gl/mixer: make fbo instance field private and provide accessor function

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4608>

subprojects/gst-plugins-base/ext/gl/gstglmosaic.c

@@ -217,6 +217,7 @@ static void
 _mosaic_render (GstGLContext * context, GstGLMosaic * mosaic)
 {
   GstGLMixer *mixer = GST_GL_MIXER (mosaic);
+  GstGLFramebuffer *fbo = gst_gl_mixer_get_framebuffer (mixer);
 
   if (!mosaic->shader) {
     gchar *frag_str = g_strdup_printf ("%s%s",
@@ -230,8 +231,10 @@ _mosaic_render (GstGLContext * context, GstGLMosaic * mosaic)
     g_free (frag_str);
   }
 
-  gst_gl_framebuffer_draw_to_texture (mixer->fbo, mosaic->out_tex,
+  gst_gl_framebuffer_draw_to_texture (fbo, mosaic->out_tex,
       gst_gl_mosaic_callback, mosaic);
+
+  gst_clear_object (&fbo);
 }
 
 static gboolean

subprojects/gst-plugins-base/ext/gl/gstglstereomix.c

@@ -63,6 +63,7 @@
 
 #include "gstglelements.h"
 #include "gstglstereomix.h"
+#include <gst/gl/gl.h>
 
 #define GST_CAT_DEFAULT gst_gl_stereo_mix_debug
 GST_DEBUG_CATEGORY (gst_gl_stereo_mix_debug);

subprojects/gst-plugins-base/ext/gl/gstglstereomix.h

@@ -22,7 +22,7 @@
 #ifndef __GST_GL_STEREO_MIX_H__
 #define __GST_GL_STEREO_MIX_H__
 
-#include <gst/gl/gstglmixer.h>
+#include <gst/gl/gl.h>
 
 G_BEGIN_DECLS
 

subprojects/gst-plugins-base/ext/gl/gstglvideomixer.c

@@ -1845,9 +1845,12 @@ static void
 _video_mixer_process_gl (GstGLContext * context, GstGLVideoMixer * video_mixer)
 {
   GstGLMixer *mixer = GST_GL_MIXER (video_mixer);
+  GstGLFramebuffer *fbo = gst_gl_mixer_get_framebuffer (mixer);
 
-  gst_gl_framebuffer_draw_to_texture (mixer->fbo, video_mixer->out_tex,
+  gst_gl_framebuffer_draw_to_texture (fbo, video_mixer->out_tex,
       gst_gl_video_mixer_callback, video_mixer);
+
+  gst_clear_object (&fbo);
 }
 
 static gboolean

subprojects/gst-plugins-base/gst-libs/gst/gl/gl.h

@@ -52,5 +52,7 @@
 #include <gst/gl/gstglsyncmeta.h>
 #include <gst/gl/gstgloverlaycompositor.h>
 #include <gst/gl/gstglquery.h>
+#include <gst/gl/gstglbasemixer.h>
+#include <gst/gl/gstglmixer.h>
 
 #endif /* __GST_GL_H__ */

subprojects/gst-plugins-base/gst-libs/gst/gl/gstglbasemixer.c

@@ -1,5 +1,4 @@
-/* Generic video mixer plugin
- *
+/*
  * GStreamer
  * Copyright (C) 2015 Matthew Waters <matthew@centricular.com>
  *
@@ -27,6 +26,20 @@
 #include <gst/video/video.h>
 
 #include "gstglbasemixer.h"
+#include <gst/gl/gl.h>
+
+/**
+ * SECTION:gstglbasemixer
+ * @short_description: #GstVideoAggregator subclass for transforming OpenGL resources
+ * @title: GstGLBaseMixer
+ * @see_also: #GstVideoAggregator, #GstGLMixer
+ *
+ * #GstGLBaseMixer handles the nitty gritty details of retrieving an OpenGL
+ * context.  It provides some virtual methods to know when the OpenGL context
+ * is available and is not available within this element.
+ *
+ * Since: 1.24
+ */
 
