Add BaseTransform/Cairo/Navigation example

This example implements a BaseTransform subclass, which overlays
a video with a moving line and which reacts on navigation events
and paints a circle at the position where a mouse button 1 was pressed.

samples/Makefile.am

@@ -6,7 +6,7 @@ if HAVE_GTK_SHARP
 TARGETS += gtk-video-player.exe
 endif
 if HAVE_MONO_CAIRO
-TARGETS += appsrc.exe
+TARGETS += appsrc.exe transform-sample.exe
 endif
 endif
 DEBUGS = $(addsuffix .mdb, $(TARGETS))
@@ -40,6 +40,9 @@ mp3launchparse.exe: $(srcdir)/MP3LaunchParse.cs $(assemblies)
 appsrc.exe: $(srcdir)/AppSrc.cs $(assemblies)
 	$(CSC) -out:$@ $(GLIBSHARP_LIBS) $(references) $(MONO_CAIRO_LIBS) $(srcdir)/AppSrc.cs
 
+transform-sample.exe: $(srcdir)/TransformSample.cs $(assemblies)
+	$(CSC) -out:$@ $(GLIBSHARP_LIBS) $(references) $(MONO_CAIRO_LIBS) $(srcdir)/TransformSample.cs
+
 gtk-video-player.exe: $(srcdir)/GtkVideoPlayer.cs $(assemblies)
 	$(CSC) -out:$@ $(GLIBSHARP_LIBS) $(references) $(GTK_SHARP_LIBS) $(srcdir)/GtkVideoPlayer.cs
 

samples/TransformSample.cs

@@ -0,0 +1,122 @@
+using Gst;
+using Gst.Video;
+using Gst.Interfaces;
+using Cairo;
+using System;
+
+public class TransformSample : Gst.Video.VideoFilter {
+  private int lastX = -1, lastY = -1;
+  private int width = 0, height = 0;
+
+  static bool Register () {
+    Gst.GLib.GType gtype = (Gst.GLib.GType) typeof (TransformSample);
+    SetDetails (gtype, "Transform Sample", "Filter/Effect/Video",
+                "Draws a moving line on top of a video stream and handles mouse clicks",
+                "Sebastian Dröge <sebastian.droege@collabora.co.uk>");
+
+    Caps tmp = VideoUtil.FormatToTemplateCaps ( (BitConverter.IsLittleEndian) ? VideoFormat.BGRX : VideoFormat.XRGB);
+    Caps caps = tmp.Copy ();
+    caps[0]["width"] = 640;
+    caps[0]["height"] = 480;
+    caps.Append (tmp);
+
+    AddPadTemplate (gtype, new PadTemplate ("src", PadDirection.Src, PadPresence.Always, caps));
+    AddPadTemplate (gtype, new PadTemplate ("sink", PadDirection.Sink, PadPresence.Always, caps));
+    return ElementFactory.Register (null, "transformsample", (uint) Gst.Rank.None, gtype);
+  }
+
+  protected override FlowReturn OnTransformIp (Gst.Buffer buf) {
+    if (!buf.IsWritable)
+      return FlowReturn.Error;
+
+    Cairo.ImageSurface img = new Cairo.ImageSurface (buf.Data, Cairo.Format.Rgb24, width, height, width*4);
+
+    using (Cairo.Context context = new Cairo.Context (img)) {
+      double dx = (double) ( (buf.Timestamp / Clock.MSecond) % 2180) / 5;
+      context.Save ();
+      context.Scale (width / 640.0, height / 480.0);
+      context.MoveTo (300, 10 + dx);
+      context.LineTo (500 - dx, 400);
+      context.LineWidth = 4.0;
+      context.Color = new Color (0, 0, 1.0);
+      context.Stroke();
+      context.Restore ();
+
+      if (lastX != -1 && lastY != -1) {
+        context.Color = new Color (1.0, 0, 0);
+        context.Translate (lastX, lastY);
+        context.Scale (Math.Min (width / 640.0, height / 480.0), Math.Min (width / 640.0, height / 480.0));
+        context.Arc (0, 0, 10.0, 0.0, 2 * Math.PI);
+        context.Fill();
+      }
+    }
+
+    img.Destroy ();
+    return base.OnTransformIp (buf);
+  }
+
+  protected override bool OnSetCaps (Caps incaps, Caps outcaps) {
+    width = (int) incaps[0]["width"];
+    height = (int) incaps[0]["height"];
+    return base.OnSetCaps (incaps, outcaps);
+  }
+
+  protected override bool OnSrcEvent (Gst.Event evt) {
+    NavigationEventType t = NavigationEvent.EventGetType (evt);
+
+    if (t == NavigationEventType.MouseButtonPress) {
+      double x, y;
+      int btn;
+
+      if (NavigationEvent.ParseMouseButtonEvent (evt, out btn, out x, out y)) {
+        if (btn == 1) {
+          lastX = (int) x;
+          lastY = (int) y;
+        }
+      }
+    } else if (t == NavigationEventType.MouseButtonRelease) {
+      lastX = lastY = -1;
+    }
+
+    return base.OnSrcEvent (evt);
+  }
+
+  static void Main (string[] args) {
+    Gst.Application.Init ();
+    TransformSample.Register ();
+
+    Pipeline pipeline = new Pipeline ();
+    Element videotestsrc = ElementFactory.Make ("videotestsrc");
+    Element transform = new TransformSample ();
+    Element ffmpegcolorspace = ElementFactory.Make ("ffmpegcolorspace");
+    Element videosink = ElementFactory.Make ("autovideosink");
+
+    pipeline.Add (videotestsrc, transform, ffmpegcolorspace, videosink);
+    Element.Link (videotestsrc, transform, ffmpegcolorspace, videosink);
+
+    Gst.GLib.MainLoop loop = new Gst.GLib.MainLoop ();
+
+    pipeline.Bus.AddSignalWatch();
+    pipeline.Bus.Message += delegate (object sender, MessageArgs margs) {
+      Message message = margs.Message;
+
+      switch (message.Type) {
+        case MessageType.Error:
+          Enum err;
+          string msg;
+
+          message.ParseError (out err, out msg);
+          System.Console.WriteLine (String.Format ("Error message: {0}", msg));
+          loop.Quit ();
+          break;
+        case MessageType.Eos:
+          loop.Quit ();
+          break;
+      }
+    };
+
+    pipeline.SetState (State.Playing);
+    loop.Run ();
+    pipeline.SetState (State.Null);
+  }
+}