Add a new libjpeg API function (jpeg_skip_scanlines()) to allow for partially decoding a JPEG image.

git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1582 632fc199-4ca6-4c93-a231-07263d6284db

jdsample.c

@@ -22,51 +22,11 @@
  *   Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7.
  */
 
-#define JPEG_INTERNALS
-#include "jinclude.h"
-#include "jpeglib.h"
+#include "jdsample.h"
 #include "jsimd.h"
 #include "jpegcomp.h"
 
 
-/* Pointer to routine to upsample a single component */
-typedef void (*upsample1_ptr) (j_decompress_ptr cinfo,
-                               jpeg_component_info * compptr,
-                               JSAMPARRAY input_data,
-                               JSAMPARRAY * output_data_ptr);
-
-/* Private subobject */
-
-typedef struct {
-  struct jpeg_upsampler pub;    /* public fields */
-
-  /* Color conversion buffer.  When using separate upsampling and color
-   * conversion steps, this buffer holds one upsampled row group until it
-   * has been color converted and output.
-   * Note: we do not allocate any storage for component(s) which are full-size,
-   * ie do not need rescaling.  The corresponding entry of color_buf[] is
-   * simply set to point to the input data array, thereby avoiding copying.
-   */
-  JSAMPARRAY color_buf[MAX_COMPONENTS];
-
-  /* Per-component upsampling method pointers */
-  upsample1_ptr methods[MAX_COMPONENTS];
-
-  int next_row_out;             /* counts rows emitted from color_buf */
-  JDIMENSION rows_to_go;        /* counts rows remaining in image */
-
-  /* Height of an input row group for each component. */
-  int rowgroup_height[MAX_COMPONENTS];
-
-  /* These arrays save pixel expansion factors so that int_expand need not
-   * recompute them each time.  They are unused for other upsampling methods.
-   */
-  UINT8 h_expand[MAX_COMPONENTS];
-  UINT8 v_expand[MAX_COMPONENTS];
-} my_upsampler;
-
-typedef my_upsampler * my_upsample_ptr;
-
 
 /*
  * Initialize for an upsampling pass.