Image file that can be read by QPixmap of PyQt5

2021/04/02 categories:PyQt5| tags:PyQt5|Python|QPixmap|

v I created a program to check the format of the image file that can be read by QPixmap.

Reading image files with QPixmap

QPixmap constructor is as follows, and if you pass the file name to the first argument of the QPixmap constructor, the image file will be displayed. It can be read and converted to QPixmap.

QPixmap::QPixmap(const QString &fileName, const char *format = nullptr, Qt::ImageConversionFlags flags = Qt::AutoColor)

If the file does not exist or the format is unknown, QPixmap will be null, and isNull () will determine if it is null. I can do it.

Try loading various image files

Reference seems to support the following formats.

Format	Description	Qt’s support
BMP	Windows Bitmap	Read/write
GIF	Graphic Interchange Format (optional)	Read
JPG	Joint Photographic Experts Group	Read/write
JPEG	Joint Photographic Experts Group	Read/write
PNG	Portable Network Graphics	Read/write
PBM	Portable Bitmap	Read
PGM	Portable Graymap	Read
PPM	Portable Pixmap	Read/write
XBM	X11 Bitmap	Read/write
XPM	X11 Pixmap	Read/write

Try loading various image files

I converted the format with Paint and Inkscape and read the following file.

test1.bmp
test1.emf
test1.eps
test1.fx
test1.gif
test1.jpg
test1.odg
test1.pdf
test1.png
test1.pov
test1.ps
test1.svg
test1.tex
test1.tif
test1.wmf

Using the source code described below, I tried a test to display an image with GUI. The format that could not be read by QPixmap is displayed as “The file does not exist or is of an unknown format”, and the format that can be read is the program that displays the image.

How to check supported formats

Further reading the reference, QImageReader.supportedImageFormats describes how to get the supported formats.

from PyQt5 import QtGui

for byteArray in QtGui.QImageReader().supportedImageFormats():
    print( bytes(byteArray).decode() )

When I ran the above code, I got the following results:

bmp
cur
gif
icns
ico
jpeg
jpg
pbm
pgm
png
ppm
svg
svgz
tga
tif
tiff
wbmp
webp
xbm
xpm

Source code

The code used to load various image files is as follows.

# -*- coding: utf-8 -*-
import sys
from pathlib import Path
from PyQt5 import QtWidgets, QtCore, QtGui

class Widget(QtWidgets.QWidget):
    def __init__(self):
        super(Widget, self).__init__()

        self.model = QtGui.QStandardItemModel()

        self.list = QtWidgets.QListView(self)
        self.list.setModel(self.model)
        self.list.setMaximumWidth(150)
        self.list.clicked.connect(self.listClicked)

        self.scene = QtWidgets.QGraphicsScene()
        self.view = QtWidgets.QGraphicsView(self)
        self.view.setScene(self.scene)

        self.setLayout( QtWidgets.QHBoxLayout() )
        self.layout().addWidget(self.list)
        self.layout().addWidget(self.view)

    def appendRow(self, data, text):
        item = QtGui.QStandardItem(text)
        item.setData(data)
        self.model.appendRow(item)

    def listClicked(self, clickedIndex):
        path = str( self.model.itemFromIndex(clickedIndex).data().absolute() )
        pixmap = QtGui.QPixmap(path)
        self.scene.clear()
        if pixmap.isNull():
            textItem = QtWidgets.QGraphicsTextItem('The file does not exist \nor is of an unknown format')
            self.scene.addItem(textItem)
            self.scene.setSceneRect( textItem.boundingRect() )
        else:
            self.scene.addPixmap(pixmap)
            self.scene.setSceneRect( QtCore.QRectF(pixmap.rect()) )
        self.view.fitInView(self.scene.items()[0], QtCore.Qt.KeepAspectRatio)

if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    w = Widget()
    for path in Path().glob('test1.*'):
        w.appendRow(path, path.name)
    w.show()
    app.exec()