looqs/gui/pdfworker.cpp

#include <QApplication>
#include <QScreen>
#include <QDebug>
#include <QScopedPointer>
#include <QMutexLocker>
#include <QtConcurrent/QtConcurrent>
#include <QtConcurrent/QtConcurrentMap>
#include <QPainter>
#include <atomic>
#include "pdfworker.h"

static QMutex cacheMutex;
struct Renderer
{

	typedef PdfPreview result_type;
	double scaleX;
	double scaleY;
	QHash<QString, Poppler::Document *> documentcache;
	QVector<QString> wordsToHighlight;
	Renderer(double scaleX, double scaleY, QVector<QString> wordsToHighlight)
	{
		this->scaleX = scaleX;
		this->scaleY = scaleY;
		this->wordsToHighlight = wordsToHighlight;
	}

	~Renderer()
	{
		qDeleteAll(documentcache);
	}

	Poppler::Document *document(QString path)
	{
		if(documentcache.contains(path))
		{
			return documentcache.value(path);
		}
		Poppler::Document *result = Poppler::Document::load(path);
		if(result == nullptr)
		{
			// TODO: some kind of user feedback would be nice
			return nullptr;
		}
		result->setRenderHint(Poppler::Document::TextAntialiasing);
		QMutexLocker locker(&cacheMutex);
		documentcache.insert(path, result);
		return result;
	}

	PdfPreview operator()(const PdfPreview &preview)
	{
		PdfPreview result = preview;
		Poppler::Document *doc = document(preview.documentPath);
		if(doc == nullptr)
		{
			return preview;
		}
		if(doc->isLocked())
		{
			return preview;
		}
		int p = (int)preview.page - 1;
		if(p < 0)
		{
			p = 0;
		}
		Poppler::Page *pdfPage = doc->page(p);
		QImage img = pdfPage->renderToImage(scaleX, scaleY);
		for(QString &word : wordsToHighlight)
		{
			QList<QRectF> rects = pdfPage->search(word, Poppler::Page::CaseInsensitive);
			for(QRectF &rect : rects)
			{
				QPainter painter(&img);
				painter.scale(scaleX / 72.0, scaleY / 72.0);
				painter.fillRect(rect, QColor(255, 255, 0, 64));
			}
		}
		result.previewImage = img;
		return result;
	}
};

QFuture<PdfPreview> PdfWorker::generatePreviews(const QVector<SearchResult> paths, QVector<QString> wordsToHighlight,
												double scalefactor)
{
	QVector<PdfPreview> previews;

	for(const SearchResult &sr : paths)
	{
		for(int page : sr.pages)
		{
			PdfPreview p;
			p.documentPath = sr.fileData.absPath;
			p.page = page;
			previews.append(p);
		}
	}

	double scaleX = QGuiApplication::primaryScreen()->physicalDotsPerInchX() * scalefactor;
	double scaleY = QGuiApplication::primaryScreen()->physicalDotsPerInchY() * scalefactor;

	QSettings setting;
	return QtConcurrent::mapped(previews, Renderer(scaleX, scaleY, wordsToHighlight));
}