camerabin2: Add methods for preview image message posting

Adds a helper struct and functions for implementing a preview message
in camerabin2.

gst-libs/gst/basecamerabinsrc/gstbasecamerasrc.h

@@ -52,6 +52,8 @@ typedef struct _GstBaseCameraSrcClass GstBaseCameraSrcClass;
 #define GST_BASE_CAMERA_SRC_IMAGE_PAD_NAME "imgsrc"
 #define GST_BASE_CAMERA_SRC_VIDEO_PAD_NAME "vidsrc"
 
+#define GST_BASE_CAMERA_SRC_PREVIEW_MESSAGE_NAME "preview-image"
+
 /**
  * GstBaseCameraSrc:
  */

gst/camerabin2/Makefile.am

@@ -17,7 +17,7 @@ libgstcamerabin2_la_CFLAGS = \
 libgstcamerabin2_la_LIBADD = \
 	$(top_builddir)/gst-libs/gst/interfaces/libgstphotography-$(GST_MAJORMINOR).la \
 	$(top_builddir)/gst-libs/gst/basecamerabinsrc/libgstbasecamerabinsrc-$(GST_MAJORMINOR).la \
-	$(GST_PLUGINS_BASE_LIBS) -lgstinterfaces-$(GST_MAJORMINOR) -lgsttag-$(GST_MAJORMINOR) \
+	$(GST_PLUGINS_BASE_LIBS) -lgstinterfaces-$(GST_MAJORMINOR) -lgsttag-$(GST_MAJORMINOR) -lgstapp-$(GST_MAJORMINOR) \
 	$(GST_BASE_LIBS) $(GST_LIBS)
 
 libgstcamerabin2_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)

gst/camerabin2/camerabingeneral.c

@@ -28,8 +28,11 @@
  */
 #include <string.h>
 
-#include "camerabingeneral.h"
 #include <glib.h>
+#include <gst/app/gstappsrc.h>
+#include <gst/app/gstappsink.h>
+#include <gst/basecamerabinsrc/gstbasecamerasrc.h>
+#include "camerabingeneral.h"
 
