pdf_build.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"

void
pdf_initgstate(pdf_gstate *gs)
{
	gs->linewidth = 1.0;
	gs->linecap = 0;
	gs->linejoin = 0;
	gs->miterlimit = 10;
	gs->dashphase = 0;
	gs->dashlen = 0;
	memset(gs->dashlist, 0, sizeof(gs->dashlist));

	gs->stroke.kind = PDF_MCOLOR;
	gs->stroke.cs = fz_keepcolorspace(pdf_devicegray);
	gs->stroke.v[0] = 0;
	gs->stroke.indexed = nil;
	gs->stroke.pattern = nil;
	gs->stroke.shade = nil;
	gs->stroke.alpha = 1.0;

	gs->fill.kind = PDF_MCOLOR;
	gs->fill.cs = fz_keepcolorspace(pdf_devicegray);
	gs->fill.v[0] = 0;
	gs->fill.indexed = nil;
	gs->fill.pattern = nil;
	gs->fill.shade = nil;
	gs->fill.alpha = 1.0;

	gs->blendmode = FZ_BNORMAL;

	gs->charspace = 0;
	gs->wordspace = 0;
	gs->scale = 1;
	gs->leading = 0;
	gs->font = nil;
	gs->size = -1;
	gs->render = 0;
	gs->rise = 0;

	gs->head = nil;
}

fz_error *
pdf_newovernode(fz_node **nodep, pdf_gstate *gs)
{
    if (gs->blendmode == FZ_BNORMAL)
	return fz_newovernode(nodep);
    else
	return fz_newblendnode(nodep, gs->blendmode, 0, 0);
}

fz_error *
pdf_setcolorspace(pdf_csi *csi, int what, fz_colorspace *cs)
{
	pdf_gstate *gs = csi->gstate + csi->gtop;
	fz_error *error;
	pdf_material *mat;

	error = pdf_flushtext(csi);
	if (error)
		return fz_rethrow(error, "cannot finish text node (state change)");

	mat = what == PDF_MFILL ? &gs->fill : &gs->stroke;

	fz_dropcolorspace(mat->cs);

	mat->kind = PDF_MCOLOR;
	mat->cs = fz_keepcolorspace(cs);

	mat->v[0] = 0;	/* FIXME: default color */
	mat->v[1] = 0;	/* FIXME: default color */
	mat->v[2] = 0;	/* FIXME: default color */
	mat->v[3] = 1;	/* FIXME: default color */

	if (!strcmp(cs->name, "Indexed"))
	{
		mat->kind = PDF_MINDEXED;
		mat->indexed = (pdf_indexed*)cs;
		mat->cs = mat->indexed->base;
	}

	if (!strcmp(cs->name, "Lab"))
		mat->kind = PDF_MLAB;

	return fz_okay;
}

fz_error *
pdf_setcolor(pdf_csi *csi, int what, float *v)
{
	pdf_gstate *gs = csi->gstate + csi->gtop;
	fz_error *error;
	pdf_indexed *ind;
	pdf_material *mat;
	int i, k;

	error = pdf_flushtext(csi);
	if (error)
		return fz_rethrow(error, "cannot finish text node (state change)");

	mat = what == PDF_MFILL ? &gs->fill : &gs->stroke;

	switch (mat->kind)
	{
	case PDF_MPATTERN:
		if (!strcmp(mat->cs->name, "Lab"))
			goto Llab;
		if (!strcmp(mat->cs->name, "Indexed"))
			goto Lindexed;
		/* fall through */

	case PDF_MCOLOR:
		for (i = 0; i < mat->cs->n; i++)
			mat->v[i] = v[i];
		break;

	case PDF_MLAB:
Llab:
		mat->v[0] = v[0] / 100.0;
		mat->v[1] = (v[1] + 100) / 200.0;
		mat->v[2] = (v[2] + 100) / 200.0;
		break;

	case PDF_MINDEXED:
Lindexed:
		ind = mat->indexed;
		i = CLAMP(v[0], 0, ind->high);
		for (k = 0; k < ind->base->n; k++)
			mat->v[k] = ind->lookup[ind->base->n * i + k] / 255.0;
		break;

	default:
		return fz_throw("color incompatible with material");
	}

	return fz_okay;
}

fz_error *
pdf_setpattern(pdf_csi *csi, int what, pdf_pattern *pat, float *v)
{
	pdf_gstate *gs = csi->gstate + csi->gtop;
	fz_error *error;
	pdf_material *mat;

	error = pdf_flushtext(csi);
	if (error)
		return fz_rethrow(error, "cannot finish text node (state change)");

	mat = what == PDF_MFILL ? &gs->fill : &gs->stroke;

	if (mat->pattern)
		pdf_droppattern(mat->pattern);

