path: root/src/gui/kernel/qhighdpiscaling_p.h

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#ifndef QHIGHDPISCALING_P_H
#define QHIGHDPISCALING_P_H

#include <QtCore/qglobal.h>
#include <QtCore/qmargins.h>
#include <QtCore/qrect.h>
#include <QtCore/qvector.h>
#include <QtGui/qregion.h>

// This file implmements utility functions for high-dpi scaling on operating
// systems that do not provide native scaling support.
//
// The functions support creating a logical device-independent
// coordinate system which is related to the device pixel coordinate
// through a scaling factor.
//
// Several scaling factors can be set:
//   - A process-global scale factor
//       - the QT_HIGHDPI_SCALE_FACTOR environment variable.
//       - QHighDpiScaling::setFactor(factor);
//   - A per-window scale factor
//       - QHighDpiScaling::setWindowFactor(window, factor);
//
// With these functions in use  most of the Qt API will then operate in
// the device-independent coordinate system. For example, setting
// the scale factor to 2.0 will make Qt see half of the "device"
// window geometry. Desktop and event geometry will be scaled
// to match.
//
// Integer scaling factors work best. Glitch-free graphics at non-integer
// scaling factors can not be guaranteed.

QT_BEGIN_NAMESPACE

class Q_GUI_EXPORT QHighDpiScaling {
public:
    static bool isActive() { return m_active; }
    static qreal factor(const QWindow *window = 0);
    static void setFactor(qreal factor);
    static void setWindowFactor(QWindow *window, qreal factor);
private:
    static qreal m_factor;
    static bool m_active;
    static bool m_perWindowActive;
};

// Coordinate system conversion functions:
// qHighDpiToDeviceIndependentPixels   : from physical(screen/backing) to logical pixels
// qHighDpiToDevicePixels              : from logical to physical pixels
inline QRect qHighDpiToDeviceIndependentPixels(const QRect &pixelRect, const QWindow *window = 0)
{
    const qreal scaleFactor = QHighDpiScaling::factor(window);
    return QRect(pixelRect.topLeft() / scaleFactor, pixelRect.size() / scaleFactor);
}

inline QRect qHighDpiToDevicePixels(const QRect &pointRect, const QWindow *window = 0)
{
    const qreal scaleFactor = QHighDpiScaling::factor(window);
    return QRect(pointRect.topLeft() * scaleFactor, pointRect.size() * scaleFactor);
}

inline QRectF qHighDpiToDeviceIndependentPixels(const QRectF &pixelRect, const QWindow *window = 0)
{
    const qreal scaleFactor = QHighDpiScaling::factor(window);
    return QRectF(pixelRect.topLeft() / scaleFactor, pixelRect.size() / scaleFactor);
}

inline QRectF qHighDpiToDevicePixels(const QRectF &pointRect, const QWindow *window = 0)
{
   const qreal scaleFactor = QHighDpiScaling::factor(window);
   return QRectF(pointRect.topLeft() * scaleFactor, pointRect.size() * scaleFactor);
}

inline QSize qHighDpiToDeviceIndependentPixels(const QSize &pixelSize, const QWindow *window = 0)
{
    return pixelSize / QHighDpiScaling::factor(window);
}

// For converting minimum/maximum sizes of QWindow, limits to 0..QWINDOWSIZE_MAX
Q_GUI_EXPORT QSize qHighDpiToDevicePixelsConstrained(const QSize &size, const QWindow *window = 0);

inline QSize qHighDpiToDevicePixels(const QSize &pointSize, const QWindow *window = 0)
{
    return pointSize * QHighDpiScaling::factor(window);
}

inline QSizeF qHighDpiToDeviceIndependentPixels(const QSizeF &pixelSize, const QWindow *window = 0)
{
    return pixelSize / QHighDpiScaling::factor(window);
}

inline QSizeF qHighDpiToDevicePixels(const QSizeF &pointSize, const QWindow *window = 0)
{
    return pointSize * QHighDpiScaling::factor(window);
}

inline QPoint qHighDpiToDeviceIndependentPixels(const QPoint &pixelPoint, const QWindow *window = 0)
{
    return pixelPoint / QHighDpiScaling::factor(window);
}

inline QPoint qHighDpiToDevicePixels(const QPoint &pointPoint, const QWindow *window = 0)
{
    return pointPoint * QHighDpiScaling::factor(window);
}

