def _fit_in_view(view, rect, flags=Qt.IgnoreAspectRatio):
        if view.scene() is None or rect.isNull():
            return
        view.last_scene_roi = rect
        unity = view.transform().mapRect(QRectF(0, 0, 1, 1))
        view.scale(1 / unity.width(), 1 / unity.height())
        view_rect = view.viewport().rect()
        scene_rect = view.transform().mapRect(rect)
        xratio = view_rect.width() / scene_rect.width()
        yratio = view_rect.height() / scene_rect.height()
        if flags == Qt.KeepAspectRatio:
            xratio = yratio = min(xratio, yratio)
        elif flags == Qt.KeepAspectRatioByExpanding:
            xratio = yratio = max(xratio, yratio)
        view.scale(xratio, yratio)
        view.centerOn(rect.center())

    # name must match because we're overriding QMainWindow method 

def updateImage(self, opencv_rgb_image):

        self.cv_img_rgb = opencv_rgb_image

        height, width, channel = self.cv_img_rgb.shape
        bytesPerLine = 3 * width
        self.q_image = QImage(self.cv_img_rgb.data, width,
                              height, bytesPerLine, QImage.Format_RGB888)
        # self.QPixmap=QPixmap.fromImage(self.q_image)
        # scaredPixmap = self.QPixmap.scaled(self,self.frame_lbl.frameSize, aspectRatioMode=Qt.IgnoreAspectRatio)
        self.frame_lbl.setPixmap(QPixmap.fromImage(self.q_image).scaled(self.frame_lbl.size(), aspectRatioMode=Qt.KeepAspectRatio)) 

def __init__(self):
        QGraphicsView.__init__(self)

        # Image is displayed as a QPixmap in a QGraphicsScene attached to this QGraphicsView.
        self.scene = QGraphicsScene()
        self.setScene(self.scene)

        # Store a local handle to the scene's current image pixmap.
        self._pixmapHandle = None

        # Image aspect ratio mode.
        # !!! ONLY applies to full image. Aspect ratio is always ignored when zooming.
        #   Qt.IgnoreAspectRatio: Scale image to fit viewport.
        #   Qt.KeepAspectRatio: Scale image to fit inside viewport, preserving aspect ratio.
        #   Qt.KeepAspectRatioByExpanding: Scale image to fill the viewport, preserving aspect ratio.
        self.aspectRatioMode = Qt.KeepAspectRatio

        # Scroll bar behaviour.
        #   Qt.ScrollBarAlwaysOff: Never shows a scroll bar.
        #   Qt.ScrollBarAlwaysOn: Always shows a scroll bar.
        #   Qt.ScrollBarAsNeeded: Shows a scroll bar only when zoomed.
        self.setHorizontalScrollBarPolicy(Qt.ScrollBarAsNeeded)
        self.setVerticalScrollBarPolicy(Qt.ScrollBarAsNeeded)

        # Stack of QRectF zoom boxes in scene coordinates.
        self.zoomStack = []

        # Flags for enabling/disabling mouse interaction.
        self.canZoom = True
        self.canPan = True 

def updateViewer(self):
        """ Show current zoom (if showing entire image, apply current aspect ratio mode).
        """
        if not self.hasImage():
            return
        if len(self.zoomStack) and self.sceneRect().contains(self.zoomStack[-1]):
            self.fitInView(self.zoomStack[-1], Qt.IgnoreAspectRatio)  # Show zoomed rect (ignore aspect ratio).
        else:
            self.zoomStack = []  # Clear the zoom stack (in case we got here because of an invalid zoom).
            self.fitInView(self.sceneRect(), self.aspectRatioMode)  # Show entire image (use current aspect ratio mode). 

def makeItem(self, size, cname):
        item = QListWidgetItem(self)
        item.setData(Qt.UserRole + 1, cname)  # 把颜色放进自定义的data里面
        item.setSizeHint(size)
        label = QLabel(self)  # 自定义控件
        label.setMargin(2)  # 往内缩进2
        label.resize(size)
        pixmap = QPixmap(size.scaled(96, 96, Qt.IgnoreAspectRatio))  # 调整尺寸
        pixmap.fill(QColor(cname))
        label.setPixmap(pixmap)
        self.setItemWidget(item, label) 

def makeItem(self, size, cname):
        item = QListWidgetItem(self)
        item.setData(Qt.UserRole + 1, cname)  # 把颜色放进自定义的data里面
        item.setSizeHint(size)
        label = QLabel(self)  # 自定义控件
        label.setMargin(2)  # 往内缩进2
        label.resize(size)
        pixmap = QPixmap(size.scaled(96, 96, Qt.IgnoreAspectRatio))  # 调整尺寸
        pixmap.fill(QColor(cname))
        label.setPixmap(pixmap)
        self.setItemWidget(item, label) 

def _do_load_thumbnail(self):
        pixmap = QPixmap(self.path)
        if not pixmap.isNull():
            self.icon.setPixmap(
                pixmap.scaled(
                    48, 48, Qt.IgnoreAspectRatio, Qt.SmoothTransformation
                )
            ) 

def apply_pixmap(self):
        """Apply a scaled pixmap without modifying the dimension of the original one."""
        if self.pixmap:
            self.setPixmap(
                self.pixmap.scaled(
                    self.size(), Qt.IgnoreAspectRatio, Qt.SmoothTransformation
                )
            )