pdf_interpret.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）

						istransparency = 1;
				}

				error = runxobject(csi, xref, xobj, istransparency);
				if (error)
					return fz_rethrow(error, "cannot draw xobject");
			}
		}

		else if (!strcmp(buf, "sh"))
		{
			fz_obj *dict;
			fz_obj *obj;
			fz_shade *shd;

			if (csi->top != 1)
				goto syntaxerror;

			dict = fz_dictgets(rdb, "Shading");
			if (!dict)
				return fz_throw("cannot find Shading dictionary");

			obj = fz_dictget(dict, csi->stack[csi->top - 1]);
			if (!obj)
				return fz_throw("cannot find shade resource: %s", fz_toname(csi->stack[csi->top - 1]));

			shd = pdf_finditem(xref->store, PDF_KSHADE, obj);
			if (!shd)
				return fz_throw("cannot find shade in store");

			error = pdf_addshade(gstate, shd);
			if (error) return fz_rethrow(error, "cannot draw shade");
		}

		else if (!strcmp(buf, "d0"))
		{
			fz_warn("unimplemented: d0 charprocs");
		}

		else if (!strcmp(buf, "d1"))
		{
		}

		else
		{
			/* don't fail on unknown keywords if braced by BX/EX */
			if (!csi->xbalance)
				fz_warn("unknown keyword: %s", buf);
		}
	}

	else switch (buf[0])
	{

	case 'q':
		if (csi->top != 0)
			goto syntaxerror;
		error = gsave(csi);
		if (error)
			return fz_rethrow(error, "cannot gsave");
		break;

	case 'Q':
		if (csi->top != 0)
			goto syntaxerror;
		error = grestore(csi);
		if (error)
			return fz_rethrow(error, "cannot grestore");
		break;

	case 'w':
		if (csi->top != 1)
			goto syntaxerror;
		gstate->linewidth = fz_toreal(csi->stack[0]);
		break;

	case 'J':
		if (csi->top != 1)
			goto syntaxerror;
		gstate->linecap = fz_toint(csi->stack[0]);
		break;

	case 'j':
		if (csi->top != 1)
			goto syntaxerror;
		gstate->linejoin = fz_toint(csi->stack[0]);
		break;

	case 'M':
		if (csi->top != 1)
			goto syntaxerror;
		gstate->miterlimit = fz_toreal(csi->stack[0]);
		break;

	case 'd':
		if (csi->top != 2)
			goto syntaxerror;
		{
			int i;
			fz_obj *array = csi->stack[0];
			gstate->dashlen = fz_arraylen(array);
			if (gstate->dashlen > 32)
				return fz_throw("assert: dash pattern too big");
			for (i = 0; i < gstate->dashlen; i++)
				gstate->dashlist[i] = fz_toreal(fz_arrayget(array, i));
			gstate->dashphase = fz_toreal(csi->stack[1]);
		}
		break;

	case 'i':
		if (csi->top != 1)
			goto syntaxerror;
		/* flatness */
		break;

	case 'm':
		if (csi->top != 2)
			goto syntaxerror;
		a = fz_toreal(csi->stack[0]);
		b = fz_toreal(csi->stack[1]);
		error = fz_moveto(csi->path, a, b);
		if (error) return fz_rethrow(error, "cannot create path node");
		break;

	case 'l':
		if (csi->top != 2)
			goto syntaxerror;
		a = fz_toreal(csi->stack[0]);
		b = fz_toreal(csi->stack[1]);
		error = fz_lineto(csi->path, a, b);
		if (error) return fz_rethrow(error, "cannot create path node");
		break;

	case 'c':
		if (csi->top != 6)
			goto syntaxerror;
		a = fz_toreal(csi->stack[0]);
		b = fz_toreal(csi->stack[1]);
		c = fz_toreal(csi->stack[2]);
		d = fz_toreal(csi->stack[3]);
		e = fz_toreal(csi->stack[4]);
		f = fz_toreal(csi->stack[5]);
		error = fz_curveto(csi->path, a, b, c, d, e, f);
		if (error) return fz_rethrow(error, "cannot create path node");
		break;

	case 'v':
		if (csi->top != 4)
			goto syntaxerror;
		a = fz_toreal(csi->stack[0]);
		b = fz_toreal(csi->stack[1]);
		c = fz_toreal(csi->stack[2]);
		d = fz_toreal(csi->stack[3]);
		error = fz_curvetov(csi->path, a, b, c, d);
		if (error) return fz_rethrow(error, "cannot create path node");
		break;

	case 'y':
		if (csi->top != 4)
			goto syntaxerror;
		a = fz_toreal(csi->stack[0]);
		b = fz_toreal(csi->stack[1]);
		c = fz_toreal(csi->stack[2]);
		d = fz_toreal(csi->stack[3]);
		error = fz_curvetoy(csi->path, a, b, c, d);
		if (error) return fz_rethrow(error, "cannot create path node");
		break;

