我有一个MouseArea，我想要从中心开始，然后按一下上/下/左/右键的绝对位置。我的问题是我不知道如何清除MouseArea上的锚点，以便我可以指定绝对位置：
import QtQuick 1.1
Rectangle {
id: screen
width: 360
height: 360
function moveMouseArea(x,y) {
mouseArea.pos.x += x;
mouseArea.pos.y += y;
mouseArea.state = "moved";
mouseAreaPosText.text = 'Mouse area was moved... new pos: '
+ mouseArea.pos.x + ',' + mouseArea.pos.y;
}
Item {
id: keyHandler
focus: true
Keys.onPressed: {
if (event.key == Qt.Key_Up) {
moveMouseArea(0,-1);
}
if (event.key == Qt.Key_Down) {
moveMouseArea(0,1);
}
if (event.key == Qt.Key_Left) {
moveMouseArea(-1,0);
}
if (event.key == Qt.Key_Right) {
moveMouseArea(1,0);
}
}
}
states:
State {
name: "moved"
AnchorChanges {
target: mouseArea
anchors.bottom: undefined
anchors.left: undefined
anchors.right: undefined
anchors.top: undefined
}
}
MouseArea {
id: mouseArea
anchors.centerIn: parent
width: 250
height: 250
onClicked: {
console.log("clicked!");
}
onPositionChanged: {
console.log("position changed!");
}
Rectangle {
anchors.fill: parent
border.width: 2
border.color: "black"
color: "transparent"
}
Text {
id: mouseAreaPosText
anchors.centerIn: parent
}
}
}
起初我刚刚尝试将mouseArea.anchors设置为undefined，但是有一个关于anchor是一个只读属性的错误。然后我发现了AnchorChanges，但是我找不到删除/清除锚点的方法;将anchorors.bottom等设置为undefined不起作用。
解决方法
根据
docs，将anchor属性设置为undefined应该可以工作。我不太明白为什么AnchorChanges不允许设置anchors.centerIn，但是您可以在moveMouseArea函数中解决它：
function moveMouseArea(x,y) {
mouseArea.anchors.centerIn = undefined; // <-- reset anchor before state change
mouseArea.pos.x += x;
mouseArea.pos.y += y;
mouseArea.state = "moved";
mouseAreaPosText.text = 'Mouse area was moved... new pos: '
+ mouseArea.pos.x + ',' + mouseArea.pos.y;
}
