Table of contents
1. Demand
Mainly for the following needs:
- Drag-and-drop generation of callout boxes
- Dragging and moving the callout box
- Drag and zoom the callout box
- Double-click outside the label box to automatically destroy
2. Basic ideas
Maintain a list of coordinates for a callout box. Mainly by creating the start point coordinates and end point coordinates of the callout frame, the drag-and-drop generation of the callout frame is realized; by updating the list, drag-and-drop movement and scaling are realized; by emptying the list, double-click destruction is realized.
3. Realize
Refer to the blog "PYQT5 realizes dragging and changing the size of the rectangular box (realization of the simple version of the text box)"
The image address in this code img = QPixmap('./3.png')needs to be updated by itself.
from PyQt5.QtWidgets import QWidget, QApplication, QLabel
from PyQt5.QtCore import QRect, Qt
from PyQt5.QtGui import QImage, QPixmap, QPainter, QPen
import cv2
import sys
class MyLabel(QLabel):
#x0 = 0
#y0 = 0
#x1 = 0
#y1 = 0
flag = False # 是否按下鼠标
move = False # 是否进行拖拽整体移动
biggerLeft = False # 是否进行拖拽放大缩小，坐标点在标注框的左边
biggerRight = False # 是否进行拖拽放大缩小，坐标点在标注框的右边
biggerButton = False # 是否进行拖拽放大缩小，坐标点在标注框的下边
biggerTop = False # 是否进行拖拽放大缩小，坐标点在标注框的上边
rect = [] # 标注框的起始点坐标和终点坐标，形如 [start_x, start_y, end_x, end_y]
# 鼠标双击事件
def mouseDoubleClickEvent(self, event):
self.rect = []
print("双击事件发生！")
self.update()
#鼠标单击事件
def mousePressEvent(self,event):
self.flag = True
#self.x0 = event.x()
#self.y0 = event.y()
if self.rect:
# 此时已经存在标注框，再点击，则为拖拽整体移动或者放大缩小
# 整体移动：当点击坐标位于标注框内，则说明为整体移动
# 放大缩小：当点击坐标位于标注框的四条边上，则说明为放大缩小
# 框的左上角和右下角
topleft_x = min(self.rect[0], self.rect[2])
topleft_y = min(self.rect[1], self.rect[3])
buttonright_x = max(self.rect[0], self.rect[2])
buttonright_y = max(self.rect[1], self.rect[3])
# 整体移动的判定：点坐标在左上角和右下角之间
if (event.x() > topleft_x + 5) and (event.x() < buttonright_x - 5) and (event.y() > topleft_y+ 5) and (event.y() < buttonright_y - 5):
print("判定为整体移动")
self.move = True
self.preMousePosition = event.pos()
# 放大缩小的判定：点坐标在框的四条边上
# 上边，下边、左边、右边
# 当点坐标在标注框的左边时
if (event.x() > topleft_x - 5) and (event.x() < topleft_x + 5) and (event.y() > topleft_y) and (event.y() < buttonright_y):
print("判定为放大缩小，点坐标在标注框的左边上")
self.biggerLeft = True
self.preMousePosition = event.pos()
# 当点坐标在标注框的右边时
if (event.x() > buttonright_x - 5) and (event.x() < buttonright_x + 5) and (event.y() > topleft_y) and (event.y() < buttonright_y):
print("判定为放大缩小，点坐标在标注框的右边上")
self.biggerRight = True
self.preMousePosition = event.pos()
# 当点坐标在标注框的下边时
if (event.x() > topleft_x) and (event.x() < buttonright_x) and (event.y() > buttonright_y - 5) and (event.y() < buttonright_y + 5):
print("判定为放大缩小，点坐标在标注框的下边上")
self.biggerButton = True
self.preMousePosition = event.pos()
# 当点坐标在标注框的上边时
if (event.x() > topleft_x) and (event.x() < buttonright_x) and (event.y() > topleft_y - 5) and (event.y() < topleft_y + 5):
print("判定为放大缩小，点坐标在标注框的上边上")
self.biggerTop = True
self.preMousePosition = event.pos()
else:
# 如果当前没有标注框，则说明点击后开始拖拽生成标注框
# 此时，没有整体移动和放大缩小
self.move = False
