Merge pull request #513 from YACReader/continuous-scroll-support

YACReader 10: Implement continuous scrolling

YACReader/YACReader.pro

@@ -62,6 +62,7 @@ HEADERS +=  ../common/comic.h \
             goto_dialog.h \
             magnifying_glass.h \
             main_window_viewer.h \
+            continuous_page_widget.h \
             mouse_handler.h \
             viewer.h \
             options_dialog.h \
@@ -98,6 +99,7 @@ SOURCES +=  ../common/comic.cpp \
             goto_dialog.cpp \
             magnifying_glass.cpp \
             main_window_viewer.cpp \
+            continuous_page_widget.cpp \
             mouse_handler.cpp \
             viewer.cpp \
             options_dialog.cpp \

YACReader/configuration.h

@@ -82,6 +82,8 @@ public:
     void setDoublePage(bool b) { settings->setValue(DOUBLE_PAGE, b); }
     bool getDoubleMangaPage() { return settings->value(DOUBLE_MANGA_PAGE).toBool(); }
     void setDoubleMangaPage(bool b) { settings->setValue(DOUBLE_MANGA_PAGE, b); }
+    bool getContinuousScroll() { return settings->value(CONTINUOUS_SCROLL, false).toBool(); }
+    void setContinuousScroll(bool b) { settings->setValue(CONTINUOUS_SCROLL, b); }
     bool getEnlargeImages() { return settings->value(ENLARGE_IMAGES, true).toBool(); }
     void setEnlargeImages(bool b) { settings->setValue(ENLARGE_IMAGES, b); }
 

