playmat_utils.h

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#ifndef COCKATRICE_PLAYMAT_UTILS_H
#define COCKATRICE_PLAYMAT_UTILS_H
 
#include <QRectF>
#include <QSize>
#include <QSizeF>
#include <libcockatrice/deck_list/deck_list.h>
 
namespace PlaymatUtils
{

constexpr qreal MAX_ZOOM = 4.0;

inline qreal playmatVisibleWidth(const QSize &fullCardSize, const PlaymatParams &params)
{
    const qreal srcW = fullCardSize.width();
    const qreal marginL = params.marginPctL * srcW;
    const qreal marginR = params.marginPctR * srcW;
    return qMax(0.0, srcW - marginL - marginR);
}

inline qreal playmatClampedZoom(const QSize &fullCardSize, const PlaymatParams &params)
{
    const qreal minDim = qMin<qreal>(fullCardSize.width(), fullCardSize.height());
    const qreal visibleW = playmatVisibleWidth(fullCardSize, params);
    const qreal zoomOutFloor = (minDim > 0.0 && visibleW > 0.0) ? visibleW / minDim : 1.0;
    // The floor deliberately bypasses MAX_ZOOM: when the art is much wider
    // than tall, keeping the square window inside it requires more than 4x
    // zoom-out, and honoring that larger floor keeps side within
    // min(card width, height). Zooming IN is still capped at MAX_ZOOM.
    return qMin(MAX_ZOOM, qMax(params.zoom, zoomOutFloor));
}

inline qreal playmatWindowSide(const QSize &fullCardSize, const PlaymatParams &params)
{
    const qreal visibleW = playmatVisibleWidth(fullCardSize, params);
    if (visibleW <= 0.0) {
        return 0.0;
    }
    return visibleW / playmatClampedZoom(fullCardSize, params);
}

inline QRectF computeArtSourceRect(const QSize &fullCardSize, const PlaymatParams &params)
{
    const qreal srcW = fullCardSize.width();
    const qreal srcH = fullCardSize.height();
 
    // Square sampling window, keeps art unskewed, never exceeds the card on
    // either axis thanks to the zoom floor in playmatWindowSide().
    const qreal side = playmatWindowSide(fullCardSize, params);
 
    // verticalOffset places the TOP edge of the sampling window itself within
    // its travel, so the full [0, 1] parameter range is live at every zoom and
    // the window can always reach the very top (0.0) and bottom (1.0) of the
    // art.
    const qreal offset = qBound(0.0, params.verticalOffset, 1.0);
    const qreal y = offset * qMax(0.0, srcH - side);
 
    // Horizontally the sampling window sits centered inside the trimmed span
    // (margins pan it), zooming out can make it wider than that span, so it
    // is then kept within the image, an edge stop, never an invalid rect.
    const qreal outerW = playmatVisibleWidth(fullCardSize, params);
    const qreal x = qBound(0.0, params.marginPctL * srcW + (outerW - side) / 2.0, qMax(0.0, srcW - side));
 
    return QRectF(x, y, side, side);
}

inline QRectF coverFitRect(const QRectF &dstArea, const QSizeF &srcSize)
{
    const qreal srcAspect = srcSize.width() / srcSize.height();
    const qreal dstAspect = dstArea.width() / dstArea.height();
 
    if (srcAspect > dstAspect) {
        const qreal dstW = dstArea.height() * srcAspect;
        return QRectF(dstArea.left() + (dstArea.width() - dstW) / 2.0, dstArea.top(), dstW, dstArea.height());
    }
 
    const qreal dstH = dstArea.width() / srcAspect;
    return QRectF(dstArea.left(), dstArea.top() + (dstArea.height() - dstH) / 2.0, dstArea.width(), dstH);
}

inline QRectF aspectFitRect(const QRectF &dstArea, qreal aspect)
{
    if (aspect <= 0.0) {
        return dstArea;
    }
    qreal w = qMin(dstArea.width(), dstArea.height() * aspect);
    qreal h = w / aspect;
    return QRectF(dstArea.left() + (dstArea.width() - w) / 2.0, dstArea.top() + (dstArea.height() - h) / 2.0, w, h);
}
 
} // namespace PlaymatUtils
 
#endif // COCKATRICE_PLAYMAT_UTILS_H