diff options
| author | DRC <information@libjpeg-turbo.org> | 2016-02-19 18:32:10 -0600 |
|---|---|---|
| committer | Matt Sarett <msarett@google.com> | 2016-02-22 12:41:17 -0500 |
| commit | 0ef076fb7b326dc201b4ab3bd30fefd4e35ad1c4 (patch) | |
| tree | 25418d0a0c4af0db25df96f084bf62fc9ab103ff /jdinput.c | |
| parent | 83a8b415ea3dfa7b5c584c4239dd39b56f2bf6e0 (diff) | |
libjpeg API: Partial scanline decompression
This, in combination with the existing jpeg_skip_scanlines() function,
provides the ability to crop the image both horizontally and vertically
while decompressing (certain restrictions apply-- see libjpeg.txt.)
This also cleans up the documentation of the line skipping feature and
removes the "strip decompression" feature from djpeg, since the new
cropping feature is a superset of it.
Refer to #34 for discussion.
Closes #34
Cherry picked from upstream:
https://github.com/libjpeg-turbo/libjpeg-turbo/commit/3ab68cf563f6edc2608c085f5c8b2d5d5c61157e
BUG:27290496
Change-Id: Id11312fa43959531bc6bea04ebb657c6e1140363
Diffstat (limited to 'jdinput.c')
| -rw-r--r-- | jdinput.c | 11 |
1 files changed, 9 insertions, 2 deletions
@@ -4,8 +4,10 @@ * This file was part of the Independent JPEG Group's software: * Copyright (C) 1991-1997, Thomas G. Lane. * libjpeg-turbo Modifications: - * Copyright (C) 2010, D. R. Commander. - * For conditions of distribution and use, see the accompanying README file. + * Copyright (C) 2010, 2016, D. R. Commander. + * Copyright (C) 2015, Google, Inc. + * For conditions of distribution and use, see the accompanying README.ijg + * file. * * This file contains input control logic for the JPEG decompressor. * These routines are concerned with controlling the decompressor's input @@ -104,6 +106,11 @@ initial_setup (j_decompress_ptr cinfo) compptr->height_in_blocks = (JDIMENSION) jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, (long) (cinfo->max_v_samp_factor * DCTSIZE)); + /* Set the first and last MCU columns to decompress from multi-scan images. + * By default, decompress all of the MCU columns. + */ + cinfo->master->first_MCU_col[ci] = 0; + cinfo->master->last_MCU_col[ci] = compptr->width_in_blocks - 1; /* downsampled_width and downsampled_height will also be overridden by * jdmaster.c if we are doing full decompression. The transcoder library * doesn't use these values, but the calling application might. |