YACReader/continuous_page_widget.cpp

@@ -0,0 +1,393 @@
+#include "continuous_page_widget.h"
+#include "render.h"
+
+#include <QPainter>
+#include <QPaintEvent>
+#include <algorithm>
+#include <limits>
+
+ContinuousPageWidget::ContinuousPageWidget(QWidget *parent)
+    : QWidget(parent)
+{
+    QSizePolicy sp(QSizePolicy::Preferred, QSizePolicy::Preferred);
+    sp.setHeightForWidth(true);
+    setSizePolicy(sp);
+    setMouseTracking(true);
+    initTheme(this);
+}
+
+void ContinuousPageWidget::applyTheme(const Theme &)
+{
+    update();
+}
+
+void ContinuousPageWidget::setRender(Render *r)
+{
+    render = r;
+}
+
+void ContinuousPageWidget::setNumPages(int count)
+{
+    numPages = count;
+    defaultPageSize = QSize(800, 1200);
+    pageSizes.fill(QSize(0, 0), count);
+    relayout(false);
+}
+
+void ContinuousPageWidget::setZoomFactor(int zoom)
+{
+    if (zoomFactor == zoom) {
+        return;
+    }
+    zoomFactor = zoom;
+    relayout(true);
+    update();
+}
+
+void ContinuousPageWidget::probeBufferedPages()
+{
+    if (!render || numPages == 0) {
+        return;
+    }
+
+    bool changed = false;
+    for (int i = 0; i < numPages; ++i) {
+        const QImage *img = render->bufferedImage(i);
+        bool hasKnownSize = pageSizes[i].width() > 0 && pageSizes[i].height() > 0;
+        if (img && !img->isNull() && !hasKnownSize) {
+            pageSizes[i] = img->size();
+            if (defaultPageSize == QSize(800, 1200)) {
+                defaultPageSize = img->size();
+            }
+            changed = true;
+        }
+    }
+
+    if (changed) {
+        relayout(true);
+        update();
+    }
+}
+
+void ContinuousPageWidget::reset()
+{
+    numPages = 0;
+    pageSizes.clear();
+    yPositions.clear();
+    currentTotalHeight = 0;
+    layoutSnapshot = LayoutSnapshot();
+    defaultPageSize = QSize(800, 1200);
+    setMinimumHeight(0);
+    setMaximumHeight(QWIDGETSIZE_MAX);
+    updateGeometry();
+    update();
+}
+
+int ContinuousPageWidget::centerPage(int scrollY, int viewportHeight) const
+{
+    const int centerY = scrollY + std::max(0, viewportHeight / 2);
+    return pageAtY(centerY);
+}
+
+int ContinuousPageWidget::yPositionForPage(int pageIndex) const
+{
+    if (pageIndex < 0 || pageIndex >= yPositions.size()) {
+        return 0;
+    }
+    return yPositions[pageIndex];
+}
+
+int ContinuousPageWidget::totalHeight() const
+{
+    return currentTotalHeight;
+}
+
+bool ContinuousPageWidget::hasHeightForWidth() const
+{
+    return true;
+}
+
+int ContinuousPageWidget::heightForWidth(int w) const
+{
+    if (numPages == 0 || w <= 0) {
+        return 0;
+    }
+
+    int h = 0;
+    for (int i = 0; i < numPages; ++i) {
+        QSize scaled = scaledPageSize(i, w);
+        h += scaled.height();
+    }
+    return h;
+}
+
+QSize ContinuousPageWidget::sizeHint() const
+{
+    return QSize(defaultPageSize.width(), currentTotalHeight > 0 ? currentTotalHeight : 0);
+}
+
+void ContinuousPageWidget::onPageAvailable(int absolutePageIndex)
+{
+    if (!render || absolutePageIndex < 0 || absolutePageIndex >= numPages) {
+        return;
+    }
+
+    const QImage *img = render->bufferedImage(absolutePageIndex);
+    if (!img || img->isNull()) {
+        return;
+    }
+
+    QSize naturalSize = img->size();
+
+    // update default page size from the first real page we see
+    if (defaultPageSize == QSize(800, 1200) && !naturalSize.isNull()) {
+        defaultPageSize = naturalSize;
+    }
+
+    bool sizeChanged = (pageSizes[absolutePageIndex] != naturalSize);
+    pageSizes[absolutePageIndex] = naturalSize;
+
+    if (sizeChanged) {
+        // keep anchor page visually stable while refined page sizes arrive
+        relayout(true);
+    }
+
+    // repaint the region where this page lives
+    if (absolutePageIndex < yPositions.size()) {
+        QSize scaled = scaledPageSize(absolutePageIndex, width());
+        QRect pageRect(0, yPositions[absolutePageIndex], scaled.width(), scaled.height());
+        update(pageRect);
+    }
+}
+
+void ContinuousPageWidget::paintEvent(QPaintEvent *event)
+{
+    if (numPages == 0 || !render) {
+        return;
+    }
+
+    QPainter painter(this);
+
+    QRect visibleRect = event->rect();
+    int firstPage = pageAtY(visibleRect.top());
+    int lastPage = pageAtY(visibleRect.bottom());
+
+    int w = width();
+    for (int i = firstPage; i <= lastPage && i < numPages; ++i) {
+        int y = yPositions[i];
+        QSize scaled = scaledPageSize(i, w);
+        // center horizontally if page is narrower than widget
+        int x = (w - scaled.width()) / 2;
+        if (x < 0) {
+            x = 0;
+        }
+        QRect pageRect(x, y, scaled.width(), scaled.height());
+
+        const QImage *img = render->bufferedImage(i);
+        if (img && !img->isNull()) {
+            if (img->size() != scaled) {
+                painter.drawImage(pageRect, img->scaled(scaled, Qt::IgnoreAspectRatio, Qt::SmoothTransformation));
+            } else {
+                painter.drawImage(pageRect, *img);
+            }
+        } else {
+            // placeholder
+            painter.fillRect(pageRect, QColor(45, 45, 45));
+            painter.setPen(theme.viewer.defaultTextColor);
+            painter.drawText(pageRect, Qt::AlignCenter, tr("Loading page %1").arg(i + 1));
+        }
+    }
+}
+
+void ContinuousPageWidget::resizeEvent(QResizeEvent *event)
+{
+    QWidget::resizeEvent(event);
+    relayout(true);
+}
+
+void ContinuousPageWidget::setAnchorPage(int page)
+{
+    anchorPage = page;
+}
+
+void ContinuousPageWidget::setViewportState(int scrollY, int viewportHeight)
+{
+    viewportScrollY = std::max(0, scrollY);
+    currentViewportHeight = std::max(0, viewportHeight);
+    hasViewportState = true;
+}
+
+void ContinuousPageWidget::updateLayout()
+{
+    relayout(false);
+}
+
+void ContinuousPageWidget::updateLayoutWithAnchor()
+{
+    relayout(true);
+}
+
+void ContinuousPageWidget::relayout(bool preserveAnchor)
+{
+    int w = width();
+    if (w <= 0) {
+        w = parentWidget() ? parentWidget()->width() : 0;
+    }
+    if (w <= 0) {
+        w = defaultPageSize.width();
+    }
+
+    const LayoutSnapshot oldSnapshot = layoutSnapshot;
+
+    ViewportAnchor anchor;
+    if (preserveAnchor && hasViewportState && !oldSnapshot.yPositions.isEmpty()) {
+        anchor = anchorFromViewport(oldSnapshot, viewportScrollY, currentViewportHeight);
+    } else if (preserveAnchor && anchorPage >= 0) {
+        anchor.pageIndex = anchorPage;
+        anchor.offsetRatio = 0.5f;
+        anchor.valid = true;
+    }
+
+    layoutSnapshot = buildLayoutSnapshot(w);
+
+#ifndef NDEBUG
+    Q_ASSERT(layoutSnapshot.yPositions.size() == numPages);
+    Q_ASSERT(layoutSnapshot.scaledSizes.size() == numPages);
+    for (int i = 0; i < layoutSnapshot.scaledSizes.size(); ++i) {
+        Q_ASSERT(layoutSnapshot.scaledSizes[i].width() > 0);
+        Q_ASSERT(layoutSnapshot.scaledSizes[i].height() > 0);
+        if (i > 0) {
+            Q_ASSERT(layoutSnapshot.yPositions[i] >= layoutSnapshot.yPositions[i - 1]);
+        }
+    }
+#endif
+
+    yPositions = layoutSnapshot.yPositions;
+    currentTotalHeight = layoutSnapshot.totalHeight;
+
+    setFixedHeight(currentTotalHeight);
+    updateGeometry();
+
+    if (!preserveAnchor || !anchor.valid || currentViewportHeight <= 0) {
+        return;
+    }
+
+    const int newScrollForAnchor = resolveAnchorToScrollY(layoutSnapshot, anchor, currentViewportHeight);
+    emit layoutScrollPositionRequested(newScrollForAnchor);
+}
+
+ContinuousPageWidget::LayoutSnapshot ContinuousPageWidget::buildLayoutSnapshot(int w) const
+{
+    LayoutSnapshot snapshot;
+
+    if (numPages <= 0 || w <= 0) {
+        return snapshot;
+    }
+
+    snapshot.yPositions.resize(numPages);
+    snapshot.scaledSizes.resize(numPages);
+
+    qint64 y = 0;
+    for (int i = 0; i < numPages; ++i) {
+        snapshot.yPositions[i] = static_cast<int>(std::min<qint64>(y, std::numeric_limits<int>::max()));
+        QSize scaled = scaledPageSize(i, w);
+        scaled.setWidth(std::max(1, scaled.width()));
+        scaled.setHeight(std::max(1, scaled.height()));
+        snapshot.scaledSizes[i] = scaled;
+        y += scaled.height();
+    }
+
+    snapshot.totalHeight = static_cast<int>(std::min<qint64>(y, static_cast<qint64>(QWIDGETSIZE_MAX)));
+    return snapshot;
+}
+
+int ContinuousPageWidget::pageAtY(const LayoutSnapshot &snapshot, int y) const
+{
+    if (snapshot.yPositions.isEmpty()) {
+        return 0;
+    }
+
+    auto it = std::upper_bound(snapshot.yPositions.constBegin(), snapshot.yPositions.constEnd(), y);
+    if (it == snapshot.yPositions.constBegin()) {
+        return 0;
+    }
+    --it;
+    return static_cast<int>(it - snapshot.yPositions.constBegin());
+}
+
+ContinuousPageWidget::ViewportAnchor ContinuousPageWidget::anchorFromViewport(const LayoutSnapshot &snapshot, int scrollY, int viewportHeight) const
+{
+    ViewportAnchor anchor;
+
+    if (snapshot.yPositions.isEmpty() || viewportHeight <= 0) {
+        return anchor;
+    }
+
+    const int maxScroll = std::max(0, snapshot.totalHeight - viewportHeight);
+    const int clampedScroll = qBound(0, scrollY, maxScroll);
+    const int anchorY = clampedScroll + viewportHeight / 2;
+    const int page = pageAtY(snapshot, anchorY);
+
+    if (page < 0 || page >= snapshot.scaledSizes.size()) {
+        return anchor;
+    }
+
+    const int pageTop = snapshot.yPositions[page];
+    const int pageHeight = std::max(1, snapshot.scaledSizes[page].height());
+    const float ratio = static_cast<float>(anchorY - pageTop) / static_cast<float>(pageHeight);
+
+    anchor.pageIndex = page;
+    anchor.offsetRatio = qBound(0.0f, ratio, 1.0f);
+    anchor.valid = true;
+    return anchor;
+}
+
+int ContinuousPageWidget::resolveAnchorToScrollY(const LayoutSnapshot &snapshot, const ViewportAnchor &anchor, int viewportHeight) const
+{
+    if (!anchor.valid || viewportHeight <= 0 || snapshot.yPositions.isEmpty()) {
+        return 0;
+    }
+
+    if (anchor.pageIndex < 0 || anchor.pageIndex >= snapshot.yPositions.size() || anchor.pageIndex >= snapshot.scaledSizes.size()) {
+        return 0;
+    }
+
+    const int pageTop = snapshot.yPositions[anchor.pageIndex];
+    const int pageHeight = std::max(1, snapshot.scaledSizes[anchor.pageIndex].height());
+    const int anchorY = pageTop + qRound(anchor.offsetRatio * pageHeight);
+    const int maxScroll = std::max(0, snapshot.totalHeight - viewportHeight);
+    const int target = anchorY - viewportHeight / 2;
+    return qBound(0, target, maxScroll);
+}
+
+int ContinuousPageWidget::pageAtY(int y) const
+{
+    return pageAtY(layoutSnapshot, y);
+}
+
+QSize ContinuousPageWidget::scaledPageSize(int pageIndex, int forWidth) const
+{
+    QSize natural = (pageIndex < pageSizes.size() && pageSizes[pageIndex].width() > 0 && pageSizes[pageIndex].height() > 0)
+            ? pageSizes[pageIndex]
+            : defaultPageSize;
+
+    float scale = scaleForPage(pageIndex, forWidth);
+    int scaledW = std::max(1, qRound(natural.width() * scale));
+    int scaledH = std::max(1, qRound(natural.height() * scale));
+    return QSize(scaledW, scaledH);
+}
+
+float ContinuousPageWidget::scaleForPage(int pageIndex, int forWidth) const
+{
+    QSize natural = (pageIndex < pageSizes.size() && pageSizes[pageIndex].width() > 0 && pageSizes[pageIndex].height() > 0)
+            ? pageSizes[pageIndex]
+            : defaultPageSize;
+
+    if (natural.width() <= 0 || forWidth <= 0) {
+        return 1.0f;
+    }
+
+    float baseScale = static_cast<float>(forWidth) / natural.width();
+    float zoomMultiplier = zoomFactor / 100.0f;
+    return baseScale * zoomMultiplier;
+}

