from PyQt6.QtWidgets import QGraphicsView, QGraphicsScene, QGraphicsPixmapItem
from PyQt6.QtGui import QPixmap, QWheelEvent, QPainter, QImage
from PyQt6.QtCore import Qt

class ImageCanvas(QGraphicsView):
    _pixmapItem: QGraphicsPixmapItem
    empty = True

    def __init__(self):
        super().__init__()
        self.scene = QGraphicsScene()
        self.setScene(self.scene)
        
        self._pixmapItem = QGraphicsPixmapItem()
        self.scene.addItem(self._pixmapItem)
        
        self.setRenderHints(QPainter.RenderHint.Antialiasing | QPainter.RenderHint.SmoothPixmapTransform)
        self.setDragMode(self.DragMode.ScrollHandDrag)
        self.setTransformationAnchor(self.ViewportAnchor.AnchorUnderMouse)
    
    def wheelEvent(self, event: QWheelEvent):
        zoom_in_factor = 1.25
        zoom_out_factor = 1.0 / zoom_in_factor
        if event.angleDelta().y() > 0:
            self.scale(zoom_in_factor, zoom_in_factor)
        else:
            self.scale(zoom_out_factor, zoom_out_factor)


    def updatePixmap(self, image: QImage):
        pixmap = QPixmap.fromImage(image)
        self._pixmapItem.setPixmap(pixmap)
        if self.empty:
            self.reset()
            self.empty = False

    def clear(self):
        self.scene.removeItem(self._pixmapItem)
        self._pixmapItem = QGraphicsPixmapItem()
        self.scene.addItem(self._pixmapItem)
        
        self.empty = True

    def reset(self):
        self.resetTransform()  # Reset the zoom level to default
        self.fitInView(self._pixmapItem, Qt.AspectRatioMode.KeepAspectRatio)  # Fit the image to the view