Qt 5.7 | Qt Quick | Qt Quick Demo - StocQt | StockChart.qml Example File

Qt 5.7.1 Reference Documentation

# StockChart.qml Example File

demos/stocqt/content/StockChart.qml

      /****************************************************************************
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      ** Copyright (C) 2015 The Qt Company Ltd.
      ** Contact: http://www.qt.io/licensing/
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      ** This file is part of the examples of the Qt Toolkit.
      **
      ** $QT_BEGIN_LICENSE:BSD$
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      import QtQuick 2.0
      import "."

      Rectangle {
          id: chart
          width: 320
          height: 200

          property var stockModel: null
          property var startDate: new Date()
          property var endDate: new Date()
          property string activeChart: "year"
          property var settings
          property int gridSize: 4
          property real gridStep: gridSize ? (width - canvas.tickMargin) / gridSize : canvas.xGridStep

          function update() {
              endDate = new Date();
              if (chart.activeChart === "year") {
                  chart.startDate = new Date(chart.endDate.getFullYear() - 1,
                                             chart.endDate.getMonth(),
                                             chart.endDate.getDate());
                  chart.gridSize = 12;
              }
              else if (chart.activeChart === "month") {
                  chart.startDate = new Date(chart.endDate.getFullYear(),
                                             chart.endDate.getMonth() - 1,
                                             chart.endDate.getDate());
                  gridSize = 0;
              }
              else if (chart.activeChart === "week") {
                  chart.startDate = new Date(chart.endDate.getFullYear(),
                                             chart.endDate.getMonth(),
                                             chart.endDate.getDate() - 7);
                  gridSize = 0;
              }
              else {
                  chart.startDate = new Date(2005, 3, 25);
                  gridSize = 4;
              }

              canvas.requestPaint();
          }

          Row {
              id: activeChartRow
              anchors.left: chart.left
              anchors.right: chart.right
              anchors.top: chart.top
              anchors.topMargin: 4
              spacing: 52
              onWidthChanged: {
                  var buttonsLen = maxButton.width + yearButton.width + monthButton.width + weekButton.width;
                  var space = (width - buttonsLen) / 3;
                  spacing = Math.max(space, 10);
              }

              Button {
                  id: maxButton
                  text: "Max"
                  buttonEnabled: chart.activeChart === "max"
                  onClicked: {
                      chart.activeChart = "max";
                      chart.update();
                  }
              }
              Button {
                  id: yearButton
                  text: "Year"
                  buttonEnabled: chart.activeChart === "year"
                  onClicked: {
                      chart.activeChart = "year";
                      chart.update();
                  }
              }
              Button {
                  id: monthButton
                  text: "Month"
                  buttonEnabled: chart.activeChart === "month"
                  onClicked: {
                      chart.activeChart = "month";
                      chart.update();
                  }
              }
              Button {
                  id: weekButton
                  text: "Week"
                  buttonEnabled: chart.activeChart === "week"
                  onClicked: {
                      chart.activeChart = "week";
                      chart.update();
                  }
              }
          }

          Text {
              id: fromDate
              color: "#000000"
              font.family: Settings.fontFamily
              font.pointSize: 8
              anchors.left: parent.left
              anchors.bottom: parent.bottom
              text: "| " + startDate.toDateString()
          }

          Text {
              id: toDate
              color: "#000000"
              font.family: Settings.fontFamily
              font.pointSize: 8
              anchors.right: parent.right
              anchors.rightMargin: canvas.tickMargin
              anchors.bottom: parent.bottom
              text: endDate.toDateString() + " |"
          }

