- Qt 5.5
- Qt Quick Extras
- Qt Quick Extras - Dashboard
- DashboardGaugeStyle.qml Example File
- Qt 5.5.1 Reference Documentation

# DashboardGaugeStyle.qml Example File

dashboard/qml/DashboardGaugeStyle.qml

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
    **
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    ** modification, are permitted provided that the following conditions are
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    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
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    import QtQuick 2.2
    import QtQuick.Controls.Styles 1.4

    CircularGaugeStyle {
        tickmarkInset: toPixels(0.04)
        minorTickmarkInset: tickmarkInset
        labelStepSize: 20
        labelInset: toPixels(0.23)

        property real xCenter: outerRadius
        property real yCenter: outerRadius
        property real needleLength: outerRadius - tickmarkInset * 1.25
        property real needleTipWidth: toPixels(0.02)
        property real needleBaseWidth: toPixels(0.06)
        property bool halfGauge: false

        function toPixels(percentage) {
            return percentage * outerRadius;
        }

        function degToRad(degrees) {
            return degrees * (Math.PI / 180);
        }

        function radToDeg(radians) {
            return radians * (180 / Math.PI);
        }

        function paintBackground(ctx) {
            if (halfGauge) {
                ctx.beginPath();
                ctx.rect(0, 0, ctx.canvas.width, ctx.canvas.height / 2);
                ctx.clip();
            }

            ctx.beginPath();
            ctx.fillStyle = "black";
            ctx.ellipse(0, 0, ctx.canvas.width, ctx.canvas.height);
            ctx.fill();

            ctx.beginPath();
            ctx.lineWidth = tickmarkInset;
            ctx.strokeStyle = "black";
            ctx.arc(xCenter, yCenter, outerRadius - ctx.lineWidth / 2, outerRadius - ctx.lineWidth / 2, 0, Math.PI * 2);
            ctx.stroke();

            ctx.beginPath();
            ctx.lineWidth = tickmarkInset / 2;
            ctx.strokeStyle = "#222";
            ctx.arc(xCenter, yCenter, outerRadius - ctx.lineWidth / 2, outerRadius - ctx.lineWidth / 2, 0, Math.PI * 2);
            ctx.stroke();

            ctx.beginPath();
            var gradient = ctx.createRadialGradient(xCenter, yCenter, outerRadius * 0.8, xCenter, yCenter, outerRadius);
            gradient.addColorStop(0, Qt.rgba(1, 1, 1, 0));
            gradient.addColorStop(0.7, Qt.rgba(1, 1, 1, 0.13));
            gradient.addColorStop(1, Qt.rgba(1, 1, 1, 1));
            ctx.fillStyle = gradient;
            ctx.arc(xCenter, yCenter, outerRadius - tickmarkInset, outerRadius - tickmarkInset, 0, Math.PI * 2);
            ctx.fill();
        }

        background: Canvas {
            onPaint: {
                var ctx = getContext("2d");
                ctx.reset();
                paintBackground(ctx);
            }

            Text {
                id: speedText
                font.pixelSize: toPixels(0.3)
                text: kphInt
                color: "white"
                horizontalAlignment: Text.AlignRight
                anchors.horizontalCenter: parent.horizontalCenter
                anchors.top: parent.verticalCenter
                anchors.topMargin: toPixels(0.1)

                readonly property int kphInt: control.value
            }
            Text {
                text: "km/h"
                color: "white"
                font.pixelSize: toPixels(0.09)
                anchors.top: speedText.bottom
                anchors.horizontalCenter: parent.horizontalCenter
            }
        }

        needle: Canvas {
            implicitWidth: needleBaseWidth
            implicitHeight: needleLength

            property real xCenter: width / 2
            property real yCenter: height / 2

            onPaint: {
                var ctx = getContext("2d");
                ctx.reset();

                ctx.beginPath();
                ctx.moveTo(xCenter, height);
                ctx.lineTo(xCenter - needleBaseWidth / 2, height - needleBaseWidth / 2);
                ctx.lineTo(xCenter - needleTipWidth / 2, 0);
                ctx.lineTo(xCenter, yCenter - needleLength);
                ctx.lineTo(xCenter, 0);
                ctx.closePath();
                ctx.fillStyle = Qt.rgba(0.66, 0, 0, 0.66);
                ctx.fill();

                ctx.beginPath();
                ctx.moveTo(xCenter, height)
                ctx.lineTo(width, height - needleBaseWidth / 2);
                ctx.lineTo(xCenter + needleTipWidth / 2, 0);
                ctx.lineTo(xCenter, 0);
                ctx.closePath();
                ctx.fillStyle = Qt.lighter(Qt.rgba(0.66, 0, 0, 0.66));
                ctx.fill();
            }
        }

        foreground: null
    }