Cache for frame grabbing

Implemetented a cache for hovering over movies, saving the pictures from
ffmpeg. For that SmGlobals got a new member *frameCache, handling all
the dirty file access.

I first tried to implement it as a helper, but that produced too much
duplicate code.

5 files changed, 124 insertions, 24 deletions

diff --git a/filestreewidget.cpp b/filestreewidget.cpp
index b6189c5..857b848 100644
--- a/filestreewidget.cpp
+++ b/filestreewidget.cpp
@@ -408,7 +408,7 @@ void FilesTreeView::doHover(const QModelIndex &idx){
 	bool scale = true;
 	mCurHover = idx;
 	if(idx.data(FilesTreeModel::FileTypeRole).toInt() == FilesTreeModel::Movie){
-		pm = Helper::grabFrame(idx.data(FilesTreeModel::FullPathRole).toString());
+		pm = SmGlobals::instance()->frameCache()->entry(idx.data(FilesTreeModel::FullPathRole).toString());
 		if(pm.isNull()){
 			return;
 		}
diff --git a/helper.cpp b/helper.cpp
index 126b83d..6cb5cd2 100644
--- a/helper.cpp
+++ b/helper.cpp
@@ -167,27 +167,6 @@ namespace Helper {
 		return retval;
 	}
 
-	const QPixmap grabFrame(const QString &file, QString when){
-		QSettings s;
-		QString ffMpegPath = s.value("paths/ffmpeg").toString();
-		if(when.isEmpty()){
-			when = s.value("ui/grabframe", "00:00:00").toString();
-		}
-		QString tmptmp = QString("%1/smhover-XXXXXX.png").arg(QDir::tempPath());
-		QTemporaryFile tmpPic(tmptmp);
-		if(tmpPic.open()){
-			QStringList ffMpegArgs = QStringList() << "-vframes" << "1" << "-ss" << when << "-i" << file << "-y" << tmpPic.fileName();
-			QProcess ffmpeg;
-			ffmpeg.start(ffMpegPath, ffMpegArgs);
-			if(!ffmpeg.waitForStarted()){
-				return QPixmap();
-			}
-			ffmpeg.waitForFinished();
-			return QPixmap(tmpPic.fileName());
-		}
-		return QPixmap();
-	}
-
 	bool SortFileInfoList::operator ()(const QFileInfo &lhs, const QFileInfo &rhs) const {
 		return lhs.fileName().toLower() < rhs.fileName().toLower();
 	}
diff --git a/helper.h b/helper.h
index fb6ef1c..c9d1ad3 100644
--- a/helper.h
+++ b/helper.h
@@ -25,7 +25,6 @@ namespace Helper {
 	const QString createArchivePath(const QString &path, const QString &md5, bool withMd5 = false);
 	QPair<QString, QStringList> programData(const QString &prefix, const QString &preferred = QString());
 	const QString durationFromSecs(qint64 secs);
-	const QPixmap grabFrame(const QString &file, QString when = QString());
 	class SortFileInfoList : public std::binary_function<QFileInfo, QFileInfo, bool> {
 		public:
 			bool operator()(const QFileInfo &lhs, const QFileInfo &rhs) const;
diff --git a/smglobals.cpp b/smglobals.cpp
index 9b4837c..f163ac1 100644
--- a/smglobals.cpp
+++ b/smglobals.cpp
@@ -10,6 +10,12 @@
 #include <QStringList>
 #include <QMessageBox>
 #include <QSettings>
+#include <QDir>
+#include <QFile>
+#include <QDataStream>
+#include <QFileInfo>
+#include <QTemporaryFile>
+#include <QProcess>
 
 #include <QX11Info>
 #include <X11/Xlib.h>
@@ -28,6 +34,7 @@ SmGlobals::~SmGlobals(){
 		delete model;
 	}
 	QSqlDatabase::removeDatabase("treedb");
+	delete mFrameCache;
 }
 
 SmGlobals *SmGlobals::instance(){
@@ -84,6 +91,13 @@ PictureViewer *SmGlobals::pictureViewer() {
 	return mPictureViewer;
 }
 
+SmGlobals::FrameCache *SmGlobals::frameCache() {
+	if(!mFrameCache){
+		mFrameCache = new SmGlobals::FrameCache;
+	}
+	return mFrameCache;
+}
+
 QSize SmGlobals::cursorSize() {
 	if(!mCursorSize.isValid()){
 		XFixesCursorImage *curImage = XFixesGetCursorImage(QX11Info::display());
@@ -93,4 +107,87 @@ QSize SmGlobals::cursorSize() {
 	return mCursorSize;
 }
 
