问题描述
我有一个 PyQt 应用程序,我必须在其中实现通过 QPainter
生成的点的 drap n drop 功能。我的问题是我什至可以将这些点拖到窗口范围之外,例如我可以将点拖到标题栏或任务栏并留在那里,一旦离开那里,我就不能再将它们拖回我的主窗口。
代码:
import sys
import numpy as np
from PyQt4 import QtCore,QtGui
class Canvas(QtGui.QWidget):
DELTA = 100 #for the minimum distance
def __init__(self,parent=None):
super(Canvas,self).__init__(parent)
self.draggin_idx = -1
self.points = np.array([[x[0],x[1]] for x in [[100,200],[200,[100,400],400]]],dtype=np.float)
self.id = None
self.points_dict = {}
for i,x in enumerate(self.points):
point=(int(x[0]),int(x[1]))
self.points_dict[i] = point
def paintEvent(self,e):
qp = QtGui.QPainter()
qp.begin(self)
self.drawPoints(qp)
self.drawLines(qp)
qp.end()
def drawPoints(self,qp):
# qp.setPen(QtCore.Qt.red)
pen = QtGui.QPen()
pen.setWidth(10)
pen.setColor(QtGui.QColor('red'))
qp.setPen(pen)
for x,y in self.points:
qp.drawPoint(x,y)
def drawLines(self,qp):
# pen.setWidth(5)
# pen.setColor(QtGui.QColor('red'))
qp.setPen(QtCore.Qt.red)
qp.drawLine(self.points_dict[0][0],self.points_dict[0][1],self.points_dict[1][0],self.points_dict[1][1])
qp.drawLine(self.points_dict[1][0],self.points_dict[1][1],self.points_dict[3][0],self.points_dict[3][1])
qp.drawLine(self.points_dict[3][0],self.points_dict[3][1],self.points_dict[2][0],self.points_dict[2][1])
qp.drawLine(self.points_dict[2][0],self.points_dict[2][1],self.points_dict[0][0],self.points_dict[0][1])
def _get_point(self,evt):
return np.array([evt.pos().x(),evt.pos().y()])
#get the click coordinates
def mousepressEvent(self,evt):
if evt.button() == QtCore.Qt.LeftButton and self.draggin_idx == -1:
point = self._get_point(evt)
int_point = (int(point[0]),int(point[1]))
min_dist = ((int_point[0]-self.points_dict[0][0])**2 + (int_point[1]-self.points_dict[0][1])**2)**0.5
for i,x in enumerate(list(self.points_dict.values())):
distance = ((int_point[0]-x[0])**2 + (int_point[1]-x[1])**2)**0.5
if min_dist >= distance:
min_dist = distance
self.id = i
#dist will hold the square distance from the click to the points
dist = self.points - point
dist = dist[:,0]**2 + dist[:,1]**2
dist[dist>self.DELTA] = np.inf #obviate the distances above DELTA
if dist.min() < np.inf:
self.draggin_idx = dist.argmin()
def mouseMoveEvent(self,evt):
if self.draggin_idx != -1:
point = self._get_point(evt)
self.points[self.draggin_idx] = point
self.update()
def mouseReleaseEvent(self,evt):
if evt.button() == QtCore.Qt.LeftButton and self.draggin_idx != -1:
point = self._get_point(evt)
int_point = (int(point[0]),int(point[1]))
self.points_dict[self.id] = int_point
self.points[self.draggin_idx] = point
self.draggin_idx = -1
self.update()
if __name__ == "__main__":
app = QtGui.QApplication([])
win = Canvas()
win.showMaximized()
sys.exit(app.exec_())
解决方法
这与绘画无关(显然不能“走出去”),而与您获取坐标的方式有关。
只要确保该点在小部件的边缘内即可:
def _get_point(self,evt):
pos = evt.pos()
if pos.x() < 0:
pos.setX(0)
elif pos.x() > self.width():
pos.setX(self.width())
if pos.y() < 0:
pos.setY(0)
elif pos.y() > self.height():
pos.setY(self.height())
return np.array([pos.x(),pos.y()])