3 * Copyright (C) 2010 Filippo Argiolas <filippo.argiolas@gmail.com>
5 * Permission is hereby granted, free of charge, to any person obtaining a
6 * copy of this software and associated documentation files (the "Software"),
7 * to deal in the Software without restriction, including without limitation
8 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
9 * and/or sell copies of the Software, and to permit persons to whom the
10 * Software is furnished to do so, subject to the following conditions:
12 * The above copyright notice and this permission notice shall be included in
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16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
21 * DEALINGS IN THE SOFTWARE.
23 * Alternatively, the contents of this file may be used under the
24 * GNU Lesser General Public License Version 2.1 (the "LGPL"), in
25 * which case the following provisions apply instead of the ones
28 * This library is free software; you can redistribute it and/or
29 * modify it under the terms of the GNU Library General Public
30 * License as published by the Free Software Foundation; either
31 * version 2 of the License, or (at your option) any later version.
33 * This library is distributed in the hope that it will be useful,
34 * but WITHOUT ANY WARRANTY; without even the implied warranty of
35 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
36 * Library General Public License for more details.
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41 * Boston, MA 02110-1301, USA.
45 * SECTION:element-stretch
47 * @see_also: geometrictransform
49 * The stretch element stretches the image in a circle around the center point.
51 * ## Example launch line
53 * gst-launch-1.0 -v videotestsrc ! stretch ! videoconvert ! autovideosink
65 #include "gststretch.h"
66 #include "geometricmath.h"
68 GST_DEBUG_CATEGORY_STATIC (gst_stretch_debug);
69 #define GST_CAT_DEFAULT gst_stretch_debug
77 #define DEFAULT_INTENSITY 0.5
78 #define MAX_SHRINK_AMOUNT 3.0
80 #define gst_stretch_parent_class parent_class
81 G_DEFINE_TYPE (GstStretch, gst_stretch, GST_TYPE_CIRCLE_GEOMETRIC_TRANSFORM);
84 gst_stretch_set_property (GObject * object, guint prop_id, const GValue * value,
88 GstGeometricTransform *gt;
91 gt = GST_GEOMETRIC_TRANSFORM_CAST (object);
92 stretch = GST_STRETCH_CAST (object);
97 v = g_value_get_double (value);
98 if (v != stretch->intensity) {
99 stretch->intensity = v;
100 gst_geometric_transform_set_need_remap (gt);
104 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
107 GST_OBJECT_UNLOCK (gt);
111 gst_stretch_get_property (GObject * object, guint prop_id,
112 GValue * value, GParamSpec * pspec)
116 stretch = GST_STRETCH_CAST (object);
120 g_value_set_double (value, stretch->intensity);
123 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
129 stretch_map (GstGeometricTransform * gt, gint x, gint y, gdouble * in_x,
132 GstCircleGeometricTransform *cgt = GST_CIRCLE_GEOMETRIC_TRANSFORM_CAST (gt);
133 GstStretch *stretch = GST_STRETCH_CAST (gt);
135 gdouble norm_x, norm_y;
138 gdouble width = gt->width;
139 gdouble height = gt->height;
142 /* normalize in ((-1.0, -1.0), (1.0, 1.0) and traslate the center */
143 norm_x = 2.0 * (x / width - cgt->x_center);
144 norm_y = 2.0 * (y / height - cgt->y_center);
146 /* calculate radius, normalize to 1 for future convenience */
147 r = sqrt (0.5 * (norm_x * norm_x + norm_y * norm_y));
149 /* actually "stretch" name is a bit misleading, what the transform
150 * really does is shrink the center and gradually return to normal
151 * size while r increases. The shrink thing drags pixels giving
152 * stretching the image around the center */
154 /* a is the current maximum shrink amount, it goes from 1.0 to
155 * MAX_SHRINK_AMOUNT * intensity */
156 /* smoothstep goes from 0.0 when r == 0 to b when r == radius */
157 /* total shrink factor is MAX_SHRINK_AMOUNT at center and gradually
158 * decreases while r goes to radius */
159 a = 1.0 + (MAX_SHRINK_AMOUNT - 1.0) * stretch->intensity;
162 norm_x *= a - b * gst_gm_smoothstep (0.0, cgt->radius, r);
163 norm_y *= a - b * gst_gm_smoothstep (0.0, cgt->radius, r);
166 *in_x = (0.5 * norm_x + cgt->x_center) * width;
167 *in_y = (0.5 * norm_y + cgt->y_center) * height;
169 GST_DEBUG_OBJECT (stretch, "Inversely mapped %d %d into %lf %lf",
176 gst_stretch_class_init (GstStretchClass * klass)
178 GObjectClass *gobject_class;
179 GstElementClass *gstelement_class;
180 GstGeometricTransformClass *gstgt_class;
182 gobject_class = (GObjectClass *) klass;
183 gstelement_class = (GstElementClass *) klass;
184 gstgt_class = (GstGeometricTransformClass *) klass;
186 gst_element_class_set_static_metadata (gstelement_class,
188 "Transform/Effect/Video",
189 "Stretch the image in a circle around the center point",
190 "Filippo Argiolas <filippo.argiolas@gmail.com>");
192 gobject_class->set_property = gst_stretch_set_property;
193 gobject_class->get_property = gst_stretch_get_property;
195 g_object_class_install_property (gobject_class, PROP_INTENSITY,
196 g_param_spec_double ("intensity", "intensity",
197 "Intensity of the stretch effect",
198 0.0, 1.0, DEFAULT_INTENSITY,
199 GST_PARAM_CONTROLLABLE | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
201 gstgt_class->map_func = stretch_map;
205 gst_stretch_init (GstStretch * filter)
207 GstGeometricTransform *gt = GST_GEOMETRIC_TRANSFORM (filter);
209 filter->intensity = DEFAULT_INTENSITY;
210 gt->off_edge_pixels = GST_GT_OFF_EDGES_PIXELS_CLAMP;
214 gst_stretch_plugin_init (GstPlugin * plugin)
216 GST_DEBUG_CATEGORY_INIT (gst_stretch_debug, "stretch", 0, "stretch");
218 return gst_element_register (plugin, "stretch", GST_RANK_NONE,