
613    return gbm->surface_create(gbm, width, height, format, 0,
614                               modifiers, count);
615 }
616 
617 /**
618  * Destroys the given surface and frees all resources associated with
619  * it.
620  *
621  * All buffers locked with gbm_surface_lock_front_buffer() should be
622  * released prior to calling this function.
623  *
624  * \param surf The surface
625  */
626 GBM_EXPORT void
gbm_surface_destroy(struct gbm_surface * surf)627 gbm_surface_destroy(struct gbm_surface *surf)
628 {
629    surf->gbm->surface_destroy(surf);
630 }
631 
632 /**
633  * Lock the surface's current front buffer
634  *
635  * Lock rendering to the surface's current front buffer until it is
636  * released with gbm_surface_release_buffer().
637  *
638  * This function must be called exactly once after calling
639  * eglSwapBuffers.  Calling it before any eglSwapBuffer has happened
640  * on the surface or two or more times after eglSwapBuffers is an
641  * error.  A new bo representing the new front buffer is returned.  On
642  * multiple invocations, all the returned bos must be released in
643  * order to release the actual surface buffer.
644  *
645  * \param surf The surface
646  *
647  * \return A buffer object that should be released with
648  * gbm_surface_release_buffer() when no longer needed.  The implementation
649  * is free to reuse buffers released with gbm_surface_release_buffer() so
650  * this bo should not be destroyed using gbm_bo_destroy().  If an error
651  * occurs this function returns %NULL.
652  */
653 GBM_EXPORT struct gbm_bo *
gbm_surface_lock_front_buffer(struct gbm_surface * surf)654 gbm_surface_lock_front_buffer(struct gbm_surface *surf)
655 {
656    return surf->gbm->surface_lock_front_buffer(surf);
657 }
658 
659 /**
660  * Release a locked buffer obtained with gbm_surface_lock_front_buffer()
661  *
662  * Returns the underlying buffer to the gbm surface.  Releasing a bo
663  * will typically make gbm_surface_has_free_buffer() return 1 and thus
664  * allow rendering the next frame, but not always. The implementation
665  * may choose to destroy the bo immediately or reuse it, in which case
666  * the user data associated with it is unchanged.
667  *
668  * \param surf The surface
669  * \param bo The buffer object
670  */
671 GBM_EXPORT void
gbm_surface_release_buffer(struct gbm_surface * surf,struct gbm_bo * bo)672 gbm_surface_release_buffer(struct gbm_surface *surf, struct gbm_bo *bo)
673 {
674    surf->gbm->surface_release_buffer(surf, bo);
675 }
676 
677 /**
678  * Return whether or not a surface has free (non-locked) buffers
679  *
680  * Before starting a new frame, the surface must have a buffer
681  * available for rendering.  Initially, a gbm surface will have a free
682  * buffer, but after one or more buffers have been locked (\sa
683  * gbm_surface_lock_front_buffer()), the application must check for a
684  * free buffer before rendering.
685  *
686  * If a surface doesn't have a free buffer, the application must
687  * return a buffer to the surface using gbm_surface_release_buffer()
688  * and after that, the application can query for free buffers again.
689  *
690  * \param surf The surface
691  * \return 1 if the surface has free buffers, 0 otherwise
692  */
693 GBM_EXPORT int
gbm_surface_has_free_buffers(struct gbm_surface * surf)694 gbm_surface_has_free_buffers(struct gbm_surface *surf)
695 {
696    return surf->gbm->surface_has_free_buffers(surf);
697 }
698