[shotwell/wip/webp: 30/30] wip: Actually decode WebP

[Jens Georg <jensgeorg src gnome org>]

commit 3bba3dbf3ef5b923a2d9ed13b642ed119b8d8652
Author: Jens Georg <mail jensge org>
Date:   Thu Aug 31 22:25:49 2017 +0200

    wip: Actually decode WebP

 meson.build                 |    3 +
 src/meson.build             |    2 +-
 src/photos/WebPSupport.vala |   86 +++++++++++++++++++++++++++++++++++++++----
 vapi/libwebp.vapi           |    5 ++
 vapi/libwebpdemux.vapi      |   43 +++++++++++++++++++++
 5 files changed, 130 insertions(+), 9 deletions(-)
---
diff --git a/meson.build b/meson.build
index 072ad0a..448dfe2 100644
--- a/meson.build
+++ b/meson.build
@@ -57,6 +57,9 @@ libraw = dependency('libraw', version : '>= 0.13.2')
 libexif = dependency('libexif', version : '>= 0.6.16')
 unity = dependency('unity', required : false)
 
+webpdemux = dependency('libwebpdemux')
+webp = dependency('libwebp')
+
 unity_available = false
 if unity.found() and get_option('unity-support')
   unity_available = true
diff --git a/src/meson.build b/src/meson.build
index dea0273..62d3866 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -19,7 +19,7 @@ processor = executable('shotwell-graphics-processor',
 
 shotwell_deps = [gio, gee, sqlite, gtk, sqlite, posix, gphoto2,
                  gstreamer_pbu, gio_unix, gudev, gexiv2, gmodule,
-                 libraw, libexif, sw_plugin]
+                 libraw, libexif, sw_plugin, webpdemux, webp]
 if unity_available
     shotwell_deps += [unity]
 endif
diff --git a/src/photos/WebPSupport.vala b/src/photos/WebPSupport.vala
index 22eeaeb..abaa01d 100644
--- a/src/photos/WebPSupport.vala
+++ b/src/photos/WebPSupport.vala
@@ -101,8 +101,11 @@ private class WebpFileFormatProperties : PhotoFileFormatProperties {
 }
 
 private class WebpSniffer : PhotoFileSniffer {
+    private DetectedPhotoInformation detected = null;
+
     public WebpSniffer(File file, PhotoFileSniffer.Options options) {
         base (file, options);
+        detected = new DetectedPhotoInformation();
     }
 
     public override DetectedPhotoInformation? sniff(out bool is_corrupted) throws Error {
@@ -112,14 +115,74 @@ private class WebpSniffer : PhotoFileSniffer {
         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;
+         // valac chokes on the ternary operator here
+        Checksum? md5_checksum = null;
+        if (calc_md5)
+            md5_checksum = new Checksum(ChecksumType.MD5);
+
+        detected.metadata = new PhotoMetadata();
+        try {
+            detected.metadata.read_from_file(file);
+        } catch (Error err) {
+            // no metadata detected
+            detected.metadata = null;
+        }
+
+        if (calc_md5 && detected.metadata != null) {
+            detected.exif_md5 = detected.metadata.exif_hash();
+            detected.thumbnail_md5 = detected.metadata.thumbnail_hash();
+        }
+
+        // if no MD5, don't read as much, as the needed info will probably be gleaned
+        // in the first 8K to 16K
+        uint8[] buffer = calc_md5 ? new uint8[64 * 1024] : new uint8[8 * 1024];
+        size_t count = 0;
+
+        // loop through until all conditions we're searching for are met
+        FileInputStream fins = file.read(null);
+        var ba = new ByteArray();
+        for (;;) {
+            size_t bytes_read = fins.read(buffer, null);
+            if (bytes_read <= 0)
+                break;
+
+            ba.append(buffer[0:bytes_read]);
+
+            count += bytes_read;
+
+            if (calc_md5)
+                md5_checksum.update(buffer, bytes_read);
+
+            WebP.Data d = WebP.Data();
+            d.bytes = ba.data;
+
+            WebP.ParsingState state;
+            var demux = new WebP.Demuxer.partial(d, out state);
+
+            if (state > WebP.ParsingState.PARSED_HEADER) {
+                detected.file_format = PhotoFileFormat.WEBP;
+                detected.format_name = "WebP";
+                detected.channels = 4;
+                detected.bits_per_channel = 8;
+                detected.image_dim.width = (int) demux.get(WebP.FormatFeature.CANVAS_WIDTH);
+                detected.image_dim.height = (int) demux.get(WebP.FormatFeature.CANVAS_HEIGHT);
+
+                // if not searching for anything else, exit
+                if (!calc_md5)
+                    break;
+                }
+        }
+
+        if (fins != null)
+            fins.close(null);
+
+        if (calc_md5)
+            detected.md5 = md5_checksum.get_string();
+
+        // if size and area are not ready, treat as corrupted file (entire file was read)
+        is_corrupted = false; //!size_ready || !area_prepared;
+
+        return detected;
     }
 }
 
