Warning, /plasma/kinfocenter/Modules/energy/ui/Graph.qml is written in an unsupported language. File is not indexed.

 /*
  * SPDX-FileCopyrightText: 2015 David Edmundson <david@davidedmundson.co.uk>
  *
  * SPDX-License-Identifier: LGPL-2.1-or-later
  *
  */
 
 import QtQuick 2.3
 
 /**
  * We need to draw a graph, all other libs are not suitable as we are basically
  * a connected scatter plot with non linear X spacing.
  * Currently this is not available in kdeclarative nor kqtquickcharts
  *
  * We only paint once, so canvas is fast enough for our purposes.
  * It is designed to look identical to those in ksysguard.
  */
 
 Canvas
 {
     width: 500
     height: 500
     id: canvas
     antialiasing: true
 
     property int xPadding: 45
     property int yPadding: 40
 
     property var data //expect an array of QPointF
 
     property real yMax: 100
     property real xMax: 100
     property real yMin: 0
     property real xMin: 0
     property real yStep: 20
 
     property string yUnits: ""
     property string xUnits: ""
 
     property real xDuration: 3600
     property real xDivisions: 6
     property real xDivisionWidth: 600000
     property real xTicksAt: xTicksAtDontCare
 
     //internal
 
     property real plotWidth: width - xPadding * 1.5
     property real plotHeight: height - yPadding * 2
 
     onDataChanged: {
         canvas.requestPaint();
     }
 
     //take a QPointF
     function scalePoint(plot, currentUnixTime) {
         var scaledX = (plot.x - (currentUnixTime / 1000 - xDuration)) / xDuration * plotWidth;
         var scaledY = (plot.y - yMin)  * plotHeight / (yMax - yMin);
 
         return Qt.point(xPadding + scaledX,
             height - yPadding - scaledY);
     }
 
     SystemPalette {
         id: palette;
         colorGroup: SystemPalette.Active
     }
 
 
     onPaint: {
         var c = canvas.getContext('2d');
 
         c.clearRect(0,0, width, height)
 
         //draw the background
         c.fillStyle = palette.base
         c.fillRect(xPadding, yPadding, plotWidth, plotHeight);
 
         //reset for fonts and stuff
         c.fillStyle = palette.text
 
         //Draw the lines
 
         c.lineWidth = 1;
         c.lineJoin = 'round';
         c.lineCap = 'round';
         c.strokeStyle = 'rgba(255, 0, 0, 1)';
         var gradient = c.createLinearGradient(0,0,0,height);
         gradient.addColorStop(0, 'rgba(255, 0, 0, 0.2)');
         gradient.addColorStop(1, 'rgba(255, 0, 0, 0.05)');
         c.fillStyle = gradient;
 
         // For scaling
         var currentUnixTime = Date.now()
         var xMinUnixTime = currentUnixTime - xDuration * 1000
 
         // Draw the line graph
         c.beginPath();
 
         var index = 0
 
         while ((index < data.length - 1) && (data[index].x < (xMinUnixTime / 1000))) {
             index++
         }
 
         var firstPoint = scalePoint(data[index], currentUnixTime)
         c.moveTo(firstPoint.x, firstPoint.y)
 
         var point
         for (var i = index + 1; i < data.length; i++) {
             if (data[i].x > (xMinUnixTime / 1000)) {
                 point = scalePoint(data[i], currentUnixTime)
                 c.lineTo(point.x, point.y)
             }
         }
             
         c.stroke();
         c.strokeStyle = 'rgba(0, 0, 0, 0)';
         c.lineTo(point.x, height - yPadding);
         c.lineTo(firstPoint.x, height - yPadding);
         c.fill();
 
         c.closePath()
 
         // Draw the frame on top
 
         //draw an outline
         c.strokeStyle = 'rgba(0,50,0,0.02)';
         c.lineWidth = 1;
         c.rect(xPadding - 1, yPadding - 1, plotWidth + 2, plotHeight + 2);
 
