1 files changed, 181 insertions, 0 deletions
diff --git a/src/photos/PngSupport.vala b/src/photos/PngSupport.vala
new file mode 100644
index 0000000..ffc7faa
--- /dev/null
+++ b/src/photos/PngSupport.vala
@@ -0,0 +1,181 @@
+/* Copyright 2010-2014 Yorba Foundation
+ *
+ * This software is licensed under the GNU LGPL (version 2.1 or later).
+ * See the COPYING file in this distribution.
+ */
+
+class PngFileFormatProperties : PhotoFileFormatProperties {
+    private static string[] KNOWN_EXTENSIONS = { "png" };
+    private static string[] KNOWN_MIME_TYPES = { "image/png" };
+
+    private static PngFileFormatProperties instance = null;
+
+    public static void init() {
+        instance = new PngFileFormatProperties();
+    }
+    
+    public static PngFileFormatProperties get_instance() {
+        return instance;
+    }
+    
+    public override PhotoFileFormat get_file_format() {
+        return PhotoFileFormat.PNG;
+    }
+    
+    public override PhotoFileFormatFlags get_flags() {
+        return PhotoFileFormatFlags.NONE;
+    }
+
+    public override string get_user_visible_name() {
+        return _("PNG");
+    }
+
+    public override string get_default_extension() {
+        return KNOWN_EXTENSIONS[0];
+    }
+    
+    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;
+    }
+}
+
+public class PngSniffer : GdkSniffer {
+    private const uint8[] MAGIC_SEQUENCE = { 137, 80, 78, 71, 13, 10, 26, 10 };
+
+    public PngSniffer(File file, PhotoFileSniffer.Options options) {
+        base (file, options);
+    }
+
+    private static bool is_png_file(File file) throws Error {
+        FileInputStream instream = file.read(null);
+
+        uint8[] file_lead_sequence = new uint8[MAGIC_SEQUENCE.length];
+
+        instream.read(file_lead_sequence, null);
+
+        for (int i = 0; i < MAGIC_SEQUENCE.length; i++) {
+            if (file_lead_sequence[i] != MAGIC_SEQUENCE[i])
+                return false;
+        }
+
+        return true;
+    }
+
+    public override DetectedPhotoInformation? sniff() throws Error {
+        if (!is_png_file(file))
+            return null;
+
+        DetectedPhotoInformation? detected = base.sniff();
+        if (detected == null)
+            return null;
+
+        return (detected.file_format == PhotoFileFormat.PNG) ? detected : null;
+    }
+}
+
+public class PngReader : GdkReader {
+    public PngReader(string filepath) {
+        base (filepath, PhotoFileFormat.PNG);
+    }
+    
+    public override Gdk.Pixbuf scaled_read(Dimensions full, Dimensions scaled) throws Error {
+        Gdk.Pixbuf result = null;
+        /* if we encounter a situation where there are two orders of magnitude or more of
+           difference between the full image size and the scaled size, and if the full image
+           size has five or more decimal digits of precision, Gdk.Pixbuf.from_file_at_scale( ) can
+           fail due to what appear to be floating-point round-off issues. This isn't surprising,
+           since 32-bit floats only have 6-7 decimal digits of precision in their mantissa. In
+           this case, we prefetch the image at a larger scale and then downsample it to the
+           desired scale as a post-process step. This short-circuits Gdk.Pixbuf's buggy
+           scaling code. */
+        if (((full.width > 9999) || (full.height > 9999)) && ((scaled.width < 100) ||
+             (scaled.height < 100))) {
+            Dimensions prefetch_dimensions = full.get_scaled_by_constraint(1000,
+                ScaleConstraint.DIMENSIONS);
+                                  
+            result = new Gdk.Pixbuf.from_file_at_scale(get_filepath(), prefetch_dimensions.width,
+                prefetch_dimensions.height, false);
+
+            result = result.scale_simple(scaled.width, scaled.height, Gdk.InterpType.HYPER);
+        } else {
+            result = new Gdk.Pixbuf.from_file_at_scale(get_filepath(), scaled.width,
+                scaled.height, false);
+        }
+
+        return result;
+    }
+}
+
+public class PngWriter : PhotoFileWriter {
+    public PngWriter(string filepath) {
+        base (filepath, PhotoFileFormat.PNG);
+    }
+    
+    public override void write(Gdk.Pixbuf pixbuf, Jpeg.Quality quality) throws Error {
+        pixbuf.save(get_filepath(), "png", "compression", "9", null);
+    }
+}
+
+public class PngMetadataWriter : PhotoFileMetadataWriter {
+    public PngMetadataWriter(string filepath) {
+        base (filepath, PhotoFileFormat.PNG);
+    }
+    
+    public override void write_metadata(PhotoMetadata metadata) throws Error {
+        metadata.write_to_file(get_file());
+    }
+}
+
+public class PngFileFormatDriver : PhotoFileFormatDriver {
+    private static PngFileFormatDriver instance = null;
+    
+    public static void init() {
+        instance = new PngFileFormatDriver();
+        PngFileFormatProperties.init();
+    }
+    
+    public static PngFileFormatDriver get_instance() {
+        return instance;
+    }
+    
+    public override PhotoFileFormatProperties get_properties() {
+        return PngFileFormatProperties.get_instance();
+    }
+    
+    public override PhotoFileReader create_reader(string filepath) {
+        return new PngReader(filepath);
+    }
+    
+    public override bool can_write_image() {
+        return true;
+    }
+    
+    public override bool can_write_metadata() {
+        return true;
+    }
+    
+    public override PhotoFileWriter? create_writer(string filepath) {
+        return new PngWriter(filepath);
+    }
+    
+    public override PhotoFileMetadataWriter? create_metadata_writer(string filepath) {
+        return new PngMetadataWriter(filepath);
+    }
+    
+    public override PhotoFileSniffer create_sniffer(File file, PhotoFileSniffer.Options options) {
+        return new PngSniffer(file, options);
+    }
+    
+    public override PhotoMetadata create_metadata() {
+        return new PhotoMetadata();
+    }
+}
+