support reading compressed files, same as LAMMPS itself.

tools/lammps-gui/fileviewer.cpp

@@ -17,11 +17,14 @@
 
 #include <QApplication>
 #include <QFile>
+#include <QFileInfo>
 #include <QIcon>
 #include <QKeySequence>
+#include <QProcess>
 #include <QSettings>
 #include <QShortcut>
 #include <QString>
+#include <QStringList>
 #include <QTextCursor>
 #include <QTextStream>
 
@@ -37,10 +40,52 @@ FileViewer::FileViewer(const QString &_filename, QWidget *parent) :
 
     // open and read file. Set editor to read-only.
     QFile file(fileName);
-    if (file.open(QIODevice::Text | QIODevice::ReadOnly)) {
+    QFileInfo finfo(file);
+    QString command;
+    QString content;
+    QProcess decomp;
+    QStringList args = {"-cdf", fileName};
+    bool compressed  = false;
+
+    // match suffix with decompression program
+    if (finfo.suffix() == "gz") {
+        command    = "gizp";
+        compressed = true;
+    } else if (finfo.suffix() == "bz2") {
+        command    = "bzip2";
+        compressed = true;
+    } else if (finfo.suffix() == "zst") {
+        command    = "zstd";
+        compressed = true;
+    } else if (finfo.suffix() == "xz") {
+        command    = "xz";
+        compressed = true;
+    } else if (finfo.suffix() == "lzma") {
+        command = "xz";
+        args.insert(1, "--format=lzma");
+        compressed = true;
+    } else if (finfo.suffix() == "lz4") {
+        command    = "lz4";
+        compressed = true;
+    }
+
+    // read compressed file from pipe
+    if (compressed) {
+        decomp.start(command, args, QIODevice::ReadOnly);
+        if (decomp.waitForStarted()) {
+            while (decomp.waitForReadyRead())
+                content += decomp.readAll();
+        } else {
+            content = "\nCould not open compressed file %1 with decompression program %2\n";
+            content = content.arg(fileName).arg(command);
+        }
+        decomp.close();
+    } else if (file.open(QIODevice::Text | QIODevice::ReadOnly)) {
+        // read plain text
         QTextStream in(&file);
-        QString content = in.readAll();
+        content = in.readAll();
         file.close();
+    }
 
     QFont text_font;
     QSettings settings;
@@ -55,7 +100,6 @@ FileViewer::FileViewer(const QString &_filename, QWidget *parent) :
     setWindowIcon(QIcon(":/icons/lammps-icon-128x128.png"));
     setWindowTitle("LAMMPS-GUI - Viewer - " + fileName);
 }
-}
 
 void FileViewer::quit()
 {