docs/specs/WL_bind_wayland_display.spec

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