// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0

#include "stylehelper.h"

#include "theme/theme.h"
#include "hostosinfo.h"
#include "qtcassert.h"

#include <QApplication>
#include <QCommonStyle>
#include <QFileInfo>
#include <QFontDatabase>
#include <QPainter>
#include <QPixmapCache>
#include <QStyleOption>
#include <QWindow>

#include <qmath.h>

// Clamps float color values within (0, 255)
static int clamp(float x)
{
    const int val = x > 255 ? 255 : static_cast<int>(x);
    return val < 0 ? 0 : val;
}

// Clamps float color values within (0, 255)
/*
static int range(float x, int min, int max)
{
    int val = x > max ? max : x;
    return val < min ? min : val;
}
*/

namespace Utils {

QColor StyleHelper::mergedColors(const QColor &colorA, const QColor &colorB, int factor)
{
    const int maxFactor = 100;
    QColor tmp = colorA;
    tmp.setRed((tmp.red() * factor) / maxFactor + (colorB.red() * (maxFactor - factor)) / maxFactor);
    tmp.setGreen((tmp.green() * factor) / maxFactor + (colorB.green() * (maxFactor - factor)) / maxFactor);
    tmp.setBlue((tmp.blue() * factor) / maxFactor + (colorB.blue() * (maxFactor - factor)) / maxFactor);
    return tmp;
}

QColor StyleHelper::alphaBlendedColors(const QColor &colorA, const QColor &colorB)
{
    const int alpha = colorB.alpha();
    const int antiAlpha = 255 - alpha;

    return QColor(
                (colorA.red() * antiAlpha + colorB.red() * alpha) / 255,
                (colorA.green() * antiAlpha + colorB.green() * alpha) / 255,
                (colorA.blue() * antiAlpha + colorB.blue() * alpha) / 255
                );
}

qreal StyleHelper::sidebarFontSize()
{
    return HostOsInfo::isMacHost() ? 10 : 7.5;
}

QColor StyleHelper::notTooBrightHighlightColor()
{
    QColor highlightColor = QApplication::palette().highlight().color();
    if (0.5 * highlightColor.saturationF() + 0.75 - highlightColor.valueF() < 0)
        highlightColor.setHsvF(highlightColor.hsvHueF(), 0.1 + highlightColor.saturationF() * 2.0, highlightColor.valueF());
    return highlightColor;
}


QPalette StyleHelper::sidebarFontPalette(const QPalette &original)
{
    QPalette palette = original;
    const QColor textColor = creatorTheme()->color(Theme::ProgressBarTitleColor);
    palette.setColor(QPalette::WindowText, textColor);
    palette.setColor(QPalette::Text, textColor);
    return palette;
}

QColor StyleHelper::panelTextColor(bool lightColored)
{
    if (!lightColored)
        return Qt::white;
    else
        return Qt::black;
}

// Invalid by default, setBaseColor needs to be called at least once
QColor StyleHelper::m_baseColor;
QColor StyleHelper::m_requestedBaseColor;

QColor StyleHelper::baseColor(bool lightColored)
{
    static const QColor windowColor = QApplication::palette().color(QPalette::Window);
    static const bool windowColorAsBase = creatorTheme()->flag(Theme::WindowColorAsBase);

    return (lightColored || windowColorAsBase) ? windowColor : m_baseColor;
}

QColor StyleHelper::highlightColor(bool lightColored)
{
    QColor result = baseColor(lightColored);
    if (!lightColored)
        result.setHsv(result.hue(),
                  clamp(result.saturation()),
                  clamp(result.value() * 1.16));
    else
        result.setHsv(result.hue(),
                  clamp(result.saturation()),
                  clamp(result.value() * 1.06));
    return result;
}

QColor StyleHelper::shadowColor(bool lightColored)
{
    QColor result = baseColor(lightColored);
    result.setHsv(result.hue(),
                  clamp(result.saturation() * 1.1),
                  clamp(result.value() * 0.70));
    return result;
}

QColor StyleHelper::borderColor(bool lightColored)
{
    QColor result = baseColor(lightColored);
    result.setHsv(result.hue(),
                  result.saturation(),
                  result.value() / 2);
    return result;
}

