gui: Begin support to also preview results in plain text files

gui/previewgeneratorplaintext.cpp

@@ -0,0 +1,81 @@
+#include <QTextStream>
+
+#include "previewgeneratorplaintext.h"
+#include "previewresultplaintext.h"
+
+PreviewResult *PreviewGeneratorPlainText::generate(RenderConfig config, QString documentPath, unsigned int page)
+{
+	PreviewResultPlainText *result = new PreviewResultPlainText(documentPath, page);
+	QFile file(documentPath);
+	if(!file.open(QFile::ReadOnly | QFile::Text))
+	{
+		return result;
+	}
+	QTextStream in(&file);
+
+	QString resulText = "";
+	QString content = in.readAll();
+	QMap<int, QString> snippet;
+
+	int coveredRange = 0;
+
+	int lastWordPos = 0;
+	QHash<QString, int> countmap;
+
+	for(QString &word : config.wordsToHighlight)
+	{
+
+		int lastPos = 0;
+		int index = content.indexOf(word, lastPos, Qt::CaseInsensitive);
+		while(index != -1)
+		{
+			countmap[word] = countmap.value(word, 0) + 1;
+
+			if(index >= lastWordPos && index <= coveredRange)
+			{
+				break;
+			}
+			int begin = index - 50;
+			if(begin < 0)
+			{
+				begin = 0;
+			}
+			int after = index + 50;
+			if(after > content.size())
+			{
+				after = content.size();
+			}
+
+			snippet[index] = "...<br>" + content.mid(begin, after) + "...<br>";
+			coveredRange = after;
+			lastPos = index;
+
+			index = content.indexOf(word, lastPos + 1, Qt::CaseInsensitive);
+		}
+		lastWordPos = lastPos;
+	}
+
+	auto i = snippet.constBegin();
+	while(i != snippet.constEnd())
+	{
+		resulText.append(i.value());
+		++i;
+	}
+
+	for(QString &word : config.wordsToHighlight)
+	{
+		resulText.replace(word, "<span style=\"background-color: yellow;\">" + word + "</span>", Qt::CaseInsensitive);
+	}
+
+	QFileInfo info{documentPath};
+
+	QString header = "<b>" + info.fileName() + "</b> ";
+	for(QString &word : config.wordsToHighlight)
+	{
+		header += word + ": " + QString::number(countmap[word]) + " ";
+	}
+	header += "<hr>";
+
+	result->setText(header + resulText.replace("\n", "<br>"));
+	return result;
+}