examples: Add a video overlay example for WIN32 videosink elements

User can set the target WIN32 video element via "videosink" command line
option. Default is glimagesink.

tests/examples/overlay/meson.build

@@ -31,3 +31,12 @@ if x11_dep.found()
     endif
   endif
 endif
+
+if host_system == 'windows'
+  executable('win32-videooverlay', 'win32-videooverlay.c',
+    c_args : gst_plugins_base_args,
+    include_directories : [configinc, libsinc],
+    dependencies : [gst_dep, video_dep],
+    install: false,
+  )
+endif

tests/examples/overlay/win32-videooverlay.c

@@ -0,0 +1,207 @@
+/*
+ * GStreamer
+ * Copyright (C) 2019 Seungha Yang <seungha.yang@navercorp.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <gst/gst.h>
+#include <gst/video/videooverlay.h>
+#include <gst/video/gstvideosink.h>
+#include <windows.h>
+#include <string.h>
+
+static GMainLoop *loop = NULL;
+static gboolean visible = FALSE;
+static GIOChannel *msg_io_channel;
+static HWND hwnd = NULL;
+
+#define DEFAULT_VIDEO_SINK "glimagesink"
+
+static LRESULT
+window_proc (HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
+{
+  switch (message) {
+    case WM_DESTROY:
+      hwnd = NULL;
+
+      if (loop) {
+        g_main_loop_quit (loop);
+      }
+      return 0;
+    default:
+      break;
+  }
+
+  return DefWindowProc (hWnd, message, wParam, lParam);
+}
+
+static gboolean
+bus_msg (GstBus * bus, GstMessage * msg, gpointer user_data)
+{
+  GstElement *pipeline = GST_ELEMENT (user_data);
+  switch (GST_MESSAGE_TYPE (msg)) {
+    case GST_MESSAGE_ASYNC_DONE:
+      /* make window visible when we have something to show */
+      if (!visible && hwnd) {
+        ShowWindow (hwnd, SW_SHOW);
+        visible = TRUE;
+      }
+
+      gst_element_set_state (pipeline, GST_STATE_PLAYING);
+      break;
+    case GST_MESSAGE_ERROR:{
+      GError *err;
+      gchar *dbg;
+
+      gst_message_parse_error (msg, &err, &dbg);
+      g_printerr ("ERROR %s \n", err->message);
+      if (dbg != NULL)
+        g_printerr ("ERROR debug information: %s\n", dbg);
+      g_clear_error (&err);
+      g_free (dbg);
+
+      g_main_loop_quit (loop);
+      break;
+    }
+    default:
+      break;
+  }
+
+  return TRUE;
+}
+
+static gboolean
+msg_cb (GIOChannel * source, GIOCondition condition, gpointer data)
+{
+  MSG msg;
+
+  if (!PeekMessage (&msg, NULL, 0, 0, PM_REMOVE))
+    return G_SOURCE_CONTINUE;
+
+  TranslateMessage (&msg);
+  DispatchMessage (&msg);
+
+  return G_SOURCE_CONTINUE;
+}
+
+gint
+main (gint argc, gchar ** argv)
+{
+  GstElement *pipeline, *src, *sink;
+  GstStateChangeReturn sret;
+  WNDCLASSEX wc = { 0, };
+  HINSTANCE hinstance = GetModuleHandle (NULL);
+  GstBus *bus;
+  GIOChannel *msg_io_channel;
+  GOptionContext *option_ctx;
+  GError *error = NULL;
+  gchar *video_sink = NULL;
+  gchar *title = NULL;
+  RECT wr = { 0, 0, 320, 240 };
+  gint exitcode = 0;
+  GOptionEntry options[] = {
+    {"videosink", 0, 0, G_OPTION_ARG_STRING, &video_sink,
+        "Video sink to use (default is glimagesink)", NULL}
+    ,
+    {NULL}
+  };
+
+  option_ctx = g_option_context_new ("WIN32 video overlay example");
+  g_option_context_add_main_entries (option_ctx, options, NULL);
+  g_option_context_set_help_enabled (option_ctx, TRUE);
+  if (!g_option_context_parse (option_ctx, &argc, &argv, &error)) {
+    g_printerr ("option parsing failed: %s\n", error->message);
+    g_clear_error (&error);
+    exit (1);
+  }
+
+  g_option_context_free (option_ctx);
+  gst_init (NULL, NULL);
+
+  /* prepare window */
+  wc.cbSize = sizeof (WNDCLASSEX);
+  wc.style = CS_HREDRAW | CS_VREDRAW;
+  wc.lpfnWndProc = window_proc;
+  wc.hInstance = hinstance;
+  wc.hCursor = LoadCursor (NULL, IDC_ARROW);
+  wc.lpszClassName = "GstWIN32VideoOverlay";
+  RegisterClassEx (&wc);
+
+  title = g_strdup_printf ("%s - Win32-VideoOverlay",
+      video_sink ? video_sink : DEFAULT_VIDEO_SINK);
+
+  AdjustWindowRect (&wr, WS_OVERLAPPEDWINDOW, FALSE);
+  hwnd = CreateWindowEx (0, wc.lpszClassName,
+      title,
+      WS_CLIPSIBLINGS | WS_CLIPCHILDREN | WS_OVERLAPPEDWINDOW,
+      CW_USEDEFAULT, CW_USEDEFAULT,
+      wr.right - wr.left, wr.bottom - wr.top, (HWND) NULL, (HMENU) NULL,
+      hinstance, NULL);
+
+  loop = g_main_loop_new (NULL, FALSE);
+  msg_io_channel = g_io_channel_win32_new_messages (0);
+  g_io_add_watch (msg_io_channel, G_IO_IN, msg_cb, NULL);
+
+  /* prepare the pipeline */
+  pipeline = gst_pipeline_new ("win32-overlay");
+  src = gst_element_factory_make ("videotestsrc", NULL);
+  if (video_sink) {
+    sink = gst_element_factory_make (video_sink, NULL);
+  } else {
+    sink = gst_element_factory_make (DEFAULT_VIDEO_SINK, NULL);
+  }
+
+  if (!sink) {
+    g_printerr ("%s element is not available\n",
+        video_sink ? video_sink : DEFAULT_VIDEO_SINK);
+    goto terminate;
+  }
+
+  gst_bin_add_many (GST_BIN (pipeline), src, sink, NULL);
+  gst_element_link (src, sink);
+
+  gst_video_overlay_set_window_handle (GST_VIDEO_OVERLAY (sink),
+      (guintptr) hwnd);
+
+  gst_bus_add_watch (GST_ELEMENT_BUS (pipeline), bus_msg, pipeline);
+
+  /* run the pipeline */
+  sret = gst_element_set_state (pipeline, GST_STATE_PAUSED);
+  if (sret == GST_STATE_CHANGE_FAILURE) {
+    g_printerr ("Pipeline doesn't want to pause\n");
+  } else {
+    g_main_loop_run (loop);
+  }
+
+  gst_element_set_state (pipeline, GST_STATE_NULL);
+  gst_bus_remove_watch (GST_ELEMENT_BUS (pipeline));
+
+terminate:
+  if (hwnd)
+    DestroyWindow (hwnd);
+
+  gst_object_unref (pipeline);
+  g_io_channel_unref (msg_io_channel);
+  g_main_loop_unref (loop);
+  g_free (title);
+
+  return exitcode;
+}