Better handling of 'uncacheable' Type3 glyphs. Bug 692745.

Some Type 3 fonts contain glyphs that rely on inheriting various
aspects of the graphics state from their calling code. (i.e. a
glyph might use d0, then fill an area without setting a color
first).

While the spec is vague on this point, we believe that technically
it is invalid. Previously mupdf defaulted all elements of the graphic
state back when beginning to draw the glyph. This does not match
what Acrobat does though, so we change the approach taken.

We now watch (by use of bits in the device flags word) for the use
of parts of the graphics state before it is set. If such use is
detected, then we note that the glyph is 'uncacheable' and render
it direct.

This seems to match Acrobats behaviour.

1 files changed, 135 insertions, 46 deletions

diff --git a/pdf/pdf_interpret.c b/pdf/pdf_interpret.c
index 2cfa5d99..7bb2da9c 100644
--- a/pdf/pdf_interpret.c
+++ b/pdf/pdf_interpret.c
@@ -88,6 +88,7 @@ struct pdf_csi_s
 
 	/* text object state */
 	fz_text *text;
+	fz_rect text_bbox;
 	fz_matrix tlm;
 	fz_matrix tm;
 	int text_mode;
@@ -432,6 +433,19 @@ pdf_show_path(pdf_csi *csi, int doclose, int dofill, int dostroke, int even_odd)
 	fz_path *path;
 	fz_rect bbox;
 
+	if (dostroke) {
+		if (csi->dev->flags & (FZ_DEVFLAG_STROKECOLOR_UNDEFINED | FZ_DEVFLAG_LINEJOIN_UNDEFINED | FZ_DEVFLAG_LINEWIDTH_UNDEFINED))
+			csi->dev->flags |= FZ_DEVFLAG_UNCACHEABLE;
+		else if (gstate->stroke_state.dash_len != 0 && csi->dev->flags & (FZ_DEVFLAG_STARTCAP_UNDEFINED | FZ_DEVFLAG_DASHCAP_UNDEFINED | FZ_DEVFLAG_ENDCAP_UNDEFINED))
+			csi->dev->flags |= FZ_DEVFLAG_UNCACHEABLE;
+		else if (gstate->stroke_state.linejoin == FZ_LINEJOIN_MITER && (csi->dev->flags & FZ_DEVFLAG_MITERLIMIT_UNDEFINED))
+			csi->dev->flags |= FZ_DEVFLAG_UNCACHEABLE;
+	}
+	if (dofill) {
+		if (csi->dev->flags & FZ_DEVFLAG_FILLCOLOR_UNDEFINED)
+			csi->dev->flags |= FZ_DEVFLAG_UNCACHEABLE;
+	}
+
 	path = csi->path;
 	csi->path = fz_new_path(ctx);
 
@@ -540,7 +554,6 @@ pdf_flush_text(pdf_csi *csi)
 	int dostroke = 0;
 	int doclip = 0;
 	int doinvisible = 0;
-	fz_rect bbox;
 	fz_context *ctx = csi->dev->ctx;
 
 	if (!csi->text)
@@ -566,9 +579,7 @@ pdf_flush_text(pdf_csi *csi)
 
 	fz_try(ctx)
 	{
-		bbox = fz_bound_text(ctx, text, gstate->ctm);
-
-		pdf_begin_group(csi, bbox);
+		pdf_begin_group(csi, csi->text_bbox);
 
