3 WL_bind_wayland_display
7 EGL_WL_bind_wayland_display
11 Kristian Høgsberg <krh@bitplanet.net>
12 Benjamin Franzke <benjaminfranzke@googlemail.com>
20 Version 1, March 1, 2011
24 EGL Extension #not assigned
28 Requires EGL 1.4 or later. This extension is written against the
29 wording of the EGL 1.4 specification.
31 EGL_KHR_base_image is required.
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
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.
49 Open-source; freely implementable.
51 New Procedures and Functions
53 EGLBoolean eglBindWaylandDisplayWL(EGLDisplay dpy,
54 struct wl_display *display);
56 EGLBoolean eglUnbindWaylandDisplayWL(EGLDisplay dpy,
57 struct wl_display *display);
59 EGLBoolean eglQueryWaylandBufferWL(EGLDisplay dpy,
60 struct wl_buffer *buffer,
61 EGLint attribute, EGLint *value);
65 Accepted as <target> in eglCreateImageKHR
67 EGL_WAYLAND_BUFFER_WL 0x31D5
69 Accepted in the <attrib_list> parameter of eglCreateImageKHR:
71 EGL_WAYLAND_PLANE_WL 0x31D6
73 Possible values for EGL_TEXTURE_FORMAT:
75 EGL_TEXTURE_Y_U_V_WL 0x31D7
76 EGL_TEXTURE_Y_UV_WL 0x31D8
77 EGL_TEXTURE_Y_XUXV_WL 0x31D9
80 Additions to the EGL 1.4 Specification:
82 To bind a server side wl_display to an EGLDisplay, call
84 EGLBoolean eglBindWaylandDisplayWL(EGLDisplay dpy,
85 struct wl_display *display);
87 To unbind a server side wl_display from an EGLDisplay, call
89 EGLBoolean eglUnbindWaylandDisplayWL(EGLDisplay dpy,
90 struct wl_display *display);
92 eglBindWaylandDisplayWL returns EGL_FALSE when there is already a
93 wl_display bound to EGLDisplay otherwise EGL_TRUE.
95 eglUnbindWaylandDisplayWL returns EGL_FALSE when there is no
96 wl_display bound to the EGLDisplay currently otherwise EGL_TRUE.
98 A wl_buffer can have several planes, typically in case of planar
99 YUV formats. Depending on the exact YUV format in use, the
100 compositor will have to create one or more EGLImages for the
101 various planes. The eglQueryWaylandBufferWL function should be
102 used to first query the wl_buffer texture format using
103 EGL_TEXTURE_FORMAT as the attribute. If the wl_buffer object is
104 not an EGL wl_buffer (wl_shm and other wayland extensions can
105 create wl_buffer objects of different types), this query will
106 return EGL_FALSE. In that case the wl_buffer can not be used with
107 EGL and the compositor should have another way to get the buffer
110 If eglQueryWaylandBufferWL succeeds, the returned value will be
111 one of EGL_TEXTURE_RGB, EGL_TEXTURE_RGBA, EGL_TEXTURE_Y_U_V_WL,
112 EGL_TEXTURE_Y_UV_WL, EGL_TEXTURE_Y_XUXV_WL. The value returned
113 describes how many EGLImages must be used, which components will
114 be sampled from each EGLImage and how they map to rgba components
115 in the shader. The naming conventions separates planes by _ and
116 within each plane, the order or R, G, B, A, Y, U, and V indicates
117 how those components map to the rgba value returned by the
118 sampler. X indicates that the corresponding component in the rgba
121 RGB and RGBA buffer types:
124 One plane, samples RGB from the texture to rgb in the
125 shader. Alpha channel is not valid.
128 One plane, samples RGBA from the texture to rgba in the
134 Three planes, samples Y from the first plane to r in
135 the shader, U from the second plane to r, and V from
136 the third plane to r.
139 Two planes, samples Y from the first plane to r in
140 the shader, U and V from the second plane to rg.
142 EGL_TEXTURE_Y_XUXV_WL
143 Two planes, samples Y from the first plane to r in
144 the shader, U and V from the second plane to g and a.
146 After querying the wl_buffer layout, create EGLImages for the
147 planes by calling eglCreateImageKHR with wl_buffer as
148 EGLClientBuffer, EGL_WAYLAND_BUFFER_WL as the target, NULL
149 context. If no attributes are given, an EGLImage will be created
150 for the first plane. For multi-planar buffers, specify the plane
151 to create the EGLImage for by using the EGL_WAYLAND_PLANE_WL
152 attribute. The value of the attribute is the index of the plane,
153 as defined by the buffer format. Writing to an EGLImage created
154 from a wl_buffer in any way (such as glTexImage2D, binding the
155 EGLImage as a renderbuffer etc) will result in undefined behavior.
157 Further, eglQueryWaylandBufferWL accepts attributes EGL_WIDTH and
158 EGL_HEIGHT to query the width and height of the wl_buffer.
164 Version 1, March 1, 2011
165 Initial draft (Benjamin Franzke)
166 Version 2, July 5, 2012
167 Add EGL_WAYLAND_PLANE_WL attribute to allow creating an EGLImage
168 for different planes of planar buffer. (Kristian Høgsberg)
169 Version 3, July 10, 2012
170 Add eglQueryWaylandBufferWL and the various buffer
171 formats. (Kristian Høgsberg)
172 Version 4, July 19, 2012
173 Use EGL_TEXTURE_FORMAT, EGL_TEXTURE_RGB, and EGL_TEXTURE_RGBA,
174 and just define the new YUV texture formats. Add support for
175 EGL_WIDTH and EGL_HEIGHT in the query attributes (Kristian Høgsberg)