	case 'h':
		if (csi->top != 0)
			goto syntaxerror;
		error = fz_closepath(csi->path);
		if (error) return fz_rethrow(error, "cannot create path node");
		break;

	case 'S':
		if (csi->top != 0)
			goto syntaxerror;
		error = pdf_showpath(csi, 0, 0, 1, 0);
		if (error) return fz_rethrow(error, "cannot draw path");
		break;

	case 's':
		if (csi->top != 0)
			goto syntaxerror;
		error = pdf_showpath(csi, 1, 0, 1, 0);
		if (error) return fz_rethrow(error, "cannot draw path");
		break;

	case 'F':
	case 'f':
		if (csi->top != 0)
			goto syntaxerror;
		error = pdf_showpath(csi, 0, 1, 0, 0);
		if (error) return fz_rethrow(error, "cannot draw path");
		break;

	case 'B':
		if (csi->top != 0)
			goto syntaxerror;
		error = pdf_showpath(csi, 0, 1, 1, 0);
		if (error) return fz_rethrow(error, "cannot draw path");
		break;

	case 'b':
		if (csi->top != 0)
			goto syntaxerror;
		error = pdf_showpath(csi, 1, 1, 1, 0);
		if (error) return fz_rethrow(error, "cannot draw path");
		break;

	case 'n':
		if (csi->top != 0)
			goto syntaxerror;
		error = pdf_showpath(csi, 0, 0, 0, csi->clipevenodd);
		if (error) return fz_rethrow(error, "cannot draw path");
		break;

	case 'W':
		if (csi->top != 0)
			goto syntaxerror;
		csi->clip = 1;
		csi->clipevenodd = 0;
		break;

	case 'g':	
		if (csi->top != 1)
			goto syntaxerror;

		v[0] = fz_toreal(csi->stack[0]);
		error = pdf_setcolorspace(csi, PDF_MFILL, pdf_devicegray);
		if (error) return fz_rethrow(error, "cannot set gray colorspace");
		error = pdf_setcolor(csi, PDF_MFILL, v);
		if (error) return fz_rethrow(error, "cannot set gray color");
		break;

	case 'G':
		if (csi->top != 1)
			goto syntaxerror;

		v[0] = fz_toreal(csi->stack[0]);
		error = pdf_setcolorspace(csi, PDF_MSTROKE, pdf_devicegray);
		if (error) return fz_rethrow(error, "cannot set gray colorspace");
		error = pdf_setcolor(csi, PDF_MSTROKE, v);
		if (error) return fz_rethrow(error, "cannot set gray color");
		break;

	case 'k':
		if (csi->top != 4)
			goto syntaxerror;

		v[0] = fz_toreal(csi->stack[0]);
		v[1] = fz_toreal(csi->stack[1]);
		v[2] = fz_toreal(csi->stack[2]);
		v[3] = fz_toreal(csi->stack[3]);

		error = pdf_setcolorspace(csi, PDF_MFILL, pdf_devicecmyk);
		if (error) return fz_rethrow(error, "cannot set cmyk colorspace");
		error = pdf_setcolor(csi, PDF_MFILL, v);
		if (error) return fz_rethrow(error, "cannot set cmyk color");
		break;

	case 'K':
		if (csi->top != 4)
			goto syntaxerror;

		v[0] = fz_toreal(csi->stack[0]);
		v[1] = fz_toreal(csi->stack[1]);
		v[2] = fz_toreal(csi->stack[2]);
		v[3] = fz_toreal(csi->stack[3]);

		error = pdf_setcolorspace(csi, PDF_MSTROKE, pdf_devicecmyk);
		if (error) return fz_rethrow(error, "cannot set cmyk colorspace");
		error = pdf_setcolor(csi, PDF_MSTROKE, v);
		if (error) return fz_rethrow(error, "cannot set cmyk color");
		break;

	case '\'':
		if (csi->top != 1)
			goto syntaxerror;

		m = fz_translate(0, -gstate->leading);
		csi->tlm = fz_concat(m, csi->tlm);
		csi->tm = csi->tlm;

		error = pdf_showtext(csi, csi->stack[0]);
		if (error) return fz_rethrow(error, "cannot draw text");
		break;

	case '"':
		if (csi->top != 3)
			goto syntaxerror;

		gstate->wordspace = fz_toreal(csi->stack[0]);
		gstate->charspace = fz_toreal(csi->stack[1]);

		m = fz_translate(0, -gstate->leading);
		csi->tlm = fz_concat(m, csi->tlm);
		csi->tm = csi->tlm;

