examples/widgets/imageviewer¶
(You can also check this code in the repository)
# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
from __future__ import annotations
"""PySide6 port of the widgets/imageviewer example from Qt v6.0"""
from argparse import ArgumentParser, RawTextHelpFormatter
import sys
from PySide6.QtWidgets import (QApplication)
from imageviewer import ImageViewer
if __name__ == '__main__':
arg_parser = ArgumentParser(description="Image Viewer",
formatter_class=RawTextHelpFormatter)
arg_parser.add_argument('file', type=str, nargs='?', help='Image file')
args = arg_parser.parse_args()
app = QApplication(sys.argv)
image_viewer = ImageViewer()
if args.file and not image_viewer.load_file(args.file):
sys.exit(-1)
image_viewer.show()
sys.exit(app.exec())
# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
from __future__ import annotations
from PySide6.QtPrintSupport import QPrintDialog, QPrinter
from PySide6.QtWidgets import (QApplication, QDialog, QFileDialog, QLabel,
QMainWindow, QMessageBox, QScrollArea,
QSizePolicy)
from PySide6.QtGui import (QColorSpace, QGuiApplication,
QImageReader, QImageWriter, QKeySequence,
QPalette, QPainter, QPixmap)
from PySide6.QtCore import QDir, QStandardPaths, Qt, Slot
ABOUT = """<p>The <b>Image Viewer</b> example shows how to combine QLabel
and QScrollArea to display an image. QLabel is typically used
for displaying a text, but it can also display an image.
QScrollArea provides a scrolling view around another widget.
If the child widget exceeds the size of the frame, QScrollArea
automatically provides scroll bars. </p><p>The example
demonstrates how QLabel's ability to scale its contents
(QLabel.scaledContents), and QScrollArea's ability to
automatically resize its contents
(QScrollArea.widgetResizable), can be used to implement
zooming and scaling features. </p><p>In addition the example
shows how to use QPainter to print an image.</p>
"""
class ImageViewer(QMainWindow):
def __init__(self, parent=None):
super().__init__(parent)
self._scale_factor = 1.0
self._first_file_dialog = True
self._image_label = QLabel()
self._image_label.setBackgroundRole(QPalette.Base)
self._image_label.setSizePolicy(QSizePolicy.Ignored,
QSizePolicy.Ignored)
self._image_label.setScaledContents(True)
self._scroll_area = QScrollArea()
self._scroll_area.setBackgroundRole(QPalette.Dark)
self._scroll_area.setWidget(self._image_label)
self._scroll_area.setVisible(False)
self.setCentralWidget(self._scroll_area)
self._create_actions()
self.resize(QGuiApplication.primaryScreen().availableSize() * 3 / 5)
def load_file(self, fileName):
reader = QImageReader(fileName)
reader.setAutoTransform(True)
new_image = reader.read()
native_filename = QDir.toNativeSeparators(fileName)
if new_image.isNull():
error = reader.errorString()
QMessageBox.information(self, QGuiApplication.applicationDisplayName(),
f"Cannot load {native_filename}: {error}")
return False
self._set_image(new_image)
self.setWindowFilePath(fileName)
w = self._image.width()
h = self._image.height()
d = self._image.depth()
color_space = self._image.colorSpace()
description = color_space.description() if color_space.isValid() else 'unknown'
message = f'Opened "{native_filename}", {w}x{h}, Depth: {d} ({description})'
self.statusBar().showMessage(message)
return True
def _set_image(self, new_image):
self._image = new_image
if self._image.colorSpace().isValid():
self._image.convertToColorSpace(QColorSpace.SRgb)
self._image_label.setPixmap(QPixmap.fromImage(self._image))
self._scale_factor = 1.0
self._scroll_area.setVisible(True)
self._print_act.setEnabled(True)
self._fit_to_window_act.setEnabled(True)
self._update_actions()
if not self._fit_to_window_act.isChecked():
self._image_label.adjustSize()
def _save_file(self, fileName):
writer = QImageWriter(fileName)
native_filename = QDir.toNativeSeparators(fileName)
if not writer.write(self._image):
error = writer.errorString()
message = f"Cannot write {native_filename}: {error}"
QMessageBox.information(self, QGuiApplication.applicationDisplayName(),
message)
return False
self.statusBar().showMessage(f'Wrote "{native_filename}"')
return True
@Slot()
def _open(self):
dialog = QFileDialog(self, "Open File")
self._initialize_image_filedialog(dialog, QFileDialog.AcceptOpen)
while (dialog.exec() == QDialog.Accepted
and not self.load_file(dialog.selectedFiles()[0])):
pass
@Slot()
def _save_as(self):
dialog = QFileDialog(self, "Save File As")
self._initialize_image_filedialog(dialog, QFileDialog.AcceptSave)
while (dialog.exec() == QDialog.Accepted
and not self._save_file(dialog.selectedFiles()[0])):
pass
@Slot()
def _print_(self):
printer = QPrinter()
dialog = QPrintDialog(printer, self)
if dialog.exec() == QDialog.Accepted:
with QPainter(printer) as painter:
pixmap = self._image_label.pixmap()
rect = painter.viewport()
size = pixmap.size()
size.scale(rect.size(), Qt.KeepAspectRatio)
painter.setViewport(rect.x(), rect.y(), size.width(), size.height())
painter.setWindow(pixmap.rect())
painter.drawPixmap(0, 0, pixmap)
@Slot()
def _copy(self):
QGuiApplication.clipboard().setImage(self._image)
@Slot()
def _paste(self):
new_image = QGuiApplication.clipboard().image()
if new_image.isNull():
self.statusBar().showMessage("No image in clipboard")
else:
self._set_image(new_image)
self.setWindowFilePath('')
w = new_image.width()
h = new_image.height()
d = new_image.depth()
message = f"Obtained image from clipboard, {w}x{h}, Depth: {d}"
self.statusBar().showMessage(message)
@Slot()
def _zoom_in(self):
self._scale_image(1.25)
@Slot()
def _zoom_out(self):
self._scale_image(0.8)
@Slot()
def _normal_size(self):
self._image_label.adjustSize()
self._scale_factor = 1.0
@Slot()
def _fit_to_window(self):
fit_to_window = self._fit_to_window_act.isChecked()
self._scroll_area.setWidgetResizable(fit_to_window)
if not fit_to_window:
self._normal_size()
self._update_actions()
@Slot()
def _about(self):
QMessageBox.about(self, "About Image Viewer", ABOUT)
def _create_actions(self):
file_menu = self.menuBar().addMenu("&File")
self._open_act = file_menu.addAction("&Open...")
