Support for number charts, transposition when generating charts.

src/pco_chordspkg/html.nim

@@ -9,6 +9,8 @@ type
     currentKey: ChordChartPitch
     sourceKey: ChordChartPitch
     currentSection: ChordChartNode
+    numberChart: bool
+    transposeSteps: int
 
 const DEFAULT_STYLESHEET* = """
 <style>
@@ -69,6 +71,10 @@ h3 .section-text {
   margin-right: 0.5em;
 }
 
+.chord .flavor {
+  font-variant-position: super;
+}
+
 .song-order h3 {
   font-style: italic;
   font-weight: normal;
@@ -89,17 +95,58 @@ h3 .section-text {
 </style>
 """
 
-proc transpose(ctx: FormatContext, chord: ChordChartChord): string =
-  let distance = ctx.currentKey - ctx.sourceKey
+func scaleDegree(root: ChordChartPitch, p: ChordChartPitch): string =
+  let distance = p - root
+  case distance:
+  of 0: "1"
+  of 1: "♭2"
+  of 2: "2"
+  of 3: "♭3"
+  of 4: "3"
+  of 5: "4"
+  of 6: "♭5"
+  of 7: "5"
+  of 8: "♭6"
+  of 9: "6"
+  of 10: "♭7"
+  of 11: "7"
+  else: raise newException(Exception, "Impossible")
 
-  if distance != 0:
-    result = $(chord.rootPitch + distance)
+func format(ctx: FormatContext, chord: ChordChartChord, useNumber = false): string =
+  if not useNumber and chord.original.isSome: return chord.original.get
+
+  elif useNumber:
+    result = "<span class=root>" &
+      ctx.currentKey.scaleDegree(chord.rootPitch) & "</span>"
+
+    if chord.flavor.isSome:
+      result &= "<span class=flavor>" & chord.flavor.get & "</span>"
+
+    if chord.bassPitch.isSome:
+      result &= "<span class=bass>/" &
+        ctx.currentKey.scaleDegree(chord.bassPitch.get) & "</span>"
+
+  else:
+    result = $chord.rootPitch
     if chord.flavor.isSome: result &= chord.flavor.get
-    if chord.bassPitch.isSome: result &= "/" & $(chord.bassPitch.get + distance)
+    if chord.bassPitch.isSome: result &= "/" & $chord.bassPitch.get
     #debug "transposed " & $ctx.sourceKey & " -> " & $ctx.currentKey &
     #  " (distance " & $distance & ")\p\tchord: " & $chord & " to " & result
 
-  else: result = chord.original
+proc transpose(ctx: FormatContext, chord: ChordChartChord): ChordChartChord =
+  result = chord
+
+  let distance = ctx.currentKey - ctx.sourceKey
+  if distance != 0:
+    result = ChordChartChord(
+      original: none[string](),
+      rootPitch: chord.rootPitch + distance,
+      flavor:
+        if chord.flavor.isSome: some(chord.flavor.get)
+        else: none[string](),
+      bassPitch:
+        if chord.bassPitch.isSome: some(chord.bassPitch.get + distance)
+        else: none[ChordChartPitch]())
 
 func makeSongOrder(songOrder, indent: string): string =
   result = indent & "<section class=song-order>\p" &
@@ -143,7 +190,8 @@ proc toHtml(ctx: var FormatContext, node: ChordChartNode, indent: string): strin
     result &= "'>"
 
     if node.chord.isSome:
-      result &= "<span class=chord>" & ctx.transpose(node.chord.get) & "</span>"
+      result &= "<span class=chord>" &
+        ctx.format(ctx.transpose(node.chord.get), ctx.numberChart) & "</span>"
 
     result &= "<span class=lyric>"
     if node.word.isSome: result &= node.word.get
@@ -169,8 +217,8 @@ proc toHtml(ctx: var FormatContext, node: ChordChartNode, indent: string): strin
       result &= "</section><section>" & headingVal & "</section><section>"
 
   of ccnkRedefineKey:
-    let oldKey = ctx.sourceKey
-    ctx.sourceKey = node.newKey
+    let oldKey = ctx.currentKey
+    ctx.sourceKey = node.newKey + ctx.transposeSteps
     ctx.currentKey = ctx.sourceKey
 
     if oldKey != ctx.currentKey:
@@ -183,14 +231,21 @@ proc toHtml(ctx: var FormatContext, node: ChordChartNode, indent: string): strin
 
 proc toHtml*(
     cc: ChordChart,
+    transpose = 0,
+    numberChart = false,
     stylesheets = @[DEFAULT_STYLESHEET],
     scripts: seq[string] = @[]): string =
 
   var ctx = FormatContext(
     chart: cc,
-    currentKey: cc.metadata.key,
-    sourceKey: cc.metadata.key,
-    currentSection: EMPTY_CHORD_CHART_NODE)
+    currentKey: cc.metadata.key.rootPitch + transpose,
+    sourceKey: cc.metadata.key.rootPitch,
+    currentSection: EMPTY_CHORD_CHART_NODE,
+    numberChart: numberChart,
+    transposeSteps: transpose)
+
+  debug "Formatting:\p\tsource key: " & $ctx.sourceKey & "\p\ttransposing: " &
+    $transpose & "\p\ttarget key: " & $ctx.currentKey
 
   result = """<!doctype html>
 <html>
@@ -210,11 +265,11 @@ proc toHtml*(
   result &= "  </head>\p  <body>"
 
   var indent = "      "
-  #
+
   # Title
   result &= indent & "<h1>" & cc.metadata.title & "</h1>\p"
 
-  var metadataPieces = @["Key: " & $cc.metadata.key]
+  var metadataPieces = @["Key: " & ctx.format(ctx.transpose(cc.metadata.key))]
   if cc.metadata.contains("time signature"):
     metadataPieces.add(cc.metadata["time signature"])
   if cc.metadata.contains("bpm"):