          Canvas {
              id: canvas

              // Uncomment below lines to use OpenGL hardware accelerated rendering.
              // See Canvas documentation for available options.
              // renderTarget: Canvas.FramebufferObject
              // renderStrategy: Canvas.Threaded

              anchors.top: activeChartRow.bottom
              anchors.left: parent.left
              anchors.right: parent.right
              anchors.bottom: fromDate.top

              property int pixelSkip: 1
              property int numPoints: 1
              property int tickMargin: 34

              property real xGridStep: (width - tickMargin) / numPoints
              property real yGridOffset: height / 26
              property real yGridStep: height / 12

              function drawBackground(ctx) {
                  ctx.save();
                  ctx.fillStyle = "#ffffff";
                  ctx.fillRect(0, 0, canvas.width, canvas.height);
                  ctx.strokeStyle = "#d7d7d7";
                  ctx.beginPath();
                  // Horizontal grid lines
                  for (var i = 0; i < 12; i++) {
                      ctx.moveTo(0, canvas.yGridOffset + i * canvas.yGridStep);
                      ctx.lineTo(canvas.width, canvas.yGridOffset + i * canvas.yGridStep);
                  }

                  // Vertical grid lines
                  var height = 35 * canvas.height / 36;
                  var yOffset = canvas.height - height;
                  var xOffset = 0;
                  for (i = 0; i < chart.gridSize; i++) {
                      ctx.moveTo(xOffset + i * chart.gridStep, yOffset);
                      ctx.lineTo(xOffset + i * chart.gridStep, height);
                  }
                  ctx.stroke();

                  // Right ticks
                  ctx.strokeStyle = "#666666";
                  ctx.beginPath();
                  var xStart = canvas.width - tickMargin;
                  ctx.moveTo(xStart, 0);
                  ctx.lineTo(xStart, canvas.height);
                  for (i = 0; i < 12; i++) {
                      ctx.moveTo(xStart, canvas.yGridOffset + i * canvas.yGridStep);
                      ctx.lineTo(canvas.width, canvas.yGridOffset + i * canvas.yGridStep);
                  }
                  ctx.moveTo(0, canvas.yGridOffset + 9 * canvas.yGridStep);
                  ctx.lineTo(canvas.width, canvas.yGridOffset + 9 * canvas.yGridStep);
                  ctx.closePath();
                  ctx.stroke();

                  ctx.restore();
              }

              // Returns a shortened, readable version of the potentially
              // large volume number.
              function volumeToString(value) {
                  if (value < 1000)
                      return value;
                  var exponent = parseInt(Math.log(value) / Math.log(1000));
                  var shortVal = parseFloat(parseFloat(value) / Math.pow(1000, exponent)).toFixed(1);

                  // Drop the decimal point on 3-digit values to make it fit
                  if (shortVal >= 100.0) {
                      shortVal = parseFloat(shortVal).toFixed(0);
                  }
                  return shortVal + "KMBTG".charAt(exponent - 1);
              }

              function drawScales(ctx, high, low, vol)
              {
                  ctx.save();
                  ctx.strokeStyle = "#888888";
                  ctx.font = "10px Open Sans"
                  ctx.beginPath();

                  // prices on y-axis
                  var x = canvas.width - tickMargin + 3;
                  var priceStep = (high - low) / 9.0;
                  for (var i = 0; i < 10; i += 2) {
                      var price = parseFloat(high - i * priceStep).toFixed(1);
                      ctx.text(price, x, canvas.yGridOffset + i * yGridStep - 2);
                  }

                  // volume scale
                  for (i = 0; i < 3; i++) {
                      var volume = volumeToString(vol - (i * (vol/3)));
                      ctx.text(volume, x, canvas.yGridOffset + (i + 9) * yGridStep + 10);
                  }

                  ctx.closePath();
                  ctx.stroke();
                  ctx.restore();
              }

              function drawPrice(ctx, from, to, color, price, points, highest, lowest)
              {
                  ctx.save();
                  ctx.globalAlpha = 0.7;
                  ctx.strokeStyle = color;
                  ctx.lineWidth = 3;
                  ctx.beginPath();

                  var end = points.length;

                  var range = highest - lowest;
                  if (range == 0) {
                      range = 1;
                  }

                  for (var i = 0; i < end; i += pixelSkip) {
                      var x = points[i].x;
                      var y = points[i][price];
                      var h = 9 * yGridStep;

                      y = h * (lowest - y)/range + h + yGridOffset;

