我有以下自定义QML Item
,它将代表一个密码输入GUI元素:
import QtQuick 2.0
import QtQuick.Layouts 1.2
import QtQuick.Controls 1.3
import "../items"
Item
{
id: ueKeypad
width: 512
height: 512
Rectangle
{
id: ueKeypadWrapper
antialiasing: true
anchors.fill: parent
ColumnLayout
{
id: ueKeypadLayoutMain
antialiasing: true
layoutDirection: Qt.LeftToRight
spacing: 8
anchors.fill: parent
ColumnLayout
{
id: ueKeypadTitleLayout
layoutDirection: Qt.LeftToRight
Layout.fillWidth: true
Layout.minimumHeight: 24
Layout.preferredHeight: 24
Layout.maximumHeight: 24
Text
{
Layout.fillWidth: true
Layout.fillHeight: true
text: qsTr("PIN ENTRY")
clip: true
font.bold: true
font.pointSize: 24
textFormat: Text.RichText
verticalAlignment: Text.AlignVCenter
horizontalAlignment: Text.AlignHCenter
} // Text
} // ColumnLayout
GridLayout
{
id: ueKeypadNumbersLayout
Layout.fillWidth: true
Layout.fillHeight: true
Layout.alignment: Qt.AlignHCenter|Qt.AlignVCenter
layoutDirection: Qt.LeftToRight
columnSpacing: 8
rowSpacing: 8
flow: GridLayout.LeftToRight
columns: 3
UeButton
{
id: ueKeypadButton1
Layout.minimumHeight: 32
Layout.preferredHeight: 32
Layout.maximumHeight: 32
ueText: qsTr("1")
}
UeButton
{
id: ueKeypadButton2
Layout.minimumHeight: 32
Layout.preferredHeight: 32
Layout.maximumHeight: 32
ueText: qsTr("2")
}
UeButton
{
id: ueKeypadButton3
Layout.minimumHeight: 32
Layout.preferredHeight: 32
Layout.maximumHeight: 32
ueText: qsTr("3")
}
UeButton
{
id: ueKeypadButton4
Layout.minimumHeight: 32
Layout.preferredHeight: 32
Layout.maximumHeight: 32
ueText: qsTr("4")
}
UeButton
{
id: ueKeypadButton5
Layout.minimumHeight: 32
Layout.preferredHeight: 32
Layout.maximumHeight: 32
ueText: qsTr("5")
}
UeButton
{
id: ueKeypadButton6
Layout.minimumHeight: 32
Layout.preferredHeight: 32
Layout.maximumHeight: 32
ueText: qsTr("6")
}
UeButton
{
id: ueKeypadButton7
Layout.minimumHeight: 32
Layout.preferredHeight: 32
Layout.maximumHeight: 32
ueText: qsTr("7")
}
UeButton
{
id: ueKeypadButton8
Layout.minimumHeight: 32
Layout.preferredHeight: 32
Layout.maximumHeight: 32
ueText: qsTr("8")
}
UeButton
{
id: ueKeypadButton9
Layout.minimumHeight: 32
Layout.preferredHeight: 32
Layout.maximumHeight: 32
ueText: qsTr("9")
}
} // GridLayout
RowLayout
{
id: ueKeypadActionLayout
Layout.fillWidth: true
Layout.fillHeight: true
Layout.alignment: Qt.AlignHCenter|Qt.AlignVCenter
layoutDirection: Qt.LeftToRight
spacing: 8
UeButton
{
id: ueKeypadButtonOk
ueText: qsTr("Ok")
} // UeButton
UeButton
{
id: ueKeypadButton0
ueText: qsTr("0")
Layout.minimumHeight: 32
Layout.preferredHeight: 32
Layout.maximumHeight: 32
} // UeButton
UeButton
{
id: ueKeypadButtonCancel
ueText: qsTr("Cancel")
} // UeButton
} // RowLayout
} // ColumnLayout
} // Rectangle
} // Item
它使用自定义QML Button
,名为 UeButton
:
import QtQuick.Controls 1.4
import QtQuick.Controls.Styles 1.4
import QtQuick 2.5
Button
{
property string ueText
id: ueButton
text: ueText
style: ButtonStyle
{
background: Rectangle
{
antialiasing: true
smooth: true
gradient: Gradient
{
GradientStop
{
position: 0
color: "#ffffff"
} // GradientStop
GradientStop
{
position: 0.418
color: "#000000"
} // GradientStop
} // Gradient
border.color: "steelblue"
border.width: control.activeFocus?2:1
radius: 4
} // background
label: Text
{
color: "#ffffff"
font.bold: true
verticalAlignment: Text.AlignVCenter
horizontalAlignment: Text.AlignHCenter
font.pointSize: 16
text: control.text
} // label
} // ButtonStyle
} // ueButton
如果我在QtCreator的Designer工具中查看第一个代码,我会遇到以下情况:
为什么 Button
不会分布在 GridLayout
上?同样是低于 RowLayout
,其 Item
(三个 Item
类型为 UeButton
)没有居中并在整个 RowLayout
上对齐?
1 回答
Layout
的附加属性可确保包含的Item
的大小正确w.r.t.给定的约束 .可以拉伸
Item
以填充可用空间(fillWidth
/fillHeight
),强制在某个值(minimumWidth
/minimumHeight
)下不缩小或不放大某个其他值(maximumWidth
/maximumHeight
) . 您还可以强制Item
占用多个行/列(rowSpan
/columnSpan
)并假设特定大小(preferredWidth
/preferredHeight
,这意味着minimum
==maximum
) .优先顺序是:
preferred
<minimum
/maximum
<width
/height
向左设置属性会自动丢弃右侧的属性 . 您可以轻松理解这背后的原因 . 由于任何
Item
的大小在这些值下都不能缩小,因此该方案可能有点implicitWidth/implicitHeight
. 根据上述约束,fill
属性确保Item
填充可用空间:如果未定义fill
,则Item
不能根据其约束增长或缩小 .现在,如果您希望
Button
维护它们的方面并仍然拉伸网格,则可以使用中间Item
. 将Layout
附加属性应用于外部Item
时,Button
可以是centerIn
并且不受影响 .示例代码:
相反,如果您希望
Button
填充可用空间,只需指定fillWidth
/fillHeight
. 由于没有设置其他布局约束(例如minimum*
,maximum*
),Button
正确占用了所有可用空间 . 以下是重新审视的代码 . 正如所料,width
和height
被简单地丢弃: