QResource: add support for resources compressed with Zstandard

See next commit for details on why this is a good idea.

[ChangeLog][Important Behavior Changes] The Qt resource system now
supports compressing content using the Zstandard (https://zstd.net)
algorithm. Compared to zlib, it compresses better for the same CPU time,
so this algorithm is the default. QResource::isCompressed() returns true
for either compression algorithm. Use QResource::compressionAlgorithm()
to find out which algorithm to decompress. QFile will automatically
decompress using the correct algorithm.

Change-Id: I343f2beed55440a7ac0bfffd1562e9a8f94933a7
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Reviewed-by: Samuel Gaist <samuel.gaist@idiap.ch>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/corelib/io/qresource.h b/src/corelib/io/qresource.h
index 895cf0456e..9aa17608ce 100644
--- a/src/corelib/io/qresource.h
+++ b/src/corelib/io/qresource.h
@@ -54,6 +54,12 @@ class QResourcePrivate;
 class Q_CORE_EXPORT QResource
 {
 public:
+    enum Compression {
+        NoCompression,
+        ZlibCompression,
+        ZstdCompression
+    };
+
     QResource(const QString &file=QString(), const QLocale &locale=QLocale());
     ~QResource();
 
@@ -67,6 +73,7 @@ public:
     bool isValid() const;
 
     bool isCompressed() const;
+    Compression compressionAlgorithm() const;
     qint64 size() const;
     const uchar *data() const;
     QDateTime lastModified() const;