self._open_act.triggered.connect(self._open)
self._open_act.setShortcut(QKeySequence.Open)
self._save_as_act = file_menu.addAction("&Save As...")
self._save_as_act.triggered.connect(self._save_as)
self._save_as_act.setEnabled(False)
self._print_act = file_menu.addAction("&Print...")
self._print_act.triggered.connect(self._print_)
self._print_act.setShortcut(QKeySequence.Print)
self._print_act.setEnabled(False)
file_menu.addSeparator()
self._exit_act = file_menu.addAction("E&xit")
self._exit_act.triggered.connect(self.close)
self._exit_act.setShortcut("Ctrl+Q")
edit_menu = self.menuBar().addMenu("&Edit")
self._copy_act = edit_menu.addAction("&Copy")
self._copy_act.triggered.connect(self._copy)
self._copy_act.setShortcut(QKeySequence.Copy)
self._copy_act.setEnabled(False)
self._paste_act = edit_menu.addAction("&Paste")
self._paste_act.triggered.connect(self._paste)
self._paste_act.setShortcut(QKeySequence.Paste)
view_menu = self.menuBar().addMenu("&View")
self._zoom_in_act = view_menu.addAction("Zoom &In (25%)")
self._zoom_in_act.setShortcut(QKeySequence.ZoomIn)
self._zoom_in_act.triggered.connect(self._zoom_in)
self._zoom_in_act.setEnabled(False)
self._zoom_out_act = view_menu.addAction("Zoom &Out (25%)")
self._zoom_out_act.triggered.connect(self._zoom_out)
self._zoom_out_act.setShortcut(QKeySequence.ZoomOut)
self._zoom_out_act.setEnabled(False)
self._normal_size_act = view_menu.addAction("&Normal Size")
self._normal_size_act.triggered.connect(self._normal_size)
self._normal_size_act.setShortcut("Ctrl+S")
self._normal_size_act.setEnabled(False)
view_menu.addSeparator()
self._fit_to_window_act = view_menu.addAction("&Fit to Window")
self._fit_to_window_act.triggered.connect(self._fit_to_window)
self._fit_to_window_act.setEnabled(False)
self._fit_to_window_act.setCheckable(True)
self._fit_to_window_act.setShortcut("Ctrl+F")
help_menu = self.menuBar().addMenu("&Help")
about_act = help_menu.addAction("&About")
about_act.triggered.connect(self._about)
about_qt_act = help_menu.addAction("About &Qt")
about_qt_act.triggered.connect(QApplication.aboutQt)
def _update_actions(self):
has_image = not self._image.isNull()
self._save_as_act.setEnabled(has_image)
self._copy_act.setEnabled(has_image)
enable_zoom = not self._fit_to_window_act.isChecked()
self._zoom_in_act.setEnabled(enable_zoom)
self._zoom_out_act.setEnabled(enable_zoom)
self._normal_size_act.setEnabled(enable_zoom)
def _scale_image(self, factor):
self._scale_factor *= factor
new_size = self._scale_factor * self._image_label.pixmap().size()
self._image_label.resize(new_size)
self._adjust_scrollbar(self._scroll_area.horizontalScrollBar(), factor)
self._adjust_scrollbar(self._scroll_area.verticalScrollBar(), factor)
self._zoom_in_act.setEnabled(self._scale_factor < 3.0)
self._zoom_out_act.setEnabled(self._scale_factor > 0.333)
def _adjust_scrollbar(self, scrollBar, factor):
pos = int(factor * scrollBar.value()
+ ((factor - 1) * scrollBar.pageStep() / 2))
scrollBar.setValue(pos)
def _initialize_image_filedialog(self, dialog, acceptMode):
if self._first_file_dialog:
self._first_file_dialog = False
locations = QStandardPaths.standardLocations(QStandardPaths.PicturesLocation)
directory = locations[-1] if locations else QDir.currentPath()
dialog.setDirectory(directory)
mime_types = [m.data().decode('utf-8') for m in QImageWriter.supportedMimeTypes()]
mime_types.sort()
dialog.setMimeTypeFilters(mime_types)
dialog.selectMimeTypeFilter("image/jpeg")
dialog.setAcceptMode(acceptMode)
if acceptMode == QFileDialog.AcceptSave:
dialog.setDefaultSuffix("jpg")