From cb1ad7e76569629d08a702893ca767b7816ad946 Mon Sep 17 00:00:00 2001 From: Nigel Tao Date: Tue, 13 Oct 2009 17:14:49 -0700 Subject: [PATCH] Documentation for png.Decode and png.Encode. R=r,rsc APPROVED=r DELTA=7 (5 added, 0 deleted, 2 changed) OCL=35651 CL=35692 --- src/pkg/image/png/reader.go | 2 ++ src/pkg/image/png/writer.go | 7 +++++-- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/src/pkg/image/png/reader.go b/src/pkg/image/png/reader.go index 86240cd54b..12c59e49c1 100644 --- a/src/pkg/image/png/reader.go +++ b/src/pkg/image/png/reader.go @@ -412,6 +412,8 @@ func (d *decoder) checkHeader(r io.Reader) os.Error { return nil; } +// Decode reads a PNG formatted image from r and returns it as an image.Image. +// The type of Image returned depends on the PNG contents. func Decode(r io.Reader) (image.Image, os.Error) { var d decoder; err := d.checkHeader(r); diff --git a/src/pkg/image/png/writer.go b/src/pkg/image/png/writer.go index 2526fb3718..ce6c3f3d0e 100644 --- a/src/pkg/image/png/writer.go +++ b/src/pkg/image/png/writer.go @@ -316,9 +316,12 @@ func (e *encoder) writeIEND() { e.writeChunk(e.tmp[0:0], "IEND"); } +// Encode writes the Image m to w in PNG format. Any Image may be encoded, but +// images that are not image.NRGBA might be encoded lossily. func Encode(w io.Writer, m image.Image) os.Error { - // Obviously, negative widths and heights are invalid. Furthermore, - // the PNG spec section 11.2.2 says that zero is an invalid dimension. + // Obviously, negative widths and heights are invalid. Furthermore, the PNG + // spec section 11.2.2 says that zero is invalid. Excessively large images are + // also rejected. mw, mh := int64(m.Width()), int64(m.Height()); if mw <= 0 || mh <= 0 || mw >= 1<<32 || mh >= 1<<32 { return FormatError("invalid image size: " + strconv.Itoa64(mw) + "x" + strconv.Itoa64(mw));