PyBlocks/node_graphics_view.py at main · YashwanthProfile/PyBlocks · GitHub

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from PyQt5.QtWidgets import QGraphicsView
from PyQt5.QtCore import Qt, QEvent
from PyQt5.QtGui import QPainter, QMouseEvent, QWheelEvent

class customgraphics_view(QGraphicsView):
    def __init__(self, graphicScene, parent=None):
        super().__init__(parent)

        self.graphicScene = graphicScene

        self.initUI()

        self.setScene(self.graphicScene)

        self.zoomInFactor   = 1.25 # 25%
        self.zoomClamp      = True
        self.zoom           = 10
        self.zoomStep       = 1
        self.zoomRange      = [0, 10]


    def initUI(self):
        # These things can be turned off for performance issues? --------------------------------------------------------------------------------
        self.setRenderHints(QPainter.Antialiasing | QPainter.HighQualityAntialiasing | QPainter.TextAntialiasing | QPainter.SmoothPixmapTransform)
        self.setViewportUpdateMode(QGraphicsView.FullViewportUpdate)
        # ---------------------------------------------------------------------------------------------------------------------------------------

        self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)

        self.setTransformationAnchor(QGraphicsView.AnchorUnderMouse) # Zooms under the current mouse pos | Default is scene center


    def mousePressEvent(self, event: QMouseEvent | None):
        if event.button() == Qt.MiddleButton:
            self.middleMouseButtonPress(event)

        elif event.button() == Qt.LeftButton:
            self.leftMouseButtonPress(event)

        elif event.button() == Qt.RightButton:
            self.rightMouseButtonPress(event)

        else:
            super().mousePressEvent(event)

    def mouseReleaseEvent(self, event: QMouseEvent | None) -> None:
        if event.button() == Qt.MiddleButton:
            self.middleMouseButtonRelease(event)

        elif event.button() == Qt.LeftButton:
            self.leftMouseButtonRelease(event)

        elif event.button() == Qt.RightButton:
            self.rightMouseButtonRelease(event)

        else:
            super().mouseReleaseEvent(event)


    def middleMouseButtonPress(self, event):
        releaseEvent = QMouseEvent(QEvent.MouseButtonRelease, event.localPos(), event.screenPos(),
                                   Qt.LeftButton, Qt.NoButton, event.modifiers())
        super().mouseReleaseEvent(releaseEvent)
        self.setDragMode(QGraphicsView.ScrollHandDrag)
        fakeEvent = QMouseEvent(event.type(), event.localPos(), event.screenPos(),
                                Qt.LeftButton, event.buttons() | Qt.LeftButton, event.modifiers())
        super().mousePressEvent(fakeEvent)


    def middleMouseButtonRelease(self, event):
        fakeEvent = QMouseEvent(event.type(), event.localPos(), event.screenPos(),
                                Qt.LeftButton, event.buttons() & ~Qt.LeftButton, event.modifiers())
        super().mouseReleaseEvent(fakeEvent)
        self.setDragMode(QGraphicsView.NoDrag)


    def leftMouseButtonPress(self, event):
        return super().mousePressEvent(event)

    def leftMouseButtonRelease(self, event):
        return super().mouseReleaseEvent(event)


    def rightMouseButtonPress(self, event):
        return super().mousePressEvent(event)

    def rightMouseButtonRelease(self, event):
        return super().mouseReleaseEvent(event)

    # Over right wheel to zoom from scroll
    def wheelEvent(self, event: QWheelEvent | None):
        # Calculate our zoom factor
        zoomOutFactor = 1 / self.zoomInFactor


        # Calculate zoom
        if event.angleDelta().y() > 0: # ZOOM IN
            zoomFactor = self.zoomInFactor
            self.zoom += self.zoomStep

        else: # ZOOM OUT
            zoomFactor = zoomOutFactor
            self.zoom -= self.zoomStep

        clamped = False
        if self.zoom  < self.zoomRange[0]: self.zoom, clamped = self.zoomRange[0], True # clamps the zoom out?
        if self.zoom  > self.zoomRange[1]: self.zoom, clamped = self.zoomRange[1], True # clamps the zoom in?

        # set scene scale
        if not clamped or self.zoomClamp is False:
            self.scale(zoomFactor, zoomFactor)