YACReader/continuous_page_widget.h

@@ -0,0 +1,86 @@
+#ifndef CONTINUOUS_PAGE_WIDGET_H
+#define CONTINUOUS_PAGE_WIDGET_H
+
+#include <QWidget>
+#include <QSize>
+#include <QVector>
+
+#include "themable.h"
+
+class Render;
+
+class ContinuousPageWidget : public QWidget, protected Themable
+{
+    Q_OBJECT
+public:
+    explicit ContinuousPageWidget(QWidget *parent = nullptr);
+
+    void setRender(Render *r);
+    void setNumPages(int count);
+    void setZoomFactor(int zoom);
+    void probeBufferedPages();
+    void reset();
+
+    int centerPage(int scrollY, int viewportHeight) const;
+    int yPositionForPage(int pageIndex) const;
+    int totalHeight() const;
+
+    bool hasHeightForWidth() const override;
+    int heightForWidth(int w) const override;
+    QSize sizeHint() const override;
+
+    void setAnchorPage(int page);
+    void setViewportState(int scrollY, int viewportHeight);
+
+signals:
+    // emitted after layout recomputation when the preserved viewport anchor
+    // resolves to an absolute scroll position
+    void layoutScrollPositionRequested(int scrollY);
+
+public slots:
+    void onPageAvailable(int absolutePageIndex);
+
+protected:
+    void paintEvent(QPaintEvent *event) override;
+    void resizeEvent(QResizeEvent *event) override;
+    void applyTheme(const Theme &theme) override;
+
+private:
+    struct LayoutSnapshot {
+        QVector<int> yPositions;
+        QVector<QSize> scaledSizes;
+        int totalHeight = 0;
+    };
+
+    struct ViewportAnchor {
+        int pageIndex = -1;
+        float offsetRatio = 0.0f;
+        bool valid = false;
+    };
+
+    void updateLayout();
+    void updateLayoutWithAnchor();
+    void relayout(bool preserveAnchor);
+    LayoutSnapshot buildLayoutSnapshot(int w) const;
+    int pageAtY(const LayoutSnapshot &snapshot, int y) const;
+    ViewportAnchor anchorFromViewport(const LayoutSnapshot &snapshot, int scrollY, int viewportHeight) const;
+    int resolveAnchorToScrollY(const LayoutSnapshot &snapshot, const ViewportAnchor &anchor, int viewportHeight) const;
+    int pageAtY(int y) const;
+    QSize scaledPageSize(int pageIndex, int forWidth) const;
+    float scaleForPage(int pageIndex, int forWidth) const;
+
+    Render *render = nullptr;
+    int numPages = 0;
+    QVector<QSize> pageSizes;
+    QVector<int> yPositions;
+    int currentTotalHeight = 0;
+    LayoutSnapshot layoutSnapshot;
+    QSize defaultPageSize { 800, 1200 };
+    int zoomFactor = 100;
+    int anchorPage = -1;
+    int viewportScrollY = 0;
+    int currentViewportHeight = 0;
+    bool hasViewportState = false;
+};
+
+#endif // CONTINUOUS_PAGE_WIDGET_H

YACReader/main.cpp

@@ -144,7 +144,7 @@ int main(int argc, char *argv[])
     QDir().mkpath(YACReader::getSettingsPath());
 
     Logger &logger = Logger::instance();
-    logger.setLoggingLevel(QsLogging::InfoLevel);
+    logger.setLoggingLevel(QsLogging::TraceLevel);
 
     if (parser.isSet("loglevel")) {
         if (parser.value("loglevel") == "trace") {

