cecilios
commented
2 years ago Very interesting question!
Using the measure number to point to a certain place in the score is tricky. Although for most common scores, just providing the measure number does the job, it is necessary to take into account that for polymetric music (music in which not all instruments have the same time signature), the measure number is not an absolute value, common to all score instruments (score parts), but it is relative to an instrument.
Due to this, I didn't I coded in Lomse methods using the measure number. But I'm observing that Lomse users ask for measure number as parameter so I recently started to code methods using measures. Currently there are very few methods using measures and most Lomse methods receiving as parameter a measure number also receives the instrument number to which the measure refers, with a default value of 0 (first instrument). The first measure (anacruxis or not) is always measure=0.
And most methods have an alternative signature using instead a MeasureLocator, an struct for describing any location on the score:
struct MeasureLocator
{
int iInstr; //instrument number (0..n)
int iMeasure; //measure number (0..m), for the instrument
TimeUnits location; //TimeUnits from start of measure
MeasureLocator() : iInstr(0), iMeasure(0), location(0.0) {}
MeasureLocator(int i, int m, TimeUnits l) : iInstr(i), iMeasure(m), location(l) {}
};Now, returning to your questions:
How to get the clicked measure according to the xy coordinates of the mouse click
Currently, there is no a simple way of getting the measure number. A possible way of doing it would be:
//get mouse click point (pixels)
int xm = mouse_x;
int ym = mouse_y;
//get clicked object (e.g. staffObj, auxObj, staff, whatever)
ImoObj* pImo = spInteractor->find_object_at(Pixels(xm), Pixels(ym));
//get score page
int iPage = pGView->page_at_screen_point(double(xm), double(ym));
//get information for positioning a caret at that point
LUnits x(xm);
LUnits y(ym);
spInteractor->screen_point_to_page_point(&x, &y);
DocCursorState state = pGView->click_event_to_cursor_state(iPage, LUnits(x), LUnits(y), pImo, pGmo);
//get measure number and instrument from caret state
SpElementCursorState elmState = state.get_delegate_state();
ScoreCursorState* pState = static_cast<ScoreCursorState*>( elmState.get() );
int iMeasure = pState->measure();
int iInstr = pState->instrument();Certainly, this is not an acceptable API and it forces to access and to understand some internal objects. I'm going to fix this by including specific API methods, (suggestions welcome!) probably:
//get mouse click point
Pixels x = Pixels( mouse_x );
Pixels y = Pixels( mouse_y );
//get clicked instrument and measure
int iMeasure = spInteractor->find_measure_at(x, y);
int iInstr = spInteractor->find_instrument_at(x, y);
MeasureLocator ml = spInteractor->find_locator_for(x, y);I'm currently busy with other tasks but hope to have this done along next week.
How to highlight the clicked measure
Currently there are no methods for highlighting one or more measures. The only available option is to place a fragment mark (See https://lenmus.github.io/lomse/classFragmentMark.html). You will find there an example for placing a mark at the desired measure.
My first impression is that adding methods for highlighting one or more measures should be simple. So I'm going to add this to the list of things to do in the coming days.
How to play from a given measure
ScorePlayer object has method ScorePlayer::play_from_measure(iMeasure, ...). See https://lenmus.github.io/lomse/classScorePlayer.html
But parameter iMeasure does not start in 0, but goes from 1 to n. And the method does not receive the instrument number, so it is not appropriate for polymetric scores. I have to fix this.
ayyb1988
I am going to implement the function of touch into the scorescreen to switch to a defined position in the score and play along from there, and and I found the issue#233. Thank you very much. But there are two questions to ask