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1Name
2
3    WL_bind_wayland_display
4
5Name Strings
6
7    EGL_WL_bind_wayland_display
8
9Contact
10
11    Kristian Høgsberg <krh@bitplanet.net>
12    Benjamin Franzke <benjaminfranzke@googlemail.com>
13
14Status
15
16    Proposal
17
18Version
19
20    Version 5, July 16, 2013
21
22Number
23
24    EGL Extension #not assigned
25
26Dependencies
27
28    Requires EGL 1.4 or later.  This extension is written against the
29    wording of the EGL 1.4 specification.
30
31    EGL_KHR_base_image is required.
32
33Overview
34
35    This extension provides entry points for binding and unbinding the
36    wl_display of a Wayland compositor to an EGLDisplay.  Binding a
37    wl_display means that the EGL implementation should provide one or
38    more interfaces in the Wayland protocol to allow clients to create
39    wl_buffer objects.  On the server side, this extension also
40    provides a new target for eglCreateImageKHR, to create an EGLImage
41    from a wl_buffer
42
43    Adding an implementation specific wayland interface, allows the
44    EGL implementation to define specific wayland requests and events,
45    needed for buffer sharing in an EGL wayland platform.
46
47IP Status
48
49    Open-source; freely implementable.
50
51New Procedures and Functions
52
53    EGLBoolean eglBindWaylandDisplayWL(EGLDisplay dpy,
54                                       struct wl_display *display);
55
56    EGLBoolean eglUnbindWaylandDisplayWL(EGLDisplay dpy,
57                                         struct wl_display *display);
58
59    EGLBoolean eglQueryWaylandBufferWL(EGLDisplay dpy,
60                                       struct wl_resource *buffer,
61                                       EGLint attribute, EGLint *value);
62
63New Tokens
64
65    Accepted as <target> in eglCreateImageKHR
66
67        EGL_WAYLAND_BUFFER_WL                   0x31D5
68
69    Accepted in the <attrib_list> parameter of eglCreateImageKHR:
70
71        EGL_WAYLAND_PLANE_WL                    0x31D6
72
73    Possible values for EGL_TEXTURE_FORMAT:
74
75        EGL_TEXTURE_Y_U_V_WL                    0x31D7
76        EGL_TEXTURE_Y_UV_WL                     0x31D8
77        EGL_TEXTURE_Y_XUXV_WL                   0x31D9
78        EGL_TEXTURE_EXTERNAL_WL                 0x31DA
79
80    Accepted in the <attribute> parameter of eglQueryWaylandBufferWL:
81
82        EGL_TEXTURE_FORMAT                      0x3080
83        EGL_WAYLAND_Y_INVERTED_WL               0x31DB
84
85
86Additions to the EGL 1.4 Specification:
87
88    To bind a server side wl_display to an EGLDisplay, call
89
90        EGLBoolean eglBindWaylandDisplayWL(EGLDisplay dpy,
91                                           struct wl_display *display);
92
93    To unbind a server side wl_display from an EGLDisplay, call
94
95        EGLBoolean eglUnbindWaylandDisplayWL(EGLDisplay dpy,
96                                             struct wl_display *display);
97
98    eglBindWaylandDisplayWL returns EGL_FALSE when there is already a
99    wl_display bound to EGLDisplay otherwise EGL_TRUE.
100
101    eglUnbindWaylandDisplayWL returns EGL_FALSE when there is no
102    wl_display bound to the EGLDisplay currently otherwise EGL_TRUE.
103
104    A wl_buffer can have several planes, typically in case of planar
105    YUV formats.  Depending on the exact YUV format in use, the
106    compositor will have to create one or more EGLImages for the
107    various planes.  The eglQueryWaylandBufferWL function should be
108    used to first query the wl_buffer texture format using
109    EGL_TEXTURE_FORMAT as the attribute.  If the wl_buffer object is
110    not an EGL wl_buffer (wl_shm and other wayland extensions can
111    create wl_buffer objects of different types), this query will
112    return EGL_FALSE.  In that case the wl_buffer can not be used with
113    EGL and the compositor should have another way to get the buffer
114    contents.
