61 lines
2.3 KiB
C++
61 lines
2.3 KiB
C++
#pragma once
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#include <QtGlobal>
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#include <QImageReader>
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#include <QRect>
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#include <QSize>
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#include <algorithm>
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#include <cmath>
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namespace core {
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namespace image_decode {
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/// 提高 Qt6 解码像素上限，避免大图被 reader 直接拒绝（单位 MB）
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inline void prepareLargeImageReader() {
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#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
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QImageReader::setAllocationLimit(4096);
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#endif
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}
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/// 裁剪对话框等「仅预览」场景：像素上限（libvips 缩略与 Qt 回退共用）
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[[maybe_unused]] constexpr qint64 kPreviewMaxPixels = 16LL * 1000 * 1000;
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/// 编辑器 / 帧图替换：缩略像素上限（libvips 与 Qt 回退共用）
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[[maybe_unused]] constexpr qint64 kWorkspaceMaxPixels = 48LL * 1000 * 1000;
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/// 在 read() 前调用：若像素数超过 maxPixels，则 setScaledSize 按比例缩小（不解码全图）
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inline void downscaleReaderIfExceeds(QImageReader& reader, qint64 maxPixels) {
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const QSize sz = reader.size();
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if (!sz.isValid() || sz.width() <= 0 || sz.height() <= 0) {
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return;
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}
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const qint64 pixels = qint64(sz.width()) * qint64(sz.height());
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if (pixels <= maxPixels) {
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return;
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}
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const double s = std::sqrt(double(maxPixels) / double(pixels));
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const int nw = std::max(1, int(std::lround(sz.width() * s)));
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const int nh = std::max(1, int(std::lround(sz.height() * s)));
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reader.setScaledSize(QSize(nw, nh));
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}
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/// 将 rect 从 fromSize 坐标系线性映射到 toSize（例如预览图上的选区 → 原图逻辑像素）
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inline QRect mapRectBetweenSizes(const QRect& rect, const QSize& fromSize, const QSize& toSize) {
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if (!rect.isValid() || fromSize.width() <= 0 || fromSize.height() <= 0 || toSize.width() <= 0 ||
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toSize.height() <= 0) {
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return {};
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}
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const qreal sx = qreal(toSize.width()) / qreal(fromSize.width());
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const qreal sy = qreal(toSize.height()) / qreal(fromSize.height());
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const int x0 = int(std::floor(qreal(rect.left()) * sx));
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const int y0 = int(std::floor(qreal(rect.top()) * sy));
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const int x1 = int(std::ceil(qreal(rect.right() + 1) * sx));
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const int y1 = int(std::ceil(qreal(rect.bottom() + 1) * sy));
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QRect out(x0, y0, x1 - x0, y1 - y0);
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return out.normalized().intersected(QRect(0, 0, toSize.width(), toSize.height()));
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}
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} // namespace image_decode
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} // namespace core
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