                      if (i == 0) {
                          ctx.moveTo(x, y);
                      } else {
                          ctx.lineTo(x, y);
                      }
                  }
                  ctx.stroke();
                  ctx.restore();
              }

              function drawVolume(ctx, from, to, color, price, points, highest)
              {
                  ctx.save();
                  ctx.fillStyle = color;
                  ctx.globalAlpha = 0.8;
                  ctx.lineWidth = 0;
                  ctx.beginPath();

                  var end = points.length;
                  var margin = 0;

                  if (chart.activeChart === "month" || chart.activeChart === "week") {
                      margin = 8;
                      ctx.shadowOffsetX = 4;
                      ctx.shadowBlur = 3.5;
                      ctx.shadowColor = Qt.darker(color);
                  }

                  // To match the volume graph with price grid, skip drawing the initial
                  // volume of the first day on chart.
                  for (var i = 1; i < end; i += pixelSkip) {
                      var x = points[i - 1].x;
                      var y = points[i][price];
                      y = canvas.height * (y / highest);
                      y = 3 * y / 12;
                      ctx.fillRect(x, canvas.height - y + yGridOffset,
                                   canvas.xGridStep - margin, y);
                  }

                  ctx.stroke();
                  ctx.restore();
              }

              function drawError(ctx, msg)
              {
                  ctx.save();
                  ctx.strokeStyle = "#888888";
                  ctx.font = "24px Open Sans"
                  ctx.textAlign = "center"
                  ctx.shadowOffsetX = 4;
                  ctx.shadowOffsetY = 4;
                  ctx.shadowBlur = 1.5;
                  ctx.shadowColor = "#aaaaaa";
                  ctx.beginPath();

                  ctx.fillText(msg, (canvas.width - tickMargin) / 2,
                                    (canvas.height - yGridOffset - yGridStep) / 2);

                  ctx.closePath();
                  ctx.stroke();
                  ctx.restore();
              }

              onPaint: {
                  numPoints = stockModel.indexOf(chart.startDate);

                  if (chart.gridSize == 0)
                      chart.gridSize = numPoints

                  var ctx = canvas.getContext("2d");
                  ctx.globalCompositeOperation = "source-over";
                  ctx.lineWidth = 1;

                  drawBackground(ctx);

                  if (!stockModel.ready) {
                      drawError(ctx, "No data available.");
                      return;
                  }

                  var highestPrice = 0;
                  var highestVolume = 0;
                  var lowestPrice = -1;
                  var points = [];
                  for (var i = numPoints, j = 0; i >= 0 ; i -= pixelSkip, j += pixelSkip) {
                      var price = stockModel.get(i);
                      if (parseFloat(highestPrice) < parseFloat(price.high))
                          highestPrice = price.high;
                      if (parseInt(highestVolume, 10) < parseInt(price.volume, 10))
                          highestVolume = price.volume;
                      if (lowestPrice < 0 || parseFloat(lowestPrice) > parseFloat(price.low))
                          lowestPrice = price.low;
                      points.push({
                                      x: j * xGridStep,
                                      open: price.open,
                                      close: price.close,
                                      high: price.high,
                                      low: price.low,
                                      volume: price.volume
                                  });
                  }

                  if (settings.drawHighPrice)
                      drawPrice(ctx, 0, numPoints, settings.highColor, "high", points, highestPrice, lowestPrice);
                  if (settings.drawLowPrice)
                      drawPrice(ctx, 0, numPoints, settings.lowColor, "low", points, highestPrice, lowestPrice);
                  if (settings.drawOpenPrice)
                      drawPrice(ctx, 0, numPoints,settings.openColor, "open", points, highestPrice, lowestPrice);
                  if (settings.drawClosePrice)
                      drawPrice(ctx, 0, numPoints, settings.closeColor, "close", points, highestPrice, lowestPrice);

                  drawVolume(ctx, 0, numPoints, settings.volumeColor, "volume", points, highestVolume);
                  drawScales(ctx, highestPrice, lowestPrice, highestVolume);
              }
          }
      }