Typically, when we increase DPI without changing anything else, the image/text should decrease in size. This is because more dots/pixels are drawn per inch, hence, decreasing the size. However, I have found the opposite behaviour here where increasing the DPI will also increase the size of my drawn text. This is not what I expected, would anybody know why?
import sys
from PyQt6.QtCore import Qt
from PyQt6.QtGui import QFont, QImage, QPainter
from PyQt6.QtWidgets import QApplication, QMainWindow, QWidget
DEFAULT_WIDTH = DEFAULT_HEIGHT = 250
class QPainterWidget(QWidget):
def __init__(self):
super().__init__()
self.image = QImage(DEFAULT_WIDTH, DEFAULT_HEIGHT, QImage.Format.Format_RGB32)
self.image.fill(Qt.GlobalColor.green)
self.image.setDevicePixelRatio(1)
print(self.image.dotsPerMeterX())
self.image.setDotsPerMeterX(25000) # 5000, 10000, 15000, 20000
self.image.setDotsPerMeterY(25000)
painter = QPainter(self.image)
point_size_font = QFont('arial')
point_size_font.setPointSizeF(1)
painter.setFont(point_size_font)
painter.drawText(0, 0, DEFAULT_WIDTH//2, DEFAULT_HEIGHT//2, Qt.AlignmentFlag.AlignCenter, "point font text")
painter.end()
def paintEvent(self, event):
painter = QPainter(self)
painter.drawImage(0, 0, self.image)
painter.end()
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
self.resize(DEFAULT_WIDTH, DEFAULT_HEIGHT)
self.setCentralWidget(QPainterWidget())
app = QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec()
