Layouter, listvyer och kort

Räkna ut de olika sätten att placera saker på en sida

Placera ut ditt innehåll

Nu när vi förstår hur sidor fungerar, är det dags att lägga till saker i våran. Vi går igenom ett antal viktiga layoutkomponenter och element som är användbara när vi konstruerar vårt program.

Bli inte rädd för de stora kodstyckena. Vi går igenom allting som vi inte har täckt tidigare, och i slutet av avsnittet kommer du att ha ett snyggt program.

Listvyer

If you've ever used Discover, NeoChat, or Plasma's System Settings, you will have come across a ListView. Quite simply, it lets you display data on a list.

Kirigami.CardsListView {
    id: cardsView
    model: kountdownModel
    delegate: kountdownDelegate
}

That seems cryptic, but don't worry. Let's start from the beginning.

We add this component inside our Kirigami.ScrollablePage from the last tutorial.

We're using Kirigami.CardsListView , which is a ListView that allows us to easily display cards in a list. However, ListViews are made to show data taken from a model - to automatically populate itself from a set of data that we point it to. That's where the model property comes in: in this example, it's pointing to kountdownModel.

Modell

ListModel {
    id: kountdownModel
    // Varje ListElement är ett element i listan, och innehåller information
    ListElement {
        name: "Dog birthday!!"
        description: "Big doggo birthday blowout."
        date: 100
    }
}

We add our kountdownModel inside our Kirigami.ApplicationWindow from the last tutorial.

A model defines the way that a data entry is structured. Our kountdownModel will consist of only one element for now. By looking at our ListElement above, we can see how the data of our kountdownModel are structured: it contains a name, a description, and a date. This isn't set in stone, and you may have different sorts of data in your model. The first two are just strings, and the third is a number we're using as a placeholder.

Modeller är också användbara på det sätt de kan ändras genom användning av flera metoder. Några viktiga är:

Delegera

While our kountdownModel contains the data that will be displayed, our kountdownDelegate will handle how the data will be displayed in the ListView. Kirigami.CardsListView was designed to display card-type delegates, and we have indeed used a Kirigami.AbstractCard element as our delegate in the excerpt above.

Delegater får automatiskt egenskaperna i listelementen som vi har angivit i vår modell. Vi kan därför bara referera till egenskaperna name, description och date för våra listelement som om de var konventionella variabler inne i vår delegat.

Bygga vårt delegatkort

The Component that will represent our delegate can be added inside our Kirigami.ApplicationWindow . We will then proceed by checking what each part of our delegate component does.

Component {
    id: kountdownDelegate
    Kirigami.AbstractCard {
        contentItem: Item {
            // implicitWidth/Height definierar den naturliga bredd/höjd för ett objekt om ingen
            // bredd eller höjd anges. Inställningen nedan definierar en komponents föredragna
            // storlek baserat på dess innehåll
            implicitWidth: delegateLayout.implicitWidth
            implicitHeight: delegateLayout.implicitHeight
            GridLayout {
                id: delegateLayout
                anchors {
                    left: parent.left
                    top: parent.top
                    right: parent.right
                }
                rowSpacing: Kirigami.Units.largeSpacing
                columnSpacing: Kirigami.Units.largeSpacing
                columns: root.wideScreen ? 4 : 2

                Kirigami.Heading {
                    Layout.fillHeight: true
                    level: 1
                    text: (date < 100000) ? date : i18n("%1 days", Math.round((date-Date.now())/86400000))
                }

                ColumnLayout {
                    Kirigami.Heading {
                        Layout.fillWidth: true
                        level: 2
                        text: name
                    }
                    Kirigami.Separator {
                        Layout.fillWidth: true
                        visible: description.length > 0
                    }
                    Controls.Label {
                        Layout.fillWidth: true
                        wrapMode: Text.WordWrap
                        text: description
                        visible: description.length > 0
                    }
                }
                Controls.Button {
                    Layout.alignment: Qt.AlignRight
                    Layout.columnSpan: 2
                    text: i18n("Edit")
                    // onClicked: snart klart!
                }
            }
        }
    }
}

implicitWidth och implicitHeight

The first part we will take a look at is how to manage the width and height of our component:

Kirigami.AbstractCard {
    contentItem: Item {
        implicitWidth: delegateLayout.implicitWidth
        implicitHeight: delegateLayout.implicitHeight
        GridLayout {
            id: delegateLayout
            ...
        }
    }
}

Looking at our Kirigami.AbstractCard , the first properties we set are implicitWidth and implicitHeight. We have set these to the delegateLayout.implicitWidth and delegateLayout.implicitHeight, i.e. the implicitWidth and implicitHeight of the GridLayout element. Implicit widths and heights are properties that are set as a default, i.e. if there is no explicit width or height set for these components. We have therefore set the implicitWidth and implicitHeight of our Kirigami.AbstractCard to that of the GridLayout below to ensure it does not spill out of the card.

Layouter

The GridLayout is inside the Item component we have provided for the property contentItem. This is the Item that contains what will be displayed in your card.

We also need to choose a layout for our components so that they don't just pile on top of each other. There are three main types that we can choose from:

  • ColumnLayout lays out your components vertically, in a single column
  • RowLayout lays out your components horizontally, in a single row
  • GridLayout lays out your components in a grid with a composition of your choosing

With ColumnLayout and RowLayout, all we have to do is write our components inside the Layout component. As you can see, we went with a GridLayout, which entails a bit more handiwork.

