code review 6866051: tiff: support for writing compressed images.

tiff/consts.go

 // Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package tiff
 
 // A tiff image file contains one or more images. The metadata
 // of each image is contained in an Image File Directory (IFD),
 // which contains entries of 12 bytes each and is described
 // on page 14-16 of the specification. An IFD entry consists of
@@ skipping 91 matching lines @@
 const (
         mBilevel imageMode = iota
         mPaletted
         mGray
         mGrayInvert
         mRGB
         mRGBA
         mNRGBA
 )
 
-// Compression describes the type of compression used in Options.
+// CompressionType describes the type of compression used in Options.
 type CompressionType int
 
 const (
         Uncompressed CompressionType = iota
+        Deflate
 )
+
+// specValue returns the compression type constant from the TIFF spec that
+// is equivalent to c.
+func (c CompressionType) specValue() uint32 {
+        switch c {
+        case Deflate:
+                return cDeflate
+        }
+        return cNone
+}