QML 布局:如何为行或列布局中的项目赋予权重? [英] QML Layouts: How to give weights to items in a row or column layout?

问题描述

我试图通过为每个项目指定一种重量来找出按比例布局项目的方法.例如 Android 的 布局.

I'm trying to figure out a way to layout items proportionally by specifying a kind of weight for each item. For example the way Android does their layouts.

我试图实现它的方式是这样的:

The way I'm trying to achieve it is like so:

import QtQuick 2.10
import QtQuick.Controls 2.3
import QtQuick.Layouts 1.3

GridLayout {
    columns: 4
    width: 640
    height: 480

    Rectangle {
        color: "red"
        Layout.fillHeight: true
        Layout.fillWidth: true
        Layout.columnSpan: 1
    }
    Rectangle {
        color: "#80000000"
        Layout.fillHeight: true
        Layout.fillWidth: true
        Layout.columnSpan: 2
    }
    Rectangle {
        color: "blue"
        Layout.fillHeight: true
        Layout.fillWidth: true
        Layout.columnSpan: 1
    }
}

我希望中间矩形的宽度是其他两个矩形的总和，但它们的宽度都是相等的.

I would expect the width of the middle rectangle to be the sum of the other two rectangles, but instead they are all equal widths.

在 Layout 附加属性上使用关系绑定似乎总是会导致奇怪的绑定循环.我知道我可以只使用 Row 来代替关系绑定，但如果可能的话，我更喜欢使用 Layouts.

Using relational bindings on the Layout attached properties seems to always lead to weird binding loops. I know I could just use a Row instead with relational bindings, but I'd prefer to use Layouts if possible.

编辑

这似乎按我想要的方式工作，但我不知道为什么会这样.它的行为就像 preferredWidth 值是项目的重量一样.

This seems to work the way I want it to, but I don't know why it works. It behaves as if the preferredWidth value is the weight of the item.

import QtQuick 2.10
import QtQuick.Controls 2.3
import QtQuick.Layouts 1.3

RowLayout {
    width: 640
    height: 480

    Rectangle {
        color: "red"
        Layout.fillHeight: true
        Layout.fillWidth: true
        Layout.preferredWidth: 1
    }
    Rectangle {
        color: "#80000000"
        Layout.fillHeight: true
        Layout.fillWidth: true
        Layout.preferredWidth: 2
    }
    Rectangle {
        color: "blue"
        Layout.fillHeight: true
        Layout.fillWidth: true
        Layout.preferredWidth: 1
    }
}

推荐答案

不确定是否有意，但 Layout.preferredWidth(或 Layout.preferredHeight for ColumnLayouts)可以用作重量".当还指定 Layout.minimumWidth 时，事情就会中断，但我认为在尝试根据权重实现布局时指定最小尺寸没有多大意义.

Not sure if intentional or not but Layout.preferredWidth (or Layout.preferredHeight for ColumnLayouts) can be used as a "weight". Things break when also specifying Layout.minimumWidth, but I don't think it makes much sense to be specify minimum dimensions when trying to implement layouts in terms of weights anyways.

import QtQuick 2.10
import QtQuick.Controls 2.3
import QtQuick.Layouts 1.3

RowLayout {
    width: 640
    height: 480

    Rectangle {
        color: "red"
        Layout.fillHeight: true
        Layout.fillWidth: true
        Layout.preferredWidth: 1
    }
    Rectangle {
        color: "#80000000"
        Layout.fillHeight: true
        Layout.fillWidth: true
        Layout.preferredWidth: 2
    }
    Rectangle {
        color: "blue"
        Layout.fillHeight: true
        Layout.fillWidth: true
        Layout.preferredWidth: 1
    }
}

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