QColor StyleHelper::toolBarBorderColor()
{
    const QColor base = baseColor();
    return QColor::fromHsv(base.hue(),
                           base.saturation() ,
                           clamp(base.value() * 0.80f));
}

// We try to ensure that the actual color used are within
// reasonalbe bounds while generating the actual baseColor
// from the users request.
void StyleHelper::setBaseColor(const QColor &newcolor)
{
    m_requestedBaseColor = newcolor;

    const QColor themeBaseColor = creatorTheme()->color(Theme::PanelStatusBarBackgroundColor);
    const QColor defaultBaseColor = QColor(DEFAULT_BASE_COLOR);
    QColor color;

    if (defaultBaseColor == newcolor) {
        color = themeBaseColor;
    } else {
        const int valueDelta = (newcolor.value() - defaultBaseColor.value()) / 3;
        const int value = qBound(0, themeBaseColor.value() + valueDelta, 255);

        color.setHsv(newcolor.hue(),
                     newcolor.saturation() * 0.7,
                     value);
    }

    if (color.isValid() && color != m_baseColor) {
        m_baseColor = color;
        const QList<QWidget *> widgets = QApplication::topLevelWidgets();
        for (QWidget *w : widgets)
            w->update();
    }
}

static void verticalGradientHelper(QPainter *p, const QRect &spanRect, const QRect &rect, bool lightColored)
{
    QColor highlight = StyleHelper::highlightColor(lightColored);
    QColor shadow = StyleHelper::shadowColor(lightColored);
    QLinearGradient grad(spanRect.topRight(), spanRect.topLeft());
    grad.setColorAt(0, highlight.lighter(117));
    grad.setColorAt(1, shadow.darker(109));
    p->fillRect(rect, grad);

    QColor light(255, 255, 255, 80);
    p->setPen(light);
    p->drawLine(rect.topRight() - QPoint(1, 0), rect.bottomRight() - QPoint(1, 0));
    QColor dark(0, 0, 0, 90);
    p->setPen(dark);
    p->drawLine(rect.topLeft(), rect.bottomLeft());
}

void StyleHelper::verticalGradient(QPainter *painter, const QRect &spanRect, const QRect &clipRect, bool lightColored)
{
    if (StyleHelper::usePixmapCache()) {

        QColor keyColor = baseColor(lightColored);
        const QString key = QString::asprintf("mh_vertical %d %d %d %d %d",
            spanRect.width(), spanRect.height(), clipRect.width(),
            clipRect.height(), keyColor.rgb());

        QPixmap pixmap;
        if (!QPixmapCache::find(key, &pixmap)) {
            pixmap = QPixmap(clipRect.size());
            QPainter p(&pixmap);
            QRect rect(0, 0, clipRect.width(), clipRect.height());
            verticalGradientHelper(&p, spanRect, rect, lightColored);
            p.end();
            QPixmapCache::insert(key, pixmap);
        }

        painter->drawPixmap(clipRect.topLeft(), pixmap);
    } else {
        verticalGradientHelper(painter, spanRect, clipRect, lightColored);
    }
}

static void horizontalGradientHelper(QPainter *p, const QRect &spanRect, const
QRect &rect, bool lightColored)
{
    if (lightColored) {
        QLinearGradient shadowGradient(rect.topLeft(), rect.bottomLeft());
        shadowGradient.setColorAt(0, 0xf0f0f0);
        shadowGradient.setColorAt(1, 0xcfcfcf);
        p->fillRect(rect, shadowGradient);
        return;
    }

    QColor base = StyleHelper::baseColor(lightColored);
    QColor highlight = StyleHelper::highlightColor(lightColored);
    QColor shadow = StyleHelper::shadowColor(lightColored);
    QLinearGradient grad(rect.topLeft(), rect.bottomLeft());
    grad.setColorAt(0, highlight.lighter(120));
    if (rect.height() == StyleHelper::navigationWidgetHeight()) {
        grad.setColorAt(0.4, highlight);
        grad.setColorAt(0.401, base);
    }
    grad.setColorAt(1, shadow);
    p->fillRect(rect, grad);

