1 files changed, 121 insertions, 0 deletions
diff --git a/src/video-support/AVIChunk.vala b/src/video-support/AVIChunk.vala
new file mode 100644
index 0000000..970f443
--- /dev/null
+++ b/src/video-support/AVIChunk.vala
@@ -0,0 +1,121 @@
+private class AVIChunk {
+    private GLib.File file = null;
+    private string section_name = "";
+    private uint64 section_size = 0;
+    private uint64 section_offset = 0;
+    private GLib.DataInputStream input = null;
+    private AVIChunk? parent = null;
+    private const int MAX_STRING_TO_SECTION_LENGTH = 1024;
+
+    public AVIChunk(GLib.File file) {
+        this.file = file;
+    }
+
+    private AVIChunk.with_input_stream(GLib.DataInputStream input, AVIChunk parent) {
+        this.input = input;
+        this.parent = parent;
+    }
+
+    public void open_file() throws GLib.Error {
+        close_file();
+        input = new GLib.DataInputStream(file.read());
+        input.set_byte_order(DataStreamByteOrder.LITTLE_ENDIAN);
+        section_size = 0;
+        section_offset = 0;
+        section_name = "";
+    }
+
+    public void close_file() throws GLib.Error {
+        if (null != input) {
+            input.close();
+            input = null;
+        }
+    }
+
+    public void nonsection_skip(uint64 skip_amount) throws GLib.Error {
+        skip_uint64(input, skip_amount);
+    }
+
+    public void skip(uint64 skip_amount) throws GLib.Error {
+        advance_section_offset(skip_amount);
+        skip_uint64(input, skip_amount);
+    }
+
+    public AVIChunk get_first_child_chunk() {
+        return new AVIChunk.with_input_stream(input, this);
+    }
+
+    private void advance_section_offset(uint64 amount) {
+        if ((section_offset + amount) > section_size)
+            amount = section_size - section_offset;
+
+        section_offset += amount;
+        if (null != parent) {
+            parent.advance_section_offset(amount);
+        }
+    }
+
+    public uchar read_byte() throws GLib.Error {
+        advance_section_offset(1);
+        return input.read_byte();
+    }
+
+    public uint16 read_uint16() throws GLib.Error {
+       advance_section_offset(2);
+       return input.read_uint16();
+    }
+
+    public void read_chunk() throws GLib.Error {
+        // don't use checked reads here because they advance the section offset, which we're trying
+        // to determine here
+        GLib.StringBuilder sb = new GLib.StringBuilder();
+        sb.append_c((char) input.read_byte());
+        sb.append_c((char) input.read_byte());
+        sb.append_c((char) input.read_byte());
+        sb.append_c((char) input.read_byte());
+        section_name = sb.str;
+        section_size = input.read_uint32();
+        section_offset = 0;
+    }
+
+    public string read_name() throws GLib.Error {
+        GLib.StringBuilder sb = new GLib.StringBuilder();
+        sb.append_c((char) read_byte());
+        sb.append_c((char) read_byte());
+        sb.append_c((char) read_byte());
+        sb.append_c((char) read_byte());
+        return sb.str;
+    }
+
+    public void next_chunk() throws GLib.Error {
+        skip(section_size_remaining());
+        section_size = 0;
+        section_offset = 0;
+    }
+
+    public string get_current_chunk_name() {
+        return section_name;
+    }
+
+    public bool is_last_chunk() {
+        return section_size == 0;
+    }
+
+    public uint64 section_size_remaining() {
+        assert(section_size >= section_offset);
+        return section_size - section_offset;
+    }
+
+    // Reads section contents into a string.
+    public string section_to_string() throws GLib.Error {
+        GLib.StringBuilder sb = new GLib.StringBuilder();
+        while (section_offset < section_size) {
+            sb.append_c((char) read_byte());
+            if (sb.len > MAX_STRING_TO_SECTION_LENGTH) {
+                return sb.str;
+            }
+        }
+        return sb.str;
+    }
+
+}