self.biggerLeft = False
self.biggerRight = False
self.biggerButton = False
self.biggerTop = False
self.rect = [event.x(), event.y(), event.x(), event.y()]
#鼠标释放事件
def mouseReleaseEvent(self,event):
self.flag = False
self.biggerLeft = False
self.biggerRight = False
self.biggerButton = False
self.biggerTop = False
self.move = False
#鼠标移动事件
def mouseMoveEvent(self,event):
start_x, start_y = self.rect[0:2]
if self.flag: # 按下鼠标，开始拖拽
# 拖拽可能有三种情况
# 情况1：在已有标注框的情况下，进行放大缩小
# 情况1.1：标注框的左边
if self.biggerLeft:
print("放大缩小：左边进行x轴方向的缩放")
differ = event.pos() - self.preMousePosition
# 更新标注框
start_x, start_y, end_x, end_y = self.rect
if start_x < end_x:
start_x += differ.x()
else:
end_x += differ.x()
self.rect = [start_x, start_y, end_x, end_y]
self.preMousePosition = event.pos()
# 情况1.2：标注框的右边
elif self.biggerRight:
print("放大缩小：右边进行x轴方向的缩放")
differ = event.pos() - self.preMousePosition
# 更新标注框
start_x, start_y, end_x, end_y = self.rect
if start_x > end_x:
start_x += differ.x()
else:
end_x += differ.x()
self.rect = [start_x, start_y, end_x, end_y]
self.preMousePosition = event.pos()
# 情况1.3：标注框的下边
elif self.biggerButton:
print("放大缩小：下边进行y轴方向的缩放")
differ = event.pos() - self.preMousePosition
# 更新标注框
start_x, start_y, end_x, end_y = self.rect
if start_y > end_y:
start_y += differ.y()
else:
end_y += differ.y()
self.rect = [start_x, start_y, end_x, end_y]
self.preMousePosition = event.pos()
# 情况1.4：标注框的上边
elif self.biggerTop:
print("放大缩小：上边进行y轴方向的缩放")
differ = event.pos() - self.preMousePosition
# 更新标注框
start_x, start_y, end_x, end_y = self.rect
if start_y < end_y:
start_y += differ.y()
else:
end_y += differ.y()
self.rect = [start_x, start_y, end_x, end_y]
self.preMousePosition = event.pos()
# 情况2：在已有标注框的情况下，进行整体移动
elif self.move:
differ = event.pos() - self.preMousePosition
# 更新标注框
start_x, start_y, end_x, end_y = self.rect
start_x, start_y = start_x + differ.x(), start_y + differ.y()
end_x, end_y = end_x + differ.x(), end_y + differ.y()
self.rect = [start_x, start_y, end_x, end_y]
self.preMousePosition = event.pos()
print("整体移动")
# 情况3：做标注框
else:
#self.x1 = event.x()
#self.y1 = event.y()
self.rect = [start_x, start_y, event.x(), event.y()]
self.update()
#绘制事件
def paintEvent(self, event):
super().paintEvent(event)
if len(self.rect) == 0: return
# rect =QRect(self.x0, self.y0, abs(self.x1-self.x0), abs(self.y1-self.y0))
# 这里换成任意方向的矩形框
# 标注框的左上角和右下角坐标
x0 = min(self.rect[0], self.rect[2])
y0 = min(self.rect[1], self.rect[3])
x1 = max(self.rect[0], self.rect[2])
y1 = max(self.rect[1], self.rect[3])
width = x1 - x0
height = y1 - y0
# 矩形
rect =QRect(x0, y0, width, height)
painter = QPainter(self)
painter.setPen(QPen(Qt.red,2,Qt.SolidLine))
painter.drawRect(rect)
class Example(QWidget):
def __init__(self):
super().__init__()
self.initUI()
def initUI(self):
self.resize(675, 500)
self.move(100,50)
self.setWindowTitle('在label中绘制矩形')
self.lb = MyLabel(self) #重定义的label
# 这里直接读取图片
img = QPixmap('./3.png')
# 往显示视频的Label里 显示QImage
self.lb.setPixmap(img)
self.lb.setCursor(Qt.CrossCursor)#图片可以绘制
self.show()
if __name__ == '__main__':
app = QApplication(sys.argv)
x = Example()
sys.exit(app.exec_())