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https://github.com/YACReader/yacreader
synced 2026-03-01 10:22:58 -05:00
Extract the layout logic to a view model to simplify the update logic in continuous scroll mode
This commit is contained in:
luisangelsm
committed by
Luis Ángel San Martín
Luis Ángel San Martín
parent
f61c5280c9
commit
0bd291ba98
@ -1,10 +1,9 @@
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#include "continuous_page_widget.h"
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#include "continuous_view_model.h"
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#include "render.h"
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#include <QPainter>
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#include <QPaintEvent>
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#include <algorithm>
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#include <limits>
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ContinuousPageWidget::ContinuousPageWidget(QWidget *parent)
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: QWidget(parent)
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@ -26,80 +25,32 @@ void ContinuousPageWidget::setRender(Render *r)
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render = r;
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}
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void ContinuousPageWidget::setNumPages(int count)
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void ContinuousPageWidget::setViewModel(ContinuousViewModel *viewModel)
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{
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numPages = count;
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defaultPageSize = QSize(800, 1200);
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pageSizes.fill(QSize(0, 0), count);
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relayout(false);
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}
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void ContinuousPageWidget::setZoomFactor(int zoom)
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{
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if (zoomFactor == zoom) {
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return;
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}
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zoomFactor = zoom;
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relayout(true);
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update();
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}
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void ContinuousPageWidget::probeBufferedPages()
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{
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if (!render || numPages == 0) {
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if (continuousViewModel == viewModel) {
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return;
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}
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bool changed = false;
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for (int i = 0; i < numPages; ++i) {
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const QImage *img = render->bufferedImage(i);
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bool hasKnownSize = pageSizes[i].width() > 0 && pageSizes[i].height() > 0;
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if (img && !img->isNull() && !hasKnownSize) {
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pageSizes[i] = img->size();
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if (defaultPageSize == QSize(800, 1200)) {
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defaultPageSize = img->size();
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}
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changed = true;
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}
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if (continuousViewModel) {
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disconnect(continuousViewModel, &ContinuousViewModel::stateChanged, this, QOverload<>::of(&ContinuousPageWidget::update));
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}
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if (changed) {
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relayout(true);
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update();
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}
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}
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continuousViewModel = viewModel;
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if (continuousViewModel) {
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connect(continuousViewModel, &ContinuousViewModel::stateChanged, this, QOverload<>::of(&ContinuousPageWidget::update));
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}
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void ContinuousPageWidget::reset()
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{
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numPages = 0;
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pageSizes.clear();
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yPositions.clear();
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currentTotalHeight = 0;
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layoutSnapshot = LayoutSnapshot();
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defaultPageSize = QSize(800, 1200);
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setMinimumHeight(0);
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setMaximumHeight(QWIDGETSIZE_MAX);
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updateGeometry();
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update();
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}
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int ContinuousPageWidget::centerPage(int scrollY, int viewportHeight) const
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void ContinuousPageWidget::reset()
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{
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const int centerY = scrollY + std::max(0, viewportHeight / 2);
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return pageAtY(centerY);
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}
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int ContinuousPageWidget::yPositionForPage(int pageIndex) const
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{
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if (pageIndex < 0 || pageIndex >= yPositions.size()) {
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return 0;
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}
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return yPositions[pageIndex];
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}
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int ContinuousPageWidget::totalHeight() const
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{
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return currentTotalHeight;
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setMinimumHeight(0);
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setMaximumHeight(QWIDGETSIZE_MAX);
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updateGeometry();
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update();
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}
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bool ContinuousPageWidget::hasHeightForWidth() const
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@ -109,26 +60,24 @@ bool ContinuousPageWidget::hasHeightForWidth() const
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int ContinuousPageWidget::heightForWidth(int w) const
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{
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if (numPages == 0 || w <= 0) {
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if (!continuousViewModel || w <= 0) {
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return 0;
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}
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int h = 0;
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for (int i = 0; i < numPages; ++i) {
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QSize scaled = scaledPageSize(i, w);
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h += scaled.height();
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}
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return h;
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Q_UNUSED(w)
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return continuousViewModel->totalHeight();
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}
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QSize ContinuousPageWidget::sizeHint() const
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{
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return QSize(defaultPageSize.width(), currentTotalHeight > 0 ? currentTotalHeight : 0);
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if (!continuousViewModel) {
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return QSize(800, 0);
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}
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return QSize(width(), continuousViewModel->totalHeight());
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}
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void ContinuousPageWidget::onPageAvailable(int absolutePageIndex)
