FretBend supports alter (interval), prebend, and release

music21/articulations.py

@@ -76,18 +76,15 @@
 '''
 from __future__ import annotations
 
-import typing as t
 import unittest
 
 from music21 import base
 from music21 import common
 from music21.common.classTools import tempAttribute
 from music21 import environment
-from music21 import style
 from music21 import spanner
+from music21 import style
 
-if t.TYPE_CHECKING:
-    from music21 import interval
 
 
 environLocal = environment.Environment('articulations')
@@ -582,10 +579,57 @@ class PullOff(spanner.Spanner, TechnicalIndication):
     pass
 
 class FretBend(FretIndication):
-    bendAlter: interval.IntervalBase|None = None
-    preBend: t.Any = None
-    release: t.Any = None
-    withBar: t.Any = None
+    '''
+    Bend indication for fretted instruments
+
+    Bend in musicxml
+
+    Number is an identifier for the articulation. Defaults to 0.
+
+    BendAlter is the interval of the bend in number of semitones,
+    bend-alter in musicxml. Defaults to None.
+
+    PreBend indicates if the string is bent before
+    the onset of the note. Defaults to False.
+
+    Release is the quarterLength value from the start
+    of the note for releasing the bend, if Any. Defaults to None.
+
+    WithBar indicates what whammy bar movement is used, if any.
+    MusicXML supports 'scoop' or 'dip'. Defaults to None.
+
+    >>> fb = articulations.FretBend(1,bendAlter=interval.ChromaticInterval(-2),release=0.5)
+    >>> fb
+    <music21.articulations.FretBend 1>
+    >>> fb.preBend
+    False
+    >>> fb.withBar
+
+    >>> fb.bendAlter
+    <music21.interval.ChromaticInterval -2>
+    >>> fb.release 
+    0.5
+    '''
+    bendAlter: interval.Interval | interval.ChromaticInterval | None
+    preBend: bool
+    release: OffsetQL | None
+    withBar: str | None
+
+    def __init__(
+        self,
+        number: int = 0,
+        *,
+        bendAlter: interval.Interval | interval.ChromaticInterval | None = None,
+        preBend: bool = False,
+        release: OffsetQL | None = None,
+        withBar: str | None = None,
+        **keywords
+        ):
+        super().__init__(number=number, **keywords)
+        self.bendAlter = bendAlter
+        self.preBend = preBend
+        self.release = release
+        self.withBar = withBar
 
 class FretTap(FretIndication):
     pass

music21/musicxml/m21ToXml.py

@@ -5473,11 +5473,18 @@ def articulationToXmlTechnical(self, articulationMark: articulations.Articulatio
         >>> mxOther = MEX.articulationToXmlTechnical(g)
         >>> MEX.dump(mxOther)
         <other-technical>unda maris</other-technical>
+
+        Same with technical marks not yet supported.
+        TODO: support HammerOn, PullOff, Hole, Arrow.
+
+        >>> h = articulations.HammerOn()
+        >>> mxOther = MEX.articulationToXmlTechnical(h)
+        >>> MEX.dump(mxOther)
+        <other-technical />
         '''
         # these technical have extra information
         # TODO: hammer-on
         # TODO: pull-off
-        # TODO: bend
         # TODO: hole
         # TODO: arrow
         musicXMLTechnicalName = None
@@ -5489,7 +5496,7 @@ def articulationToXmlTechnical(self, articulationMark: articulations.Articulatio
             musicXMLTechnicalName = 'other-technical'
 
         # TODO: support additional technical marks listed above
-        if musicXMLTechnicalName in ('bend', 'hole', 'arrow'):
+        if musicXMLTechnicalName in ('hole', 'arrow'):
             musicXMLTechnicalName = 'other-technical'
 
         mxTechnicalMark = Element(musicXMLTechnicalName)
@@ -5523,7 +5530,8 @@ def articulationToXmlTechnical(self, articulationMark: articulations.Articulatio
             if t.TYPE_CHECKING:
                 assert isinstance(articulationMark, articulations.FretIndication)
             mxTechnicalMark.text = str(articulationMark.number)
-
+        if musicXMLTechnicalName == 'bend':
+            self.setBend(mxTechnicalMark, articulationMark)
         # harmonic needs to check for whether it is artificial or natural, and
         # whether it is base-pitch, sounding-pitch, or touching-pitch
         if musicXMLTechnicalName == 'harmonic':
@@ -5539,6 +5547,63 @@ def articulationToXmlTechnical(self, articulationMark: articulations.Articulatio
         # mxArticulations.append(mxArticulationMark)
         return mxTechnicalMark
 
