sloposk/src/layout/KeyGeometry.cpp

#include "KeyGeometry.h"

#include <algorithm>

qreal rowUnits(const Row &row)
{
    qreal units = 0;
    for (const KeyDef &key : row)
        units += key.width;
    return units;
}

QList<QRectF> computeKeyRects(const Layer &layer, QSizeF size, KeyboardMetrics metrics)
{
    QList<QRectF> rects;
    if (layer.rows.isEmpty())
        return rects;

    qreal maxUnits = 0;
    for (const Row &row : layer.rows)
        maxUnits = std::max(maxUnits, rowUnits(row));

    const qreal innerWidth = size.width() - 2 * metrics.padding;
    const qreal innerHeight = size.height() - 2 * metrics.padding;
    const int rowCount = int(layer.rows.size());

    // Each cell includes one trailing gap; the last gap of a row is dropped.
    const qreal unitWidth = (innerWidth + metrics.gap) / maxUnits;
    const qreal rowHeight = (innerHeight - (rowCount - 1) * metrics.gap) / rowCount;

    qreal y = metrics.padding;
    for (const Row &row : layer.rows) {
        qreal x = metrics.padding + (maxUnits - rowUnits(row)) * unitWidth / 2;
        for (const KeyDef &key : row) {
            const qreal cellWidth = key.width * unitWidth;
            rects.append(QRectF(x, y, std::max<qreal>(0, cellWidth - metrics.gap), rowHeight));
            x += cellWidth;
        }
        y += rowHeight + metrics.gap;
    }
    return rects;
}