Qt 5.11 | Qt Quick | Qt Quick Demo - StocQt | StockChart.qml Example File

Qt 5.11.3 Reference Documentation

# StockChart.qml Example File

demos/stocqt/content/StockChart.qml

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      import QtQuick 2.0
      import QtQuick.Layouts 1.1
      import "."

      Rectangle {
          id: chart

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

          function update() {
              endDate = new Date(stockModel.newest);
              if (chart.activeChart === "month") {
                  chart.startDate = new Date(stockModel.newest.getFullYear(),
                                             stockModel.newest.getMonth() - 1,
                                             stockModel.newest.getDate());
                  gridSize = 4;
              }
              else if (chart.activeChart === "quarter") {
                  chart.startDate = new Date(stockModel.newest.getFullYear(),
                                             stockModel.newest.getMonth() - 3,
                                             stockModel.newest.getDate());
                  gridSize = 3;
              }
              else if (chart.activeChart === "halfyear") {
                  chart.startDate = new Date(stockModel.newest.getFullYear(),
                                             stockModel.newest.getMonth() - 6,
                                             stockModel.newest.getDate());
                  gridSize = 6;
              }
              else {
                  chart.startDate = new Date(stockModel.newest.getFullYear(),
                                             stockModel.newest.getMonth(),
                                             stockModel.newest.getDate() - 7);
                  gridSize = 0;
              }

              canvas.requestPaint();
          }

          GridLayout {
              anchors.fill: parent
              columns: 6
              rows: 3
              columnSpacing: 4
              Button {
                  id: weekButton
                  text: "Week"
                  buttonEnabled: chart.activeChart === "week"
                  onClicked: {
                      chart.activeChart = "week";
                      chart.update();
                  }
              }

              Button {
                  id: monthButton
                  text: "Month"
                  buttonEnabled: chart.activeChart === "month"
                  onClicked: {
                      chart.activeChart = "month";
                      chart.update();
                  }
              }

              Button {
                  id: quarterlyButton
                  text: "3 Months"
                  buttonEnabled: chart.activeChart === "quarter"
                  onClicked: {
                      chart.activeChart = "quarter";
                      chart.update();
                  }
              }

              Button {
                  id: halfYearlyButton
                  text: "6 Months"
                  buttonEnabled: chart.activeChart === "halfyear"
                  onClicked: {
                      chart.activeChart = "halfyear";
                      chart.update();
                  }
              }

              Canvas {
                  id: canvas
                  Layout.fillWidth: true
                  Layout.fillHeight: true
                  Layout.columnSpan: 6
                  // Uncomment below lines to use OpenGL hardware accelerated rendering.
                  // See Canvas documentation for available options.
                  // renderTarget: Canvas.FramebufferObject
                  // renderStrategy: Canvas.Threaded

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

                  property real xGridStep: (canvas.width - tickMargin) / numPoints
                  property real yGridOffset: canvas.height / 26
                  property real yGridStep: canvas.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 = numPoints > 200 ? 1 : 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);
                  }
              }

              Text {
                  id: fromDate
                  color: "#000000"
                  font.family: Settings.fontFamily
                  font.pointSize: 8
                  Layout.alignment: Qt.AlignLeft
                  text: "| " + startDate.toDateString()
              }
              Text {
                  id: toDate
                  color: "#000000"
                  font.family: Settings.fontFamily
                  font.pointSize: 8
                  Layout.alignment: Qt.AlignRight
                  Layout.rightMargin: canvas.tickMargin
                  Layout.columnSpan: 5
                  text: endDate.toDateString() + " |"
              }
          }
      }