    QLinearGradient shadowGradient(spanRect.topLeft(), spanRect.topRight());
        shadowGradient.setColorAt(0, QColor(0, 0, 0, 30));
    QColor lighterHighlight;
    lighterHighlight = highlight.lighter(130);
    lighterHighlight.setAlpha(100);
    shadowGradient.setColorAt(0.7, lighterHighlight);
        shadowGradient.setColorAt(1, QColor(0, 0, 0, 40));
    p->fillRect(rect, shadowGradient);
}

void StyleHelper::horizontalGradient(QPainter *painter, const QRect &spanRect, const QRect &clipRect, bool lightColored)
{
    if (StyleHelper::usePixmapCache()) {

        QColor keyColor = baseColor(lightColored);
        const QString key = QString::asprintf("mh_horizontal %d %d %d %d %d %d",
            spanRect.width(), spanRect.height(), clipRect.width(),
            clipRect.height(), keyColor.rgb(), spanRect.x());

        QPixmap pixmap;
        if (!QPixmapCache::find(key, &pixmap)) {
            pixmap = QPixmap(clipRect.size());
            QPainter p(&pixmap);
            QRect rect = QRect(0, 0, clipRect.width(), clipRect.height());
            horizontalGradientHelper(&p, spanRect, rect, lightColored);
            p.end();
            QPixmapCache::insert(key, pixmap);
        }

        painter->drawPixmap(clipRect.topLeft(), pixmap);

    } else {
        horizontalGradientHelper(painter, spanRect, clipRect, lightColored);
    }
}

static void menuGradientHelper(QPainter *p, const QRect &spanRect, const QRect &rect)
{
    QLinearGradient grad(spanRect.topLeft(), spanRect.bottomLeft());
    QColor menuColor = StyleHelper::mergedColors(StyleHelper::baseColor(), QColor(244, 244, 244), 25);
    grad.setColorAt(0, menuColor.lighter(112));
    grad.setColorAt(1, menuColor);
    p->fillRect(rect, grad);
}

void StyleHelper::drawArrow(QStyle::PrimitiveElement element, QPainter *painter, const QStyleOption *option)
{
    if (option->rect.width() <= 1 || option->rect.height() <= 1)
        return;

    const qreal devicePixelRatio = painter->device()->devicePixelRatio();
    const bool enabled = option->state & QStyle::State_Enabled;
    QRect r = option->rect;
    int size = qMin(r.height(), r.width());
    QPixmap pixmap;
    const QString pixmapName = QString::asprintf("StyleHelper::drawArrow-%d-%d-%d-%f",
                       element, size, enabled, devicePixelRatio);
    if (!QPixmapCache::find(pixmapName, &pixmap)) {
        QImage image(size * devicePixelRatio, size * devicePixelRatio, QImage::Format_ARGB32_Premultiplied);
        image.fill(Qt::transparent);
        QPainter painter(&image);

        QStyleOption tweakedOption(*option);
        tweakedOption.state = QStyle::State_Enabled;

        auto drawCommonStyleArrow = [&tweakedOption, element, &painter](const QRect &rect, const QColor &color) -> void
        {
            static const QCommonStyle* const style = qobject_cast<QCommonStyle*>(QApplication::style());
            if (!style)
                return;

            // Workaround for QTCREATORBUG-28470
            QPalette pal = tweakedOption.palette;
            pal.setBrush(QPalette::Base, pal.text()); // Base and Text differ, causing a detachment.
                                                      // Inspired by tst_QPalette::cacheKey()
            pal.setColor(QPalette::ButtonText, color.rgb());

            tweakedOption.palette = pal;
            tweakedOption.rect = rect;
            painter.setOpacity(color.alphaF());
            style->QCommonStyle::drawPrimitive(element, &tweakedOption, &painter);
        };

        if (!enabled) {
            drawCommonStyleArrow(image.rect(), creatorTheme()->color(Theme::IconsDisabledColor));
        } else {
            if (creatorTheme()->flag(Theme::ToolBarIconShadow))
                drawCommonStyleArrow(image.rect().translated(0, devicePixelRatio), toolBarDropShadowColor());
            drawCommonStyleArrow(image.rect(), creatorTheme()->color(Theme::IconsBaseColor));
        }
        painter.end();
        pixmap = QPixmap::fromImage(image);
        pixmap.setDevicePixelRatio(devicePixelRatio);
        QPixmapCache::insert(pixmapName, pixmap);
    }
    int xOffset = r.x() + (r.width() - size)/2;
    int yOffset = r.y() + (r.height() - size)/2;
    painter->drawPixmap(xOffset, yOffset, pixmap);
}

void StyleHelper::menuGradient(QPainter *painter, const QRect &spanRect, const QRect &clipRect)
{
    if (StyleHelper::usePixmapCache()) {
        const QString key = QString::asprintf("mh_menu %d %d %d %d %d",
            spanRect.width(), spanRect.height(), clipRect.width(),
            clipRect.height(), StyleHelper::baseColor().rgb());