YACReader/main_window_viewer.cpp

@@ -77,6 +77,7 @@ MainWindowViewer::~MainWindowViewer()
     delete rightRotationAction;
     delete doublePageAction;
     delete doubleMangaPageAction;
+    delete continuousScrollAction;
     delete increasePageZoomAction;
     delete decreasePageZoomAction;
     delete resetZoomAction;
@@ -309,28 +310,38 @@ void MainWindowViewer::createActions()
     fitToPageAction->setCheckable(true);
     connect(fitToPageAction, &QAction::triggered, this, &MainWindowViewer::fitToPageSwitch);
 
+    continuousScrollAction = new QAction(tr("Continuous scroll"), this);
+    continuousScrollAction->setToolTip(tr("Switch to continuous scroll mode"));
+    continuousScrollAction->setIcon(QIcon(":/images/viewer_toolbar/toContinuousScroll.svg"));
+    continuousScrollAction->setCheckable(true);
+    continuousScrollAction->setChecked(Configuration::getConfiguration().getContinuousScroll());
+    connect(continuousScrollAction, &QAction::toggled, viewer, &Viewer::setContinuousScroll);
+
     // fit modes have to be exclusive and checkable
     auto fitModes = new QActionGroup(this);
     fitModes->addAction(adjustHeightAction);
     fitModes->addAction(adjustWidthAction);
     fitModes->addAction(adjustToFullSizeAction);
     fitModes->addAction(fitToPageAction);
+    fitModes->addAction(continuousScrollAction);
 
-    switch (Configuration::getConfiguration().getFitMode()) {
-    case YACReader::FitMode::ToWidth:
-        adjustWidthAction->setChecked(true);
-        break;
-    case YACReader::FitMode::ToHeight:
-        adjustHeightAction->setChecked(true);
-        break;
-    case YACReader::FitMode::FullRes:
-        adjustToFullSizeAction->setChecked(true);
-        break;
-    case YACReader::FitMode::FullPage:
-        fitToPageAction->setChecked(true);
-        break;
-    default:
-        fitToPageAction->setChecked(true);
+    if (Configuration::getConfiguration().getContinuousScroll()) {
+        continuousScrollAction->setChecked(true);
+    } else {
+        switch (Configuration::getConfiguration().getFitMode()) {
+        case YACReader::FitMode::ToWidth:
+            adjustWidthAction->setChecked(true);
+            break;
+        case YACReader::FitMode::ToHeight:
+            adjustHeightAction->setChecked(true);
+            break;
+        case YACReader::FitMode::FullRes:
+            adjustToFullSizeAction->setChecked(true);
+            break;
+        case YACReader::FitMode::FullPage:
+        default:
+            fitToPageAction->setChecked(true);
+        }
     }
 
     resetZoomAction = new QAction(tr("Reset zoom"), this);
@@ -536,11 +547,14 @@ void MainWindowViewer::createToolBars()
     auto fitToPageTBAction = actionWithCustomIcon(QIcon(addExtensionToIconPathInToolbar(":/images/viewer_toolbar/fitToPage")), fitToPageAction);
     comicToolBar->addAction(fitToPageTBAction);
 
+    auto continuousScroollTBAction = actionWithCustomIcon(QIcon(addExtensionToIconPathInToolbar(":/images/viewer_toolbar/toContinuousScroll")), continuousScrollAction);
+
     auto fitModes = new QActionGroup(this);
     fitModes->addAction(adjustToWidthTBAction);
     fitModes->addAction(adjustToHeightTBAction);
     fitModes->addAction(adjustToFullSizeTBAction);
     fitModes->addAction(fitToPageTBAction);
+    fitModes->addAction(continuousScroollTBAction);
 
     zoomSliderAction = new YACReaderSlider(this);
     zoomSliderAction->hide();
@@ -555,6 +569,7 @@ void MainWindowViewer::createToolBars()
     comicToolBar->addAction(actionWithCustomIcon(QIcon(addExtensionToIconPathInToolbar(":/images/viewer_toolbar/rotateR")), rightRotationAction));
     comicToolBar->addAction(actionWithCustomIcon(QIcon(addExtensionToIconPathInToolbar(":/images/viewer_toolbar/doublePage")), doublePageAction));
     comicToolBar->addAction(actionWithCustomIcon(QIcon(addExtensionToIconPathInToolbar(":/images/viewer_toolbar/doubleMangaPage")), doubleMangaPageAction));
+    comicToolBar->addAction(continuousScroollTBAction);
 
     comicToolBar->addSeparator();
 
@@ -603,6 +618,7 @@ void MainWindowViewer::createToolBars()
     viewer->addAction(rightRotationAction);
     viewer->addAction(doublePageAction);
     viewer->addAction(doubleMangaPageAction);
+    viewer->addAction(continuousScrollAction);
     YACReader::addSperator(viewer);
 
     viewer->addAction(showMagnifyingGlassAction);
@@ -675,6 +691,7 @@ void MainWindowViewer::createToolBars()
     viewMenu->addSeparator();
     viewMenu->addAction(doublePageAction);
     viewMenu->addAction(doubleMangaPageAction);
+    viewMenu->addAction(continuousScrollAction);
     viewMenu->addSeparator();
     viewMenu->addAction(showMagnifyingGlassAction);
 
@@ -1247,6 +1264,7 @@ void MainWindowViewer::setUpShortcutsManagement()
                                                  << rightRotationAction
                                                  << doublePageAction
                                                  << doubleMangaPageAction
+                                                 << continuousScrollAction
                                                  << adjustToFullSizeAction
                                                  << fitToPageAction
                                                  << increasePageZoomAction
@@ -1540,6 +1558,7 @@ void MainWindowViewer::setActionsEnabled(bool enabled)
                            showMagnifyingGlassAction,
                            doublePageAction,
                            doubleMangaPageAction,
+                           continuousScrollAction,
                            adjustToFullSizeAction,
                            fitToPageAction,
                            showZoomSliderlAction,
@@ -1613,6 +1632,7 @@ void MainWindowViewer::applyTheme(const Theme &theme)
     setIcon(showDictionaryAction, toolbarTheme.showDictionaryAction, toolbarTheme.showDictionaryAction18x18);
     setIcon(adjustToFullSizeAction, toolbarTheme.adjustToFullSizeAction, toolbarTheme.adjustToFullSizeAction18x18);
     setIcon(fitToPageAction, toolbarTheme.fitToPageAction, toolbarTheme.fitToPageAction18x18);
+    setIcon(continuousScrollAction, toolbarTheme.continuousScrollAction, toolbarTheme.continuousScrollAction18x18);
     setIcon(showFlowAction, toolbarTheme.showFlowAction, toolbarTheme.showFlowAction18x18);
 }
 

