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5563 | serge | 1 | Name |
2 | |||
3 | WL_bind_wayland_display |
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4 | |||
5 | Name Strings |
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6 | |||
7 | EGL_WL_bind_wayland_display |
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8 | |||
9 | Contact |
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10 | |||
11 | Kristian Høgsberg |
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12 | Benjamin Franzke |
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13 | |||
14 | Status |
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15 | |||
16 | Proposal |
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17 | |||
18 | Version |
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19 | |||
20 | Version 1, March 1, 2011 |
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21 | |||
22 | Number |
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23 | |||
24 | EGL Extension #not assigned |
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25 | |||
26 | Dependencies |
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27 | |||
28 | Requires EGL 1.4 or later. This extension is written against the |
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29 | wording of the EGL 1.4 specification. |
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30 | |||
31 | EGL_KHR_base_image is required. |
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32 | |||
33 | Overview |
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34 | |||
35 | This extension provides entry points for binding and unbinding the |
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36 | wl_display of a Wayland compositor to an EGLDisplay. Binding a |
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37 | wl_display means that the EGL implementation should provide one or |
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38 | more interfaces in the Wayland protocol to allow clients to create |
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39 | wl_buffer objects. On the server side, this extension also |
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40 | provides a new target for eglCreateImageKHR, to create an EGLImage |
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41 | from a wl_buffer |
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42 | |||
43 | Adding an implementation specific wayland interface, allows the |
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44 | EGL implementation to define specific wayland requests and events, |
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45 | needed for buffer sharing in an EGL wayland platform. |
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46 | |||
47 | IP Status |
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48 | |||
49 | Open-source; freely implementable. |
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50 | |||
51 | New Procedures and Functions |
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52 | |||
53 | EGLBoolean eglBindWaylandDisplayWL(EGLDisplay dpy, |
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54 | struct wl_display *display); |
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55 | |||
56 | EGLBoolean eglUnbindWaylandDisplayWL(EGLDisplay dpy, |
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57 | struct wl_display *display); |
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58 | |||
59 | EGLBoolean eglQueryWaylandBufferWL(EGLDisplay dpy, |
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60 | struct wl_buffer *buffer, |
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61 | EGLint attribute, EGLint *value); |
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62 | |||
63 | New Tokens |
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64 | |||
65 | Accepted as |
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66 | |||
67 | EGL_WAYLAND_BUFFER_WL 0x31D5 |
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68 | |||
69 | Accepted in the |
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70 | |||
71 | EGL_WAYLAND_PLANE_WL 0x31D6 |
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72 | |||
73 | Possible values for EGL_TEXTURE_FORMAT: |
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74 | |||
75 | EGL_TEXTURE_Y_U_V_WL 0x31D7 |
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76 | EGL_TEXTURE_Y_UV_WL 0x31D8 |
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77 | EGL_TEXTURE_Y_XUXV_WL 0x31D9 |
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78 | |||
79 | |||
80 | Additions to the EGL 1.4 Specification: |
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81 | |||
82 | To bind a server side wl_display to an EGLDisplay, call |
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83 | |||
84 | EGLBoolean eglBindWaylandDisplayWL(EGLDisplay dpy, |
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85 | struct wl_display *display); |
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86 | |||
87 | To unbind a server side wl_display from an EGLDisplay, call |
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88 | |||
89 | EGLBoolean eglUnbindWaylandDisplayWL(EGLDisplay dpy, |
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90 | struct wl_display *display); |
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91 | |||
92 | eglBindWaylandDisplayWL returns EGL_FALSE when there is already a |
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93 | wl_display bound to EGLDisplay otherwise EGL_TRUE. |
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94 | |||
95 | eglUnbindWaylandDisplayWL returns EGL_FALSE when there is no |
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96 | wl_display bound to the EGLDisplay currently otherwise EGL_TRUE. |
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97 | |||
98 | A wl_buffer can have several planes, typically in case of planar |
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99 | YUV formats. Depending on the exact YUV format in use, the |
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100 | compositor will have to create one or more EGLImages for the |
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101 | various planes. The eglQueryWaylandBufferWL function should be |
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102 | used to first query the wl_buffer texture format using |
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103 | EGL_TEXTURE_FORMAT as the attribute. If the wl_buffer object is |
