104 lines
3.3 KiB
Markdown
104 lines
3.3 KiB
Markdown
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title = "Positioning"
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+++
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QtQuick has multiple ways to position components. This page has instructions for where and how
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to use them.
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## Anchors
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Anchors can be used to position components relative to another neighboring component.
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It is faster than [manual positioning](#manual-positioning) and covers a lot of simple
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use cases.
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The [Qt Documentation: Positioning with Anchors](https://doc.qt.io/qt-6/qtquick-positioning-anchors.html)
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page has comprehensive documentation of anchors.
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## Layouts
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Layouts are useful when you have many components that need to be positioned relative to
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eachother such as a list.
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The [Qt Documentation: Layouts Overview](https://doc.qt.io/qt-6/qtquicklayouts-overview.html)
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page has good documentation of the basic layout types and how to use them.
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Note: layouts by default have a nonzero spacing.
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## Manual Positioning
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If layouts and anchors can't easily fulfill your usecase, you can also manually position and size
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components by setting their `x`, `y`, `width` and `height` properties, which are relative to
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the parent component.
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This example puts a 100x100px blue rectangle at x=20,y=40 in the parent item. Ensure the size
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of the parent is large enough for its content or positioning based on them will break.
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```qml
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Item {
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// make sure the component is large enough to fit its children
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implicitWidth: childrenRect.width
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implicitHeight: childrenRect.height
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Rectangle {
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color: "blue"
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x: 20
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y: 40
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width: 100
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height: 100
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}
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}
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```
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## Notes
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### Component Size
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The [Item.implicitHeight] and [Item.implicitWidth] properties control the *base size* of a
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component, before layouts are applied. These properties are *not* the same as
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[Item.height] and [Item.width] which are the final size of the component.
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You should nearly always use the implicit size properties when creating a component,
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however using the normal width and height properties is fine if you know an
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item will never go in a layout.
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[Item.height]: https://doc.qt.io/qt-6/qml-qtquick-item.html#height-prop
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[Item.width]: https://doc.qt.io/qt-6/qml-qtquick-item.html#width-prop
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[Item.implicitHeight]: https://doc.qt.io/qt-6/qml-qtquick-item.html#implicitHeight-prop
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[Item.implicitWidth]: https://doc.qt.io/qt-6/qml-qtquick-item.html#implicitWidth-prop
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This example component puts a colored rectangle behind some text, and will act the same
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way in a layout as the text by itself.
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```qml {filename="TextWithBkgColor.qml"}
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Rectangle {
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implicitWidth: text.implicitWidth
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implicitHeight: text.implicitHeight
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Text {
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id: text
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text: "hello!"
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}
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}
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```
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If you want to size your component based on multiple others or use any other math you can.
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```qml {filename="PaddedTexts.qml"}
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Item {
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// width of both texts plus 5
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implicitWidth: text1.implicitWidth + text2.implicitWidth + 5
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// max height of both texts plus 5
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implicitHeight: Math.min(text1.implicitHeight, text2.implicitHeight) + 5
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Text {
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id: text1
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text: "text1"
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}
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Text {
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id: text2
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anchors.left: text1.left
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text: "text2"
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}
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}
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```
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### Coordinate space
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You should always position or size components relative to the closest possible
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parent. Often this is just the `parent` property.
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Refrain from using things like the size of your screen to size a component,
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as this will break as soon as anything up the component hierarchy changes, such
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as adding padding to a bar.
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