need ideas on styling a ListView

mzimmers

@JoeCFD that's not quite what I want. What I think I need is:

a Rectangle with the color I would normally use in my delegate. This would have the rounded corners. (z: 1)
another Rectangle with height = (first rectangle - (firstRectangleRadius * 2), vertically centered. This Rectangle would be colored to represent the dividers. (z: 2)
my ListView elements, with the same color as the first Rectangle. (z: 3)

But I don't know how to code this. When I try to introduce the first Rectangle, it hides my list, even if I use the z values.

JoeCFD

@mzimmers I do not think that is a good idea. Delegates are made for rows. Your round corners are global settings.
Normally you use alternative colors in listview(just like in tables) to display different rows. Pretty much standard practice. Therefore, no dividers are needed.

mzimmers

@JoeCFD OK, but isn't there some way to put the two Rectangles I mentioned behind the entire ListView?

jeremy_k

import QtQuick 2.15
import QtQuick.Window 2.15

Window {
    width: 640
    height: 480
    visible: true

    Rectangle {
        id: background
        anchors.fill: parent
        color: "blue"
    }

    ListView {
        model: 10
        anchors.centerIn: parent
        height: parent.height / 2
        width: parent.width / 2
        spacing: 2
        boundsBehavior: Flickable.StopAtBounds

        delegate: Rectangle {
            height: 10
            width: ListView.view.width
            Text {
                text: index
                anchors.centerIn: parent
            }
        }

        Rectangle {
            anchors.centerIn: parent.contentItem
            border.width: 15
            border.color: background.color
            width: parent.contentItem.width + border.width * 2
            height: parent.contentItem.height + border.width * 2
            radius: border.width * 2
            color: "transparent"
        }
    }
}

mzimmers

@jeremy_k that's getting really close to what I need. Now, regarding the background rectangle, how best to set its height to the effective height of the ListView instead of filling the Window?

Thanks!

jeremy_k

    ListView {
        id: listView
        model: 10
        anchors.centerIn: parent
        height: parent.height / 2
        width: parent.width / 2
        spacing: 2
        boundsBehavior: Flickable.StopAtBounds

        delegate: Rectangle {
            height: 10
            width: ListView.view.width
        }

        Rectangle {
            anchors.fill: overlay
            color: "blue"
            z: -1
        }
        Rectangle {
            id: overlay
            anchors.centerIn: parent.contentItem
            border.width: 15
            border.color: "blue"
            width: parent.contentItem.width + border.width * 2
            height: parent.contentItem.height + border.width * 2
            radius: border.width * 2
            color: "transparent"
        }
    }

jeremy_k

@JoeCFD said in need ideas on styling a ListView:

@mzimmers I do not think that is a good idea. Delegates are made for rows. Your round corners are global settings.

DelegateChooser, explicit use of a Loader, or hiding/showing items that are always present are all viable techniques.

Going this route, I might do something like:

ListView {
    delegate: Rectangle {
        id: d
        Image {
            source: d.index == 0 ? topCorner
                    : d.index == (d.ListView.view.count - 1) ? bottomCorner
                    : undefined
        }
}

Normally you use alternative colors in listview(just like in tables) to display different rows. Pretty much standard practice. Therefore, no dividers are needed.

That's a common design choice, but certainly not universal. Wanting a different appearance isn't unreasonable.

mzimmers

I think I got it (sorry for the lengthy code include, but I wanted to show everything):

// Roundlist.qml

import QtQuick
import QtQuick.Controls
import QtQuick.Layouts

Item {
    height: parent.height
    width: parent.width

    Rectangle {
        id: rect1
        property real rectRadius: 5.0
        property real rowHeight: 60.0
        property real rowSpacing: 3.0

        height: activityView.height + (rectRadius * 2)
        width: parent.width
        radius: rect1.rectRadius
        anchors {
            horizontalCenter: parent.horizontalCenter
            verticalCenter: parent.verticalCenter
        }
        color: 'white'

        Rectangle {
            id: rect2
            height: activityView.height
            width: rect1.width
            anchors.verticalCenter: rect1.verticalCenter
            color: mainWindow.color

            ListModel {
                id: activityModel
                ListElement { text: "aaa" }
                ListElement { text: "bbb" }
                ListElement { text: "ccc" }
                ListElement { text: "ddd" }
                ListElement { text: "eee" }
            }

            Component {
                id: activityDelegate
                Rectangle {
                    height: rect1.rowHeight
                    width: rect1.width
                    color: rect1.color
                    Text {
                        text: model.text
                        anchors {
                            horizontalCenter: parent.horizontalCenter
                            verticalCenter: parent.verticalCenter
                        }
                    }
                }
            }

            ListView {
                id: activityView
                implicitHeight: contentItem.childrenRect.height
                width: rect1.width
                spacing: rect1.rowSpacing
                clip: true
                model: activityModel
                delegate: activityDelegate

            }
        }
    }
}

It works by itself, though I'm having problem embedding it in a ColumnLayout - instead of appearing inline, it overlays the other items. It should look something like this:

But it comes out like this (please ignore the different text in the rows):

Here's how I'm trying to use it (heavily edited):

Flickable {
	id: flickable
	Layout.fillHeight: true
	Layout.fillWidth: true
	clip: true
	contentHeight: pumpStuff.height

	ColumnLayout {
		id: pumpStuff
		height: parent.height
		width: flickable.width - (scroller.width * 2)

		RowLayout {
			id: actions
		}

		Text {
			id: parameters
		}

		Roundlist {}

		RowLayout {
			id: activities
		}
	}
	ScrollBar.vertical: ScrollBar {
		id: scroller
		policy: ScrollBar.AlwaysOn//AsNeeded
	}
}

Any idea why this is happening?

