path: root/mupdf/pdf_resources.c

#include <fitz.h>
#include <mupdf.h>

/*

Go through resource dictionary and resolve some levels of
indirect references so we end up with a stylized structure.
The resources referenced are all pre-loaded which inserts
them into the resource store for later lookup when interpreting
content streams.

All resources except colorspaces are automatically inserted
in the resource store when they are parsed. For colorspaces
named in resource dictionaries, we have to insert them ourselves
since we cannot take the risk of having to resolve objects
while in the middle of parsing a content stream.

<<
	/Font <<
		/F0 1 0 R
		/F1 2 0 R
		/F2 3 0 R
	>>
	/ExtGState <<
		/Gs0 << ... /Font 1 0 R ... >>
		/Gs1 << ... >>
	>>
	/ColorSpace <<
		/Cs0 5 0 R
		/Cs1 [ /ICCBased 5 0 R ]
		/Cs2 [ /CalRGB << ... >> ]
		/CsX [ /Pattern /DeviceRGB ]
	>>
	/Pattern <<
		/Pat0 20 0 R
	>>
	/Shading << 
		/Sh0 30 0 R
	>>
	/XObject <<
		/Im0 10 0 R
		/Fm0 11 0 R
	>>
>>

*/

static fz_error *
preloadcolorspace(pdf_xref *xref, fz_obj *ref)
{
	fz_error *error;
	fz_colorspace *colorspace;
	fz_obj *obj = ref;

	if (pdf_finditem(xref->store, PDF_KCOLORSPACE, ref))
		return nil;

	error = pdf_resolve(&obj, xref);
	if (error)
		return error;
	error = pdf_loadcolorspace(&colorspace, xref, obj);
	fz_dropobj(obj);
	if (error)
		return error;

	pdf_logrsrc("rsrc colorspace %s\n", colorspace->name);

	error = pdf_storeitem(xref->store, PDF_KCOLORSPACE, ref, colorspace);
	if (error)
	{
		fz_dropcolorspace(colorspace);
		return error;
	}

	return nil;
}

static fz_error *
preloadpattern(pdf_xref *xref, fz_obj *ref)
{
	fz_error *error;
	pdf_pattern *pattern;
	fz_shade *shade;
	fz_obj *type;
	fz_obj *obj = ref;

	error = pdf_resolve(&obj, xref);
	if (error)
		return error;

	type = fz_dictgets(obj, "PatternType");

	if (fz_toint(type) == 1)
	{
		error = pdf_loadpattern(&pattern, xref, obj, ref);
		fz_dropobj(obj);
		return error;
	}

	else if (fz_toint(type) == 2)
	{
		error = pdf_loadshade(&shade, xref, obj, ref);
		fz_dropobj(obj);
		return error;
	}

	else
	{
		fz_dropobj(obj);
		return fz_throw("syntaxerror: unknown Pattern type");
	}
}

static fz_error *
preloadshading(pdf_xref *xref, fz_obj *ref)
{
	fz_error *error;
	fz_shade *shade;
	fz_obj *obj = ref;
	error = pdf_resolve(&obj, xref);
	if (error) return error;
	error = pdf_loadshade(&shade, xref, obj, ref);
	fz_dropobj(obj);
	return error;
}

static fz_error *
preloadxobject(pdf_xref *xref, fz_obj *ref)
{
	fz_error *error;
	pdf_xobject *xobject;
	pdf_image *image;
	fz_obj *obj = ref;
	fz_obj *subtype;

	error = pdf_resolve(&obj, xref);
	if (error)
		return error;

	subtype = fz_dictgets(obj, "Subtype");

	if (!strcmp(fz_toname(subtype), "Form"))
	{
		error = pdf_loadxobject(&xobject, xref, obj, ref);
		fz_dropobj(obj);
		return error;
	}

	else if (!strcmp(fz_toname(subtype), "Image"))
	{
		error = pdf_loadimage(&image, xref, obj, ref);
		fz_dropobj(obj);
		return error;
	}

	else
	{
		fz_dropobj(obj);
		return fz_throw("syntaxerror: unknown XObject subtype");
	}
}

static fz_error *
preloadfont(pdf_xref *xref, fz_obj *ref)
{
	fz_error *error;
	pdf_font *font;
	fz_obj *obj = ref;
	error = pdf_resolve(&obj, xref);
	if (error)
		return error;
	error = pdf_loadfont(&font, xref, obj, ref);
	return error;
}

