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Update NEWS & README for next release V0.1.3

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Update ChangeLog, NEWS & README file for next release V0.1.3
This commit is contained in:
Vikas Arora
2011-08-25 09:11:08 +05:30
parent 6215595cd1
commit fac15ec78e
3 changed files with 185 additions and 1 deletions
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@@ -322,6 +322,7 @@ is supplied. No decoding is involved when using it.
A lower-level API is available from the header file <webp/decode_vp8.h>
Incremental decoding API:
=========================
@@ -365,6 +366,75 @@ WebPINewRGB() or WebPINewYUV().
Please have a look at the src/webp/decode.h header for further details.
Advanced Decoding API:
=========================
WebP decoding supports Advanced API to provide ability to have on-the-fly
cropping and rescaling, something of great usefulness on memory-constraint
environments like mobile phones. Basically, the memory usage will scale with
the output's size, not the input's when one only need a quick preview or a
zoomed in portion of an otherwise too-large picture. Some CPU can be saved
too, incidentally.
-------------------------------------- BEGIN PSEUDO EXAMPLE
// A) Init a configuration object
WebPDecoderConfig config;
CHECK(WebPInitDecoderConfig(&config));
// B) optional: retrieve the bitstream's features.
CHECK(WebPGetFeatures(data, data_size, &config.input) == VP8_STATUS_OK);
// C) Adjust 'config' options, if needed
config.no_fancy = 1;
config.options.use_scaling = 1;
config.options.scaled_width = scaledWidth();
config.options.scaled_height = scaledHeight();
// etc.
// D) Specify 'config' output options for specifying output colorspace.
// Optionally the external image decode buffer can also be specified.
config.output.colorspace = MODE_BGRA;
// Optionally, the config.output can be pointed to an external buffer as
// well for decoding the image. This externally supplied memory buffer
// should be big enough to store the decoded picture.
config.output.u.BGRA.rgba = (uint8_t*) memory_buffer;
config.output.u.RGBA.stride = scanline_stride;
config.output.u.RGBA.size = total_size_of_the_memory_buffer;
config.output.is_external_memory = 1;
// E) Decode the WebP image. There are two variants w.r.t decoding image.
// The first one (E.1) decodes the full image and the second one (E.2) is
// used to incrementally decode the image using small input buffers.
// Any one of these steps can be used to decode the WebP image.
// E.1) Decode full image.
CHECK(WebPDecode(data, data_size, &config) == VP8_STATUS_OK);
// E.2) Decode image incrementally.
WebPIDecoder* const idec = WebPIDecode(NULL, NULL, &config);
CHECK(idec != NULL);
while (bytes_remaining > 0) {
VP8StatusCode status = WebPIAppend(idec, input, bytes_read);
if (status == VP8_STATUS_OK || status == VP8_STATUS_SUSPENDED) {
bytes_remaining -= bytes_read;
} else {
break;
}
}
WebPIDelete(idec);
// F) Decoded image is now in config.output (and config.output.u.RGBA).
// It can be saved, displayed or otherwise processed.
// G) Reclaim memory allocated in config's object. It's safe to call
// this function even if the memory is external and wasn't allocated
// by WebPDecode().
WebPFreeDecBuffer(&config.output);
-------------------------------------- END PSEUDO EXAMPLE
Bugs:
=====