YACReader/main_window_viewer.h

@@ -140,6 +140,7 @@ private:
     QAction *closeAction;
     QAction *doublePageAction;
     QAction *doubleMangaPageAction;
+    QAction *continuousScrollAction;
     QAction *showShorcutsAction;
     QAction *showDictionaryAction;
     QAction *adjustToFullSizeAction;

YACReader/render.cpp

@@ -546,6 +546,17 @@ QPixmap *Render::getCurrentDoubleMangaPage()
     }
 }
 
+const QImage *Render::bufferedImage(int absolutePageIndex) const
+{
+    int offset = absolutePageIndex - currentIndex;
+    int pos = currentPageBufferedIndex + offset;
+    if (pos < 0 || pos >= buffer.size()) {
+        return nullptr;
+    }
+    const QImage *img = buffer[pos];
+    return (img && !img->isNull()) ? img : nullptr;
+}
+
 bool Render::currentPageIsDoublePage()
 {
     if (currentIndex == 0 && Configuration::getConfiguration().getSettings()->value(COVER_IS_SP, true).toBool()) {
@@ -627,6 +638,8 @@ void Render::setComic(Comic *c)
 
 void Render::prepareAvailablePage(int page)
 {
+    emit pageRendered(page);
+
     if (!doublePage) {
         if (currentIndex == page) {
             emit currentPageReady();

YACReader/render.h

@@ -142,6 +142,7 @@ public slots:
     bool currentPageIsDoublePage();
     bool nextPageIsDoublePage();
     bool previousPageIsDoublePage();
+    const QImage *bufferedImage(int absolutePageIndex) const;
     void goTo(int index);
     void doublePageSwitch();
     void setManga(bool manga);
@@ -197,6 +198,7 @@ signals:
     void isLast();
     void isCover();
 
+    void pageRendered(int absolutePageIndex);
     void bookmarksUpdated();
 
 private:

YACReader/themes/theme.h

@@ -102,6 +102,8 @@ struct ToolbarTheme {
     QIcon adjustToFullSizeAction18x18;
     QIcon fitToPageAction;
     QIcon fitToPageAction18x18;
+    QIcon continuousScrollAction;
+    QIcon continuousScrollAction18x18;
     QIcon showFlowAction;
     QIcon showFlowAction18x18;
 };

YACReader/themes/theme_factory.cpp

@@ -139,6 +139,7 @@ Theme makeTheme(const ThemeParams &params)
     setToolbarIconPairT(theme.toolbar.showDictionaryAction, theme.toolbar.showDictionaryAction18x18, ":/images/viewer_toolbar/translator.svg");
     setToolbarIconPairT(theme.toolbar.adjustToFullSizeAction, theme.toolbar.adjustToFullSizeAction18x18, ":/images/viewer_toolbar/full.svg");
     setToolbarIconPairT(theme.toolbar.fitToPageAction, theme.toolbar.fitToPageAction18x18, ":/images/viewer_toolbar/fitToPage.svg");
+    setToolbarIconPairT(theme.toolbar.continuousScrollAction, theme.toolbar.continuousScrollAction18x18, ":/images/viewer_toolbar/toContinuousScroll.svg");
     setToolbarIconPairT(theme.toolbar.showFlowAction, theme.toolbar.showFlowAction18x18, ":/images/viewer_toolbar/flow.svg");
     // end Toolbar & actions
 

YACReader/viewer.cpp

@@ -1,4 +1,5 @@
 #include "viewer.h"
+#include "continuous_page_widget.h"
 #include "configuration.h"
 #include "magnifying_glass.h"
 #include "goto_flow_widget.h"
@@ -23,6 +24,7 @@ Viewer::Viewer(QWidget *parent)
       information(false),
       doublePage(false),
       doubleMangaPage(false),
+      continuousScroll(false),
       zoom(100),
       currentPage(nullptr),
       wheelStop(false),
@@ -40,15 +42,30 @@ Viewer::Viewer(QWidget *parent)
     translatorAnimation->setDuration(150);
     translatorXPos = -10000;
     translator->move(-translator->width(), 10);
-    // current comic page
+    // current comic page (used in non-continuous mode when a comic is open)
     content = new QLabel(this);
-    configureContent(tr("Press 'O' to open comic."));
+    content->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
+    if (!(devicePixelRatioF() > 1))
+        content->setScaledContents(true);
+    content->setAlignment(Qt::AlignTop | Qt::AlignHCenter);
+    content->setMouseTracking(true);
 
-    setWidget(content);
+    // dedicated widget for status messages ("Press 'O' to open comic.", "Loading...", etc.)
+    messageLabel = new QLabel(this);
+    messageLabel->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
+    messageLabel->setAlignment(Qt::AlignTop | Qt::AlignHCenter);
+    messageLabel->setText(tr("Press 'O' to open comic."));
+    messageLabel->setFont(QFont("courier new", 12));
+    messageLabel->setMouseTracking(true);
+
+    setWidget(messageLabel);
     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
     setFrameStyle(QFrame::NoFrame);
     setAlignment(Qt::AlignCenter);
+
+    continuousWidget = new ContinuousPageWidget();
+    continuousWidget->installEventFilter(this);
     //---------------------------------------
     mglass = new MagnifyingGlass(
             Configuration::getConfiguration().getMagnifyingGlassSize(),
@@ -63,7 +80,6 @@ Viewer::Viewer(QWidget *parent)
     });
 
     mglass->hide();
-    content->setMouseTracking(true);
     setMouseTracking(true);
 
     showCursor();
@@ -81,6 +97,7 @@ Viewer::Viewer(QWidget *parent)
     bd = new BookmarksDialog(this->parentWidget());
 
     render = new Render();
+    continuousWidget->setRender(render);
 
     hideCursorTimer = new QTimer();
     hideCursorTimer->setSingleShot(true);
@@ -91,6 +108,9 @@ Viewer::Viewer(QWidget *parent)
     if (Configuration::getConfiguration().getDoubleMangaPage())
         doubleMangaPageSwitch();
 