 #define GST_CAT_DEFAULT gst_gl_base_mixer_debug
 GST_DEBUG_CATEGORY (gst_gl_base_mixer_debug);
@@ -663,7 +676,7 @@ gst_gl_base_mixer_change_state (GstElement * element, GstStateChange transition)
  *
  * Returns: (transfer full) (nullable): the #GstGLContext found by @mix
  *
- * Since: 1.18
+ * Since: 1.24
  */
 GstGLContext *
 gst_gl_base_mixer_get_gl_context (GstGLBaseMixer * mix)

subprojects/gst-plugins-base/gst-libs/gst/gl/gstglbasemixer.h

@@ -23,8 +23,8 @@
 
 #include <gst/gst.h>
 #include <gst/video/video.h>
-#include <gst/gl/gl.h>
 #include <gst/video/gstvideoaggregator.h>
+#include <gst/gl/gstglcontext.h>
 
 G_BEGIN_DECLS
 
@@ -54,6 +54,8 @@ struct _GstGLBaseMixerPadClass
   GstVideoAggregatorPadClass parent_class;
 };
 
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GstGLBaseMixerPad, gst_object_unref);
+
 GST_GL_API
 GType gst_gl_base_mixer_pad_get_type (void);
 
@@ -96,6 +98,8 @@ struct _GstGLBaseMixerClass
   gpointer _padding[GST_PADDING];
 };
 
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GstGLBaseMixer, gst_object_unref);
+
 GST_GL_API
 GType gst_gl_base_mixer_get_type(void);
 

subprojects/gst-plugins-base/gst-libs/gst/gl/gstglmixer.c

@@ -30,8 +30,20 @@
 
 #include "gstglmixer.h"
 
+#include <gst/gl/gl.h>
 #include <gst/gl/gstglfuncs.h>
 
+/**
+ * SECTION:gstglmixer
+ * @short_description: #GstVideoAggregator subclass for transforming RGBA textures
+ * @title: GstGLMixer
+ * @see_also: #GstGLBaseMixer, #GstVideoAggregator
+ *
+ * #GstGLMixer helps implement an element that operates on RGBA textures.
+ *
+ * Since: 1.24
+ */
+
 #define GST_CAT_DEFAULT gst_gl_mixer_debug
 GST_DEBUG_CATEGORY (gst_gl_mixer_debug);
 
@@ -57,6 +69,8 @@ struct _GstGLMixerPrivate
   gboolean gl_resource_ready;
   GMutex gl_resource_lock;
   GCond gl_resource_cond;
+
+  GstGLFramebuffer *fbo;
 };
 
 #define gst_gl_mixer_parent_class parent_class
@@ -533,9 +547,15 @@ _mixer_create_fbo (GstGLContext * context, GstGLMixer * mix)
   guint out_width = GST_VIDEO_INFO_WIDTH (&vagg->info);
   guint out_height = GST_VIDEO_INFO_HEIGHT (&vagg->info);
 
-  mix->fbo =
-      gst_gl_framebuffer_new_with_default_depth (context, out_width,
-      out_height);
+  g_mutex_lock (&mix->priv->gl_resource_lock);
+  if (!mix->priv->fbo)
+    mix->priv->fbo =
+        gst_gl_framebuffer_new_with_default_depth (context, out_width,
+        out_height);
+  g_cond_signal (&mix->priv->gl_resource_cond);
+  if (mix->priv->fbo)
+    mix->priv->gl_resource_ready = TRUE;
+  g_mutex_unlock (&mix->priv->gl_resource_lock);
 }
 
 static gboolean
@@ -554,7 +574,7 @@ gst_gl_mixer_gl_stop (GstGLBaseMixer * base_mix)
     mixer_class->reset (mix);
 
   g_mutex_lock (&mix->priv->gl_resource_lock);
-  gst_clear_object (&mix->fbo);
+  gst_clear_object (&mix->priv->fbo);
   g_mutex_unlock (&mix->priv->gl_resource_lock);
 
