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Extract the layout logic to a view model to simplify the update logic in continuous scroll mode

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luisangelsm
2026-02-26 16:19:58 +01:00
committed by Luis Ángel San Martín
parent f61c5280c9
commit 0bd291ba98
7 changed files with 506 additions and 375 deletions
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79
YACReader/continuous_view_model.h Normal file
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#ifndef CONTINUOUS_VIEW_MODEL_H
#define CONTINUOUS_VIEW_MODEL_H
#include <QObject>
#include <QSize>
#include <QVector>
class ContinuousViewModel : public QObject
{
Q_OBJECT
public:
explicit ContinuousViewModel(QObject *parent = nullptr);
void reset();
void setNumPages(int count);
void setZoomFactor(int zoom);
void setViewportSize(int width, int height);
void setScrollYFromUser(int scrollY);
void setAnchorPage(int page);
void setCurrentPage(int page);
void setPageNaturalSize(int pageIndex, const QSize &size);
int numPages() const;
int totalHeight() const;
int scrollY() const;
int viewportHeight() const;
int zoomFactor() const;
int centerPage() const;
int yPositionForPage(int pageIndex) const;
int pageAtY(int y) const;
QSize scaledPageSize(int pageIndex) const;
signals:
void stateChanged();
private:
struct LayoutSnapshot {
QVector<int> yPositions;
QVector<QSize> scaledSizes;
int totalHeight = 0;
};
struct ViewportAnchor {
int pageIndex = -1;
float offsetRatio = 0.0f;
bool valid = false;
};
enum class RecomputePolicy {
PreserveViewportAnchor,
PreserveScrollClamped,
ScrollToPageTop
};
void recompute(RecomputePolicy policy, int targetPage = -1);
LayoutSnapshot buildLayoutSnapshot(int width) const;
ViewportAnchor anchorFromViewport(const LayoutSnapshot &snapshot, int scrollY, int viewportHeight) const;
int resolveAnchorToScrollY(const LayoutSnapshot &snapshot, const ViewportAnchor &anchor, int viewportHeight) const;
int pageAtY(const LayoutSnapshot &snapshot, int y) const;
int maxScrollFor(const LayoutSnapshot &snapshot) const;
QSize scaledPageSizeForWidth(int pageIndex, int width) const;
float scaleForPage(int pageIndex, int width) const;
int numPagesValue = 0;
QVector<QSize> pageSizes;
QSize defaultPageSize { 800, 1200 };
int zoomFactorValue = 100;
int viewportWidth = 0;
int viewportHeightValue = 0;
int scrollYValue = 0;
int anchorPage = -1;
LayoutSnapshot layoutSnapshot;
};
#endif // CONTINUOUS_VIEW_MODEL_H