        QPixmap pixmap;
        if (!QPixmapCache::find(key, &pixmap)) {
            pixmap = QPixmap(clipRect.size());
            QPainter p(&pixmap);
            QRect rect = QRect(0, 0, clipRect.width(), clipRect.height());
            menuGradientHelper(&p, spanRect, rect);
            p.end();
            QPixmapCache::insert(key, pixmap);
        }

        painter->drawPixmap(clipRect.topLeft(), pixmap);
    } else {
        menuGradientHelper(painter, spanRect, clipRect);
    }
}

QPixmap StyleHelper::disabledSideBarIcon(const QPixmap &enabledicon)
{
    QImage im = enabledicon.toImage().convertToFormat(QImage::Format_ARGB32);
    for (int y=0; y<im.height(); ++y) {
        auto scanLine = reinterpret_cast<QRgb*>(im.scanLine(y));
        for (int x=0; x<im.width(); ++x) {
            QRgb pixel = *scanLine;
            char intensity = char(qGray(pixel));
            *scanLine = qRgba(intensity, intensity, intensity, qAlpha(pixel));
            ++scanLine;
        }
    }
    return QPixmap::fromImage(im);
}

// Draws a cached pixmap with shadow
void StyleHelper::drawIconWithShadow(const QIcon &icon, const QRect &rect,
                                     QPainter *p, QIcon::Mode iconMode, int dipRadius, const QColor &color, const QPoint &dipOffset)
{
    QPixmap cache;
    const int devicePixelRatio = p->device()->devicePixelRatio();
    QString pixmapName = QString::fromLatin1("icon %0 %1 %2 %3")
            .arg(icon.cacheKey()).arg(iconMode).arg(rect.height()).arg(devicePixelRatio);

    if (!QPixmapCache::find(pixmapName, &cache)) {
        // High-dpi support: The in parameters (rect, radius, offset) are in
        // device-independent pixels. The call to QIcon::pixmap() below might
        // return a high-dpi pixmap, which will in that case have a devicePixelRatio
        // different than 1. The shadow drawing caluculations are done in device
        // pixels.
        QWindow *window = dynamic_cast<QWidget*>(p->device())->window()->windowHandle();
        QPixmap px = icon.pixmap(window, rect.size(), iconMode);
        int radius = dipRadius * devicePixelRatio;
        QPoint offset = dipOffset * devicePixelRatio;
        cache = QPixmap(px.size() + QSize(radius * 2, radius * 2));
        cache.fill(Qt::transparent);

        QPainter cachePainter(&cache);
        if (iconMode == QIcon::Disabled) {
            const bool hasDisabledState =
                    icon.availableSizes().count() == icon.availableSizes(QIcon::Disabled).count();
            if (!hasDisabledState)
                px = disabledSideBarIcon(icon.pixmap(window, rect.size()));
        } else if (creatorTheme()->flag(Theme::ToolBarIconShadow)) {
            // Draw shadow
            QImage tmp(px.size() + QSize(radius * 2, radius * 2 + 1), QImage::Format_ARGB32_Premultiplied);
            tmp.fill(Qt::transparent);

            QPainter tmpPainter(&tmp);
            tmpPainter.setCompositionMode(QPainter::CompositionMode_Source);
            tmpPainter.drawPixmap(QRect(radius, radius, px.width(), px.height()), px);
            tmpPainter.end();

            // blur the alpha channel
            QImage blurred(tmp.size(), QImage::Format_ARGB32_Premultiplied);
            blurred.fill(Qt::transparent);
            QPainter blurPainter(&blurred);
            qt_blurImage(&blurPainter, tmp, radius, false, true);
            blurPainter.end();

            tmp = blurred;

