Port the imageviewer example

Task-number: PYSIDE-841
Change-Id: Icb833db3bf18e6943b0579a3a3a064024d57e084
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>

3 files changed, 380 insertions, 0 deletions

diff --git a/examples/widgets/imageviewer/imageviewer.py b/examples/widgets/imageviewer/imageviewer.py
new file mode 100644
index 000000000..b18c365af
--- /dev/null
+++ b/examples/widgets/imageviewer/imageviewer.py
@@ -0,0 +1,313 @@
+#############################################################################
+##
+## Copyright (C) 2021 The Qt Company Ltd.
+## Contact: http://www.qt.io/licensing/
+##
+## This file is part of the Qt for Python examples of the Qt Toolkit.
+##
+## $QT_BEGIN_LICENSE:BSD$
+## You may use this file under the terms of the BSD license as follows:
+##
+## "Redistribution and use in source and binary forms, with or without
+## modification, are permitted provided that the following conditions are
+## met:
+##   * Redistributions of source code must retain the above copyright
+##     notice, this list of conditions and the following disclaimer.
+##   * Redistributions in binary form must reproduce the above copyright
+##     notice, this list of conditions and the following disclaimer in
+##     the documentation and/or other materials provided with the
+##     distribution.
+##   * Neither the name of The Qt Company Ltd nor the names of its
+##     contributors may be used to endorse or promote products derived
+##     from this software without specific prior written permission.
+##
+##
+## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+## LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+## A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+## OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+## SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+## LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+## DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+## THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+## (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+##
+## $QT_END_LICENSE$
+##
+#############################################################################
+
+from PySide6.QtPrintSupport import QPrintDialog, QPrinter
+from PySide6.QtWidgets import (QApplication, QDialog, QFileDialog, QLabel,
+                               QMainWindow, QMenuBar, QMessageBox, QScrollArea,
+                               QScrollBar, QSizePolicy, QStatusBar)
+from PySide6.QtGui import (QAction, QClipboard, QColorSpace, QGuiApplication,
+                           QImage, QImageReader, QImageWriter, QKeySequence,
+                           QPalette, QPainter, QPixmap, QScreen)
+from PySide6.QtCore import QDir, QMimeData, 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(ImageViewer, self).__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()
+        message = f'Opened "{native_filename}", {w}x{h}, Depth: {d}'
+        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:
+            painter = QPainter(printer)
+            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)
+            painter.end()
+
+    @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")
diff --git a/examples/widgets/imageviewer/imageviewer.pyproject b/examples/widgets/imageviewer/imageviewer.pyproject
new file mode 100644
index 000000000..d2db1ffbb
--- /dev/null
+++ b/examples/widgets/imageviewer/imageviewer.pyproject
@@ -0,0 +1,3 @@
+{
+    "files": ["main.py", "imageviewer.py"]
+}
diff --git a/examples/widgets/imageviewer/main.py b/examples/widgets/imageviewer/main.py
new file mode 100644
index 000000000..3fc729ddb
--- /dev/null
+++ b/examples/widgets/imageviewer/main.py
@@ -0,0 +1,64 @@
+#############################################################################
+##
+## Copyright (C) 2021 The Qt Company Ltd.
+## Contact: http://www.qt.io/licensing/
+##
+## This file is part of the Qt for Python examples of the Qt Toolkit.
+##
+## $QT_BEGIN_LICENSE:BSD$
+## You may use this file under the terms of the BSD license as follows:
+##
+## "Redistribution and use in source and binary forms, with or without
+## modification, are permitted provided that the following conditions are
+## met:
+##   * Redistributions of source code must retain the above copyright
+##     notice, this list of conditions and the following disclaimer.
+##   * Redistributions in binary form must reproduce the above copyright
+##     notice, this list of conditions and the following disclaimer in
+##     the documentation and/or other materials provided with the
+##     distribution.
+##   * Neither the name of The Qt Company Ltd nor the names of its
+##     contributors may be used to endorse or promote products derived
+##     from this software without specific prior written permission.
+##
+##
+## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+## LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+## A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+## OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+## SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+## LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+## DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+## THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+## (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+##
+## $QT_END_LICENSE$
+##
+#############################################################################
+
+"""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_())