DashboardGaugeStyle.qml Example File

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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, 0, xCenter, yCenter, outerRadius * 1.5);
         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
 }