            // blacken the image...
            tmpPainter.begin(&tmp);
            tmpPainter.setCompositionMode(QPainter::CompositionMode_SourceIn);
            tmpPainter.fillRect(tmp.rect(), color);
            tmpPainter.end();

            tmpPainter.begin(&tmp);
            tmpPainter.setCompositionMode(QPainter::CompositionMode_SourceIn);
            tmpPainter.fillRect(tmp.rect(), color);
            tmpPainter.end();

            // draw the blurred drop shadow...
            cachePainter.drawImage(QRect(0, 0, cache.rect().width(), cache.rect().height()), tmp);
        }

        // Draw the actual pixmap...
        cachePainter.drawPixmap(QRect(QPoint(radius, radius) + offset, QSize(px.width(), px.height())), px);
        cachePainter.end();
        cache.setDevicePixelRatio(devicePixelRatio);
        QPixmapCache::insert(pixmapName, cache);
    }

    QRect targetRect = cache.rect();
    targetRect.setSize(targetRect.size() / cache.devicePixelRatio());
    targetRect.moveCenter(rect.center() - dipOffset);
    p->drawPixmap(targetRect, cache);
}

// Draws a CSS-like border image where the defined borders are not stretched
// Unit for rect, left, top, right and bottom is user pixels
void StyleHelper::drawCornerImage(const QImage &img, QPainter *painter, const QRect &rect,
                                  int left, int top, int right, int bottom)
{
    // source rect for drawImage() calls needs to be specified in DIP unit of the image
    const qreal imagePixelRatio = img.devicePixelRatio();
    const qreal leftDIP = left * imagePixelRatio;
    const qreal topDIP = top * imagePixelRatio;
    const qreal rightDIP = right * imagePixelRatio;
    const qreal bottomDIP = bottom * imagePixelRatio;

    const QSize size = img.size();
    if (top > 0) { //top
        painter->drawImage(QRectF(rect.left() + left, rect.top(), rect.width() -right - left, top), img,
                           QRectF(leftDIP, 0, size.width() - rightDIP - leftDIP, topDIP));
        if (left > 0) //top-left
            painter->drawImage(QRectF(rect.left(), rect.top(), left, top), img,
                               QRectF(0, 0, leftDIP, topDIP));
        if (right > 0) //top-right
            painter->drawImage(QRectF(rect.left() + rect.width() - right, rect.top(), right, top), img,
                               QRectF(size.width() - rightDIP, 0, rightDIP, topDIP));
    }
    //left
    if (left > 0)
        painter->drawImage(QRectF(rect.left(), rect.top()+top, left, rect.height() - top - bottom), img,
                           QRectF(0, topDIP, leftDIP, size.height() - bottomDIP - topDIP));
    //center
    painter->drawImage(QRectF(rect.left() + left, rect.top()+top, rect.width() -right - left,
                              rect.height() - bottom - top), img,
                       QRectF(leftDIP, topDIP, size.width() - rightDIP - leftDIP,
                              size.height() - bottomDIP - topDIP));
    if (right > 0) //right
        painter->drawImage(QRectF(rect.left() +rect.width() - right, rect.top()+top, right, rect.height() - top - bottom), img,
                           QRectF(size.width() - rightDIP, topDIP, rightDIP, size.height() - bottomDIP - topDIP));
    if (bottom > 0) { //bottom
        painter->drawImage(QRectF(rect.left() +left, rect.top() + rect.height() - bottom,
                                  rect.width() - right - left, bottom), img,
                           QRectF(leftDIP, size.height() - bottomDIP,
                                  size.width() - rightDIP - leftDIP, bottomDIP));
        if (left > 0) //bottom-left
            painter->drawImage(QRectF(rect.left(), rect.top() + rect.height() - bottom, left, bottom), img,
                               QRectF(0, size.height() - bottomDIP, leftDIP, bottomDIP));
        if (right > 0) //bottom-right
            painter->drawImage(QRectF(rect.left() + rect.width() - right, rect.top() + rect.height() - bottom, right, bottom), img,
                               QRectF(size.width() - rightDIP, size.height() - bottomDIP, rightDIP, bottomDIP));
    }
}

