class PhotoViewer(QGraphicsView):
# 分别传递鼠标点击，移动，松开信号
mouse_clicked = pyqtSignal(QPoint)
mouse_moved = pyqtSignal(QPoint)
mouse_released = pyqtSignal(QPoint)
def __init__(self, parent):
super(PhotoViewer, self).__init__(parent)
self.init_UI()
def init_UI(self):
self._zoom = 0 # 定义图片的放大级别
self._empty = True # 定义是否含有图片（点击模式和拖动模式切换）
self._contour = False # 定义轮廓拖动模式 0
self._ocr = False # 定义文字识别模式
self._scene = QGraphicsScene(self) # 新建一个场景
self._photo = QGraphicsPixmapItem() # 新建一个图像图元
self._scene.addItem(self._photo) # 图像图元添加到场景中
self.setScene(self._scene) # 场景添加到视图中
self.setTransformationAnchor(
QGraphicsView.AnchorUnderMouse) # 坐标转换时以鼠标所在位置为中心
self.setResizeAnchor(
QGraphicsView.AnchorUnderMouse) # 视图大小调整时该如何定位其中的场景
self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff) # 垂直滚动条关闭
self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff) # 平行滚动条关闭
self.setBackgroundBrush(QBrush(QColor(30, 30, 30))) # 背景色
self.setFrameShape(QFrame.NoFrame) # 设置QFrame在它的内容周围画一个框
def hasPhoto(self):
# 是否加载图片
return not self._empty
def fitInView(self, scale=True):
# 图片自适应函数，缩放模式开启
rect = QRectF(self._photo.pixmap().rect()) # 绘制图元大小的矩形
if not rect.isNull():
self.setSceneRect(rect) # 这个矩形限定了场景的范围
if self.hasPhoto():
unity = self.transform().mapRect(QRectF(0, 0, 1, 1))
self.scale(1 / unity.width(), 1 / unity.height())
viewrect = self.viewport().rect()
scenerect = self.transform().mapRect(rect)
factor = min(viewrect.width() / scenerect.width(),
viewrect.height() / scenerect.height())
self.scale(factor, factor)
self._zoom = 0
def setPhoto(self, pixmap=None):
# 加载和重新渲染图元
# self._zoom = 0 # 重新渲染的时候保持放大比例，并不初始化为_zoom为0
if pixmap and not pixmap.isNull():
self._empty = False
self.setDragMode(QGraphicsView.ScrollHandDrag)
self._photo.setPixmap(pixmap)
else:
self._empty = True
self.setDragMode(QGraphicsView.NoDrag)
self._photo.setPixmap(QPixmap())
# 是否从新适应
# self.fitInView()
def wheelEvent(self, event):
# 鼠标滚轮控制放大缩小
if self.hasPhoto():
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
def toggleDragMode(self):
# 鼠标拖动和点击及切换函数
if self._contour or self._ocr:
self.setDragMode(QGraphicsView.NoDrag)
else:
if self.dragMode() == QGraphicsView.ScrollHandDrag:
self.setDragMode(QGraphicsView.NoDrag)
elif not self._photo.pixmap().isNull():
self.setDragMode(QGraphicsView.ScrollHandDrag)
def mousePressEvent(self, event):
# 鼠标点击返回鼠标所在的图片坐标
if self._photo.isUnderMouse():
# 注意坐标系转换 详解http://blog.51cto.com/9291927/1879128
p = self._photo.mapToItem(self._photo,
self.mapToScene(event.pos()))
self.mouse_clicked.emit(p.toPoint())
super(PhotoViewer, self).mousePressEvent(event)
def mouseMoveEvent(self, event):
if self._ocr == True: # 只有当文字识别的时候实时返回拖动的鼠标的坐标
if self._photo.isUnderMouse():
p = self._photo.mapToItem(self._photo,
self.mapToScene(event.pos()))
self.mouse_moved.emit(p.toPoint())
super(PhotoViewer, self).mouseMoveEvent(event)
def mouseReleaseEvent(self, event):
# 获取鼠标松开的坐标点
if self._photo.isUnderMouse():
p = self._photo.mapToItem(self._photo,
self.mapToScene(event.pos()))
self.mouse_released.emit(p.toPoint())
super(PhotoViewer, self).mouseReleaseEvent(event)
