Section 2: Display the Movie Model in DXMCanvas
| This class extends the DXMCanvas class. The model you set in this class,
by calling the setModel() method, is the model that will be displayed. |
class DxmMovie extends DXMCanvas {
DxmMovie() {
_model = new VCRModel();
setModel(_model);
}
VCRModel _model;
}
| This class extends the Model class. The createModel method in this class
is where you construct your model. |
class VCRModel extends Model {
| Import a movie in the model and have a switcher behavior to control
the playback rate. |
public void createModel(BvrsToRun bvrs) {
| Create a movie behavior by importing an avi file. |
URL movieBase = buildURL(getImportBase(), "Movie/");
ImageBvr[] imgArr = {null};
SoundBvr[] sndArr = {null};
NumberBvr lenNum = importMovie(buildURL(movieBase, "movie.avi"),
imgArr, sndArr);
| The playback rate switcher starts with 1, the normal rate. |
_rateSw = new ModifiableBehavior(toBvr(1));
| The playback position of the movie is the sum of the rate. Use
modulus to loop the movie since positions less than 0 or greater than
the length of the movie yields emptyImage. The specialMod is a
private function that always returns a positive number less than
lenNum. |
NumberBvr posNum = specialMod(integral((NumberBvr)_rateSw.getBvr()), lenNum);
| Use AppTriggeredEvent for the restart event. When the restart button
is pressed, the event will be triggered. Construct a recursive
position behavior - the resetablePosNum - that resets to itself when
the event occurs. Note that integral has implicit time. When a
restart posNum at the time _resetEv occurs, integration starts from
0. |
_resetEv = new AppTriggeredEvent();
NumberBvr resetablePosNum = NumberBvr.newUninitBvr();
resetablePosNum.init(until(posNum, _resetEv, resetablePosNum));
| Play the movie on top of a black background. Use substituteTime
to control the position of a movie. The localTime for movies
is implicit. |
setImage(overlay((ImageBvr)imgArr[0].substituteTime(resetablePosNum),
solidColorImage(black)));
setSound((SoundBvr)sndArr[0].loop().substituteTime(resetablePosNum));
}
| This function does a "special" mod for negative numbers. It returns
the linear distance between the passed-in numerator and the biggest
multiple of the denominator smaller than the numerator.
For example, specialMode(-1, 5) = 4, specialMod(-4, 5) = 1.
This is defined so that a decreasing number behavior passed in as the
numerator yields a consistent result whether its value is positive or
negative. |
NumberBvr specialMod(NumberBvr numNum, NumberBvr denomNum) {
return (NumberBvr)cond(gt(numNum, toBvr(0)),
mod(numNum, denomNum),
sub(denomNum, mod(abs(numNum), denomNum)));
}
| This method changes the value of the rate switcher to the given rate.
This is called by the event handlers of the playback controls. |
void setRate(int rate) {
_rateSw.switchTo(toBvr(rate*0.1));
}
| This method is called when the restart button is pressed. It resets
the rate to the normal playback rate, and triggers the event to
restart the movie. |
void restart() {
setRate(10);
_resetEv.trigger();
}
AppTriggeredEvent _resetEv;
ModifiableBehavior _rateSw;
}
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