// Tints an image with tintColor, while preserving alpha and lightness
void StyleHelper::tintImage(QImage &img, const QColor &tintColor)
{
    QPainter p(&img);
    p.setCompositionMode(QPainter::CompositionMode_Screen);

    for (int x = 0; x < img.width(); ++x) {
        for (int y = 0; y < img.height(); ++y) {
            QRgb rgbColor = img.pixel(x, y);
            int alpha = qAlpha(rgbColor);
            QColor c = QColor(rgbColor);

            if (alpha > 0) {
                c.toHsl();
                qreal l = c.lightnessF();
                QColor newColor = QColor::fromHslF(tintColor.hslHueF(), tintColor.hslSaturationF(), l);
                newColor.setAlpha(alpha);
                img.setPixel(x, y, newColor.rgba());
            }
        }
    }
}

QLinearGradient StyleHelper::statusBarGradient(const QRect &statusBarRect)
{
    QLinearGradient grad(statusBarRect.topLeft(), QPoint(statusBarRect.center().x(), statusBarRect.bottom()));
    QColor startColor = shadowColor().darker(164);
    QColor endColor = baseColor().darker(130);
    grad.setColorAt(0, startColor);
    grad.setColorAt(1, endColor);
    return grad;
}

QIcon StyleHelper::getIconFromIconFont(const QString &fontName, const QList<IconFontHelper> &parameters)
{
    QFontDatabase a;

    QTC_ASSERT(a.hasFamily(fontName), {});

    if (!a.hasFamily(fontName))
        return {};

    QIcon icon;

    for (const IconFontHelper &p : parameters) {
        const int maxDpr = qRound(qApp->devicePixelRatio());
        for (int dpr = 1; dpr <= maxDpr; dpr++) {
            QPixmap pixmap(p.size() * dpr);
            pixmap.setDevicePixelRatio(dpr);
            pixmap.fill(Qt::transparent);

            QFont font(fontName);
            font.setPixelSize(p.size().height());

            QPainter painter(&pixmap);
            painter.save();
            painter.setPen(p.color());
            painter.setFont(font);
            painter.drawText(QRectF(QPoint(0, 0), p.size()), p.iconSymbol());
            painter.restore();

            icon.addPixmap(pixmap, p.mode(), p.state());
        }
    }

    return icon;
}

QIcon StyleHelper::getIconFromIconFont(const QString &fontName, const QString &iconSymbol, int fontSize, int iconSize, QColor color)
{
    QFontDatabase a;

    QTC_ASSERT(a.hasFamily(fontName), {});

    if (a.hasFamily(fontName)) {

        QIcon icon;
        QSize size(iconSize, iconSize);

        const int maxDpr = qRound(qApp->devicePixelRatio());
        for (int dpr = 1; dpr <= maxDpr; dpr++) {
            QPixmap pixmap(size * dpr);
            pixmap.setDevicePixelRatio(dpr);
            pixmap.fill(Qt::transparent);

            QFont font(fontName);
            font.setPixelSize(fontSize);

            QPainter painter(&pixmap);
            painter.save();
            painter.setPen(color);
            painter.setFont(font);
            painter.drawText(QRectF(QPoint(0, 0), size), iconSymbol);
            painter.restore();

            icon.addPixmap(pixmap);
        }

        return icon;
    }

    return {};
}

QIcon StyleHelper::getIconFromIconFont(const QString &fontName, const QString &iconSymbol, int fontSize, int iconSize)
{
    QColor penColor = QApplication::palette("QWidget").color(QPalette::Normal, QPalette::ButtonText);
    return getIconFromIconFont(fontName, iconSymbol, fontSize, iconSize, penColor);
}

QIcon StyleHelper::getCursorFromIconFont(const QString &fontName, const QString &cursorFill, const QString &cursorOutline,
                                         int fontSize, int iconSize)
{
    QFontDatabase a;

    QTC_ASSERT(a.hasFamily(fontName), {});

    const QColor outlineColor = Qt::black;
    const QColor fillColor = Qt::white;

    if (a.hasFamily(fontName)) {

        QIcon icon;
        QSize size(iconSize, iconSize);

        const int maxDpr = qRound(qApp->devicePixelRatio());
        for (int dpr = 1; dpr <= maxDpr; dpr++) {
            QPixmap pixmap(size * dpr);
            pixmap.setDevicePixelRatio(dpr);
            pixmap.fill(Qt::transparent);