	mat->kind = PDF_MPATTERN;
	if (pat)
		mat->pattern = pdf_keeppattern(pat);
	else
		mat->pattern = nil;

	if (v)
	{
		error = pdf_setcolor(csi, what, v);
		if (error)
			return fz_rethrow(error, "cannot set color");
	}

	return fz_okay;
}

fz_error *
pdf_setshade(pdf_csi *csi, int what, fz_shade *shade)
{
	pdf_gstate *gs = csi->gstate + csi->gtop;
	fz_error *error;
	pdf_material *mat;

	error = pdf_flushtext(csi);
	if (error)
		return fz_rethrow(error, "cannot finish text node (state change)");

	mat = what == PDF_MFILL ? &gs->fill : &gs->stroke;

	if (mat->shade)
		fz_dropshade(mat->shade);

	mat->kind = PDF_MSHADE;
	mat->shade = fz_keepshade(shade);

	return fz_okay;
}

fz_error *
pdf_buildstrokepath(pdf_gstate *gs, fz_pathnode *path)
{
	fz_error *error;
	fz_stroke stroke;
	fz_dash *dash;

	stroke.linecap = gs->linecap;
	stroke.linejoin = gs->linejoin;
	stroke.linewidth = gs->linewidth;
	stroke.miterlimit = gs->miterlimit;

	if (gs->dashlen)
	{
		error = fz_newdash(&dash, gs->dashphase, gs->dashlen, gs->dashlist);
		if (error)
			return fz_rethrow(error, "cannot create dash pattern");
	}
	else
		dash = nil;

	error = fz_endpath(path, FZ_STROKE, &stroke, dash);
	if (error)
	{
		fz_dropdash(dash);
		return fz_rethrow(error, "cannot finish path node");
	}

	return fz_okay;
}

fz_error *
pdf_buildfillpath(pdf_gstate *gs, fz_pathnode *path, int eofill)
{
	fz_error *error;
	error = fz_endpath(path, eofill ? FZ_EOFILL : FZ_FILL, nil, nil);
	if (error)
		return fz_rethrow(error, "cannot finish path node");
	return fz_okay;
}

static fz_error *
addcolorshape(pdf_gstate *gs, fz_node *shape, float alpha, fz_colorspace *cs, float *v)
{
	fz_error *error;
	fz_node *mask;
	fz_node *solid;

	error = fz_newmasknode(&mask);
	if (error)
		return fz_rethrow(error, "cannot create mask node");

	error = fz_newsolidnode(&solid, alpha, cs, cs->n, v);
	if (error)
	{
		fz_dropnode(mask);
		return fz_rethrow(error, "cannot create color node");
	}

	fz_insertnodelast(mask, shape);
	fz_insertnodelast(mask, solid);
	fz_insertnodelast(gs->head, mask);

	return fz_okay;
}

static fz_error *
addinvisibleshape(pdf_gstate *gs, fz_node *shape)
{
	fz_error *error;
	fz_node *mask;
	fz_pathnode *path;

	error = fz_newmasknode(&mask);
	if (error)
		return fz_rethrow(error, "cannot create mask node");

	error = fz_newpathnode(&path);
	if (error)
	{
		fz_dropnode(mask);
		return fz_rethrow(error, "cannot create path node");
	}

	error = fz_endpath(path, FZ_FILL, nil, nil);
	if (error)
	{
		fz_dropnode(mask);
		fz_dropnode((fz_node*)path);
		return fz_rethrow(error, "cannot finish path node");
	}

	fz_insertnodelast(mask, (fz_node*)path);
	fz_insertnodelast(mask, shape);
	fz_insertnodelast(gs->head, mask);

	return fz_okay;
}

static fz_matrix getmatrix(fz_node *node)
{
	if (node->parent)
	{
		fz_matrix ptm = getmatrix(node->parent);
		if (fz_istransformnode(node))
			return fz_concat(((fz_transformnode*)node)->m, ptm);
		return ptm;
	}
	if (fz_istransformnode(node))
		return ((fz_transformnode*)node)->m;
	return fz_identity();
}

static fz_error *
addpatternshape(pdf_gstate *gs, fz_node *shape,
		pdf_pattern *pat, fz_colorspace *cs, float *v)
{
	fz_error *error;
	fz_node *xform;
	fz_node *over;
	fz_node *mask;
	fz_node *link;
	fz_matrix ctm;
	fz_matrix inv;
	fz_matrix ptm;
	fz_rect bbox;
	int x, y, x0, y0, x1, y1;