GridLayout {
    id: delegateLayout
    anchors {
        left: parent.left
        top: parent.top
        right: parent.right
    }
    rowSpacing: Kirigami.Units.largeSpacing
    columnSpacing: Kirigami.Units.largeSpacing
    columns: root.wideScreen ? 4 : 2
    ...
}

The first thing you see is our anchors. QtQuick's anchoring system provides a useful way of making sure your components are positioned in certain parts of a parent component. We have anchored our GridLayout to the left, top, and right of the parent card, ensuring our content stretches across the whole card.

Next we specify the spacing between the rows and columns within our grid, so that our components don't bunch up. Kirigami provides a number of handy predefined units to use for this purpose:

Kirigami-enhetBildpunkter
smallSpacing4 bildpunkter
largeSpacing8 bildpunkter
gridUnit18 bildpunkter

As you might remember, root is the id of our Kirigami.ApplicationWindow . It provides the wideScreen property, used to determine whether the current device screen is a widescreen (i.e. a computer monitor or a phone in landscape). We use a ternary conditional here to vary the number of columns in our grid depending on the screen we are using: if it's a widescreen, the grid will have 4 columns, else it will have 2.

Inner components

Vi skulle kunna bara skapa tre beteckningar inne i vår delegatkomponent och låta det vara nog. Men det skulle inte se särskilt snyggt ut.

GridLayout {
    ...
    Kirigami.Heading {
        Layout.fillHeight: true
        level: 1
        text: date
    }

    ColumnLayout {
        Kirigami.Heading {
            Layout.fillWidth: true
            level: 2
            text: name
        }

        Kirigami.Separator {
            Layout.fillWidth: true
            visible: description.length > 0
        }

        Controls.Label {
            Layout.fillWidth: true
            wrapMode: Text.WordWrap
            text: description
            visible: description.length > 0
        }
    }

    Controls.Button {
        Layout.alignment: Qt.AlignRight
        Layout.columnSpan: 2
        text: i18n("Edit")
    }
}

Screenshot showing how a Card looks like

  • Left, Kirigami.Heading : uses the ListElement's date as a level 1 heading.
  • Middle, ColumnLayout: has a Kirigami.Heading that displays the task name; a Kirigami.Separator , which provides the horizontal line; and a Controls.Label , that displays a task's optional description. The latter two components have a visible property, which checks if the description is empty or not and displays the components depending on the result of description.length > 0.
  • Right, Controls.Button : a button that will do something... soon!

Vårt program så långt

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import QtQuick 2.15
import QtQuick.Controls 2.15 as Controls
import QtQuick.Layouts 1.15
import org.kde.kirigami 2.20 as Kirigami

Kirigami.ApplicationWindow {
    id: root

    title: i18nc("@title:window", "Day Kountdown")

    // ListModel needed for ListView, contains elements to be displayed
    ListModel {
        id: kountdownModel
        // Each ListElement is an element on the list, containing information
        ListElement {
            name: "Dog birthday!!"
            description: "Big doggo birthday blowout."
            date: 100
        }
    }

    Component {
        id: kountdownDelegate
        Kirigami.AbstractCard {
            contentItem: Item {
                implicitWidth: delegateLayout.implicitWidth
                implicitHeight: delegateLayout.implicitHeight
                GridLayout {
                    id: delegateLayout
                    anchors {
                        left: parent.left
                        top: parent.top
                        right: parent.right
                    }
                    rowSpacing: Kirigami.Units.largeSpacing
                    columnSpacing: Kirigami.Units.largeSpacing
                    columns: root.wideScreen ? 4 : 2

                    Kirigami.Heading {
                        // Heading will be as tall as possible while respecting constraints
                        Layout.fillHeight: true
                        // Level determines the size of the heading
                        level: 1
                        text: date
                    }

                    // Layout for positioning elements vertically
                    ColumnLayout {
                        Kirigami.Heading {
                            Layout.fillWidth: true
                            level: 2
                            text: name
                        }
                        // Horizontal rule
                        Kirigami.Separator {
                            Layout.fillWidth: true
                            visible: description.length > 0
                        }
                        // Labels contain text
                        Controls.Label {
                            Layout.fillWidth: true
                            // Word wrap makes text stay within box and shift with size
                            wrapMode: Text.WordWrap
                            text: description
                            visible: description.length > 0
                        }
                    }
                    Controls.Button {
                        Layout.alignment: Qt.AlignRight
                        // Column spanning within grid layout (vertically in this case)
                        Layout.columnSpan: 2
                        text: i18n("Edit")
                        //onClicked: to be done...
                    }
                }
            }
        }
    }

    pageStack.initialPage: Kirigami.ScrollablePage {
        title: i18nc("@title", "Kountdown")

        // List view for card elements
        Kirigami.CardsListView {
            id: cardsView
            // Model contains info to be displayed
            model: kountdownModel
            // Delegate is how the information will be presented in the ListView
            delegate: kountdownDelegate
        }
    }
}

Screenshot of the app appearance after completing this lesson

Så där är vårt grundläggande kort.

Med de här stegen har vi nu lagt grundstenen för att lägga till alla funktioner i vårt program.