= Paint on an image =

On the `comp.lang.python` newsgroup (`python-list`), Laszlo Nagy asked for suggestions for a library to render antialiased images using TrueType font files.

Here is a hurriedly written program to do that ([[attachment:painttext.py|source code]]).

{{attachment:painttext.png}}

{{{
#!python
import sys
from PyQt4.QtCore import Qt
from PyQt4.QtGui import *

class Window(QWidget):

    def __init__(self, parent = None):
    
        QWidget.__init__(self, parent)
        
        self.label = QLabel()
        
        self.lineEdit = QLineEdit("ABCDE")
        self.fontComboBox = QFontComboBox()
        self.sizeSpinBox = QDoubleSpinBox()
        self.sizeSpinBox.setMinimum(1.0)
        self.sizeSpinBox.setValue(12.0)
        saveButton = QPushButton(self.tr("Save"))
        
        self.lineEdit.textChanged.connect(self.updateImage)
        self.fontComboBox.currentFontChanged.connect(self.updateImage)
        self.sizeSpinBox.valueChanged.connect(self.updateImage)
        saveButton.clicked.connect(self.saveImage)
        
        formLayout = QFormLayout()
        formLayout.addRow(self.tr("&Text:"), self.lineEdit)
        formLayout.addRow(self.tr("&Font:"), self.fontComboBox)
        formLayout.addRow(self.tr("Font &Size:"), self.sizeSpinBox)
        
        layout = QGridLayout()
        layout.addWidget(self.label, 0, 0, 1, 3, Qt.AlignCenter)
        layout.addLayout(formLayout, 1, 0, 1, 3)
        layout.addWidget(saveButton, 2, 1)
        self.setLayout(layout)
        
        self.updateImage()
        self.setWindowTitle(self.tr("Paint Text"))
    
    def updateImage(self):
    
        font = QFont(self.fontComboBox.currentFont())
        font.setPointSizeF(self.sizeSpinBox.value())
        metrics = QFontMetricsF(font)
        
        text = unicode(self.lineEdit.text())
        if not text:
            return
        
        rect = metrics.boundingRect(text)
        position = -rect.topLeft()
        
        pixmap = QPixmap(rect.width(), rect.height())
        pixmap.fill(Qt.white)
        
        painter = QPainter()
        painter.begin(pixmap)
        painter.setFont(font)
        painter.drawText(position, text)
        painter.end()
        
        self.label.setPixmap(pixmap)
    
    def saveImage(self):
    
        formats = QImageWriter.supportedImageFormats()
        formats = map(lambda suffix: u"*."+unicode(suffix), formats)
        path = unicode(QFileDialog.getSaveFileName(self, self.tr("Save Image"),
            "", self.tr("Image files (%1)").arg(u" ".join(formats))))
        
        if path:
            if not self.label.pixmap().save(path):
                QMessageBox.warning(self, self.tr("Save Image"),
                    self.tr("Failed to save file at the specified location."))


if __name__ == "__main__":

    app = QApplication(sys.argv)
    window = Window()
    window.show()
    sys.exit(app.exec_())
}}}