115
116    If eglQueryWaylandBufferWL succeeds, the returned value will be
117    one of EGL_TEXTURE_RGB, EGL_TEXTURE_RGBA, EGL_TEXTURE_Y_U_V_WL,
118    EGL_TEXTURE_Y_UV_WL, EGL_TEXTURE_Y_XUXV_WL.  The value returned
119    describes how many EGLImages must be used, which components will
120    be sampled from each EGLImage and how they map to rgba components
121    in the shader.  The naming conventions separates planes by _ and
122    within each plane, the order or R, G, B, A, Y, U, and V indicates
123    how those components map to the rgba value returned by the
124    sampler.  X indicates that the corresponding component in the rgba
125    value isn't used.
126
127    RGB and RGBA buffer types:
128
129        EGL_TEXTURE_RGB
130                One plane, samples RGB from the texture to rgb in the
131                shader.  Alpha channel is not valid.
132
133        EGL_TEXTURE_RGBA
134                One plane, samples RGBA from the texture to rgba in the
135                shader.
136
137    YUV buffer types:
138
139        EGL_TEXTURE_Y_U_V_WL
140                Three planes, samples Y from the first plane to r in
141                the shader, U from the second plane to r, and V from
142                the third plane to r.
143
144        EGL_TEXTURE_Y_UV_WL
145                Two planes, samples Y from the first plane to r in
146                the shader, U and V from the second plane to rg.
147
148        EGL_TEXTURE_Y_XUXV_WL
149                Two planes, samples Y from the first plane to r in
150                the shader, U and V from the second plane to g and a.
151
152        EGL_TEXTURE_EXTERNAL_WL
153                Treated as a single plane texture, but sampled with
154                samplerExternalOES according to OES_EGL_image_external
155
156    After querying the wl_buffer layout, create EGLImages for the
157    planes by calling eglCreateImageKHR with wl_buffer as
158    EGLClientBuffer, EGL_WAYLAND_BUFFER_WL as the target, NULL
159    context.  If no attributes are given, an EGLImage will be created
160    for the first plane.  For multi-planar buffers, specify the plane
161    to create the EGLImage for by using the EGL_WAYLAND_PLANE_WL
162    attribute.  The value of the attribute is the index of the plane,
163    as defined by the buffer format.  Writing to an EGLImage created
164    from a wl_buffer in any way (such as glTexImage2D, binding the
165    EGLImage as a renderbuffer etc) will result in undefined behavior.
166
167    Further, eglQueryWaylandBufferWL accepts attributes EGL_WIDTH and
168    EGL_HEIGHT to query the width and height of the wl_buffer.
169
170    Also, eglQueryWaylandBufferWL may accept
171    EGL_WAYLAND_Y_INVERTED_WL attribute to query orientation of
172    wl_buffer. If EGL_WAYLAND_Y_INVERTED_WL is supported
173    eglQueryWaylandBufferWL returns EGL_TRUE and value is a boolean
174    that tells if wl_buffer is y-inverted or not. If
175    EGL_WAYLAND_Y_INVERTED_WL is not supported
176    eglQueryWaylandBufferWL returns EGL_FALSE, in that case
177    wl_buffer should be treated as if value of
178    EGL_WAYLAND_Y_INVERTED_WL was EGL_TRUE.
179
180Issues
181
182Revision History
183
184    Version 1, March 1, 2011
185        Initial draft (Benjamin Franzke)
186    Version 2, July 5, 2012
187        Add EGL_WAYLAND_PLANE_WL attribute to allow creating an EGLImage
188        for different planes of planar buffer. (Kristian Høgsberg)
189    Version 3, July 10, 2012
190        Add eglQueryWaylandBufferWL and the various buffer
191        formats. (Kristian Høgsberg)
192    Version 4, July 19, 2012
193        Use EGL_TEXTURE_FORMAT, EGL_TEXTURE_RGB, and EGL_TEXTURE_RGBA,
194        and just define the new YUV texture formats.  Add support for
195        EGL_WIDTH and EGL_HEIGHT in the query attributes (Kristian Høgsberg)
196    Version 5, July 16, 2013
197        Change eglQueryWaylandBufferWL to take a resource pointer to the
198        buffer instead of a pointer to a struct wl_buffer, as the latter has
199        been deprecated. (Ander Conselvan de Oliveira)
200    Version 6, September 16, 2013
201        Add EGL_WAYLAND_Y_INVERTED_WL attribute to allow specifying
202        wl_buffer's orientation.
203