+    if (Configuration::getConfiguration().getContinuousScroll())
+        setContinuousScroll(true);
+
     createConnections();
 
     hideCursorTimer->start(2500);
@@ -122,7 +142,17 @@ Viewer::~Viewer()
     delete goToFlow;
     delete translator;
     delete translatorAnimation;
-    delete content;
+    // messageLabel, content or continuousWidget may not be owned by the scroll area
+    // (after takeWidget), so delete whichever ones are not currently set
+    if (widget() != messageLabel) {
+        delete messageLabel;
+    }
+    if (widget() != content) {
+        delete content;
+    }
+    if (widget() != continuousWidget) {
+        delete continuousWidget;
+    }
     delete hideCursorTimer;
     delete informationLabel;
     delete verticalScroller;
@@ -173,9 +203,14 @@ void Viewer::createConnections()
     connect(render, qOverload<unsigned int>(&Render::numPages), this, &Viewer::comicLoaded);
     connect(render, QOverload<int, const QByteArray &>::of(&Render::imageLoaded), goToFlow, &GoToFlowWidget::setImageReady);
     connect(render, &Render::currentPageReady, this, &Viewer::updatePage);
+    connect(render, &Render::pageRendered, continuousWidget, &ContinuousPageWidget::onPageAvailable);
+    connect(continuousWidget, &ContinuousPageWidget::layoutScrollPositionRequested, this, &Viewer::onContinuousLayoutScrollRequested);
+    connect(render, qOverload<unsigned int>(&Render::numPages), this, &Viewer::onNumPagesReady);
+    connect(verticalScrollBar(), &QScrollBar::valueChanged, this, &Viewer::onContinuousScroll);
     connect(render, &Render::processingPage, this, &Viewer::setLoadingMessage);
     connect(render, &Render::currentPageIsBookmark, this, &Viewer::pageIsBookmark);
     connect(render, &Render::pageChanged, this, &Viewer::updateInformation);
+    connect(render, &Render::pageChanged, this, &Viewer::onRenderPageChanged);
 
     connect(render, &Render::isLast, this, &Viewer::showIsLastMessage);
     connect(render, &Render::isCover, this, &Viewer::showIsCoverMessage);
@@ -304,11 +339,26 @@ void Viewer::goToLastPage()
 void Viewer::goTo(unsigned int page)
 {
     direction = 1; // in "go to" direction is always fordward
+
+    if (continuousScroll) {
+        lastCenterPage = page;
+        continuousWidget->setAnchorPage(page);
+        render->goTo(page);
+        scrollToCurrentContinuousPage();
+        return;
+    }
+
     render->goTo(page);
 }
 
 void Viewer::updatePage()
 {
+    if (continuousScroll) {
+        return;
+    }
+
+    setActiveWidget(content);
+
     QPixmap *previousPage = currentPage;
     if (doublePage) {
         if (!doubleMangaPage)
@@ -397,7 +447,11 @@ void Viewer::increaseZoomFactor()
 {
     zoom = std::min(zoom + 10, 500);
 
-    updateContentSize();
+    if (continuousScroll) {
+        continuousWidget->setZoomFactor(zoom);
+    } else {
+        updateContentSize();
+    }
     notificationsLabel->setText(QString::number(getZoomFactor()) + "%");
     notificationsLabel->flash();
 
@@ -407,7 +461,11 @@ void Viewer::decreaseZoomFactor()
 {
     zoom = std::max(zoom - 10, 30);
 
-    updateContentSize();
+    if (continuousScroll) {
+        continuousWidget->setZoomFactor(zoom);
+    } else {
+        updateContentSize();
+    }
     notificationsLabel->setText(QString::number(getZoomFactor()) + "%");
     notificationsLabel->flash();
 
@@ -435,16 +493,22 @@ void Viewer::setZoomFactor(int z)
 
 void Viewer::updateVerticalScrollBar()
 {
-    if (direction > 0)
+    if (direction > 0) {
         verticalScrollBar()->setSliderPosition(verticalScrollBar()->minimum());
-    else
+    } else {
         verticalScrollBar()->setSliderPosition(verticalScrollBar()->maximum());
+    }
 }
 
 void Viewer::scrollDown()
 {
     if (verticalScrollBar()->sliderPosition() == verticalScrollBar()->maximum()) {
-        next();
+        if (continuousScroll) {
+            shouldOpenNext = true;
+            emit openNextComic();
+        } else {
+            next();
+        }
     } else {
         int currentPos = verticalScrollBar()->sliderPosition();
         verticalScroller->setDuration(animationDuration());
@@ -460,7 +524,12 @@ void Viewer::scrollDown()
 void Viewer::scrollUp()
 {
     if (verticalScrollBar()->sliderPosition() == verticalScrollBar()->minimum()) {
-        prev();
+        if (continuousScroll) {
+            shouldOpenPrevious = true;
+            emit openPreviousComic();
+        } else {
+            prev();
+        }
     } else {
         int currentPos = verticalScrollBar()->sliderPosition();
         verticalScroller->setDuration(animationDuration());
@@ -670,6 +739,11 @@ void Viewer::wheelEventMouse(QWheelEvent *event)
         return;
     }
 
+    if (continuousScroll) {
+        animateScroll(*verticalScroller, *verticalScrollBar(), delta.y());
+        return;
+    }
+
     auto turnPageOnScroll = !Configuration::getConfiguration().getDoNotTurnPageOnScroll();
     auto getUseSingleScrollStepToTurnPage = Configuration::getConfiguration().getUseSingleScrollStepToTurnPage();
 
@@ -718,6 +792,10 @@ void Viewer::wheelEventTrackpad(QWheelEvent *event)
         verticalScrollBar()->setValue(newVerticalValue);
     }
 
+    if (continuousScroll) {
+        return;
+    }
+
     auto turnPageOnScroll = !Configuration::getConfiguration().getDoNotTurnPageOnScroll();
     auto getUseSingleScrollStepToTurnPage = Configuration::getConfiguration().getUseSingleScrollStepToTurnPage();
 
@@ -750,11 +828,16 @@ void Viewer::wheelEventTrackpad(QWheelEvent *event)
 
 void Viewer::resizeEvent(QResizeEvent *event)
 {
+    QScrollArea::resizeEvent(event);
+
+    if (continuousScroll) {
+        continuousWidget->setViewportState(verticalScrollBar()->value(), viewport()->height());
+    }
+
     updateContentSize();
     goToFlow->updateSize();
     goToFlow->move((width() - goToFlow->width()) / 2, height() - goToFlow->height());
     informationLabel->updatePosition();
-    QScrollArea::resizeEvent(event);
 }
 
 QPixmap Viewer::pixmap() const
@@ -927,6 +1010,132 @@ void Viewer::doublePageSwitch()
     Configuration::getConfiguration().setDoublePage(doublePage);
 }
 
