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from __future__ import annotations
"""Text rasterisation feature leveraging Qt font and text layout support."""
__authors__ = ["T. Vincent"]
__license__ = "MIT"
__date__ = "13/10/2016"
import logging
import numpy
from .. import qt
from ..utils.image import convertQImageToArray
from ..utils.matplotlib import rasterMathText
_logger = logging.getLogger(__name__)
[docs]
def getDefaultFontFamily() -> str:
"""Returns the default font family of the application"""
return qt.QApplication.instance().font().family()
[docs]
def rasterTextQt(
text: str,
font: qt.QFont,
dotsPerInch: float = 96.0,
) -> tuple[numpy.ndarray, float]:
"""Raster text using Qt.
It supports multiple lines.
:param text: The text to raster
:param font: Font to use
:param dotsPerInch: The DPI resolution of the created image
:return: Corresponding image in gray scale and baseline offset from top
"""
if not text:
_logger.info("Trying to raster empty text, replaced by white space")
text = " " # Replace empty text by white space to produce an image
dotsPerMeter = int(dotsPerInch * 100 / 2.54)
# get text size
image = qt.QImage(1, 1, qt.QImage.Format_Grayscale8)
image.setDotsPerMeterX(dotsPerMeter)
image.setDotsPerMeterY(dotsPerMeter)
painter = qt.QPainter()
painter.begin(image)
painter.setPen(qt.Qt.white)
painter.setFont(font)
bounds = painter.boundingRect(
qt.QRect(0, 0, 4096, 4096), qt.Qt.TextExpandTabs, text
)
painter.end()
metrics = qt.QFontMetrics(font)
offset = metrics.ascent() / 72.0 * dotsPerInch
# This does not provide the correct text bbox on macOS
# size = metrics.size(qt.Qt.TextExpandTabs, text)
# bounds = metrics.boundingRect(
# qt.QRect(0, 0, size.width(), size.height()),
# qt.Qt.TextExpandTabs,
# text)
# Add extra border
width = bounds.width() + 2
# align line size to 32 bits to ease conversion to numpy array
width = 4 * ((width + 3) // 4)
image = qt.QImage(
int(width),
int(bounds.height() + 2),
qt.QImage.Format_Grayscale8,
)
image.setDotsPerMeterX(dotsPerMeter)
image.setDotsPerMeterY(dotsPerMeter)
image.fill(0)
# Raster text
painter = qt.QPainter()
painter.begin(image)
painter.setPen(qt.Qt.white)
painter.setFont(font)
painter.drawText(bounds, qt.Qt.TextExpandTabs, text)
painter.end()
array = convertQImageToArray(image)
# Remove leading and trailing empty columns/rows but one on each side
filled_rows = numpy.nonzero(numpy.sum(array, axis=1))[0]
filled_columns = numpy.nonzero(numpy.sum(array, axis=0))[0]
if len(filled_rows) == 0 or len(filled_columns) == 0:
return array, offset
return (
numpy.ascontiguousarray(
array[
0 : filled_rows[-1] + 2,
max(0, filled_columns[0] - 1) : filled_columns[-1] + 2,
]
),
offset,
)
[docs]
def rasterText(
text: str,
font: qt.QFont,
dotsPerInch: float = 96.0,
) -> tuple[numpy.ndarray, float]:
"""Raster text using Qt or matplotlib if there may be math syntax.
It supports multiple lines.
:param text: The text to raster
:param font: Font name or QFont to use
:param dotsPerInch: Created image resolution
:return: Corresponding image in gray scale and baseline offset from top
"""
if text.count("$") >= 2:
return rasterMathText(text, font, dotsPerInch)
return rasterTextQt(text, font, dotsPerInch)