from PyQt5.QtCore import Qt, QRectF
from PyQt5.QtGui import QCursor, QImage, QPixmap
from PyQt5.QtWidgets import QGraphicsView, QGraphicsPixmapItem, QGraphicsScene, QMenu, QAction, QFileDialog
from cv2 import cvtColor,COLOR_BGR2RGB

class GraphicsView(QGraphicsView):
    def __init__(self, parent=None):
        super(GraphicsView, self).__init__(parent=parent)
        self._zoom = 0
        self._empty = True
        self._photo = QGraphicsPixmapItem()
        self._scene = QGraphicsScene(self)
        self._scene.addItem(self._photo)


        self.setScene(self._scene)
        # self.setScene(self._scene1)
        self.setAlignment(Qt.AlignCenter)  # 居中显示
        self.setDragMode(QGraphicsView.ScrollHandDrag)  # 设置拖动
        self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.setMinimumSize(640, 480)

    def contextMenuEvent(self, event):
        if not self.has_photo():
            return
        menu = QMenu()
        save_action = QAction('另存为', self)
        save_action.triggered.connect(self.save_current)  # 传递额外值
        menu.addAction(save_action)
        menu.exec(QCursor.pos())

    def save_current(self):
        file_name = QFileDialog.getSaveFileName(self, '另存为', './', 'Image files(*.jpg *.gif *.png)')[0]
        print(file_name)
        if file_name:
            self._photo.pixmap().save(file_name)

    def get_image(self):
        if self.has_photo():
            return self._photo.pixmap().toImage()

    def has_photo(self):
        return not self._empty

    def change_image(self, img):
        self.update_image(img)
        self.fitInView()

    def img_to_pixmap(self, img):
        img = cvtColor(img, COLOR_BGR2RGB)  # bgr -> rgb
        h, w, c = img.shape  # 获取图片形状
        image = QImage(img, w, h, 3 * w, QImage.Format_RGB888)
        return QPixmap.fromImage(image)

    def update_image(self, img):
        self._empty = False
        self._photo.setPixmap(self.img_to_pixmap(img))

    def fitInView(self, scale=True):
        rect = QRectF(self._photo.pixmap().rect())
        if not rect.isNull():
            self.setSceneRect(rect)

    def wheelEvent(self, event):
        if self.has_photo():
            if event.angleDelta().y() > 0:
                factor = 1.25
                self._zoom += 1
            else:
                factor = 0.8
                self._zoom -= 1
            if self._zoom > 0:
                self.scale(factor, factor)
            elif self._zoom == 0:
                self.fitInView()
            else:
                self._zoom = 0