+void Viewer::setContinuousScroll(bool enabled)
+{
+    if (continuousScroll == enabled) {
+        return;
+    }
+    continuousScroll = enabled;
+    Configuration::getConfiguration().setContinuousScroll(continuousScroll);
+
+    if (continuousScroll) {
+        continuousWidget->setZoomFactor(zoom);
+        if (render->hasLoadedComic()) {
+            continuousWidget->setViewportState(verticalScrollBar()->value(), viewport()->height());
+            continuousWidget->setNumPages(render->numPages());
+            // set the current page as model state before any layout/scroll happens
+            lastCenterPage = render->getIndex();
+            continuousWidget->setAnchorPage(lastCenterPage);
+            // pick up sizes of pages already in the buffer
+            continuousWidget->probeBufferedPages();
+            // trigger a render cycle so new pages arrive via pageRendered signal
+            render->update();
+            setActiveWidget(continuousWidget);
+            scrollToCurrentContinuousPage();
+            continuousWidget->update();
+            viewport()->update();
+        }
+        // if no comic is loaded, messageLabel stays as the active widget
+    } else {
+        lastCenterPage = -1;
+        if (render->hasLoadedComic()) {
+            updatePage();
+        }
+        // if no comic is loaded, messageLabel stays as the active widget
+    }
+}
+
+void Viewer::onContinuousScroll(int value)
+{
+    if (!continuousScroll || !render->hasLoadedComic()) {
+        return;
+    }
+
+    continuousWidget->setViewportState(value, viewport()->height());
+
+    int center = continuousWidget->centerPage(value, viewport()->height());
+
+    if (center != lastCenterPage && center >= 0) {
+        lastCenterPage = center;
+        continuousWidget->setAnchorPage(center);
+        syncingRenderFromContinuousScroll = true;
+        render->goTo(center);
+        syncingRenderFromContinuousScroll = false;
+        emit pageAvailable(true);
+    }
+}
+
+void Viewer::onContinuousLayoutScrollRequested(int scrollY)
+{
+    if (!continuousScroll) {
+        return;
+    }
+
+    auto *sb = verticalScrollBar();
+    const int target = qBound(sb->minimum(), scrollY, sb->maximum());
+
+    sb->blockSignals(true);
+    sb->setValue(target);
+    sb->blockSignals(false);
+
+    continuousWidget->setViewportState(target, viewport()->height());
+}
+
+void Viewer::scrollToCurrentContinuousPage()
+{
+    if (lastCenterPage < 0) {
+        return;
+    }
+
+    auto applyPosition = [this]() {
+        auto *sb = verticalScrollBar();
+        int targetY = continuousWidget->yPositionForPage(lastCenterPage);
+        targetY = qBound(sb->minimum(), targetY, sb->maximum());
+
+        sb->blockSignals(true);
+        sb->setValue(targetY);
+        sb->blockSignals(false);
+
+        continuousWidget->setViewportState(targetY, viewport()->height());
+
+        continuousWidget->update();
+        viewport()->update();
+    };
+
+    applyPosition();
+}
+
+void Viewer::onNumPagesReady(unsigned int numPages)
+{
+    if (continuousScroll && numPages > 0) {
+        setActiveWidget(continuousWidget);
+
+        continuousWidget->setViewportState(verticalScrollBar()->value(), viewport()->height());
+        continuousWidget->setNumPages(numPages);
+
+        int page = lastCenterPage;
+        if (page < 0) {
+            page = render->getIndex();
+        }
+        page = qBound(0, page, static_cast<int>(numPages) - 1);
+        lastCenterPage = page;
+        continuousWidget->setAnchorPage(page);
+
+        scrollToCurrentContinuousPage();
+    }
+}
+
+void Viewer::onRenderPageChanged(int page)
+{
+    if (!continuousScroll || page < 0 || page == lastCenterPage || syncingRenderFromContinuousScroll) {
+        return;
+    }
+
+    lastCenterPage = page;
+    continuousWidget->setAnchorPage(page);
+    scrollToCurrentContinuousPage();
+}
+
 void Viewer::setMangaWithoutStoringSetting(bool manga)
 {
     doubleMangaPage = manga;
@@ -948,6 +1157,8 @@ void Viewer::resetContent()
 {
     configureContent(tr("Press 'O' to open comic."));
     goToFlow->reset();
+    continuousWidget->reset();
+    lastCenterPage = -1;
     emit reset();
 }
 
@@ -958,7 +1169,9 @@ void Viewer::setLoadingMessage()
         restoreMagnifyingGlass = true;
     }
     emit pageAvailable(false);
-    configureContent(tr("Loading...please wait!"));
+    if (!continuousScroll) {
+        configureContent(tr("Loading...please wait!"));
+    }
 }
 
 void Viewer::setPageUnavailableMessage()
@@ -973,15 +1186,9 @@ void Viewer::setPageUnavailableMessage()
 
 void Viewer::configureContent(QString msg)
 {
-    content->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
-    if (!(devicePixelRatioF() > 1))
-        content->setScaledContents(true);
-    content->setAlignment(Qt::AlignTop | Qt::AlignHCenter);
-    content->setText(msg);
-    content->setFont(QFont("courier new", 12));
-    content->adjustSize();
+    messageLabel->setText(msg);
+    setActiveWidget(messageLabel);
     setFocus(Qt::ShortcutFocusReason);
-    // emit showingText();
 }
 
 void Viewer::hideCursor()
@@ -1022,7 +1229,8 @@ void Viewer::applyTheme(const Theme &theme)
     updateBackgroundColor(Configuration::getConfiguration().getBackgroundColor(viewerTheme.defaultBackgroundColor));
 
     const QString textColor = viewerTheme.defaultTextColor.name(QColor::HexArgb);
-    content->setStyleSheet(QStringLiteral("QLabel { color : %1; background: transparent; }").arg(textColor));
+    messageLabel->setStyleSheet(QStringLiteral("QLabel { color : %1; background: transparent; }").arg(textColor));
+    content->setStyleSheet(QStringLiteral("QLabel { background: transparent; }"));
 }
 
 void Viewer::animateShowTranslator()
@@ -1072,10 +1280,46 @@ void Viewer::mouseMoveEvent(QMouseEvent *event)
     mouseHandler->mouseMoveEvent(event);
 }
 
