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docs: Update the developer section of egl.html.

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Mainly to add a subsection on the lifetime of display resources.
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Chia-I Wu
2010-01-27 23:18:22 +08:00
parent 51ab599ddb
commit 14cbf324dc
1 changed files with 36 additions and 2 deletions
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docs/egl.html
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@@ -223,9 +223,43 @@ runtime.</p>
<h2>Developers</h2>
The sources of the main library and the classic drivers can be found at
<p>The sources of the main library and the classic drivers can be found at
<code>src/egl/</code>. The sources of the <code>egl</code> state tracker can
be found at <code>src/gallium/state_trackers/egl/</code>.
be found at <code>src/gallium/state_trackers/egl/</code>.</p>
<p>The suggested way to learn to write a EGL driver is to see how other drivers
are written. <code>egl_glx</code> should be a good reference. It works in any
environment that has GLX support, and it is simpler than most drivers.</p>
<h3>Lifetime of Display Resources</h3>
<p>Contexts and surfaces are examples of display resources. They might live
longer than the display that creates them.</p>
<p>In EGL, when a display is terminated through <code>eglTerminate</code>, all
display resources should be destroyed. Similarly, when a thread is released
throught <code>eglReleaseThread</code>, all current display resources should be
released. Another way to destory or release resources is through functions
such as <code>eglDestroySurface</code> or <code>eglMakeCurrent</code>.</p>
<p>When a resource that is current to some thread is destroyed, the resource
should not be destroyed immediately. EGL requires the resource to live until
it is no longer current. A driver usually calls
<code>eglIs&lt;Resource&gt;Bound</code> to check if a resource is bound
(current) to any thread in the destroy callbacks. If it is still bound, the
resource is not destroyed.</p>
<p>The main library will mark destroyed current resources as unlinked. In a
driver's <code>MakeCurrent</code> callback,
<code>eglIs&lt;Resource&gt;Linked</code> can then be called to check if a newly
released resource is linked to a display. If it is not, the last reference to
the resource is removed and the driver should destroy the resource. But it
should be careful here because <code>MakeCurrent</code> might be called with an
uninitialized display.</p>
<p>This is the only mechanism provided by the main library to help manage the
resources. The drivers are responsible to the correct behavior as defined by
EGL.</p>
<h3>TODOs</h3>