	/* patterns are painted in user space */
	ctm = getmatrix(gs->head);
	inv = fz_invertmatrix(ctm);

	error = fz_newmasknode(&mask);
	if (error)
		return fz_rethrow(error, "cannot create mask node");

	ptm = fz_concat(pat->matrix, fz_invertmatrix(ctm));
	error = fz_newtransformnode(&xform, ptm);
	if (error)
	{
		fz_dropnode(mask);
		return fz_rethrow(error, "cannot create transform node");
	}

	error = pdf_newovernode(&over, gs);
	if (error)
	{
		fz_dropnode(xform);
		fz_dropnode(mask);
		return fz_rethrow(error, "cannot create over node");
	}

	fz_insertnodelast(mask, shape);
	fz_insertnodelast(mask, xform);
	fz_insertnodelast(xform, over);
	xform = nil;

	/* over, xform, mask are now owned by the tree */

	/* get bbox of shape in pattern space for stamping */
	ptm = fz_concat(ctm, fz_invertmatrix(pat->matrix));
	bbox = fz_boundnode(shape, ptm);

	/* expand bbox by pattern bbox */
	bbox.x0 += pat->bbox.x0;
	bbox.y0 += pat->bbox.y0;
	bbox.x1 += pat->bbox.x1;
	bbox.y1 += pat->bbox.y1;

	x0 = fz_floor(bbox.x0 / pat->xstep);
	y0 = fz_floor(bbox.y0 / pat->ystep);
	x1 = fz_ceil(bbox.x1 / pat->xstep);
	y1 = fz_ceil(bbox.y1 / pat->ystep);

	for (y = y0; y <= y1; y++)
	{
		for (x = x0; x <= x1; x++)
		{
			ptm = fz_translate(x * pat->xstep, y * pat->ystep);
			error = fz_newtransformnode(&xform, ptm);
			if (error)
				return fz_rethrow(error, "cannot create transform node for stamp");
			error = fz_newlinknode(&link, pat->tree);
			if (error)
			{
				fz_dropnode(xform);
				return fz_rethrow(error, "cannot create link node for stamp");
			}
			fz_insertnodelast(xform, link);
			fz_insertnodelast(over, xform);
		}
	}

	if (pat->ismask)
	{
		error = addcolorshape(gs, mask, 1.0, cs, v);
		if (error)
			return fz_rethrow(error, "cannot add colored shape");
		return fz_okay;
	}

	fz_insertnodelast(gs->head, mask);
	return fz_okay;
}

fz_error *
pdf_addshade(pdf_gstate *gs, fz_shade *shade)
{
	fz_error *error;
	fz_node *node;

	error = fz_newshadenode(&node, shade);
	if (error)
		return fz_rethrow(error, "cannot create shade node");

	fz_insertnodelast(gs->head, node);

	return fz_okay;
}

static fz_error *
addshadeshape(pdf_gstate *gs, fz_node *shape, fz_shade *shade)
{
	fz_error *error;
	fz_node *mask;
	fz_node *color;
	fz_node *xform;
	fz_node *over;
	fz_node *bgnd;
	fz_matrix ctm;
	fz_matrix inv;

	ctm = getmatrix(gs->head);
	inv = fz_invertmatrix(ctm);

	error = fz_newtransformnode(&xform, inv);
	if (error)
		return fz_rethrow(error, "cannot create transform node");

	error = fz_newmasknode(&mask);
	if (error)
	{
		fz_dropnode(xform);
		return fz_rethrow(error, "cannot create mask node");
	}

	error = fz_newshadenode(&color, shade);
	if (error)
	{
		fz_dropnode(mask);
		fz_dropnode(xform);
		return fz_rethrow(error, "cannot create shade node");
	}

	if (shade->usebackground)
	{
		error = pdf_newovernode(&over, gs);
		if (error)
		{
			fz_dropnode(color);
			fz_dropnode(mask);
			fz_dropnode(xform);
			return fz_rethrow(error, "cannot create over node for background color");
		}

		error = fz_newsolidnode(&bgnd, 1.0f, shade->cs, shade->cs->n, shade->background);
		if (error)
		{
			fz_dropnode(over);
			fz_dropnode(color);
			fz_dropnode(mask);
			fz_dropnode(xform);
			return fz_rethrow(error, "cannot create solid node for background color");;
		}

		fz_insertnodelast(mask, shape);
		fz_insertnodelast(over, bgnd);
		fz_insertnodelast(over, color);
		fz_insertnodelast(xform, over);
		fz_insertnodelast(mask, xform);
		fz_insertnodelast(gs->head, mask);
	}
	else
	{
		fz_insertnodelast(mask, shape);
		fz_insertnodelast(xform, color);
		fz_insertnodelast(mask, xform);
		fz_insertnodelast(gs->head, mask);
	}

	return fz_okay;
}

fz_error *
pdf_addfillshape(pdf_gstate *gs, fz_node *shape)
{
	fz_error *error;

	switch (gs->fill.kind)