pdf_pattern.c

SumatraPDF是一款小型开源的pdf阅读工具。虽然玲珑小巧（只有800多KB）

#include "fitz.h"
#include "mupdf.h"

pdf_pattern *
pdf_keeppattern(pdf_pattern *pat)
{
	pat->refs ++;
	return pat;
}

void
pdf_droppattern(pdf_pattern *pat)
{
	if (--pat->refs == 0)
	{
		if (pat->tree)
			fz_droptree(pat->tree);
		fz_free(pat);
	}
}

fz_error *
pdf_loadpattern(pdf_pattern **patp, pdf_xref *xref, fz_obj *dict, fz_obj *stmref)
{
	fz_error *error;
	pdf_pattern *pat;
	fz_stream *stm;
	fz_obj *resources;
	fz_obj *obj;
	pdf_csi *csi;

	if ((*patp = pdf_finditem(xref->store, PDF_KPATTERN, stmref)))
	{
		pdf_keeppattern(*patp);
		return fz_okay;
	}

	pdf_logrsrc("load pattern (%d %d R) {\n", fz_tonum(stmref), fz_togen(stmref));

	pat = fz_malloc(sizeof(pdf_pattern));
	if (!pat)
		return fz_throw("outofmem: pattern struct");

	pat->refs = 1;
	pat->tree = nil;
	pat->ismask = fz_toint(fz_dictgets(dict, "PaintType")) == 2;
	pat->xstep = fz_toreal(fz_dictgets(dict, "XStep"));
	pat->ystep = fz_toreal(fz_dictgets(dict, "YStep"));

	pdf_logrsrc("mask %d\n", pat->ismask);
	pdf_logrsrc("xstep %g\n", pat->xstep);
	pdf_logrsrc("ystep %g\n", pat->ystep);

	obj = fz_dictgets(dict, "BBox");
	pat->bbox = pdf_torect(obj);

	pdf_logrsrc("bbox [%g %g %g %g]\n",
			pat->bbox.x0, pat->bbox.y0,
			pat->bbox.x1, pat->bbox.y1);

	obj = fz_dictgets(dict, "Matrix");
	if (obj)
		pat->matrix = pdf_tomatrix(obj);
	else
		pat->matrix = fz_identity();

	pdf_logrsrc("matrix [%g %g %g %g %g %g]\n",
			pat->matrix.a, pat->matrix.b,
			pat->matrix.c, pat->matrix.d,
			pat->matrix.e, pat->matrix.f);

	/* Store pattern now, to avoid possible recursion if objects refer back to this one */ 
	error = pdf_storeitem(xref->store, PDF_KPATTERN, stmref, pat);
	if (error)
	{
		error = fz_rethrow(error, "cannot store pattern resource");
		goto cleanupstore;
	}

	/*
	 * Resources
	 */

	obj = fz_dictgets(dict, "Resources");
	if (!obj) {
		error = fz_throw("cannot find Resources dictionary");
		goto cleanup;
	}

	error = pdf_resolve(&obj, xref);
	if (error)
	{
		error = fz_rethrow(error, "cannot resolve resource dictionary");
		goto cleanup;
	}

	error = pdf_loadresources(&resources, xref, obj);

	fz_dropobj(obj);

	if (error)
	{
		error = fz_rethrow(error, "cannot load resources");
		goto cleanup;
	}

	/*
	 * Content stream
	 */

	pdf_logrsrc("content stream\n");

	error = pdf_newcsi(&csi, pat->ismask);
	if (error)
	{
		error = fz_rethrow(error, "cannot create interpreter");
		goto cleanup;
	}

	error = pdf_openstream(&stm, xref, fz_tonum(stmref), fz_togen(stmref));
	if (error)
	{
		error = fz_rethrow(error, "cannot open pattern stream (%d %d R)", fz_tonum(stmref), fz_togen(stmref));
		goto cleanupcsi;
	}

	error = pdf_runcsi(csi, xref, resources, stm);

	fz_dropstream(stm);

	if (error)
	{
		error = fz_rethrow(error, "cannot interpret pattern stream (%d %d R)", fz_tonum(stmref), fz_togen(stmref));
		goto cleanupcsi;
	}

	pat->tree = csi->tree;
	csi->tree = nil;

	pdf_dropcsi(csi);

	fz_dropobj(resources);

	pdf_logrsrc("optimize tree\n");
	error = fz_optimizetree(pat->tree);
	if (error)
	{
		error = fz_rethrow(error, "cannot optimize pattern tree");
		goto cleanup;
	}

	pdf_logrsrc("}\n");

	*patp = pat;
	return fz_okay;

cleanupcsi:
	pdf_dropcsi(csi);
cleanup:
	pdf_removeitem(xref->store, PDF_KPATTERN, stmref);
cleanupstore:
	pdf_droppattern(pat);
	return error; /* already rethrown */
}