Add the dropsite example

It is useful for testing Drag and Drop operations.

Pick-to: 6.3 6.2
Task-number: PYSIDE-841
Change-Id: I5cd6fa20542676317223d6acfdc938d286b4347f
Reviewed-by: Christian Tismer <tismer@stackless.com>

5 files changed, 208 insertions, 0 deletions

diff --git a/examples/widgets/draganddrop/dropsite/doc/dropsite.rst b/examples/widgets/draganddrop/dropsite/doc/dropsite.rst
new file mode 100644
index 000000000..8d6c42bc8
--- /dev/null
+++ b/examples/widgets/draganddrop/dropsite/doc/dropsite.rst
@@ -0,0 +1,8 @@
+Drop Site Example
+=================
+
+The Drop Site example shows how to distinguish the various MIME formats
+available in a drag and drop operation.
+
+It accepts drops from other applications and displays the MIME formats
+provided by the drag object.
diff --git a/examples/widgets/draganddrop/dropsite/droparea.py b/examples/widgets/draganddrop/dropsite/droparea.py
new file mode 100644
index 000000000..efc4614f0
--- /dev/null
+++ b/examples/widgets/draganddrop/dropsite/droparea.py
@@ -0,0 +1,67 @@
+# Copyright (C) 2022 The Qt Company Ltd.
+# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+from PySide6.QtCore import QMimeData, Qt, Slot, Signal
+from PySide6.QtGui import QPalette, QPixmap
+from PySide6.QtWidgets import QFrame, QLabel
+
+
+class DropArea(QLabel):
+
+    changed = Signal(QMimeData)
+
+    def __init__(self, parent=None):
+        super().__init__(parent)
+        self.setMinimumSize(200, 200)
+        self.setFrameStyle(QFrame.Sunken | QFrame.StyledPanel)
+        self.setAlignment(Qt.AlignCenter)
+        self.setAcceptDrops(True)
+        self.setAutoFillBackground(True)
+        self.clear()
+
+    def dragEnterEvent(self, event):
+        self.setText("<drop content>")
+        self.setBackgroundRole(QPalette.Highlight)
+
+        event.acceptProposedAction()
+        self.changed.emit(event.mimeData())
+
+    def dragMoveEvent(self, event):
+        event.acceptProposedAction()
+
+    def dropEvent(self, event):
+        mime_data = event.mimeData()
+
+        if mime_data.hasImage():
+            self.setPixmap(QPixmap(mime_data.imageData()))
+        elif mime_data.hasFormat("text/markdown"):
+            self.setText(mime_data.data("text/markdown"))
+            self.setTextFormat(Qt.MarkdownText)
+        elif mime_data.hasHtml():
+            self.setText(mime_data.html())
+            self.setTextFormat(Qt.RichText)
+        elif mime_data.hasText():
+            self.setText(mime_data.text())
+            self.setTextFormat(Qt.PlainText)
+        elif mime_data.hasUrls():
+            url_list = mime_data.urls()
+            text = ""
+            for i in range(0, min(len(url_list), 32)):
+                text += url_list[i].path() + "\n"
+            self.setText(text)
+        else:
+            self.setText("Cannot display data")
+
+        self.setBackgroundRole(QPalette.Dark)
+        event.acceptProposedAction()
+
+    def dragLeaveEvent(self, event):
+        self.clear()
+        event.accept()
+
+    @Slot()
+    def clear(self):
+        self.setText("<drop content>")
+        self.setBackgroundRole(QPalette.Dark)
+
+        self.changed.emit(None)
diff --git a/examples/widgets/draganddrop/dropsite/dropsite.pyproject b/examples/widgets/draganddrop/dropsite/dropsite.pyproject
new file mode 100644
index 000000000..0173d5cb9
--- /dev/null
+++ b/examples/widgets/draganddrop/dropsite/dropsite.pyproject
@@ -0,0 +1,3 @@
+{
+    "files": ["main.py", "droparea.py", "dropsitewindow.py"]
+}
diff --git a/examples/widgets/draganddrop/dropsite/dropsitewindow.py b/examples/widgets/draganddrop/dropsite/dropsitewindow.py
new file mode 100644
index 000000000..5427d520d
--- /dev/null
+++ b/examples/widgets/draganddrop/dropsite/dropsitewindow.py
@@ -0,0 +1,115 @@
+# Copyright (C) 2022 The Qt Company Ltd.
+# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+import re
+from PySide6.QtCore import QMimeData, Qt, Slot
+from PySide6.QtGui import QGuiApplication
+from PySide6.QtWidgets import (QAbstractItemView, QPushButton,
+                               QDialogButtonBox, QLabel,
+                               QTableWidget, QTableWidgetItem,
+                               QVBoxLayout, QWidget)
+
+from droparea import DropArea
+
+DESCRIPTION = """This example accepts drags from other applications and
