[shotwell/wip/webp: 29/30] wip: Initial webp support

[Jens Georg <jensgeorg src gnome org>]

commit 8de9eeb7f8fd2d8023cc01343d2b9f32f40e6175
Author: Jens Georg <mail jensge org>
Date:   Wed Aug 30 21:46:55 2017 +0200

    wip: Initial webp support

 src/meson.build                 |    1 +
 src/photos/PhotoFileFormat.vala |   17 +++-
 src/photos/WebPSupport.vala     |  187 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 203 insertions(+), 2 deletions(-)
---
diff --git a/src/meson.build b/src/meson.build
index 6a901ef..dea0273 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -64,6 +64,7 @@ executable('shotwell',
             'photos/RawSupport.vala',
             'photos/PngSupport.vala',
             'photos/TiffSupport.vala',
+            'photos/WebPSupport.vala',
             'plugins/Plugins.vala',
             'plugins/StandardHostInterface.vala',
             'plugins/ManifestWidget.vala',
diff --git a/src/photos/PhotoFileFormat.vala b/src/photos/PhotoFileFormat.vala
index e642008..fe50315 100644
--- a/src/photos/PhotoFileFormat.vala
+++ b/src/photos/PhotoFileFormat.vala
@@ -58,12 +58,13 @@ public enum PhotoFileFormat {
     TIFF,
     BMP,
     GIF,
+    WEBP,
     UNKNOWN;
     
     // This is currently listed in the order of detection, that is, the file is examined from
     // left to right.  (See PhotoFileInterrogator.)
     public static PhotoFileFormat[] get_supported() {
-        return { JFIF, RAW, PNG, TIFF, BMP, GIF };
+        return { JFIF, RAW, PNG, TIFF, BMP, GIF, WEBP };
     }
     
     public static PhotoFileFormat[] get_writeable() {
@@ -141,7 +142,10 @@ public enum PhotoFileFormat {
 
             case GIF:
                 return 5;
-            
+
+            case WEBP:
+                return 6;
+
             case UNKNOWN:
             default:
                 return -1;
@@ -169,6 +173,9 @@ public enum PhotoFileFormat {
             case 5:
                 return GIF;
                             
+            case 6:
+                return WEBP;
+
             default:
                 return UNKNOWN;
         }
@@ -247,6 +254,9 @@ public enum PhotoFileFormat {
 
             case GIF:
                 Photos.GifFileFormatDriver.init();
+
+            case WEBP:
+                Photos.WebpFileFormatDriver.init();
                 break;
 
             default:
@@ -274,6 +284,9 @@ public enum PhotoFileFormat {
             case GIF:
                 return Photos.GifFileFormatDriver.get_instance();
 
