draw custom metric guides in the glyph view

custom_xHeight_manager.py

import math
from mojo.events import postEvent
from mojo.subscriber import Subscriber, registerGlyphEditorSubscriber, unregisterGlyphEditorSubscriber, listRegisteredSubscribers
from lib.tools.defaults import getDefault
from fontTools.misc import transform

border = getDefault("glyphViewVerticalPadding")
fontsize = getDefault("textFontSize")

metricsStroke = getDefault("glyphViewFontMetricsStrokeColor")
metricsText = getDefault("glyphViewMetricsTitlesColor")

KEY = "com.connordavenport.x_files"
 
 
'''
start up script to draw custom metric guides in the
glyph view using  simple text syntax in the `font.info.note`.
lines need a preceeding underscore (_), metrics name, and value.
e.g.

_Small Caps: 510
_Superior Top: 715
_Inferior Bottom: -120
'''           


class x_files(Subscriber):

    debug = True

    def build(self):
                
        glyphEditor = self.getGlyphEditor()
        self.container = glyphEditor.extensionContainer(
            identifier=KEY,
            location="background",
            clear=True
        )
        self.glyph = glyphEditor.getGlyph()

    def started(self):
        self.draw_custom_metrics(self.glyph.font)
        
    def destroy(self):
        self.container.clearSublayers()

    def glyphEditorDidSetGlyph(self, info):
        self.glyph = info["glyph"]
        font = self.glyph.font
        self.draw_custom_metrics(font)

    def glyphEditorFontInfoDidChange(self, info):
        font = info["fontInfo"].font
        self.draw_custom_metrics(font)

    def get_values(self, font):
        note = font.info.note
        custom_metrics = {}
        if note:
            lines = note.split("\n")
            for line in lines:
                if line.strip().startswith("_"):
                    entry, value = line.split(":")
                    entry = entry.strip("_ ")
                    value = value.strip()

                    if value not in custom_metrics:
                        custom_metrics[value] = {
                                                'displayvalue': None,
                                                'names': []
                                                }
                    custom_metrics[value]['displayvalue'] = value
                    custom_metrics[value]['names'].append(entry)
        return custom_metrics

    def draw_custom_metrics(self, font):
        # based on benedikt bramböck's `ShowVMetrics` tool
        
        self.container.clearSublayers()
        custom_metrics = self.get_values(font)
        postEvent(KEY + ".event", metrics=custom_metrics)
        for value in custom_metrics:
            all_names = f"        {', '.join(custom_metrics[value]['names'])} ({custom_metrics[value]['displayvalue']})"
            
            value = int(float(value))
            self.container.appendLineSublayer(
               startPoint=(-border*2, value),
               endPoint=((self.glyph.width + border)*2, value),
               strokeWidth=1,
               strokeColor=(*metricsStroke[0:3],1),
            )
            
            
            # is there a better way to get the adjusted xPos??
            off = font.lib.get('com.typemytype.robofont.italicSlantOffset', 0)
            x = y = math.radians(-font.info.italicAngle or 0)
            matrix = transform.Identity.skew(x=x, y=y)
            t = transform.Transform()
            oX, oY = (0,0)
            t = t.translate(oX, oY)
            t = t.transform(matrix)
            t = t.translate(-oX, -oY)
            trans = tuple(t)
            ot = transform.Transform(*trans)
            n = ot.transformPoint((self.glyph.width + off, value))
            
    
            self.container.appendTextLineSublayer(
               position=(n[0], value),
               size=(20, 20),
               weight="medium",
               pointSize=fontsize,
               text=all_names,
               fillColor=metricsText,
               horizontalAlignment="left",
               verticalAlignment="bottom",
            )
            

if __name__ == '__main__':
    finder = [subs for subs in listRegisteredSubscribers() if 'x_files' in subs.getIdentifier()]
    if finder:        
        for s in finder:
            unregisterGlyphEditorSubscriber(s)
    else:
        print("registering x_files")
        registerGlyphEditorSubscriber(x_files)