jdsample.c

MCB2300_ucgui_LCD320240.rar LPC2368的uc/gui的移植

/*
 * jdsample.c
 *
 * Copyright (C) 1991-1996, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains upsampling routines.
 *
 * Upsampling input data is counted in "row groups".  A row group
 * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size)
 * sample rows of each component.  Upsampling will normally produce
 * max_v_samp_factor pixel rows from each row group (but this could vary
 * if the upsampler is applying a scale factor of its own).
 *
 * An excellent reference for image resampling is
 *   Digital Image Warping, George Wolberg, 1990.
 *   Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/* Pointer to routine to upsample a single component */
typedef JMETHOD(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.
 */

METHODDEF(void)
start_pass_upsample(j_decompress_ptr cinfo)
{
	my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

	/* Mark the conversion buffer empty */
	upsample->next_row_out = cinfo->max_v_samp_factor;
	/* Initialize total-height counter for detecting bottom of image */
	upsample->rows_to_go = cinfo->output_height;
}


/*
 * Control routine to do upsampling (and color conversion).
 *
 * In this version we upsample each component independently.
 * We upsample one row group into the conversion buffer, then apply
 * color conversion a row at a time.
 */

METHODDEF(void)
sep_upsample(j_decompress_ptr cinfo, JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, JDIMENSION in_row_groups_avail, JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail)
{
	my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
	int ci;
	jpeg_component_info * compptr;
	JDIMENSION num_rows;

	GUI_USE_PARA(in_row_groups_avail);
	/* Fill the conversion buffer, if it's empty */
	if (upsample->next_row_out >= cinfo->max_v_samp_factor)
	{
		for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++)
		{
			/* Invoke per-component upsample method.  Notice we pass a POINTER
			 * to color_buf[ci], so that fullsize_upsample can change it.
			 */
			(*upsample->methods[ci]) (cinfo, compptr, input_buf[ci] + (*in_row_group_ctr * upsample->rowgroup_height[ci]), upsample->color_buf + ci);
		}
		upsample->next_row_out = 0;
	}

	/* Color-convert and emit rows */

	/* How many we have in the buffer: */
	num_rows = (JDIMENSION) (cinfo->max_v_samp_factor - upsample->next_row_out);
	/* Not more than the distance to the end of the image.  Need this test
	 * in case the image height is not a multiple of max_v_samp_factor:
	 */
	if (num_rows > upsample->rows_to_go)
	{
		num_rows = upsample->rows_to_go;
	}
	/* And not more than what the client can accept: */
	out_rows_avail -= *out_row_ctr;
	if (num_rows > out_rows_avail)
	{
		num_rows = out_rows_avail;
	}

	(*cinfo->cconvert->color_convert) (cinfo, upsample->color_buf, (JDIMENSION) upsample->next_row_out, output_buf + *out_row_ctr, (int) num_rows);

	/* Adjust counts */
	*out_row_ctr += num_rows;
	upsample->rows_to_go -= num_rows;
	upsample->next_row_out += num_rows;
	/* When the buffer is emptied, declare this input row group consumed */
	if (upsample->next_row_out >= cinfo->max_v_samp_factor)
	{
		(*in_row_group_ctr)++;
	}
}


/*
 * These are the routines invoked by sep_upsample to upsample pixel values
 * of a single component.  One row group is processed per call.
 */


/*
 * For full-size components, we just make color_buf[ci] point at the
 * input buffer, and thus avoid copying any data.  Note that this is
 * safe only because sep_upsample doesn't declare the input row group
 * "consumed" until we are done color converting and emitting it.
 */

METHODDEF(void)
fullsize_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
{
	GUI_USE_PARA(compptr);
	GUI_USE_PARA(cinfo);
	*output_data_ptr = input_data;
}


/*
 * This is a no-op version used for "uninteresting" components.
 * These components will not be referenced by color conversion.
 */

METHODDEF(void)
noop_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
{
	GUI_USE_PARA(cinfo);
	GUI_USE_PARA(compptr);
	GUI_USE_PARA(input_data);
	*output_data_ptr = NULL;	/* safety check */
}


/*
 * This version handles any integral sampling ratios.
 * This is not used for typical JPEG files, so it need not be fast.
 * Nor, for that matter, is it particularly accurate: the algorithm is
 * simple replication of the input pixel onto the corresponding output
 * pixels.  The hi-falutin sampling literature refers to this as a
 * "box filter".  A box filter tends to introduce visible artifacts,
 * so if you are actually going to use 3:1 or 4:1 sampling ratios
 * you would be well advised to improve this code.
 */

METHODDEF(void)
int_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
{
	my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
	JSAMPARRAY output_data = *output_data_ptr;
	register JSAMPROW inptr, outptr;
	register JSAMPLE invalue;
	register int h;
	JSAMPROW outend;
	int h_expand, v_expand;
	int inrow, outrow;

	h_expand = upsample->h_expand[compptr->component_index];
	v_expand = upsample->v_expand[compptr->component_index];

	inrow = outrow = 0;
	while (outrow < cinfo->max_v_samp_factor)
	{
		/* Generate one output row with proper horizontal expansion */
		inptr = input_data[inrow];
		outptr = output_data[outrow];
		outend = outptr + cinfo->output_width;
		while (outptr < outend)
		{
			invalue = *inptr++;	/* don't need GETJSAMPLE() here */
			for (h = h_expand; h > 0; h--)
			{
				*outptr++ = invalue;
			}
		}
		/* Generate any additional output rows by duplicating the first one */
		if (v_expand > 1)
		{
			jcopy_sample_rows(output_data, outrow, output_data, outrow + 1, v_expand - 1, cinfo->output_width);
		}
		inrow++;
		outrow += v_expand;
	}
}


/*
 * Fast processing for the common case of 2:1 horizontal and 1:1 vertical.
 * It's still a box filter.
 */

METHODDEF(void)
h2v1_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
{
	JSAMPARRAY output_data = *output_data_ptr;
	register JSAMPROW inptr, outptr;
	register JSAMPLE invalue;
	JSAMPROW outend;
	int inrow;

	GUI_USE_PARA(compptr);
	for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++)
	{
		inptr = input_data[inrow];
		outptr = output_data[inrow];
		outend = outptr + cinfo->output_width;
		while (outptr < outend)
		{
			invalue = *inptr++;	/* don't need GETJSAMPLE() here */