         // Draw the Y value texts
         c.fillStyle = palette.text;
         c.textAlign = "right"
         c.textBaseline = "middle";
         for(var i = 0; i <=  yMax; i += yStep) {
             var y = scalePoint(Qt.point(0,i)).y;
 
             c.fillText(i + canvas.yUnits, xPadding - 10, y);
 
             //grid line
             c.moveTo(xPadding, y)
             c.lineTo(plotWidth + xPadding, y)
         }
         c.stroke()
 
         // Draw the X value texts
         c.textAlign = "center"
         c.lineWidth = 1
         c.strokeStyle = 'rgba(%1, %2, %3, 0.15)'.arg(palette.text.r * 255).arg(palette.text.g * 255).arg(palette.text.b * 255)
 
         var xDivisions = xDuration / xDivisionWidth * 1000
         var xGridDistance = plotWidth / xDivisions
         var xTickPos
         var xTickDateTime
         var xTickDateStr
         var xTickTimeStr
 
         var currentDateTime = new Date()
         var lastDateStr = currentDateTime.toLocaleDateString(Qt.locale(), Locale.ShortFormat)
 
         var hours = currentDateTime.getHours()
         var minutes = currentDateTime.getMinutes()
         var seconds = currentDateTime.getSeconds()
        
         var diff
 
         switch (xTicksAt) {
             case xTicksAtTwelveOClock:
                 diff = ((hours - 12) * 60 * 60 + minutes * 60 + seconds)
                 break
             case xTicksAtFullHour:
                 diff = (minutes * 60 + seconds)
                 break
             case xTicksAtFullSecondHour:
                 diff = (minutes * 60 + seconds)
                 break
             case xTicksAtHalfHour:
                 diff = ((minutes - 30) * 60 + seconds)
                 break
             case xTicksAtTenMinutes:
                 diff = ((minutes % 10) * 60 + seconds)
                 break
             default:
                 diff = 0
         }
 
         var xGridOffset = plotWidth * (diff / xDuration)
         var dateChanged = false 
 
         var dashedLines = 50
         var dashedLineLength = plotHeight / dashedLines
         var dashedLineDutyCycle
 
         for (var i = xDivisions; i >= -1; i--) {
             xTickPos = i * xGridDistance + xPadding - xGridOffset
 
             if ((xTickPos > xPadding) && (xTickPos < plotWidth + xPadding)) 
             {
                 xTickDateTime = new Date(currentUnixTime - (xDivisions - i) * xDivisionWidth - diff * 1000)
                 xTickDateStr = xTickDateTime.toLocaleDateString(Qt.locale(), Locale.ShortFormat)
                 xTickTimeStr = xTickDateTime.toLocaleTimeString(Qt.locale(), Locale.ShortFormat)
 
                 if (lastDateStr != xTickDateStr) {
                     dateChanged = true
                 }
  
                 if  ((i % 2 == 0) || (xDivisions < 10))
                 {
                     // Display the time
                     c.fillText(xTickTimeStr, xTickPos, canvas.height - yPadding / 2)
     
                     // If the date has changed and is not the current day in a <= 24h graph, display it
                     // Always display the date for 48h and 1 week graphs
                     if (dateChanged || (xDuration > (60*60*48))) {
                         c.fillText(xTickDateStr, xTickPos, canvas.height - yPadding / 4)
                         dateChanged = false
                     }
 
                     // Tick markers
                     c.moveTo(xTickPos, canvas.height - yPadding)
                     c.lineTo(xTickPos, canvas.height - (yPadding * 4) / 5)
         
                     dashedLineDutyCycle = 0.5
                 } else {
                     dashedLineDutyCycle = 0.1
                 }
         
                 for (var j = 0; j < dashedLines; j++) { 
                     c.moveTo(xTickPos, yPadding + j * dashedLineLength)
                     c.lineTo(xTickPos, yPadding + j * dashedLineLength + dashedLineDutyCycle * dashedLineLength)
                 }
                lastDateStr = xTickDateStr
             }
         }
         c.stroke()
     }
 }