StockChart.qml Example File

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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() + " |"
        }
    }
}