- Qt 5.5
- Qt Quick
- Qt Quick Demo - StocQt
- StockChart.qml Example File
- Qt 5.5.1 Reference Documentation

# StockChart.qml Example File

demos/stocqt/content/StockChart.qml

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
    **
    ** "Redistribution and use in source and binary forms, with or without
    ** modification, are permitted provided that the following conditions are
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    **     the documentation and/or other materials provided with the
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    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
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    ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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    import QtQuick 2.0

    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: "Open Sans"
            font.pointSize: 8
            anchors.left: parent.left
            anchors.bottom: parent.bottom
            text: "| " + startDate.toDateString()
        }

        Text {
            id: toDate
            color: "#000000"
            font.family: "Open Sans"
            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();
            }

            onPaint: {
                if (!stockModel.ready) {
                    return;
                }

                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);

                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);
            }
        }
    }