Archive preview support (#153)

* Add archive/data preview interfaces
* Add raw data text parser

src/ipluginpreview.h

@@ -35,6 +35,12 @@ class IPluginPreview : public QObject, public IPlugin
    */
   virtual std::set<QString> supportedExtensions() const = 0;
 
+  /**
+   * @return return whether or not the preview supports raw data previews (likely
+   * sourced from an archive)
+   */
+  virtual bool supportsArchives() const { return false; }
+
   /**
    * @brief generate a preview widget for the specified file
    * @param fileName name of the file to preview
@@ -44,6 +50,18 @@ class IPluginPreview : public QObject, public IPlugin
   virtual QWidget* genFilePreview(const QString& fileName,
                                   const QSize& maxSize) const = 0;
 
+  /**
+   * @brief generate a preview widget from an archive file loaded into memory
+   * @param fileData data of file to preview
+   * @param fileName path of file in virtual filesystem
+   * @param maxSize maxiumum size of the generated widget
+   */
+  virtual QWidget* genDataPreview(const QByteArray& fileData, const QString& fileName,
+                                  const QSize& maxSize) const
+  {
+    return nullptr;
+  }
+
 private:
 };
 

src/utility.cpp

@@ -849,30 +849,35 @@ bool shellDeleteQuiet(const QString& fileName, QWidget* dialog)
 
 QString readFileText(const QString& fileName, QString* encoding)
 {
-  QStringConverter::Encoding codec = QStringConverter::Encoding::Utf8;
-  QStringEncoder encoder(codec);
-  QStringDecoder decoder(codec);
 
   QFile textFile(fileName);
   if (!textFile.open(QIODevice::ReadOnly)) {
     return QString();
   }
 
   QByteArray buffer = textFile.readAll();
-  QString text      = decoder.decode(buffer);
+  return decodeTextData(buffer);
+}
+
+QString decodeTextData(const QByteArray& fileData, QString* encoding)
+{
+  QStringConverter::Encoding codec = QStringConverter::Encoding::Utf8;
+  QStringEncoder encoder(codec);
+  QStringDecoder decoder(codec);
+  QString text = decoder.decode(fileData);
 
   // check reverse conversion. If this was unicode text there can't be data loss
   // this assumes QString doesn't normalize the data in any way so this is a bit unsafe
-  if (encoder.encode(text) != buffer) {
+  if (encoder.encode(text) != fileData) {
     log::debug("conversion failed assuming local encoding");
-    auto codecSearch = QStringConverter::encodingForData(buffer);
+    auto codecSearch = QStringConverter::encodingForData(fileData);
     if (codecSearch.has_value()) {
       codec   = codecSearch.value();
       decoder = QStringDecoder(codec);
     } else {
       decoder = QStringDecoder(QStringConverter::Encoding::System);
     }
-    text = decoder.decode(buffer);
+    text = decoder.decode(fileData);
   }
 
   if (encoding != nullptr) {

src/utility.h

@@ -454,6 +454,16 @@ QDLLEXPORT QString getStartMenuDirectory();
  **/
 QDLLEXPORT QString readFileText(const QString& fileName, QString* encoding = nullptr);
 
+/**
+ * @brief decode raw text data. This tries to guess the encoding used in the file
+ * @param fileData raw data to decode
+ * @param encoding (optional) if this is set, the target variable received the name of
+ *the encoding used
+ * @return the textual content of the file or an empty string if the file doesn't exist
+ **/
+QDLLEXPORT QString decodeTextData(const QByteArray& fileData,
+                                  QString* encoding = nullptr);
+
 /**
  * @brief delete files matching a pattern
  * @param directory in which to delete files