static fz_error *
scanfonts(pdf_xref *xref, fz_obj *rdb)
{
	fz_error *error;
	fz_obj *dict;
	fz_obj *obj;
	int i;

	dict = fz_dictgets(rdb, "ExtGState");
	if (dict)
	{
		for (i = 0; i < fz_dictlen(dict); i++)
		{
			obj = fz_dictgetval(dict, i);
			obj = fz_dictgets(obj, "Font");
			if (obj)
			{
				pdf_logrsrc("extgstate font\n");
				error = preloadfont(xref, fz_arrayget(obj, 0));
				if (error)
					return error;
			}
		}
	}

	dict = fz_dictgets(rdb, "Font");
	if (dict)
	{
		for (i = 0; i < fz_dictlen(dict); i++)
		{
			obj = fz_dictgetval(dict, i);
			error = preloadfont(xref, obj);
			if (error)
				return error;
		}
	}

	return nil;
}

static fz_error *
copyresolved(fz_obj **outp, pdf_xref *xref, fz_obj *dict)
{
	fz_error *error;
	fz_obj *key, *val, *obj;
	fz_obj *copy;
	int i;

	error = fz_newdict(&copy, fz_dictlen(dict));
	if (error)
		return error;

	for (i = 0; i < fz_dictlen(dict); i++)
	{
		key = fz_dictgetkey(dict, i);
		val = fz_dictgetval(dict, i);

		if (fz_isindirect(val))
		{
			error = pdf_loadindirect(&obj, xref, val);
			if (error)
				goto cleanup;
			error = fz_dictput(copy, key, obj);
			fz_dropobj(obj);
			if (error)
				goto cleanup;
		}
		else
		{
			error = fz_dictput(copy, key, val);
			if (error)
				goto cleanup;
		}
	}

	*outp = copy;
	return nil;

cleanup:
	fz_dropobj(copy);
	return error;
}

fz_error *
pdf_loadresources(fz_obj **rdbp, pdf_xref *xref, fz_obj *orig)
{
	fz_error *error;
	fz_obj *copy;
	fz_obj *old;
	fz_obj *new;
	fz_obj *dict;
	fz_obj *obj;
	int i;

	/*
	 * We need a store for resources.
	 */

	if (!xref->store)
	{
		error = pdf_newstore(&xref->store);
		if (error)
			return error;
	}

	pdf_logrsrc("load resources {\n");

	/*
	 * Resolve indirect objects
	 */

	error = copyresolved(&copy, xref, orig);
	if (error)
		return error;

	old = fz_dictgets(copy, "ExtGState");
	if (old)
	{
		error = copyresolved(&new, xref, old);
		if (error)
			goto cleanup;
		error = fz_dictputs(copy, "ExtGState", new);
		fz_dropobj(new);
		if (error)
			goto cleanup;
	}

	/*
	 * Load ColorSpace objects
	 */

	dict = fz_dictgets(copy, "ColorSpace");
	if (dict)
	{
		for (i = 0; i < fz_dictlen(dict); i++)
		{
			obj = fz_dictgetval(dict, i);
				error = preloadcolorspace(xref, obj);
				if (error)
					return error;
		}
	}

	/*
	 * Load Patterns (and Shadings)
	 */

	dict = fz_dictgets(copy, "Pattern");
	if (dict)
	{
		for (i = 0; i < fz_dictlen(dict); i++)
		{
			obj = fz_dictgetval(dict, i);
				error = preloadpattern(xref, obj);
				if (error)
					return error;
		}
	}

	dict = fz_dictgets(copy, "Shading");
	if (dict)
	{
		for (i = 0; i < fz_dictlen(dict); i++)
		{
			obj = fz_dictgetval(dict, i);
				error = preloadshading(xref, obj);
				if (error)
					return error;
		}
	}

	/*
	 * Load XObjects and Images
	 */

	dict = fz_dictgets(copy, "XObject");
	if (dict)
	{
		for (i = 0; i < fz_dictlen(dict); i++)
		{
			obj = fz_dictgetval(dict, i);
				error = preloadxobject(xref, obj);
				if (error)
					return error;
		}
	}

	/*
	 * Load Font objects
	 */

	error = scanfonts(xref, copy);
	if (error)
		goto cleanup;

	pdf_logrsrc("}\n");

	*rdbp = copy;
	return nil;

cleanup:
	fz_dropobj(copy);
	return error;
}