            QFont font(fontName);
            font.setPixelSize(fontSize);

            QPainter painter(&pixmap);
            painter.save();
            painter.setRenderHint(QPainter::Antialiasing, true);
            painter.setRenderHint(QPainter::TextAntialiasing, true);
            painter.setRenderHint(QPainter::LosslessImageRendering, true);
            painter.setRenderHint(QPainter::SmoothPixmapTransform, true);

            painter.setFont(font);
            painter.setPen(outlineColor);
            painter.drawText(QRectF(QPointF(0.0, 0.0), size),
                             Qt::AlignCenter, cursorOutline);

            painter.setPen(fillColor);
            painter.drawText(QRectF(QPointF(0.0, 0.0), size),
                             Qt::AlignCenter, cursorFill);

            painter.restore();

            icon.addPixmap(pixmap);
        }

        return icon;
    }

    return {};
}


QString StyleHelper::dpiSpecificImageFile(const QString &fileName)
{
    // See QIcon::addFile()
    if (qApp->devicePixelRatio() > 1.0) {
        const QString atDprfileName =
                imageFileWithResolution(fileName, qRound(qApp->devicePixelRatio()));
        if (QFile::exists(atDprfileName))
            return atDprfileName;
    }
    return fileName;
}

QString StyleHelper::imageFileWithResolution(const QString &fileName, int dpr)
{
    const QFileInfo fi(fileName);
    return dpr == 1 ? fileName :
                      fi.path() + QLatin1Char('/') + fi.completeBaseName()
                      + QLatin1Char('@') + QString::number(dpr)
                      + QLatin1String("x.") + fi.suffix();
}

QList<int> StyleHelper::availableImageResolutions(const QString &fileName)
{
    QList<int> result;
    const int maxResolutions = qApp->devicePixelRatio();
    for (int i = 1; i <= maxResolutions; ++i)
        if (QFile::exists(imageFileWithResolution(fileName, i)))
            result.append(i);
    return result;
}

double StyleHelper::luminance(const QColor &color)
{
    // calculate the luminance based on
    // https://www.w3.org/TR/2008/REC-WCAG20-20081211/#relativeluminancedef
    auto val = [](const double &colorVal) {
        return colorVal < 0.03928 ? colorVal / 12.92 : std::pow((colorVal + 0.055) / 1.055, 2.4);
    };

    static QHash<QRgb, double> cache;
    QHash<QRgb, double>::iterator it = cache.find(color.rgb());
    if (it == cache.end()) {
        it = cache.insert(color.rgb(), 0.2126 * val(color.redF())
                          + 0.7152 * val(color.greenF())
                          + 0.0722 * val(color.blueF()));
    }
    return it.value();
}

static double contrastRatio(const QColor &color1, const QColor &color2)
{
    // calculate the contrast ratio based on
    // https://www.w3.org/TR/2008/REC-WCAG20-20081211/#contrast-ratiodef
    auto contrast = (StyleHelper::luminance(color1) + .05) / (StyleHelper::luminance(color2) + .05);
    if (contrast < 1)
        return 1 / contrast;
    return contrast;
}

bool StyleHelper::isReadableOn(const QColor &background, const QColor &foreground)
{
    // following the W3C Recommendation on contrast for large Text
    // https://www.w3.org/TR/2008/REC-WCAG20-20081211/#contrast-ratiodef
    return contrastRatio(background, foreground) > 3;
}

QColor StyleHelper::ensureReadableOn(const QColor &background, const QColor &desiredForeground)
{
    if (isReadableOn(background, desiredForeground))
        return desiredForeground;

    int h, s, v;
    QColor foreground = desiredForeground;
    foreground.getHsv(&h, &s, &v);
    // adjust the color value to ensure better readability
    if (luminance(background) < .5)
        v = v + 64;
    else if (v >= 64)
        v = v - 64;
    v %= 256;

    foreground.setHsv(h, s, v);
    if (!isReadableOn(background, foreground)) {
        s = (s + 128) % 256;    // adjust the saturation to ensure better readability
        foreground.setHsv(h, s, v);
        if (!isReadableOn(background, foreground)) // we failed to create some better foreground
            return desiredForeground;
    }
    return foreground;
}

} // namespace Utils