		error = pdf_showtext(csi, csi->stack[2]);
		if (error) return fz_rethrow(error, "cannot draw text");
		break;

	default:
		/* don't fail on unknown keywords if braced by BX/EX */
		if (!csi->xbalance)
			fz_warn("unknown keyword: %s", buf);
	}

	return fz_okay;

syntaxerror:
	return fz_throw("syntaxerror near '%s'", buf);
}

fz_error *
pdf_runcsi(pdf_csi *csi, pdf_xref *xref, fz_obj *rdb, fz_stream *file)
{
	fz_error *error;
	char buf[65536];
	pdf_token_e tok;
	int len;
	fz_obj *obj;

	while (1)
	{
		if (csi->top == 31)
			return fz_throw("stack overflow");

		error = pdf_lex(&tok, file, buf, sizeof buf, &len);
		if (error)
			return fz_rethrow(error, "lexical error in content stream");

		if (csi->array)
		{
			if (tok == PDF_TCARRAY)
			{
				csi->stack[csi->top] = csi->array;
				csi->array = nil;
				csi->top ++;
			}
			else if (tok == PDF_TINT || tok == PDF_TREAL)
			{
				error = fz_newreal(&obj, atof(buf));
				if (error) return fz_rethrow(error, "cannot create number");
				error = fz_arraypush(csi->array, obj);
				fz_dropobj(obj);
				if (error) return fz_rethrow(error, "cannot add number to array");
			}
			else if (tok == PDF_TSTRING)
			{
				error = fz_newstring(&obj, buf, len);
				if (error) return fz_rethrow(error, "cannot create string");
				error = fz_arraypush(csi->array, obj);
				fz_dropobj(obj);
				if (error) return fz_rethrow(error, "cannot add string to array");
			}
			else if (tok == PDF_TEOF)
			{
				return fz_okay;
			}
			else
			{
				clearstack(csi);
				return fz_throw("syntaxerror in array");
			}
		}

		else switch (tok)
		{
		case PDF_TEOF:
			return fz_okay;

			/* optimize text-object array parsing */
		case PDF_TOARRAY:
			error = fz_newarray(&csi->array, 8);
			if (error) return fz_rethrow(error, "cannot create array");
			break;

		case PDF_TODICT:
			error = pdf_parsedict(&csi->stack[csi->top], file, buf, sizeof buf);
			if (error) return fz_rethrow(error, "cannot parse dictionary");
			csi->top ++;
			break;

		case PDF_TNAME:
			error = fz_newname(&csi->stack[csi->top], buf);
			if (error) return fz_rethrow(error, "cannot create name");
			csi->top ++;
			break;

		case PDF_TINT:
			error = fz_newint(&csi->stack[csi->top], atoi(buf));
			if (error) return fz_rethrow(error, "cannot create integer");
			csi->top ++;
			break;

		case PDF_TREAL:
			error = fz_newreal(&csi->stack[csi->top], atof(buf));
			if (error) return fz_rethrow(error, "cannot create real");
			csi->top ++;
			break;

		case PDF_TSTRING:
			error = fz_newstring(&csi->stack[csi->top], buf, len);
			if (error) return fz_rethrow(error, "cannot create string");
			csi->top ++;
			break;

		case PDF_TTRUE:
			error = fz_newbool(&csi->stack[csi->top], 1);
			if (error) return fz_rethrow(error, "cannot create true");
			csi->top ++;
			break;

		case PDF_TFALSE:
			error = fz_newbool(&csi->stack[csi->top], 0);
			if (error) return fz_rethrow(error, "cannot create false");
			csi->top ++;
			break;

		case PDF_TNULL:
			error = fz_newnull(&csi->stack[csi->top]);
			if (error) return fz_rethrow(error, "cannot create null");
			csi->top ++;
			break;

		case PDF_TKEYWORD:
			if (!strcmp(buf, "BI"))
			{
				fz_obj *obj;

				error = pdf_parsedict(&obj, file, buf, sizeof buf);
				if (error)
					return fz_rethrow(error, "cannot parse inline image dictionary");

				/* read whitespace after ID keyword */
				fz_readbyte(file);
				error = fz_readerror(file);
				if (error)
					return fz_rethrow(error, "cannot parse whitespace before inline image");

				error = runinlineimage(csi, xref, rdb, file, obj);
				fz_dropobj(obj);
				if (error)
					return fz_rethrow(error, "cannot parse inline image");
			}
			else
			{
				error = runkeyword(csi, xref, rdb, buf);
				if (error)
					return fz_rethrow(error, "cannot run '%s'", buf);
				clearstack(csi);
			}
			break;

		default:
			clearstack(csi);
			return fz_throw("syntaxerror in content stream");
		}
	}
}