+displays the MIME types provided by the drag object."""
+
+
+_WHITESPACE_PATTERN = re.compile(r"\s+")
+
+
+def simplify_whitespace(s):
+    return _WHITESPACE_PATTERN.sub(" ", s).strip()
+
+
+class DropSiteWindow(QWidget):
+
+    def __init__(self):
+        super().__init__()
+        drop_area = DropArea()
+        abstract_label = QLabel()
+        self._formats_table = QTableWidget()
+
+        button_box = QDialogButtonBox()
+        abstract_label = QLabel(DESCRIPTION)
+        abstract_label.setWordWrap(True)
+        abstract_label.adjustSize()
+
+        drop_area = DropArea()
+        drop_area.changed.connect(self.update_formats_table)
+
+        self._formats_table = QTableWidget()
+        self._formats_table.setColumnCount(2)
+        self._formats_table.setEditTriggers(QAbstractItemView.NoEditTriggers)
+        self._formats_table.setHorizontalHeaderLabels(["Format", "Content"])
+        self._formats_table.horizontalHeader().setStretchLastSection(True)
+
+        clear_button = QPushButton("Clear")
+        self._copy_button = QPushButton("Copy")
+        quit_button = QPushButton("Quit")
+
+        button_box = QDialogButtonBox()
+        button_box.addButton(clear_button, QDialogButtonBox.ActionRole)
+        button_box.addButton(self._copy_button, QDialogButtonBox.ActionRole)
+        self._copy_button.setVisible(False)
+
+        button_box.addButton(quit_button, QDialogButtonBox.RejectRole)
+
+        quit_button.clicked.connect(self.close)
+        clear_button.clicked.connect(drop_area.clear)
+        self._copy_button.clicked.connect(self.copy)
+
+        main_layout = QVBoxLayout(self)
+        main_layout.addWidget(abstract_label)
+        main_layout.addWidget(drop_area)
+        main_layout.addWidget(self._formats_table)
+        main_layout.addWidget(button_box)
+
+        self.setWindowTitle("Drop Site")
+        self.resize(700, 500)
+
+    @Slot(QMimeData)
+    def update_formats_table(self, mime_data):
+        self._formats_table.setRowCount(0)
+        self._copy_button.setEnabled(False)
+        if not mime_data:
+            return
+
+        for format in mime_data.formats():
+            format_item = QTableWidgetItem(format)
+            format_item.setFlags(Qt.ItemIsEnabled)
+            format_item.setTextAlignment(Qt.AlignTop | Qt.AlignLeft)
+
+            if format == "text/plain":
+                text = simplify_whitespace(mime_data.text())
+            elif format == "text/markdown":
+                text = mime_data.data("text/markdown").data().decode("utf8")
+            elif format == "text/html":
+                text = simplify_whitespace(mime_data.html())
+            elif format == "text/uri-list":
+                url_list = mime_data.urls()
+                text = ""
+                for i in range(0, min(len(url_list), 32)):
+                    text += url_list[i].toString() + " "
+            else:
+                data = mime_data.data(format)
+                if data.size() > 32:
+                    data.truncate(32)
+                text = data.toHex(" ").data().decode("utf8").upper()
+
+            row = self._formats_table.rowCount()
+            self._formats_table.insertRow(row)
+            self._formats_table.setItem(row, 0, QTableWidgetItem(format))
+            self._formats_table.setItem(row, 1, QTableWidgetItem(text))
+
+        self._formats_table.resizeColumnToContents(0)
+        self._copy_button.setEnabled(self._formats_table.rowCount() > 0)
+
+    @Slot()
+    def copy(self):
+        text = ""
+        for row in range(0, self._formats_table.rowCount()):
+            c1 = self._formats_table.item(row, 0).text()
+            c2 = self._formats_table.item(row, 1).text()
+            text += f"{c1}: {c2}\n"
+        QGuiApplication.clipboard().setText(text)
diff --git a/examples/widgets/draganddrop/dropsite/main.py b/examples/widgets/draganddrop/dropsite/main.py
new file mode 100644
index 000000000..bce476a61
--- /dev/null
+++ b/examples/widgets/draganddrop/dropsite/main.py
@@ -0,0 +1,15 @@
+# Copyright (C) 2022 The Qt Company Ltd.
+# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+import sys
+
+from PySide6.QtWidgets import QApplication
+
+from dropsitewindow import DropSiteWindow
+
+
+if __name__ == "__main__":
+    app = QApplication(sys.argv)
+    window = DropSiteWindow()
+    window.show()
+    sys.exit(app.exec())