 /**
  * gst_camerabin_add_element:
@@ -272,3 +275,184 @@ gst_camerabin_drop_eos_probe (GstPad * pad, GstEvent * event, gpointer u_data)
   }
   return ret;
 }
+
+static GstFlowReturn
+gst_camerabin_preview_pipeline_new_preroll (GstAppSink * appsink,
+    gpointer user_data)
+{
+  GstBuffer *buffer;
+
+  buffer = gst_app_sink_pull_preroll (appsink);
+  gst_buffer_unref (buffer);
+
+  return GST_FLOW_OK;
+}
+
+static GstFlowReturn
+gst_camerabin_preview_pipeline_new_buffer (GstAppSink * appsink,
+    gpointer user_data)
+{
+  GstBuffer *buffer;
+  GstStructure *s;
+  GstMessage *msg;
+  GstCameraBinPreviewPipelineData *data;
+
+  data = user_data;
+
+  buffer = gst_app_sink_pull_buffer (appsink);
+  s = gst_structure_new (GST_BASE_CAMERA_SRC_PREVIEW_MESSAGE_NAME,
+      "buffer", GST_TYPE_BUFFER, buffer, NULL);
+  gst_buffer_unref (buffer);
+  msg = gst_message_new_element (GST_OBJECT (data->element), s);
+
+  GST_DEBUG_OBJECT (data->element, "sending message with preview image");
+  if (gst_element_post_message (data->element, msg) == FALSE) {
+    GST_WARNING_OBJECT (data->element,
+        "This element has no bus, therefore no message sent!");
+  }
+
+  return GST_FLOW_OK;
+}
+
+/**
+ * gst_camerabin_create_preview_pipeline:
+ * @element: Owner of this pipeline
+ *
+ * Creates a new previewing pipeline that can receive buffers
+ * to be posted as camerabin preview messages for @element
+ *
+ * Returns: The newly created #GstCameraBinPreviewPipelineData
+ */
+GstCameraBinPreviewPipelineData *
+gst_camerabin_create_preview_pipeline (GstElement * element)
+{
+  GstCameraBinPreviewPipelineData *data;
+  GstElement *csp;
+  GstElement *csp2;
+  GstElement *vscale;
+  gboolean added = FALSE;
+  GstAppSinkCallbacks callbacks = { 0, };
+
+  data = g_new (GstCameraBinPreviewPipelineData, 1);
+
+  data->pipeline = gst_pipeline_new ("preview-pipeline");
+  data->appsrc = gst_element_factory_make ("appsrc", "preview-appsrc");
+  data->capsfilter = gst_element_factory_make ("capsfilter",
+      "preview-capsfilter");
+  data->appsink = gst_element_factory_make ("appsink", "preview-appsink");
+  csp = gst_element_factory_make ("ffmpegcolorspace", "preview-csp0");
+  csp2 = gst_element_factory_make ("ffmpegcolorspace", "preview-csp1");
+  vscale = gst_element_factory_make ("videoscale", "preview-vscale");
+
+  if (!data->appsrc || !data->capsfilter || !data->appsink || !csp ||
+      !csp2 || !vscale) {
+    goto error;
+  }
+
+  gst_bin_add_many (GST_BIN (data->pipeline), data->appsrc, data->capsfilter,
+      data->appsink, csp, csp2, vscale, NULL);
+  added = TRUE;
+
+  if (!gst_element_link_many (data->appsrc, csp, vscale, csp2, data->capsfilter,
+          data->appsink, NULL))
+    goto error;
+
+  callbacks.new_preroll = gst_camerabin_preview_pipeline_new_preroll;
+  callbacks.new_buffer = gst_camerabin_preview_pipeline_new_buffer;
+  gst_app_sink_set_callbacks ((GstAppSink *) data->appsink, &callbacks, data,
+      NULL);
+
+  data->element = element;
+
+  return data;
+error:
+  GST_WARNING ("Failed to create camerabin's preview pipeline");
+  if (!added) {
+    if (csp)
+      gst_object_unref (csp);
+    if (csp2)
+      gst_object_unref (csp2);
+    if (vscale)
+      gst_object_unref (vscale);
+    if (data->appsrc)
+      gst_object_unref (data->appsrc);
+    if (data->capsfilter)
+      gst_object_unref (data->capsfilter);
+    if (data->appsink)
+      gst_object_unref (data->appsink);
+  }
+  gst_camerabin_destroy_preview_pipeline (data);
+  return NULL;
+}
+
+/**
+ * gst_camerabin_destroy_preview_pipeline:
+ * @preview: the #GstCameraBinPreviewPipelineData
+ *
+ * Frees a #GstCameraBinPreviewPipelineData
+ */
+void
+gst_camerabin_destroy_preview_pipeline (GstCameraBinPreviewPipelineData *
+    preview)
+{
+  if (preview->pipeline) {
+    gst_element_set_state (preview->pipeline, GST_STATE_NULL);
+    gst_object_unref (preview->pipeline);
+  }
+  g_free (preview);
+}
+
+/**
+ * gst_camerabin_preview_pipeline_post:
+ * @preview: the #GstCameraBinPreviewPipelineData
+ * @buffer: the buffer to be posted as a preview
+ *
+ * Converts the @buffer to the desired format and posts the preview
+ * message to the bus.
+ *
+ * Returns: %TRUE on success
+ */
+gboolean
+gst_camerabin_preview_pipeline_post (GstCameraBinPreviewPipelineData * preview,
+    GstBuffer * buffer)
+{
+  g_return_val_if_fail (preview != NULL, FALSE);
+  g_return_val_if_fail (preview->pipeline != NULL, FALSE);
+  g_return_val_if_fail (buffer, FALSE);
+
+  gst_app_src_push_buffer ((GstAppSrc *) preview->appsrc,
+      gst_buffer_ref (buffer));
+
+  return TRUE;
+}
+
+/**
+ * gst_camerabin_preview_set_caps:
+ * @preview: the #GstCameraBinPreviewPipelineData
+ * @caps: the #GstCaps to be set
+ *
+ * The caps that preview buffers should have when posted
+ * on the bus 
+ */
+void
+gst_camerabin_preview_set_caps (GstCameraBinPreviewPipelineData * preview,
+    GstCaps * caps)
+{
+  GstState state, pending;
+  GstStateChangeReturn ret;
+
+  g_return_if_fail (preview != NULL);
+
+  ret = gst_element_get_state (preview->pipeline, &state, &pending, 0);
+  if (ret == GST_STATE_CHANGE_FAILURE) {
+    /* make it try again */
+    state = GST_STATE_PLAYING;
+    pending = GST_STATE_VOID_PENDING;
+  }
+
+  gst_element_set_state (preview->pipeline, GST_STATE_NULL);
+  g_object_set (preview->capsfilter, "caps", caps, NULL);
+  if (pending != GST_STATE_VOID_PENDING)
+    state = pending;
+  gst_element_set_state (preview->pipeline, state);
+}

gst/camerabin2/camerabingeneral.h

@@ -23,6 +23,22 @@
 
 #include <gst/gst.h>
 
+typedef struct
+{
+  GstElement *pipeline;
+
+  GstElement *appsrc;
+  GstElement *capsfilter;
+  GstElement *appsink;
+
+  GstElement *element;
+} GstCameraBinPreviewPipelineData;
+
+GstCameraBinPreviewPipelineData *gst_camerabin_create_preview_pipeline (GstElement * element);
+void gst_camerabin_destroy_preview_pipeline (GstCameraBinPreviewPipelineData * preview);
+gboolean gst_camerabin_preview_pipeline_post (GstCameraBinPreviewPipelineData * preview, GstBuffer * buffer);
+void gst_camerabin_preview_set_caps (GstCameraBinPreviewPipelineData * preview, GstCaps * caps);
+
 gboolean gst_camerabin_try_add_element (GstBin * bin, const gchar * srcpad, GstElement * new_elem, const gchar * dstpad);
 gboolean gst_camerabin_add_element (GstBin * bin, GstElement * new_elem);
 gboolean gst_camerabin_add_element_full (GstBin * bin, const gchar * srcpad, GstElement * new_elem, const gchar * dstpad);