+
+/** @param other A Rect.
+ * @return The intersection of this with `other'.
+ */
+Rect
+Rect::intersection (Rect const & other) const
+{
+ int const tx = max (x, other.x);
+ int const ty = max (y, other.y);
+
+ return Rect (
+ tx, ty,
+ min (x + width, other.x + other.width) - tx,
+ min (y + height, other.y + other.height) - ty
+ );
+}
+
+/** Round a number up to the nearest multiple of another number.
+ * @param a Number to round.
+ * @param t Multiple to round to.
+ * @return Rounded number.
+ */
+int
+stride_round_up (int c, int const * stride, int t)
+{
+ int const a = stride[c] + (t - 1);
+ return a - (a % t);
+}
+
+int
+stride_lookup (int c, int const * stride)
+{
+ return stride[c];
+}
+
+/** Read a sequence of key / value pairs from a text stream;
+ * the keys are the first words on the line, and the values are
+ * the remainder of the line following the key. Lines beginning
+ * with # are ignored.
+ * @param s Stream to read.
+ * @return key/value pairs.
+ */
+multimap<string, string>
+read_key_value (istream &s)
+{
+ multimap<string, string> kv;
+
+ string line;
+ while (getline (s, line)) {
+ if (line.empty ()) {
+ continue;
+ }
+
+ if (line[0] == '#') {
+ continue;
+ }
+
+ if (line[line.size() - 1] == '\r') {
+ line = line.substr (0, line.size() - 1);
+ }
+
+ size_t const s = line.find (' ');
+ if (s == string::npos) {
+ continue;
+ }
+
+ kv.insert (make_pair (line.substr (0, s), line.substr (s + 1)));
+ }
+
+ return kv;
+}
+
+string
+get_required_string (multimap<string, string> const & kv, string k)
+{
+ if (kv.count (k) > 1) {
+ throw StringError ("unexpected multiple keys in key-value set");
+ }
+
+ multimap<string, string>::const_iterator i = kv.find (k);
+
+ if (i == kv.end ()) {
+ throw StringError (String::compose ("missing key %1 in key-value set", k));
+ }
+
+ return i->second;
+}
+
+int
+get_required_int (multimap<string, string> const & kv, string k)
+{
+ string const v = get_required_string (kv, k);
+ return lexical_cast<int> (v);
+}
+
+float
+get_required_float (multimap<string, string> const & kv, string k)
+{
+ string const v = get_required_string (kv, k);
+ return lexical_cast<float> (v);
+}
+
+string
+get_optional_string (multimap<string, string> const & kv, string k)
+{
+ if (kv.count (k) > 1) {
+ throw StringError ("unexpected multiple keys in key-value set");
+ }
+
+ multimap<string, string>::const_iterator i = kv.find (k);
+ if (i == kv.end ()) {
+ return "";
+ }
+
+ return i->second;
+}
+
+int
+get_optional_int (multimap<string, string> const & kv, string k)
+{
+ if (kv.count (k) > 1) {
+ throw StringError ("unexpected multiple keys in key-value set");
+ }
+
+ multimap<string, string>::const_iterator i = kv.find (k);
+ if (i == kv.end ()) {
+ return 0;
+ }
+
+ return lexical_cast<int> (i->second);
+}
+
+/** Construct an AudioBuffers. Audio data is undefined after this constructor.
+ * @param channels Number of channels.
+ * @param frames Number of frames to reserve space for.
+ */
+AudioBuffers::AudioBuffers (int channels, int frames)
+ : _channels (channels)
+ , _frames (frames)
+ , _allocated_frames (frames)
+{
+ _data = new float*[_channels];
+ for (int i = 0; i < _channels; ++i) {
+ _data[i] = new float[frames];
+ }
+}
+
+/** Copy constructor.
+ * @param other Other AudioBuffers; data is copied.
