<p>下面是一个可移动按钮的示例,该按钮仍然正确地支持正常的单击信号:</p>
<pre><code>from PyQt4 import QtCore, QtGui
class DragButton(QtGui.QPushButton):
def mousePressEvent(self, event):
self.__mousePressPos = None
self.__mouseMovePos = None
if event.button() == QtCore.Qt.LeftButton:
self.__mousePressPos = event.globalPos()
self.__mouseMovePos = event.globalPos()
super(DragButton, self).mousePressEvent(event)
def mouseMoveEvent(self, event):
if event.buttons() == QtCore.Qt.LeftButton:
# adjust offset from clicked point to origin of widget
currPos = self.mapToGlobal(self.pos())
globalPos = event.globalPos()
diff = globalPos - self.__mouseMovePos
newPos = self.mapFromGlobal(currPos + diff)
self.move(newPos)
self.__mouseMovePos = globalPos
super(DragButton, self).mouseMoveEvent(event)
def mouseReleaseEvent(self, event):
if self.__mousePressPos is not None:
moved = event.globalPos() - self.__mousePressPos
if moved.manhattanLength() > 3:
event.ignore()
return
super(DragButton, self).mouseReleaseEvent(event)
def clicked():
print "click as normal!"
if __name__ == "__main__":
app = QtGui.QApplication([])
w = QtGui.QWidget()
w.resize(800,600)
button = DragButton("Drag", w)
button.clicked.connect(clicked)
w.show()
app.exec_()
</code></pre>
<p>在<code>mousePressEvent</code>中,我记录初始开始位置,以及在整个拖动过程中更新的位置。</p>
<p>在<code>mouseMoveEvent</code>中,我得到了小部件从单击位置到实际原点的适当偏移量,这样移动是准确的。</p>
<p>在<code>mouseReleaseEvent</code>中,我检查整个移动量是否至少大于一小部分。如果是,那么它是一个拖拽,我们忽略了正常事件,不会产生“点击”信号。否则,我们允许普通事件处理程序生成click。</p>