@@ -136,7 +199,14 @@ private class WebpReader : PhotoFileReader {
     }
 
     public override Gdk.Pixbuf unscaled_read() throws Error {
-        return new Gdk.Pixbuf(Gdk.Colorspace.RGB, true, 8, 32, 32);
+        uint8[] buffer;
+
+        FileUtils.get_data(this.get_filepath(), out buffer);
+        int width, height;
+        var pixdata = WebP.DecodeRGBA(buffer, out width, out height);
+        pixdata.length = width * height * 4;
+
+        return new Gdk.Pixbuf.from_data(pixdata, Gdk.Colorspace.RGB, true, 8, width, height, width * 4);
     }
 }
 
diff --git a/vapi/libwebp.vapi b/vapi/libwebp.vapi
new file mode 100644
index 0000000..a19fbcf
--- /dev/null
+++ b/vapi/libwebp.vapi
@@ -0,0 +1,5 @@
+[CCode (cheader_filename = "webp/decode.h")]
+namespace WebP {
+    [CCode (array_length = false, cname="WebPDecodeRGBA")]
+    public static uint8[] DecodeRGBA([CCode (array_length_pos=1)]uint8[] data, out int width, out int 
height);
+}
diff --git a/vapi/libwebpdemux.vapi b/vapi/libwebpdemux.vapi
new file mode 100644
index 0000000..7612b42
--- /dev/null
+++ b/vapi/libwebpdemux.vapi
@@ -0,0 +1,43 @@
+namespace WebP {
+    [CCode (has_type_id = false)]
+    public struct Data {
+        [CCode (array_length_cname = "size")]
+        public unowned uint8[] bytes;
+
+        public size_t size;
+
+        [CCode (cname = "WebPDataClear")]
+        public void clear();
+    }
+
+    [CCode (cprefix = "WEBP_DEMUX_", cname = "WebPDemuxState")]
+    public enum ParsingState {
+        PARSE_ERROR,
+        PARSING_HEADER,
+        PARSED_HEADER,
+        DONE
+    }
+
+    [CCode (cprefix = "WEBP_FF_")]
+    public enum FormatFeature {
+        FORMAT_FLAGS,
+        CANVAS_WIDTH,
+        CANVAS_HEIGHT,
+        LOOP_COUNT,
+        BACKGROUND_COLOR,
+        FRAME_COUNT
+    }
+
+    [Compact]
+    [CCode (free_function = "WebPDemuxDelete", cname = "WebPDemuxer", cheader_filename = "webp/demux.h", 
has_type_id = false)]
+    public class Demuxer {
+        [CCode (cname="WebPDemux")]
+        public Demuxer(Data data);
+
+        [CCode (cname="WebPDemuxPartial")]
+        public Demuxer.partial(Data data, out ParsingState state);
+
+        [CCode (cname="WebPDemuxGetI")]
+        public uint32 get(FormatFeature feature);
+    }
+}