Generalize previews: Add PreviewGenerator*

gui/previewgeneratorpdf.cpp

@@ -0,0 +1,59 @@
+#include <QMutexLocker>
+#include <QPainter>
+
+#include "previewgeneratorpdf.h"
+
+static QMutex cacheMutex;
+
+Poppler::Document *PreviewGeneratorPdf::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);
+	locker.unlock();
+	return result;
+}
+
+PreviewResult *PreviewGeneratorPdf::generate(RenderConfig config, QString documentPath, unsigned int page)
+{
+	PreviewResultPdf *result = new PreviewResultPdf(documentPath, page);
+
+	Poppler::Document *doc = document(documentPath);
+	if(doc == nullptr)
+	{
+		return result;
+	}
+	if(doc->isLocked())
+	{
+		return result;
+	}
+	int p = (int)page - 1;
+	if(p < 0)
+	{
+		p = 0;
+	}
+	Poppler::Page *pdfPage = doc->page(p);
+	QImage img = pdfPage->renderToImage(config.scaleX, config.scaleY);
+	for(QString &word : config.wordsToHighlight)
+	{
+		QList<QRectF> rects = pdfPage->search(word, Poppler::Page::SearchFlag::IgnoreCase);
+		for(QRectF &rect : rects)
+		{
+			QPainter painter(&img);
+			painter.scale(config.scaleX / 72.0, config.scaleY / 72.0);
+			painter.fillRect(rect, QColor(255, 255, 0, 64));
+		}
+	}
+	result->previewImage = img;
+	return result;
+}