Working synchronized views.

qt/pe/image_viewer.py

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+# This software is licensed under the "GPLv3" License as described in the "LICENSE" file,
+# which should be included with this package. The terms are also available at
+# http://www.gnu.org/licenses/gpl-3.0.html
+
+from PyQt5.QtCore import Qt, QSize, QRectF, QPointF, pyqtSlot, pyqtSignal, QEvent
+from PyQt5.QtGui import QPixmap, QPainter, QPalette
+from PyQt5.QtWidgets import ( QLabel, QSizePolicy, QWidget, QScrollArea, 
+                              QApplication, QAbstractScrollArea )
+
+class ImageViewer(QWidget):
+    """Displays image and allows manipulations."""
+    mouseMoved = pyqtSignal(QPointF)
+
+    def __init__(self, parent, name=""):
+        super().__init__(parent)
+        self.parent = parent
+        self.app = QApplication
+        self.pixmap = QPixmap()
+        self.m_rect = QRectF()
+        self.reference = QPointF()
+        self.delta = QPointF()
+        self.scalefactor = 1.0
+        self.drag = False
+        self.connection = None # signal bound to a slot
+        self.instance_name = name
+
+        self.area = QScrollArea(parent)
+        self.area.setBackgroundRole(QPalette.Dark)
+        self.area.setWidgetResizable(True)
+        self.area.setSizeAdjustPolicy(QAbstractScrollArea.AdjustToContents)
+        # self.area.viewport().setAttribute(Qt.WA_StaticContents)
+
+        self.label = QLabel()
+        sizePolicy = QSizePolicy(QSizePolicy.Ignored, QSizePolicy.Ignored)
+        sizePolicy.setHorizontalStretch(0)
+        sizePolicy.setVerticalStretch(0)
+        sizePolicy.setHeightForWidth(self.label.sizePolicy().hasHeightForWidth())
+        self.label.setBackgroundRole(QPalette.Base)
+        self.label.setSizePolicy(sizePolicy)
+        self.label.setAlignment(Qt.AlignCenter)
+        self.label.setScaledContents(True)
+
+        self.area.setWidget(self.label)
+        self.area.setVisible(False)
+
+    def __repr__(self):
+        return f'{self.instance_name}'
+
+    @pyqtSlot(QPointF)
+    def slot_paint_event(self, delta):
+        self.delta = delta
+        self.update()
+        print(f"{self} received signal from {self.sender()}")
+
+    def paintEvent(self, event):
+        painter = QPainter(self)
+        painter.translate(self.rect().center())
+        painter.scale(self.scalefactor, self.scalefactor)
+        painter.translate(self.delta)
+        painter.drawPixmap(self.m_rect.topLeft(), self.pixmap)
+        # print(f"{self} paintEvent delta={self.delta}")
+
+    def setCenter(self):
+        """ Resets origin """
+        self.delta = QPointF()
+        self.scalefactor = 1.0
+        self.scale(self.scalefactor)
+        self.update()
+
+    def changeEvent(self, event):
+        if event.type() == QEvent.EnabledChange:
+            print(f"{self} is now {'enabled' if self.isEnabled() else 'disabled'}")
+
+    def mousePressEvent(self, event):
+        if self.parent.bestFit:
+            event.ignore()
+            return
+        if event.buttons() == Qt.LeftButton:
+            self.drag = True
+
+        self.reference = event.pos()
+        self.app.setOverrideCursor(Qt.ClosedHandCursor)
+        self.setMouseTracking(True)
+
+    def mouseMoveEvent(self, event):
+        if self.parent.bestFit:
+            event.ignore()
+            return
+
+        self.delta += (event.pos() - self.reference) * 1.0/self.scalefactor
+        self.reference = event.pos()
+        if self.drag:
+            self.mouseMoved.emit(self.delta)
+        self.update()
+
+    def mouseReleaseEvent(self, event):
+        if self.parent.bestFit:
+            event.ignore()
+            return
+        if event.buttons() == Qt.LeftButton:
+            drag = False
+
+        self.app.restoreOverrideCursor()
+        self.setMouseTracking(False)
+
+    def wheelEvent(self, event):
+        if self.parent.bestFit:
+            event.ignore()
+            return
+
+        if event.angleDelta().y() > 0:
+            self.parent.zoomIn()
+        else:
+            self.parent.zoomOut()
+
+    def setPixmap(self, pixmap):
+        if pixmap.isNull():
+            if not self.pixmap.isNull():
+                self.pixmap = pixmap
+                self.update()
+            return
+        elif not self.isEnabled():
+            self.setEnabled(True)
+        self.pixmap = pixmap
+        self.m_rect = self.pixmap.rect()
+        self.m_rect.translate(-self.m_rect.center())
+        self.update()
+
+    def scale(self, factor):
+        self.scalefactor = factor
+        # self.label.resize(self.scalefactor * self.label.size())
+        self.update()
+
+    def sizeHint(self):
+        return QSize(400, 400)
+
+    @pyqtSlot()
+    def pixmapReset(self):
+        """Called when the pixmap is set back to original size."""
+        self.scalefactor = 1.0
+        self.update()