+ */
+AudioBuffers::AudioBuffers (AudioBuffers const & other)
+ : _channels (other._channels)
+ , _frames (other._frames)
+ , _allocated_frames (other._frames)
+{
+ _data = new float*[_channels];
+ for (int i = 0; i < _channels; ++i) {
+ _data[i] = new float[_frames];
+ memcpy (_data[i], other._data[i], _frames * sizeof (float));
+ }
+}
+
+/** AudioBuffers destructor */
+AudioBuffers::~AudioBuffers ()
+{
+ for (int i = 0; i < _channels; ++i) {
+ delete[] _data[i];
+ }
+
+ delete[] _data;
+}
+
+/** @param c Channel index.
+ * @return Buffer for this channel.
+ */
+float*
+AudioBuffers::data (int c) const
+{
+ assert (c >= 0 && c < _channels);
+ return _data[c];
+}
+
+/** Set the number of frames that these AudioBuffers will report themselves
+ * as having.
+ * @param f Frames; must be less than or equal to the number of allocated frames.
+ */
+void
+AudioBuffers::set_frames (int f)
+{
+ assert (f <= _allocated_frames);
+ _frames = f;
+}
+
+/** Make all samples on all channels silent */
+void
+AudioBuffers::make_silent ()
+{
+ for (int i = 0; i < _channels; ++i) {
+ make_silent (i);
+ }
+}
+
+/** Make all samples on a given channel silent.
+ * @param c Channel.
+ */
+void
+AudioBuffers::make_silent (int c)
+{
+ assert (c >= 0 && c < _channels);
+
+ for (int i = 0; i < _frames; ++i) {
+ _data[c][i] = 0;
+ }
+}
+
+/** Copy data from another AudioBuffers to this one. All channels are copied.
+ * @param from AudioBuffers to copy from; must have the same number of channels as this.
+ * @param frames_to_copy Number of frames to copy.
+ * @param read_offset Offset to read from in `from'.
+ * @param write_offset Offset to write to in `to'.
+ */
+void
+AudioBuffers::copy_from (AudioBuffers* from, int frames_to_copy, int read_offset, int write_offset)
+{
+ assert (from->channels() == channels());
+
+ assert (from);
+ assert (read_offset >= 0 && (read_offset + frames_to_copy) <= from->_allocated_frames);
+ assert (write_offset >= 0 && (write_offset + frames_to_copy) <= _allocated_frames);
+
+ for (int i = 0; i < _channels; ++i) {
+ memcpy (_data[i] + write_offset, from->_data[i] + read_offset, frames_to_copy * sizeof(float));
+ }
+}
+
+/** Move audio data around.
+ * @param from Offset to move from.
+ * @param to Offset to move to.
+ * @param frames Number of frames to move.
+ */
+
+void
+AudioBuffers::move (int from, int to, int frames)
+{
+ if (frames == 0) {
+ return;
+ }
+
+ assert (from >= 0);
+ assert (from < _frames);
+ assert (to >= 0);
+ assert (to < _frames);
+ assert (frames > 0);
+ assert (frames <= _frames);
+ assert ((from + frames) <= _frames);
+ assert ((to + frames) <= _frames);
+
+ for (int i = 0; i < _channels; ++i) {
+ memmove (_data[i] + to, _data[i] + from, frames * sizeof(float));
+ }
+}
+
+/** Trip an assert if the caller is not in the UI thread */
+void
+ensure_ui_thread ()
+{
+ assert (this_thread::get_id() == ui_thread);
+}
+
+/** @param v Source video frame.
+ * @param audio_sample_rate Source audio sample rate.
+ * @param frames_per_second Number of video frames per second.
+ * @return Equivalent number of audio frames for `v'.
+ */
+int64_t
+video_frames_to_audio_frames (SourceFrame v, float audio_sample_rate, float frames_per_second)
+{
+ return ((int64_t) v * audio_sample_rate / frames_per_second);
+}
+
+/** @param f Filename.
+ * @return true if this file is a still image, false if it is something else.
+ */
+bool
+still_image_file (string f)
+{
+#if BOOST_FILESYSTEM_VERSION == 3
+ string ext = boost::filesystem::path(f).extension().string();
+#else
+ string ext = boost::filesystem::path(f).extension();
+#endif
+
+ transform (ext.begin(), ext.end(), ext.begin(), ::tolower);
+
+ return (ext == ".tif" || ext == ".tiff" || ext == ".jpg" || ext == ".jpeg" || ext == ".png");
+}