Thanks...

jeremy_k

Unexpected overlapping is frequently a lack of sizing in the outermost item in a component. Eg:

Item {
    Rectangle { width: 100; height: 100 }
}

jeremy_k

@mzimmers said in need ideas on styling a ListView:

I think I got it (sorry for the lengthy code include, but I wanted to show everything):
// Roundlist.qml

import QtQuick
import QtQuick.Controls
import QtQuick.Layouts

Item {
    height: parent.height
    width: parent.width

As a style guide, never reference parent or anything outside of the component. Let the instantiator impose its constraints. Use implicitWidth and implicitHeight to specify reasonable defaults.

TomZ

Apologies if this is answered, I only read the first 2 posts of this long topic.

I worked on something very similar just last month and the QML is really simple. (full).

delegate: Item {
  height: 80
  clip: true
  Rectangle {
    // we always have the rounded circles, but if we should not see them, 
    // we move them out of the clipped area.
    height: {
         var h = 80;
         if (index == 0)
             h += 20
         if (index == MAX) // donno, bottom check.
            h += 20
        return h;
      }
      radius: 20
      y: index == 0 ? 0 : -20
  }
}

mzimmers

@jeremy_k said in need ideas on styling a ListView:

As a style guide, never reference parent or anything outside of the component. Let the instantiator impose its constraints. Use implicitWidth and implicitHeight to specify reasonable defaults.

Understood. How do you handle a case where the instantiator doesn't know the height, because (for example) there might be a variable number of rows? I'm hoping to make this reusable.

jeremy_k

@mzimmers said in need ideas on styling a ListView:

@jeremy_k said in need ideas on styling a ListView:

As a style guide, never reference parent or anything outside of the component. Let the instantiator impose its constraints. Use implicitWidth and implicitHeight to specify reasonable defaults.

Understood. How do you handle a case where the instantiator doesn't know the height, because (for example) there might be a variable number of rows? I'm hoping to make this reusable.

implicitHeight:

If width or height is not specified, an item's effective size will be determined by its implicitWidth or implicitHeight.

However, if an item is the child of a layout, the layout will determine the item's preferred size using its implicit size. In such a scenario, the explicit width or height will be ignored.

The default implicit size for most items is 0x0, however some items have an inherent implicit size which cannot be overridden, for example, Image and Text.

Setting the implicit size is useful for defining components that have a preferred size based on their content

mzimmers

@jeremy_k I see. So, this seems to work:

StackLayout {

    Home {}
    Equipment {}
    Rectangle {
        Layout.fillHeight: true
        Layout.fillWidth: true

        Roundlist {
            width: parent.width
        }
    }
}

// Roundlist.qml
Item {
    implicitHeight: activityView.height + (rect1.rectRadius * 2)
    ...

And I can live with this, though it seems weird to set the height in once place, and the width in another. Is there a cleaner way to do this?

mzimmers

@TomZ thanks for the reply. I think I prefer my implementation for my particular purposes, but I like elements of yours as well.

jeremy_k

@mzimmers said in need ideas on styling a ListView:

And I can live with this, though it seems weird to set the height in once place, and the width in another. Is there a cleaner way to do this?

The component can set implicitWidth as well, and probably should. Otherwise you might end up with a 0-width item that renders correctly on its own, but is overlapped when used in a row layout of some form.

mzimmers

@jeremy_k said in need ideas on styling a ListView:

The component can set implicitWidth as well, and probably should.

I'll do that -- just wondering whether there was any way to derive a value from the caller. But I guess the width value is just that, so...that's what I'll use. I'll just pick some value for the implicitWidth that hopefully will never get used.

Thanks for all the help...I think I'm done with this one.

jeremy_k

FontMetrics could provide an implicitWidth value based on the model's data. I presume that Text does something similar.

mzimmers

For anyone who might be reading this for an answer to their own question, I looked at @TomZ 's solution, and realized that I had a bug in my delegate - my text centering wasn't taking the rounded corners effectively adding height to the top and bottom rows. I had to alter my delegate:

Component {
    id: activityDelegate
    Rectangle {
        height: {
            var h = rect1.rowHeight;
            if (index === 0 || index === (activityModel.count - 1))
                h -= rect1.radius
            return h;
        }
        width: rect1.width
        color: rect1.color
        Text {
            text: model.parameter
            anchors {
                left: parent.left
                leftMargin: parent.height / 2
                verticalCenter: parent.verticalCenter
                verticalCenterOffset: {
                    var o = 0;
                    if (index === 0)
                        o -= (radius / 2)
                    else if (index === (activityModel.count - 1))
                        o += (radius / 2)
                    return o;
                }
            }

            font.pixelSize: 14
            font.bold: true
        }
        Styledswitch {
            id: onOff
            visible: model.switchVisible
            anchors {
                right: parent.right
                rightMargin: parent.height / 2
                verticalCenter: parent.verticalCenter
            }
        }
    }
}

As always, if this doesn't look right, please let me know, and I'll fix it.