   GST_GL_BASE_MIXER_CLASS (parent_class)->gl_stop (base_mix);
@@ -585,13 +605,15 @@ gst_gl_mixer_decide_allocation (GstAggregator * agg, GstQuery * query)
 
   g_mutex_lock (&mix->priv->gl_resource_lock);
   mix->priv->gl_resource_ready = FALSE;
-  if (mix->fbo)
-    gst_object_unref (mix->fbo);
+  gst_clear_object (&mix->priv->fbo);
+  g_mutex_unlock (&mix->priv->gl_resource_lock);
 
   gst_gl_context_thread_add (context,
       (GstGLContextThreadFunc) _mixer_create_fbo, mix);
-  if (!mix->fbo) {
-    g_cond_signal (&mix->priv->gl_resource_cond);
+
+  g_mutex_lock (&mix->priv->gl_resource_lock);
+  if (!mix->priv->fbo) {
+    mix->priv->gl_resource_ready = FALSE;
     g_mutex_unlock (&mix->priv->gl_resource_lock);
     goto context_error;
   }
@@ -676,10 +698,10 @@ gst_gl_mixer_process_textures (GstGLMixer * mix, GstBuffer * outbuf)
     goto out;
   }
 
-  mix_class->process_textures (mix, out_tex);
-
   g_mutex_unlock (&mix->priv->gl_resource_lock);
 
+  mix_class->process_textures (mix, out_tex);
+
 out:
   gst_video_frame_unmap (&out_frame);
 
@@ -760,3 +782,22 @@ gst_gl_mixer_stop (GstAggregator * agg)
 
   return GST_AGGREGATOR_CLASS (parent_class)->stop (agg);
 }
+
+/**
+ * gst_gl_mixer_get_framebuffer:
+ * @mix: the #GstGLMixer
+ *
+ * Returns: (transfer full): (nullable): The #GstGLFramebuffer in use by this @mix
+ *
+ * Since: 1.24
+ */
+GstGLFramebuffer *
+gst_gl_mixer_get_framebuffer (GstGLMixer * mix)
+{
+  GstGLFramebuffer *fbo = NULL;
+  g_mutex_lock (&mix->priv->gl_resource_lock);
+  if (mix->priv->fbo)
+    fbo = gst_object_ref (mix->priv->fbo);
+  g_mutex_unlock (&mix->priv->gl_resource_lock);
+  return fbo;
+}

subprojects/gst-plugins-base/gst-libs/gst/gl/gstglmixer.h

@@ -23,8 +23,7 @@
 
 #include <gst/gst.h>
 #include <gst/video/video.h>
-#include <gst/gl/gl.h>
-#include "gstglbasemixer.h"
+#include <gst/gl/gstglbasemixer.h>
 
 G_BEGIN_DECLS
 
@@ -60,6 +59,8 @@ struct _GstGLMixerPadClass
   GstGLBaseMixerPadClass parent_class;
 };
 
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GstGLMixerPad, gst_object_unref);
+
 GST_GL_API
 GType gst_gl_mixer_pad_get_type (void);
 
@@ -85,8 +86,6 @@ struct _GstGLMixer
 {
   GstGLBaseMixer vaggregator;
 
-  GstGLFramebuffer *fbo;
-
   GstCaps *out_caps;
 
   GstGLMixerPrivate *priv;
@@ -102,11 +101,16 @@ struct _GstGLMixerClass
   GstGLMixerProcessTextures process_textures;
 };
 
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GstGLMixer, gst_object_unref);
+
 GST_GL_API
 GType gst_gl_mixer_get_type(void);
 
 GST_GL_API
 gboolean gst_gl_mixer_process_textures (GstGLMixer * mix, GstBuffer * outbuf);
 
+GST_GL_API
+GstGLFramebuffer * gst_gl_mixer_get_framebuffer (GstGLMixer * mix);
+
 G_END_DECLS
 #endif /* __GST_GL_MIXER_H__ */