+    @staticmethod
+    def setBend(mxh: Element, bend: articulations.FretBend) -> None:
+        '''
+        Sets the bend-alter SubElement and the pre-bend,
+        release and with-bar SubElements when present.
+
+        Called from articulationToXmlTechnical
+
+        >>> MEXClass = musicxml.m21ToXml.MeasureExporter
+
+        >>> a = articulations.FretBend(bendAlter=interval.Interval(2))
+
+        >>> from xml.etree.ElementTree import Element
+        >>> mxh = Element('bend')
+
+        >>> MEXclass.setbend(mxh, a)
+        >>> MEXclass.dump(mxh)
+        <bend>
+          <bend-alter>2</bend-alter>
+        </bend>
+        >>> a.pre-bend = True
+        >>> MEXclass.setbend(mxh, a)
+        >>> MEXclass.dump(mxh)
+        <bend>
+          <bend-alter>2</bend-alter>
+          <pre-bend/>
+        </bend>
+        >>> a = articulations.FretBend(bendAlter=interval.Interval(-2), release=OffsetQL(1, 10080))
+        >>> MEXclass.setbend(mxh, a)
+        >>> MEXclass.dump(mxh)
+        <bend>
+          <bend-alter>-2</bend-alter>
+          <release offset='1'>
+        </bend>
+        >>> a = articulations.FretBend(bendAlter=interval.Interval(-2), withBar='scoop')
+        >>> MEXclass.setbend(mxh, a)
+        >>> MEXclass.dump(mxh)
+        <bend>
+          <bend-alter>1</bend-alter>
+          <with-bar>scoop</with-bar>
+        </bend>
+        '''
+        bendAlterSubElement = SubElement(mxh, 'bend-alter')
+        alter = bend.bendAlter
+        if alter is not None:
+            bendAlterSubElement.text = str(alter.semitones)
+        if bend.preBend:
+            SubElement(mxh, 'pre-bend')
+        if bend.release is not None:
+            releaseSubElement = SubElement(mxh, 'release')
+            quarterLengthValue = bend.release
+            divisionsValue = int(defaults.divisionsPerQuarter * quarterLengthValue)
+            releaseSubElement.set('offset', str(divisionsValue))
+        if bend.withBar is not None:
+            withBarSubElement = SubElement(mxh, 'with-bar')
+            withBarSubElement.text = str(bend.withBar)
+
     @staticmethod
     def setHarmonic(mxh: Element, harm: articulations.StringHarmonic) -> None:
         # noinspection PyShadowingNames

music21/musicxml/xmlObjects.py

@@ -71,8 +71,7 @@
                                # in method objectAttachedSpannersToTechnicals of m21ToXml.py
                                # ('hammer-on', articulations.HammerOn),
                                # ('pull-off', articulations.PullOff),
-                               # bend not implemented because it needs many subcomponents
-                               # ('bend', articulations.FretBend),
+                               ('bend', articulations.FretBend),
                                ('tap', articulations.FretTap),
                                ('fret', articulations.FretIndication),
                                ('heel', articulations.OrganHeel),

music21/musicxml/xmlToM21.py

@@ -3866,17 +3866,77 @@ def xmlTechnicalToArticulation(self, mxObj):
             if tag in ('heel', 'toe'):
                 if mxObj.get('substitution') is not None:
                     tech.substitution = xmlObjects.yesNoToBoolean(mxObj.get('substitution'))
+            if tag == 'bend':
+                self.setBend(mxObj, tech)
             # TODO: <bend> attr: accelerate, beats, first-beat, last-beat, shape (4.0)
             # TODO: <bent> sub-elements: bend-alter, pre-bend, with-bar, release
             # TODO: musicxml 4: release sub-element as offset attribute
-
-
             self.setPlacement(mxObj, tech)
             return tech
         else:
             environLocal.printDebug(f'Cannot translate {tag} in {mxObj}.')
             return None
 
+    def setBend(self, mxh, bend):
+        '''
+        Gets the bend amplitude from the bend-alter tag,
+        then optional pre-bend and with-bar tags are processed,
+        as well as release which is converted from divisions to music21 time.
+
+        Called from xmlTechnicalToArticulation
+
+        >>> from xml.etree.ElementTree import fromstring as EL
+        >>> MP = musicxml.xmlToM21.MeasureParser()
+
+        >>> mxTech = EL('<bend><bend-alter>2</bend-alter></bend>')
+        >>> a = MP.xmlTechnicalToArticulation(mxTech)
+        >>> a
+        <music21.articulations.FretBend 0>
+        >>> a.bendAlter.semitones
+        2
+        >>> a.release
+
+        >>> a.withBar
+
+        >>> a.preBend
+        False
+
+        >>> mxTech = EL('<bend><bend-alter>-2</bend-alter><pre-bend/></bend>')
+        >>> a = MP.xmlTechnicalToArticulation(mxTech)
+        >>> a.bendAlter.semitones
+        -2
+        >>> a.preBend
+        True
+
+        >>> mxTech = EL('<bend><bend-alter>-2</bend-alter><release offset="1"/></bend>')
+        >>> a = MP.xmlTechnicalToArticulation(mxTech)
+        >>> a.bendAlter.semitones
+        -2
+        >>> a.release
+        Fraction(1, 10080)
+
+        >>> mxTech = EL('<bend><bend-alter>-1</bend-alter><with-bar>dip</with-bar></bend>')
+        >>> a = MP.xmlTechnicalToArticulation(mxTech)
+        >>> a.bendAlter.semitones
+        -1
+        >>> a.withBar
+        'dip'
+        '''
+        alter = mxh.find('bend-alter')
+        if alter is not None:
+            if alter.text is not None:
+                bend.bendAlter = interval.Interval(float(alter.text))
+        if mxh.find('pre-bend') is not None:
+            bend.preBend = True
+        if mxh.find('with-bar') is not None:
+            bend.withBar = mxh.find('with-bar').text
+        if mxh.find('release') is not None:
+            try:
+                divisions = float(mxh.find('release').get('offset'))
+                bend.release = opFrac(divisions / self.divisions)
+            except (ValueError, TypeError) as unused_err:
+                bend.release = 0.0
+
     @staticmethod
     def setHarmonic(mxh, harm):
         '''