drop_cap.py

from reportlab.lib.geomutils import normalizeTRBL
from reportlab.lib.styles import ParagraphStyle
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfgen.canvas import Canvas
from reportlab.platypus import Flowable


class Dropcap(Flowable):
    def __init__(self, text: str = None, x_padding: float = 10, style: ParagraphStyle = ParagraphStyle('Dropcap')):
        super().__init__()
        self.text: str = text
        self.x_padding: float = x_padding
        self.style: ParagraphStyle = style
        self.width: float = pdfmetrics.stringWidth(self.text, self.style.fontName, self.style.fontSize)
        ascent, descent = pdfmetrics.getAscentDescent(self.style.fontName, self.style.fontSize)
        self.height: float = max(ascent - descent, self.style.leading)

    def wrap(self, *args):
        return self.width + self.x_padding, self.height

    def draw(self, canvas: Canvas = None):
        """This class is overloaded from Flowable's draw function.
        :param canvas: The canvas. This only gets passed to draw when called by Score directly.
        If a troparion gets split, platypus will treat the dropcap as a Flowable and call draw without
        any parameters.
        """
        if not canvas:
            canvas = self.canv

        if not self.text:
            return

        self._draw_background(canvas)

        canvas.setFillColor(self.style.textColor)
        canvas.setFont(self.style.fontName, self.style.fontSize)
        canvas.drawString(0, 0, self.text)

    def _draw_background(self, canvas: Canvas):
        """
        Draws a dropcap background. Logic copied from drawPara() method in Paragraph class.
        """
        style = self.style
        left_indent = style.leftIndent

        bw = getattr(style, 'borderWidth', None)
        bc = getattr(style, 'borderColor', None)
        bg = style.backColor

        if bg or (bc and bw):
            canvas.saveState()
            op = canvas.rect
            kwds = dict(fill=0, stroke=0)
            if bc and bw:
                canvas.setStrokeColor(bc)
                canvas.setLineWidth(bw)
                kwds['stroke'] = 1
                br = getattr(style, 'borderRadius', 0)
                if br:
                    op = canvas.roundRect
                    kwds['radius'] = br
            if bg:
                canvas.setFillColor(bg)
                kwds['fill'] = 1
            bp = getattr(style, 'borderPadding', 0)
            tbp, rbp, bbp, lbp = normalizeTRBL(bp)
            op(left_indent - lbp,
               -bbp,
               self.width - (left_indent + style.rightIndent) + lbp + rbp,
               self.height + tbp + bbp,
               **kwds)
            canvas.restoreState()