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{
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if (!render || absolutePageIndex < 0 || absolutePageIndex >= numPages) {
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if (!render || !continuousViewModel || absolutePageIndex < 0 || absolutePageIndex >= continuousViewModel->numPages()) {
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return;
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}
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@ -137,45 +86,35 @@ void ContinuousPageWidget::onPageAvailable(int absolutePageIndex)
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return;
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}
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QSize naturalSize = img->size();
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// update default page size from the first real page we see
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if (defaultPageSize == QSize(800, 1200) && !naturalSize.isNull()) {
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defaultPageSize = naturalSize;
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}
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bool sizeChanged = (pageSizes[absolutePageIndex] != naturalSize);
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pageSizes[absolutePageIndex] = naturalSize;
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if (sizeChanged) {
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// keep anchor page visually stable while refined page sizes arrive
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relayout(true);
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}
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// repaint the region where this page lives
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if (absolutePageIndex < yPositions.size()) {
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QSize scaled = scaledPageSize(absolutePageIndex, width());
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QRect pageRect(0, yPositions[absolutePageIndex], scaled.width(), scaled.height());
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if (absolutePageIndex < continuousViewModel->numPages()) {
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QSize scaled = continuousViewModel->scaledPageSize(absolutePageIndex);
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const int y = continuousViewModel->yPositionForPage(absolutePageIndex);
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int x = (width() - scaled.width()) / 2;
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if (x < 0) {
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x = 0;
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}
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QRect pageRect(x, y, scaled.width(), scaled.height());
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update(pageRect);
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}
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}
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void ContinuousPageWidget::paintEvent(QPaintEvent *event)
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{
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if (numPages == 0 || !render) {
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if (!continuousViewModel || continuousViewModel->numPages() == 0 || !render) {
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return;
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}
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QPainter painter(this);
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QRect visibleRect = event->rect();
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int firstPage = pageAtY(visibleRect.top());
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int lastPage = pageAtY(visibleRect.bottom());
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int firstPage = continuousViewModel->pageAtY(visibleRect.top());
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int lastPage = continuousViewModel->pageAtY(visibleRect.bottom());
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int w = width();
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for (int i = firstPage; i <= lastPage && i < numPages; ++i) {
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int y = yPositions[i];
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QSize scaled = scaledPageSize(i, w);
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for (int i = firstPage; i <= lastPage && i < continuousViewModel->numPages(); ++i) {
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int y = continuousViewModel->yPositionForPage(i);
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QSize scaled = continuousViewModel->scaledPageSize(i);
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// center horizontally if page is narrower than widget
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int x = (w - scaled.width()) / 2;
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if (x < 0) {
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@ -202,192 +141,7 @@ void ContinuousPageWidget::paintEvent(QPaintEvent *event)
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void ContinuousPageWidget::resizeEvent(QResizeEvent *event)
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{
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QWidget::resizeEvent(event);
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relayout(true);
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}
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void ContinuousPageWidget::setAnchorPage(int page)
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{
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anchorPage = page;
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}
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void ContinuousPageWidget::setViewportState(int scrollY, int viewportHeight)
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{
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viewportScrollY = std::max(0, scrollY);
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currentViewportHeight = std::max(0, viewportHeight);
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hasViewportState = true;
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}
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void ContinuousPageWidget::updateLayout()
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{
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relayout(false);
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}
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void ContinuousPageWidget::updateLayoutWithAnchor()
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{
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relayout(true);
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}
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void ContinuousPageWidget::relayout(bool preserveAnchor)
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{
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int w = width();
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if (w <= 0) {
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w = parentWidget() ? parentWidget()->width() : 0;
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}
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if (w <= 0) {
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w = defaultPageSize.width();
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}
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const LayoutSnapshot oldSnapshot = layoutSnapshot;
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ViewportAnchor anchor;
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if (preserveAnchor && hasViewportState && !oldSnapshot.yPositions.isEmpty()) {
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anchor = anchorFromViewport(oldSnapshot, viewportScrollY, currentViewportHeight);
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} else if (preserveAnchor && anchorPage >= 0) {
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anchor.pageIndex = anchorPage;
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anchor.offsetRatio = 0.5f;
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anchor.valid = true;
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}
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layoutSnapshot = buildLayoutSnapshot(w);
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#ifndef NDEBUG
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Q_ASSERT(layoutSnapshot.yPositions.size() == numPages);
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Q_ASSERT(layoutSnapshot.scaledSizes.size() == numPages);
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for (int i = 0; i < layoutSnapshot.scaledSizes.size(); ++i) {
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Q_ASSERT(layoutSnapshot.scaledSizes[i].width() > 0);
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Q_ASSERT(layoutSnapshot.scaledSizes[i].height() > 0);
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if (i > 0) {
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Q_ASSERT(layoutSnapshot.yPositions[i] >= layoutSnapshot.yPositions[i - 1]);
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}
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}
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#endif
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yPositions = layoutSnapshot.yPositions;
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currentTotalHeight = layoutSnapshot.totalHeight;
