VirtualScreenId.h

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// SPDX-FileCopyrightText: 2026 fuddlesworth
// SPDX-License-Identifier: LGPL-2.1-or-later
 
#pragma once
 
#include <QLatin1String>
#include <QString>
 
namespace PhosphorIdentity {
 
namespace VirtualScreenId {
 
inline constexpr QLatin1String Separator{"/vs:"};
 
inline bool isVirtual(const QString& screenId)
{
    int pos = screenId.indexOf(Separator);
    return pos > 0; // Must have non-empty physical ID before separator
}
 
inline QString extractPhysicalId(const QString& screenId)
{
    int sep = screenId.indexOf(Separator);
    return (sep > 0) ? screenId.left(sep) : screenId;
}
 
inline int extractIndex(const QString& screenId)
{
    int sep = screenId.indexOf(Separator);
    if (sep <= 0) {
        return -1;
    }
    bool ok = false;
    int index = screenId.mid(sep + Separator.size()).toInt(&ok);
    return (ok && index >= 0) ? index : -1;
}
 
inline QString make(const QString& physicalScreenId, int index)
{
    if (physicalScreenId.isEmpty() || index < 0) {
        return {};
    }
    return physicalScreenId + Separator + QString::number(index);
}
 
inline bool samePhysical(const QString& idA, const QString& idB)
{
    return extractPhysicalId(idA) == extractPhysicalId(idB);
}
 
inline bool isVirtualScreenCrossing(const QString& oldScreenId, const QString& newScreenId)
{
    if (oldScreenId.isEmpty() || newScreenId.isEmpty() || oldScreenId == newScreenId) {
        return false;
    }
    // At least one side must be a virtual ID — two plain physical IDs that
    // differ are a physical monitor change, not a VS crossing.
    if (!isVirtual(oldScreenId) && !isVirtual(newScreenId)) {
        return false;
    }
    return samePhysical(oldScreenId, newScreenId);
}
 
} // namespace VirtualScreenId
 
} // namespace PhosphorIdentity