+            case WEBP:
+                return Photos.WebpFileFormatDriver.get_instance();
+
             default:
                 error("Unsupported file format %s", this.to_string());
         }
diff --git a/src/photos/WebPSupport.vala b/src/photos/WebPSupport.vala
new file mode 100644
index 0000000..22eeaeb
--- /dev/null
+++ b/src/photos/WebPSupport.vala
@@ -0,0 +1,187 @@
+/* Copyright 2016 Software Freedom Conservancy Inc.
+ *
+ * This software is licensed under the GNU LGPL (version 2.1 or later).
+ * See the COPYING file in this distribution.
+ */
+
+namespace Photos {
+
+public class WebpFileFormatDriver : PhotoFileFormatDriver {
+    private static WebpFileFormatDriver instance = null;
+
+    public static void init() {
+        instance = new WebpFileFormatDriver();
+        WebpFileFormatProperties.init();
+    }
+
+    public static WebpFileFormatDriver get_instance() {
+        return instance;
+    }
+
+    public override PhotoFileFormatProperties get_properties() {
+        return WebpFileFormatProperties.get_instance();
+    }
+
+    public override PhotoFileReader create_reader(string filepath) {
+        return new WebpReader(filepath);
+    }
+
+    public override PhotoMetadata create_metadata() {
+        return new PhotoMetadata();
+    }
+
+    public override bool can_write_image() {
+        return false;
+    }
+
+    public override bool can_write_metadata() {
+        return true;
+    }
+
+    public override PhotoFileWriter? create_writer(string filepath) {
+        //return new WebpWriter(filepath);
+        return null;
+    }
+
+    public override PhotoFileMetadataWriter? create_metadata_writer(string filepath) {
+        return new WebpMetadataWriter(filepath);
+    }
+
+    public override PhotoFileSniffer create_sniffer(File file, PhotoFileSniffer.Options options) {
+        return new WebpSniffer(file, options);
+    }
+}
+
+private class WebpFileFormatProperties : PhotoFileFormatProperties {
+    private static string[] KNOWN_EXTENSIONS = {
+        "webp"
+    };
+
+    private static string[] KNOWN_MIME_TYPES = {
+        "image/webp"
+    };
+
+    private static WebpFileFormatProperties instance = null;
+
+    public static void init() {
+        instance = new WebpFileFormatProperties();
+    }
+
+    public static WebpFileFormatProperties get_instance() {
+        return instance;
+    }
+
+    public override PhotoFileFormat get_file_format() {
+        return PhotoFileFormat.WEBP;
+    }
+
+    public override PhotoFileFormatFlags get_flags() {
+        return PhotoFileFormatFlags.NONE;
+    }
+
+    public override string get_default_extension() {
+        return "webp";
+    }
+
+    public override string get_user_visible_name() {
+        return _("WebP");
+    }
+
+    public override string[] get_known_extensions() {
+        return KNOWN_EXTENSIONS;
+    }
+
+    public override string get_default_mime_type() {
+        return KNOWN_MIME_TYPES[0];
+    }
+
+    public override string[] get_mime_types() {
+        return KNOWN_MIME_TYPES;
+    }
+}
+
+private class WebpSniffer : PhotoFileSniffer {
+    public WebpSniffer(File file, PhotoFileSniffer.Options options) {
+        base (file, options);
+    }
+
+    public override DetectedPhotoInformation? sniff(out bool is_corrupted) throws Error {
+        // Rely on GdkSniffer to detect corruption
+        is_corrupted = false;
+
+        if (!is_webp(file))
+            return null;
+
+        var info = new DetectedPhotoInformation();
+        info.file_format = PhotoFileFormat.WEBP;
+        info.format_name = "WebP";
+        info.channels = 4;
+        info.bits_per_channel = 8;
+        info.image_dim = new Dimensions(32, 32);
+
+        return info;
+    }
+}
+
+private class WebpReader : PhotoFileReader {
+    public WebpReader(string filepath) {
+        base (filepath, PhotoFileFormat.WEBP);
+    }
+
+    public override PhotoMetadata read_metadata() throws Error {
+        PhotoMetadata metadata = new PhotoMetadata();
+        metadata.read_from_file(get_file());
+
+        return metadata;
+    }
+
+    public override Gdk.Pixbuf unscaled_read() throws Error {
+        return new Gdk.Pixbuf(Gdk.Colorspace.RGB, true, 8, 32, 32);
+    }
+}
+
+private class WebpWriter : PhotoFileWriter {
+    private const string COMPRESSION_NONE = "1";
+    private const string COMPRESSION_HUFFMAN = "2";
+    private const string COMPRESSION_LZW = "5";
+    private const string COMPRESSION_JPEG = "7";
+    private const string COMPRESSION_DEFLATE = "8";
+
+    public WebpWriter(string filepath) {
+        base (filepath, PhotoFileFormat.TIFF);
+    }
+
+    public override void write(Gdk.Pixbuf pixbuf, Jpeg.Quality quality) throws Error {
+        pixbuf.save(get_filepath(), "tiff", "compression", COMPRESSION_LZW);
+    }
+}
+
+private class WebpMetadataWriter : PhotoFileMetadataWriter {
+    public WebpMetadataWriter(string filepath) {
+        base (filepath, PhotoFileFormat.TIFF);
+    }
+
+    public override void write_metadata(PhotoMetadata metadata) throws Error {
+        metadata.write_to_file(get_file());
+    }
+}
+
+public bool is_webp(File file, Cancellable? cancellable = null) throws Error {
+    var ins = file.read();
+
+    uint8 buffer[12];
+    try {
+        ins.read(buffer, null);
+        if (buffer[0] == 'R' && buffer[1] == 'I' && buffer[2] == 'F' && buffer[3] == 'F' &&
+            buffer[8] == 'W' && buffer[9] == 'E' && buffer[10] == 'B' && buffer[11] == 'P')
+            return true;
+    } catch (Error error) {
+        debug ("Failed to read from file %s: %s", file.get_path (), error.message);
+    }
+
+    debug ("=> We have webp");
+
+    return false;
+}
+
+}