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104 | not an EGL wl_buffer (wl_shm and other wayland extensions can |
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105 | create wl_buffer objects of different types), this query will |
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106 | return EGL_FALSE. In that case the wl_buffer can not be used with |
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107 | EGL and the compositor should have another way to get the buffer |
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108 | contents. |
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109 | |||
110 | If eglQueryWaylandBufferWL succeeds, the returned value will be |
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111 | one of EGL_TEXTURE_RGB, EGL_TEXTURE_RGBA, EGL_TEXTURE_Y_U_V_WL, |
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112 | EGL_TEXTURE_Y_UV_WL, EGL_TEXTURE_Y_XUXV_WL. The value returned |
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113 | describes how many EGLImages must be used, which components will |
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114 | be sampled from each EGLImage and how they map to rgba components |
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115 | in the shader. The naming conventions separates planes by _ and |
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116 | within each plane, the order or R, G, B, A, Y, U, and V indicates |
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117 | how those components map to the rgba value returned by the |
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118 | sampler. X indicates that the corresponding component in the rgba |
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119 | value isn't used. |
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120 | |||
121 | RGB and RGBA buffer types: |
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122 | |||
123 | EGL_TEXTURE_RGB |
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124 | One plane, samples RGB from the texture to rgb in the |
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125 | shader. Alpha channel is not valid. |
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126 | |||
127 | EGL_TEXTURE_RGBA |
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128 | One plane, samples RGBA from the texture to rgba in the |
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129 | shader. |
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130 | |||
131 | YUV buffer types: |
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132 | |||
133 | EGL_TEXTURE_Y_U_V_WL |
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134 | Three planes, samples Y from the first plane to r in |
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135 | the shader, U from the second plane to r, and V from |
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136 | the third plane to r. |
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137 | |||
138 | EGL_TEXTURE_Y_UV_WL |
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139 | Two planes, samples Y from the first plane to r in |
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140 | the shader, U and V from the second plane to rg. |
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141 | |||
142 | EGL_TEXTURE_Y_XUXV_WL |
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143 | Two planes, samples Y from the first plane to r in |
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144 | the shader, U and V from the second plane to g and a. |
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145 | |||
146 | After querying the wl_buffer layout, create EGLImages for the |
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147 | planes by calling eglCreateImageKHR with wl_buffer as |
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148 | EGLClientBuffer, EGL_WAYLAND_BUFFER_WL as the target, NULL |
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149 | context. If no attributes are given, an EGLImage will be created |
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150 | for the first plane. For multi-planar buffers, specify the plane |
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151 | to create the EGLImage for by using the EGL_WAYLAND_PLANE_WL |
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152 | attribute. The value of the attribute is the index of the plane, |
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153 | as defined by the buffer format. Writing to an EGLImage created |
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154 | from a wl_buffer in any way (such as glTexImage2D, binding the |
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155 | EGLImage as a renderbuffer etc) will result in undefined behavior. |
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156 | |||
157 | Further, eglQueryWaylandBufferWL accepts attributes EGL_WIDTH and |
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158 | EGL_HEIGHT to query the width and height of the wl_buffer. |
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159 | |||
160 | Issues |
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161 | |||
162 | Revision History |
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163 | |||
164 | Version 1, March 1, 2011 |
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165 | Initial draft (Benjamin Franzke) |
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166 | Version 2, July 5, 2012 |
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167 | Add EGL_WAYLAND_PLANE_WL attribute to allow creating an EGLImage |
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168 | for different planes of planar buffer. (Kristian Høgsberg) |
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169 | Version 3, July 10, 2012 |
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170 | Add eglQueryWaylandBufferWL and the various buffer |
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171 | formats. (Kristian Høgsberg) |
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172 | Version 4, July 19, 2012 |
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173 | Use EGL_TEXTURE_FORMAT, EGL_TEXTURE_RGB, and EGL_TEXTURE_RGBA, |
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174 | and just define the new YUV texture formats. Add support for |
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175 | EGL_WIDTH and EGL_HEIGHT in the query attributes (Kristian Høgsberg) |