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setFixedHeight(currentTotalHeight);
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updateGeometry();
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if (!preserveAnchor || !anchor.valid || currentViewportHeight <= 0) {
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return;
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}
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const int newScrollForAnchor = resolveAnchorToScrollY(layoutSnapshot, anchor, currentViewportHeight);
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emit layoutScrollPositionRequested(newScrollForAnchor);
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}
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ContinuousPageWidget::LayoutSnapshot ContinuousPageWidget::buildLayoutSnapshot(int w) const
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{
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LayoutSnapshot snapshot;
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if (numPages <= 0 || w <= 0) {
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return snapshot;
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}
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snapshot.yPositions.resize(numPages);
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snapshot.scaledSizes.resize(numPages);
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qint64 y = 0;
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for (int i = 0; i < numPages; ++i) {
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snapshot.yPositions[i] = static_cast<int>(std::min<qint64>(y, std::numeric_limits<int>::max()));
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QSize scaled = scaledPageSize(i, w);
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scaled.setWidth(std::max(1, scaled.width()));
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scaled.setHeight(std::max(1, scaled.height()));
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snapshot.scaledSizes[i] = scaled;
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y += scaled.height();
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}
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snapshot.totalHeight = static_cast<int>(std::min<qint64>(y, static_cast<qint64>(QWIDGETSIZE_MAX)));
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return snapshot;
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}
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int ContinuousPageWidget::pageAtY(const LayoutSnapshot &snapshot, int y) const
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{
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if (snapshot.yPositions.isEmpty()) {
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return 0;
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}
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auto it = std::upper_bound(snapshot.yPositions.constBegin(), snapshot.yPositions.constEnd(), y);
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if (it == snapshot.yPositions.constBegin()) {
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return 0;
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}
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--it;
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return static_cast<int>(it - snapshot.yPositions.constBegin());
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}
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ContinuousPageWidget::ViewportAnchor ContinuousPageWidget::anchorFromViewport(const LayoutSnapshot &snapshot, int scrollY, int viewportHeight) const
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{
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ViewportAnchor anchor;
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if (snapshot.yPositions.isEmpty() || viewportHeight <= 0) {
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return anchor;
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}
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const int maxScroll = std::max(0, snapshot.totalHeight - viewportHeight);
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const int clampedScroll = qBound(0, scrollY, maxScroll);
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const int anchorY = clampedScroll + viewportHeight / 2;
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const int page = pageAtY(snapshot, anchorY);
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if (page < 0 || page >= snapshot.scaledSizes.size()) {
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return anchor;
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}
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const int pageTop = snapshot.yPositions[page];
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const int pageHeight = std::max(1, snapshot.scaledSizes[page].height());
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const float ratio = static_cast<float>(anchorY - pageTop) / static_cast<float>(pageHeight);
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anchor.pageIndex = page;
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anchor.offsetRatio = qBound(0.0f, ratio, 1.0f);
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anchor.valid = true;
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return anchor;
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}
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int ContinuousPageWidget::resolveAnchorToScrollY(const LayoutSnapshot &snapshot, const ViewportAnchor &anchor, int viewportHeight) const
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{
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if (!anchor.valid || viewportHeight <= 0 || snapshot.yPositions.isEmpty()) {
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return 0;
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}
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if (anchor.pageIndex < 0 || anchor.pageIndex >= snapshot.yPositions.size() || anchor.pageIndex >= snapshot.scaledSizes.size()) {
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return 0;
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}
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const int pageTop = snapshot.yPositions[anchor.pageIndex];
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const int pageHeight = std::max(1, snapshot.scaledSizes[anchor.pageIndex].height());
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const int anchorY = pageTop + qRound(anchor.offsetRatio * pageHeight);
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const int maxScroll = std::max(0, snapshot.totalHeight - viewportHeight);
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const int target = anchorY - viewportHeight / 2;
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return qBound(0, target, maxScroll);
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}
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int ContinuousPageWidget::pageAtY(int y) const
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{
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return pageAtY(layoutSnapshot, y);
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}
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QSize ContinuousPageWidget::scaledPageSize(int pageIndex, int forWidth) const
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{
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QSize natural = (pageIndex < pageSizes.size() && pageSizes[pageIndex].width() > 0 && pageSizes[pageIndex].height() > 0)
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? pageSizes[pageIndex]
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: defaultPageSize;
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float scale = scaleForPage(pageIndex, forWidth);
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int scaledW = std::max(1, qRound(natural.width() * scale));
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int scaledH = std::max(1, qRound(natural.height() * scale));
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return QSize(scaledW, scaledH);
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}
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float ContinuousPageWidget::scaleForPage(int pageIndex, int forWidth) const
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{
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QSize natural = (pageIndex < pageSizes.size() && pageSizes[pageIndex].width() > 0 && pageSizes[pageIndex].height() > 0)
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? pageSizes[pageIndex]
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: defaultPageSize;
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if (natural.width() <= 0 || forWidth <= 0) {
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return 1.0f;
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}
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float baseScale = static_cast<float>(forWidth) / natural.width();
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float zoomMultiplier = zoomFactor / 100.0f;
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return baseScale * zoomMultiplier;
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if (continuousViewModel) {
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continuousViewModel->setViewportSize(width(), continuousViewModel->viewportHeight());
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}
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}
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