-SmGlobals::SmGlobals() : mPictureViewer(0) {}
+SmGlobals::SmGlobals() : mPictureViewer(0), mFrameCache(0) {}
+
+//FrameCache
+SmGlobals::FrameCache::FrameCache(QObject *parent) : QObject(parent), mMagic(0xDEADBEEF), mCacheSubDir(".frameCache"), mCacheFileName("cache") {
+	readConfig();
+	readCache();
+}
+
+SmGlobals::FrameCache::~FrameCache(){
+	QFile outfile(mCacheFile);
+	outfile.open(QIODevice::WriteOnly | QIODevice::Truncate);
+	QDataStream ds(&outfile);
+	ds << (qint32)mMagic;
+	for(QHash<QPair<QString, QString>, QString>::const_iterator it = mFrameCache.constBegin(); it != mFrameCache.constEnd(); ++it){
+		ds << it.key().first << it.key().second << it.value();
+	}
+	outfile.close();
+}
+
+void SmGlobals::FrameCache::readConfig(){
+	QSettings s;
+	QString archive = s.value("paths/archivedir").toString();
+	if(archive.isEmpty()){
+		return;
+	}
+	QDir archiveDir(archive);
+	if(!archiveDir.exists(mCacheSubDir)){
+		archiveDir.mkdir(mCacheSubDir);
+	}
+	mCacheDir = QString("%1/%2").arg(archive).arg(mCacheSubDir);
+	mCacheFile = QString("%1/%2").arg(mCacheDir).arg(mCacheFileName);
+	mWhen = s.value("ui/grabframe", "00:00:00").toString();
+	mFfMpegPath = s.value("paths/ffmpeg").toString();
+}
+
+const QPixmap SmGlobals::FrameCache::entry(const QString &sourcePath, const QString &when){
+	QString realWhen = when;
+	if(realWhen.isEmpty()){
+		realWhen = mWhen;
+	}
+	const QPair<QString, QString> source(sourcePath, realWhen);
+	if(!mFrameCache.contains(source)){
+		grabFrame(sourcePath, realWhen);
+	}
+	return QPixmap(mFrameCache.value(source));
+}
+
+void SmGlobals::FrameCache::grabFrame(const QString &sourceFile, QString when){
+	QFileInfo sourceInfo(sourceFile);
+	if(!sourceInfo.exists()){
+		return;
+	}
+	QString tmpTemplate = QString("%1/%2_%3-XXXXXX.png").arg(mCacheDir).arg(sourceInfo.fileName()).arg(when);
+	QTemporaryFile tempFile(tmpTemplate);
+	tempFile.setAutoRemove(false);
+	if(tempFile.open()){
+		QStringList ffMpegArgs = QStringList() << "-vframes" << "1" << "-ss" << when << "-i" << sourceFile << "-y" << tempFile.fileName();
+		QProcess ffmpeg;
+		ffmpeg.start(mFfMpegPath, ffMpegArgs);
+		if(!ffmpeg.waitForStarted()){
+			return;
+		}
+		ffmpeg.waitForFinished();
+		QPair<QString, QString> pair(sourceFile, when);
+		mFrameCache.insert(pair, tempFile.fileName());
+	}
+}
+
+void SmGlobals::FrameCache::readCache(){
+	QFile cache(mCacheFile);
+	cache.open(QIODevice::ReadOnly);
+	QDataStream ds(&cache);
+	qint32 magic;
+	ds >> magic;
+	if(magic != mMagic){
+		return;
+	}
+	while(!ds.atEnd()){
+		QString source, pos, cacheFile;
+		ds >> source >> pos >> cacheFile;
+		QPair<QString, QString> pair(source, pos);
+		mFrameCache.insert(pair, cacheFile);
+	}
+}
diff --git a/smglobals.h b/smglobals.h
index 06d7b43..b994b53 100644
--- a/smglobals.h
+++ b/smglobals.h
@@ -10,17 +10,41 @@
 
 #include <QHash>
 #include <QSize>
+#include <QPair>
 
 class QAbstractItemModel;
 class PictureViewer;
+class QPixmap;
 
 class SmGlobals : public QObject {
 	Q_OBJECT
 	public:
+		class FrameCache : public QObject {
+			public:
+				FrameCache(QObject *parent = 0);
+				~FrameCache();
+				void readConfig();
+				const QPixmap entry(const QString &sourcePath, const QString &when = QString());
+
+			private:
+				void readCache();
+				void grabFrame(const QString &sourceFile, QString when);
+				QHash<QPair<QString, QString>, QString> mFrameCache;
+				const qint32 mMagic;
+				const QString mCacheSubDir;
+				const QString mCacheFileName;
+				QString mCacheDir;
+				QString mCacheFile;
+				QString mWhen;
+				QString mFfMpegPath;
+
+		};
+
 		~SmGlobals();
 		static SmGlobals *instance();
 		QAbstractItemModel *model(const QString &which);
 		PictureViewer *pictureViewer();
+		FrameCache *frameCache();
 		QSize cursorSize();
 
 	private:
@@ -30,6 +54,7 @@ class SmGlobals : public QObject {
 		static SmGlobals *mInstance;
 		QHash<QString, QAbstractItemModel*> mModels;
 		PictureViewer *mPictureViewer;
+		SmGlobals::FrameCache *mFrameCache;
 		QSize mCursorSize;
 };