geometrictransform: new filter "stretch"

Ports gleffects "stretch" filter to geometrictransform.
Shrinks the image around the center and gradually return to normal zoom
creating funny caricatures.

https://bugzilla.gnome.org/show_bug.cgi?id=625722

gst/geometrictransform/Makefile.am

@@ -11,7 +11,8 @@ libgstgeometrictransform_la_SOURCES = plugin.c \
                                       gstpinch.c \
                                       gstsphere.c \
                                       gsttwirl.c \
-                                      gstwaterripple.c
+                                      gstwaterripple.c \
+                                      gststretch.c
 
 libgstgeometrictransform_la_CFLAGS = $(GST_CFLAGS) $(GST_BASE_CFLAGS) \
 			    $(GST_PLUGINS_BASE_CFLAGS) \
@@ -35,4 +36,5 @@ noinst_HEADERS = gstgeometrictransform.h \
                  gstpinch.h \
                  gstsphere.h \
                  gsttwirl.h \
-                 gstwaterripple.h
+                 gstwaterripple.h \
+                 gststretch.h

gst/geometrictransform/geometricmath.c

@@ -189,3 +189,13 @@ geometric_math_triangle (gdouble x)
 
   return 2.0 * (r < 0.5 ? r : 1 - r);
 }
+
+/**
+ * Hermite interpolation
+ */
+gdouble
+smoothstep (gdouble edge0, gdouble edge1, gdouble x)
+{
+  gdouble t = CLAMP ((x - edge0) / (edge1 - edge0), 0.0, 1.0);
+  return t * t * (3.0 - 2.0 * t);
+}

gst/geometrictransform/geometricmath.h

@@ -63,6 +63,8 @@ gdouble noise_2 (Noise * noise, gdouble x, gdouble y);
 gdouble mod_float (gdouble a, gdouble b);
 gdouble geometric_math_triangle (gdouble x);
 
+gdouble smoothstep (gdouble edge0, gdouble edge1, gdouble x);
+
 G_END_DECLS
 
 #endif /* __GEOMETRIC_MATH_H__ */

gst/geometrictransform/gststretch.c

@@ -0,0 +1,158 @@
+/*
+ * GStreamer
+ * Copyright (C) 2010 Filippo Argiolas <filippo.argiolas@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Alternatively, the contents of this file may be used under the
+ * GNU Lesser General Public License Version 2.1 (the "LGPL"), in
+ * which case the following provisions apply instead of the ones
+ * mentioned above:
+ *
+ * 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
+#include <gst/gst.h>
+#include <math.h>
+
+#include "gststretch.h"
+#include "geometricmath.h"
+
+GST_DEBUG_CATEGORY_STATIC (gst_stretch_debug);
+#define GST_CAT_DEFAULT gst_stretch_debug
+
+GST_BOILERPLATE (GstStretch, gst_stretch, GstCircleGeometricTransform,
+    GST_TYPE_CIRCLE_GEOMETRIC_TRANSFORM);
+
+/* Clean up */
+static void
+gst_stretch_finalize (GObject * obj)
+{
+  G_OBJECT_CLASS (parent_class)->finalize (obj);
+}
+
+/* GObject vmethod implementations */
+
+static void
+gst_stretch_base_init (gpointer gclass)
+{
+  GstElementClass *element_class = GST_ELEMENT_CLASS (gclass);
+
+  gst_element_class_set_details_simple (element_class,
+      "stretch",
+      "Transform/Effect/Video",
+      "Stretch the image in a circle around the center point",
+      "Filippo Argiolas <filippo.argiolas@gmail.com>");
+}
+
+static gboolean
+stretch_map (GstGeometricTransform * gt, gint x, gint y, gdouble * in_x,
+    gdouble * in_y)
+{
+  GstCircleGeometricTransform *cgt = GST_CIRCLE_GEOMETRIC_TRANSFORM_CAST (gt);
+  GstStretch *stretch = GST_STRETCH_CAST (gt);
+
+  gdouble norm_x, norm_y;
+  gdouble r;
+
+  gdouble width = gt->width;
+  gdouble height = gt->height;
+
+  /* normalize in ((-1.0, -1.0), (1.0, 1.0) and traslate the center */
+  norm_x = 2.0 * (x / width - cgt->x_center);
+  norm_y = 2.0 * (y / height - cgt->y_center);
+
+  r = sqrt (norm_x * norm_x + norm_y * norm_y);
+
+  /* TODO: make it customizable, 0.7 is the radius of the stretch
+   * ellipse, with current way of setting radius (absolute value) it
+   * would be sqrt(hw*hw + hh*hh)/radius*radius but currently I prefer
+   * leaving it hardcoded because I don't think absolute radius makes
+   * any sense: the user either knows the video size and can easily
+   * calculate the fractional radius and set that or doesn't know the
+   * size a priori and wants to obtain the same effect no matter of
+   * the video dimensions */
+
+  /* actually "stretch" name is a bit misleading, what the transform
+   * really does is shrink the center and gradually return to normal
+   * size while r increases. The shrink thing drags pixels giving
+   * stretching the image around the center */
+  /* 2.0 is the shrink amount. Make it customizable? */
+  norm_x *= 2.0 - smoothstep (0.0, 0.7, r);
+  norm_y *= 2.0 - smoothstep (0.0, 0.7, r);
+
+  /* unnormalize */
+  *in_x = (0.5 * norm_x + cgt->x_center) * width;
+  *in_y = (0.5 * norm_y + cgt->y_center) * height;
+
+  GST_DEBUG_OBJECT (stretch, "Inversely mapped %d %d into %lf %lf",
+      x, y, *in_x, *in_y);
+
+  return TRUE;
+}
+
+static void
+gst_stretch_class_init (GstStretchClass * klass)
+{
+  GObjectClass *gobject_class;
+  GstGeometricTransformClass *gstgt_class;
+
+  gobject_class = (GObjectClass *) klass;
+  gstgt_class = (GstGeometricTransformClass *) klass;
+
+  parent_class = g_type_class_peek_parent (klass);
+
+  gobject_class->finalize = GST_DEBUG_FUNCPTR (gst_stretch_finalize);
+
+  gstgt_class->map_func = stretch_map;
+}
+
+static void
+gst_stretch_init (GstStretch * filter, GstStretchClass * gclass)
+{
+  GstGeometricTransform *gt = GST_GEOMETRIC_TRANSFORM (filter);
+
+  gt->off_edge_pixels = GST_GT_OFF_EDGES_PIXELS_CLAMP;
+}
+
+gboolean
+gst_stretch_plugin_init (GstPlugin * plugin)
+{
+  GST_DEBUG_CATEGORY_INIT (gst_stretch_debug, "stretch", 0, "stretch");
+
+  return gst_element_register (plugin, "stretch", GST_RANK_NONE,
+      GST_TYPE_STRETCH);
+}

