Taborca Code

/****************************************************************************
** This file is part of the taborca project hosted at
** sf.net/projects/taborca
** Copyright (C) 2013 Shawn Rutledge
** Contact: s@ecloud.org
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program in a file called LICENSE; if not, write to the
** Free Software Foundation, Inc.,
** 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
****************************************************************************/
#ifndef PDFPAGER_H
#define PDFPAGER_H

#include <poppler-qt6.h>

#include <QObject>
#include <QImage>
#include <QIntValidator>
#include <QMutex>
#include <QRunnable>
#include "page.h"

/**
	\brief wrapper for a Poppler::Document, used to
	select and render pages and thumbnails.
*/
class PDFPager : public QObject, QRunnable
{
	Q_OBJECT
public:
	PDFPager();
	int page() { return m_pageNum; }
	QString path() { return m_path; }

	/**
			Render thumbnails, and pre-render page images, memory permitting.
		*/
	void run();

public slots:

	/**
		Open the PDF at the given path,
		emit opened() and numPages(), then iterate through the pages
		and emit thumbnail() for each.  Finally, go back to page 0
		since it will be shown by default.
	*/
	void openPDF(QString fpath);

	/**
		Reset to original state: no file is open.
	*/
	void closePDF();

	/**
		Go to (and render) the given page.
	*/
	void page(int pnum);

	/**
		Convenience version of page(int) taking a number in string form.
	*/
	void page(QString pnum) { page(pnum.toInt()); }

	void nextPage(bool forward = true);

	/**
		Re-render the current page at the given size.
	*/
    virtual void renderSize(QSize s, bool reRender = true);

	/**
		Re-render the current page at the same size as the given rectangle.
	*/
	virtual void renderSize(const QRectF& s) { renderSize(s.size().toSize()); }

signals:
	void opened(QString fpath, int numPages);
	void closed(QString fpath);
	void numPages(int n);
	void rendering(bool t);
	void rendered(int pnum, QImage pm);
    void pageText(QStringList);
	void pageChanged(int p);
	void pageChanged(QString p);
	void thumbnail(int pnum, QImage pm, QString label);
	void statusMessage(QString msg, int timeout = 0);
	void statusClear();

public:
	/**
		The Poppler implementation.
	*/
    std::unique_ptr<Poppler::Document> pdf;

	/**
		Validator for the page number entry field on the toolbar.
	*/
	QIntValidator pageRange;

	/**
		Get the concatenated text of this page, without formatting.
	*/
	QString plainText() { return m_text; }

protected:

	/**
		Rendering implementation.
	*/
	virtual void render(int pnum, QSize renderSize = QSize(), bool emitImage = true);

	/**
		\brief Handler for completion of rendering; emits
		rendering(false) and rendered().

		This exists because	of an (unimplemented) plan to render
		higher-resolution thumbnails, and same-resolution page images,
		in a background	thread,	in a subclass of this one called PDFPageCache.
		The completion of rendering would trigger rendering of the
		next page, in that case.
	*/
	virtual void renderDone(int pnum, QImage pm);

protected:
	/**
		Current page number, the last one rendered and presumably showing
		in the main PDF view.
	*/
	int m_pageNum;

	/**
		Size at which we will render the next page.
	*/
	QSize m_renderSize;

	QSize m_thumbnailRenderSize;

	/**
		Path to the pdf as given in openPDF.
	*/
	QString m_path;

	/**
		Concatenated text from the page, e.g. existing OCR results
		from the PDF file.
	*/
	QString m_text;

	QMutex m_renderMutex;

	// Cannot be a QPixmap cache because a thread is involved
	// "QPixmap: It is not safe to use pixmaps outside the GUI thread"
	/**
	  Cache for the "main" page images
	  @todo maybe: store cached images at more than one size,
			in case the user is zooming in and out a lot
	*/
	QVector<Page> m_cache;

	/**
	  Which pages do not have valid thumbnails yet?
	  (Usually an entire document will be like that, but
	  doesn't have to be.)
	*/
	QList<int> m_nullThumbnails;

	//friend class PDFPageCache;
};

#endif // PDFPAGER_H