+bool Viewer::eventFilter(QObject *obj, QEvent *event)
+{
+    if (obj == continuousWidget && event->type() == QEvent::MouseMove) {
+        auto *mouseEvent = static_cast<QMouseEvent *>(event);
+        // Map position from continuousWidget coords to Viewer coords so the
+        // go-to-flow proximity check and cursor management work correctly.
+        QPointF viewerPos = mapFromGlobal(mouseEvent->globalPosition().toPoint());
+        QMouseEvent mappedEvent(mouseEvent->type(),
+                                viewerPos,
+                                mouseEvent->globalPosition(),
+                                mouseEvent->button(),
+                                mouseEvent->buttons(),
+                                mouseEvent->modifiers());
+        mouseHandler->mouseMoveEvent(&mappedEvent);
+    }
+    return QScrollArea::eventFilter(obj, event);
+}
+
+void Viewer::setActiveWidget(QWidget *w)
+{
+    if (widget() == w) {
+        return;
+    }
+    verticalScrollBar()->blockSignals(true);
+    takeWidget();
+    const bool isContinuous = (w == continuousWidget);
+    setWidgetResizable(isContinuous);
+    setVerticalScrollBarPolicy(isContinuous ? Qt::ScrollBarAsNeeded : Qt::ScrollBarAlwaysOff);
+    setWidget(w);
+    verticalScrollBar()->blockSignals(false);
+}
+
 void Viewer::updateZoomRatio(int ratio)
 {
     zoom = ratio;
-    updateContentSize();
+    if (continuousScroll) {
+        continuousWidget->setZoomFactor(zoom);
+    } else {
+        updateContentSize();
+    }
 }
 
 bool Viewer::getIsMangaMode()

YACReader/viewer.h

@@ -30,6 +30,7 @@ class GoToDialog;
 class YACReaderTranslator;
 class GoToFlowWidget;
 class Bookmarks;
+class ContinuousPageWidget;
 class PageLabelWidget;
 class NotificationsLabelWidget;
 
@@ -113,11 +114,13 @@ public slots:
     int getCurrentPageNumber();
     void updateZoomRatio(int ratio);
     bool getIsMangaMode();
+    void setContinuousScroll(bool enabled);
 
 private:
     bool information;
     bool doublePage;
     bool doubleMangaPage;
+    bool continuousScroll;
 
     int zoom;
 
@@ -144,6 +147,10 @@ private:
 
     //! Widgets
     QLabel *content;
+    QLabel *messageLabel;
+    ContinuousPageWidget *continuousWidget;
+    int lastCenterPage = -1;
+    bool syncingRenderFromContinuousScroll = false;
 
     YACReaderTranslator *translator;
     int translatorXPos;
@@ -183,12 +190,19 @@ private:
     // Zero when animations are disabled
     int animationDuration() const;
     void animateScroll(QPropertyAnimation &scroller, const QScrollBar &scrollBar, int delta);
+    void onContinuousScroll(int value);
+    void onContinuousLayoutScrollRequested(int scrollY);
+    void scrollToCurrentContinuousPage();
+    void onNumPagesReady(unsigned int numPages);
+    void onRenderPageChanged(int page);
+    void setActiveWidget(QWidget *w);
 
     //! Mouse handler
     std::unique_ptr<YACReader::MouseHandler> mouseHandler;
 
 protected:
     void applyTheme(const Theme &theme) override;
+    bool eventFilter(QObject *obj, QEvent *event) override;
 
 public:
     Viewer(QWidget *parent = nullptr);

YACReader/yacreader_images.qrc

@@ -55,6 +55,7 @@
     <file>../images/viewer_toolbar/shortcuts.svg</file>
     <file>../images/viewer_toolbar/showBookmarks.svg</file>
     <file>../images/viewer_toolbar/toHeight.svg</file>
+    <file>../images/viewer_toolbar/toContinuousScroll.svg</file>
     <file>../images/viewer_toolbar/toWidth.svg</file>
     <file>../images/viewer_toolbar/translator.svg</file>
     <file>../images/viewer_toolbar/zoom.svg</file>
@@ -82,6 +83,7 @@
     <file>../images/viewer_toolbar/shortcuts_18x18.svg</file>
     <file>../images/viewer_toolbar/showBookmarks_18x18.svg</file>
     <file>../images/viewer_toolbar/toHeight_18x18.svg</file>
+    <file>../images/viewer_toolbar/toContinuousScroll_18x18.svg</file>
     <file>../images/viewer_toolbar/toWidth_18x18.svg</file>
     <file>../images/viewer_toolbar/translator_18x18.svg</file>
     <file>../images/viewer_toolbar/zoom_18x18.svg</file>

common/yacreader_global_gui.h

@@ -23,6 +23,7 @@
 #define START_TO_TRAY "START_TO_TRAY"
 #define DOUBLE_PAGE "DOUBLE_PAGE"
 #define DOUBLE_MANGA_PAGE "DOUBLE_MANGA_PAGE"
+#define CONTINUOUS_SCROLL "CONTINUOUS_SCROLL"
 #define COVER_IS_SP "COVER_IS_SP"
 #define BACKGROUND_COLOR "BACKGROUND_COLOR_10"
 #define SHOW_TOOLBARS "SHOW_TOOLBARS"

images/viewer_toolbar/toContinuousScroll.svg

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg id="Layer_1" data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 16 16">
+  <defs>
+    <style>
+      .cls-1 {
+        fill: #f0f;
+      }
+    </style>
+  </defs>
+  <path class="cls-1" d="M2,2h12v1c0,.55-.45,1-1,1H3c-.55,0-1-.45-1-1v-1h0Z"/>
+  <path class="cls-1" d="M3,12h10c.55,0,1,.45,1,1v1H2v-1c0-.55.45-1,1-1Z"/>
+  <rect class="cls-1" x="2" y="5" width="12" height="6" rx="1" ry="1"/>
+</svg>

images/viewer_toolbar/toContinuousScroll_18x18.svg

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg id="Layer_1" data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 18 18">
+  <defs>
+    <style>
+      .cls-1 {
+        fill: #f0f;
+      }
+    </style>
+  </defs>
+  <path class="cls-1" d="M3,3h12v1c0,.55-.45,1-1,1H4c-.55,0-1-.45-1-1v-1h0Z"/>
+  <path class="cls-1" d="M4,13h10c.55,0,1,.45,1,1v1H3v-1c0-.55.45-1,1-1Z"/>
+  <rect class="cls-1" x="3" y="6" width="12" height="6" rx="1" ry="1"/>
+</svg>