gst/geometrictransform/gststretch.h

@@ -0,0 +1,82 @@
+/*
+ * GStreamer
+ * Copyright (C) 2010 Filippo Argiolas <filippo.argiolas@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Alternatively, the contents of this file may be used under the
+ * GNU Lesser General Public License Version 2.1 (the "LGPL"), in
+ * which case the following provisions apply instead of the ones
+ * mentioned above:
+ *
+ * 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef __GST_STRETCH_H__
+#define __GST_STRETCH_H__
+
+#include <gst/gst.h>
+#include "gstcirclegeometrictransform.h"
+
+G_BEGIN_DECLS
+/* #defines don't like whitespacey bits */
+#define GST_TYPE_STRETCH \
+  (gst_stretch_get_type())
+#define GST_STRETCH(obj) \
+  (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_STRETCH,GstStretch))
+#define GST_STRETCH_CAST(obj) \
+  ((GstStretch *)(obj))
+#define GST_STRETCH_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_STRETCH,GstStretchClass))
+#define GST_IS_STRETCH(obj) \
+  (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_STRETCH))
+#define GST_IS_STRETCH_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_STRETCH))
+typedef struct _GstStretch GstStretch;
+typedef struct _GstStretchClass GstStretchClass;
+
+struct _GstStretch
+{
+  GstCircleGeometricTransform element;
+};
+
+struct _GstStretchClass
+{
+  GstCircleGeometricTransformClass parent_class;
+};
+
+GType gst_stretch_get_type (void);
+
+gboolean gst_stretch_plugin_init (GstPlugin * plugin);
+
+G_END_DECLS
+#endif /* __GST_STRETCH_H__ */

gst/geometrictransform/plugin.c

@@ -29,6 +29,7 @@
 #include "gstsphere.h"
 #include "gsttwirl.h"
 #include "gstwaterripple.h"
+#include "gststretch.h"
 
 static gboolean
 plugin_init (GstPlugin * plugin)
@@ -57,6 +58,9 @@ plugin_init (GstPlugin * plugin)
   if (!gst_water_ripple_plugin_init (plugin))
     return FALSE;
 
+  if (!gst_stretch_plugin_init (plugin))
+    return FALSE;
+
   return TRUE;
 }