inline QPointF qHighDpiToDeviceIndependentPixels(const QPointF &pixelPoint, const QWindow *window = 0)
{
    return pixelPoint / QHighDpiScaling::factor(window);
}

inline QPointF qHighDpiToDevicePixels(const QPointF &pointPoint, const QWindow *window = 0)
{
    return pointPoint * QHighDpiScaling::factor(window);
}

inline QMargins qHighDpiToDeviceIndependentPixels(const QMargins &pixelMargins, const QWindow *window = 0)
{
    const qreal scaleFactor = QHighDpiScaling::factor(window);
    return QMargins(pixelMargins.left() / scaleFactor, pixelMargins.top() / scaleFactor,
                    pixelMargins.right() / scaleFactor, pixelMargins.bottom() / scaleFactor);
}

inline QMargins qHighDpiToDevicePixels(const QMargins &pointMargins, const QWindow *window = 0)
{
    const qreal scaleFactor = QHighDpiScaling::factor(window);
    return QMargins(pointMargins.left() * scaleFactor, pointMargins.top() * scaleFactor,
                    pointMargins.right() * scaleFactor, pointMargins.bottom() * scaleFactor);
}

inline QRegion qHighDpiToDeviceIndependentPixels(const QRegion &pixelRegion, const QWindow *window = 0)
{
    if (!QHighDpiScaling::isActive())
        return pixelRegion;

    QRegion pointRegion;
    foreach (const QRect &rect, pixelRegion.rects())
        pointRegion += qHighDpiToDeviceIndependentPixels(rect, window);
    return pointRegion;
}

inline QRegion qHighDpiToDevicePixels(const QRegion &pointRegion, const QWindow *window = 0)
{
    if (!QHighDpiScaling::isActive())
        return pointRegion;

    QRegion pixelRegon;
    foreach (const QRect &rect, pointRegion.rects())
        pixelRegon += qHighDpiToDevicePixels(rect, window);
    return pixelRegon;
}

// Any T that has operator/()
template <typename T>
T qHighDpiToDeviceIndependentPixels(const T &pixelValue, const QWindow *window = 0)
{
    if (!QHighDpiScaling::isActive())
        return pixelValue;

    return pixelValue / QHighDpiScaling::factor(window);

}

// Any T that has operator*()
template <typename T>
T qHighDpiToDevicePixels(const T &pointValue, const QWindow *window = 0)
{
    if (!QHighDpiScaling::isActive())
        return pointValue;

    return pointValue * QHighDpiScaling::factor(window);
}

// Any QVector<T> where T has operator/()
template <typename T>
QVector<T> qHighDpiToDeviceIndependentPixels(const QVector<T> &pixelValues, const QWindow *window = 0)
{
    if (!QHighDpiScaling::isActive())
        return pixelValues;

    QVector<T> pointValues;
    foreach (const T& pixelValue, pixelValues)
        pointValues.append(pixelValue / QHighDpiScaling::factor(window));
    return pointValues;
}

// Any QVector<T> where T has operator*()
template <typename T>
QVector<T> qHighDpiToDevicePixels(const QVector<T> &pointValues, const QWindow *window = 0)
{
    if (!QHighDpiScaling::isActive())
        return pointValues;

    QVector<T> pixelValues;
    foreach (const T& pointValue, pointValues)
        pixelValues.append(pointValue * QHighDpiScaling::factor(window));
    return pixelValues;
}


// Any QPair<T, U> where T and U has operator/()
template <typename T, typename U>
QPair<T, U> qHighDpiToDeviceIndependentPixels(const QPair<T, U> &pixelPair, const QWindow *window = 0)
{
    return qMakePair(qHighDpiToDeviceIndependentPixels(pixelPair.first, window),
                     qHighDpiToDeviceIndependentPixels(pixelPair.second, window));
}

// Any QPair<T, U> where T and U has operator*()
template <typename T, typename U>
QPair<T, U> qHighDpiToDevicePixels(const QPair<T, U> &pointPair, const QWindow *window = 0)
{
    return qMakePair(qHighDpiToDevicePixels(pointPair.first, window),
                     qHighDpiToDevicePixels(pointPair.second, window));
}

QT_END_NAMESPACE

#endif