 		if (doinvisible)
 			fz_ignore_text(csi->dev, text, gstate->ctm);
@@ -595,7 +606,7 @@ pdf_flush_text(pdf_csi *csi)
 				if (gstate->fill.pattern)
 				{
 					fz_clip_text(csi->dev, text, gstate->ctm, 0);
-					pdf_show_pattern(csi, gstate->fill.pattern, bbox, PDF_FILL);
+					pdf_show_pattern(csi, gstate->fill.pattern, csi->text_bbox, PDF_FILL);
 					fz_pop_clip(csi->dev);
 				}
 				break;
@@ -624,7 +635,7 @@ pdf_flush_text(pdf_csi *csi)
 				if (gstate->stroke.pattern)
 				{
 					fz_clip_stroke_text(csi->dev, text, &gstate->stroke_state, gstate->ctm);
-					pdf_show_pattern(csi, gstate->stroke.pattern, bbox, PDF_STROKE);
+					pdf_show_pattern(csi, gstate->stroke.pattern, csi->text_bbox, PDF_STROKE);
 					fz_pop_clip(csi->dev);
 				}
 				break;
@@ -664,6 +675,8 @@ pdf_show_char(pdf_csi *csi, int cid)
 	int ucsbuf[8];
 	int ucslen;
 	int i;
+	fz_rect bbox;
+	int render_direct;
 
 	tsm.a = gstate->size * gstate->scale;
 	tsm.b = 0;
@@ -697,6 +710,15 @@ pdf_show_char(pdf_csi *csi, int cid)
 
 	trm = fz_concat(tsm, csi->tm);
 
+	bbox = fz_bound_glyph(ctx, fontdesc->font, gid, trm);
+	/* Compensate for the glyph cache limited positioning precision */
+	bbox.x0 -= 1;
+	bbox.y0 -= 1;
+	bbox.x1 += 1;
+	bbox.y1 += 1;
+
+	render_direct = !fz_glyph_cacheable(fontdesc->font, gid);
+
 	/* flush buffered text if face or matrix or rendermode has changed */
 	if (!csi->text ||
 		fontdesc->font != csi->text->font ||
@@ -705,7 +727,8 @@ pdf_show_char(pdf_csi *csi, int cid)
 		fabsf(trm.b - csi->text->trm.b) > FLT_EPSILON ||
 		fabsf(trm.c - csi->text->trm.c) > FLT_EPSILON ||
 		fabsf(trm.d - csi->text->trm.d) > FLT_EPSILON ||
-		gstate->render != csi->text_mode)
+		gstate->render != csi->text_mode ||
+		render_direct)
 	{
 		pdf_flush_text(csi);
 
@@ -713,14 +736,28 @@ pdf_show_char(pdf_csi *csi, int cid)
 		csi->text->trm.e = 0;
 		csi->text->trm.f = 0;
 		csi->text_mode = gstate->render;
+		csi->text_bbox = fz_empty_rect;
 	}
 
-	/* add glyph to textobject */
-	fz_add_text(ctx, csi->text, gid, ucsbuf[0], trm.e, trm.f);
+	if (render_direct)
+	{
+		/* Render the glyph stream direct here (only happens for
+		 * type3 glyphs that seem to inherit current graphics
+		 * attributes) */
+		fz_matrix composed = fz_concat(trm, gstate->ctm);
+		fz_render_t3_glyph_direct(ctx, csi->dev, fontdesc->font, gid, composed, gstate);
+	}
+	else
+	{
+		csi->text_bbox = fz_union_rect(csi->text_bbox, bbox);
+
+		/* add glyph to textobject */
+		fz_add_text(ctx, csi->text, gid, ucsbuf[0], trm.e, trm.f);
 
-	/* add filler glyphs for one-to-many unicode mapping */
-	for (i = 1; i < ucslen; i++)
-		fz_add_text(ctx, csi->text, -1, ucsbuf[i], trm.e, trm.f);
+		/* add filler glyphs for one-to-many unicode mapping */
+		for (i = 1; i < ucslen; i++)
+			fz_add_text(ctx, csi->text, -1, ucsbuf[i], trm.e, trm.f);
+	}
 
 	if (fontdesc->wmode == 0)
 	{
@@ -858,8 +895,49 @@ pdf_init_gstate(pdf_gstate *gs, fz_matrix ctm)
 	gs->luminosity = 0;
 }
 
+static pdf_material *
+pdf_keep_material(pdf_material *mat)
+{
+	if (mat->colorspace)
+		fz_keep_colorspace(mat->colorspace);
+	if (mat->pattern)
+		pdf_keep_pattern(mat->pattern);
+	if (mat->shade)
+		fz_keep_shade(mat->shade);
+	return mat;
+}
+
+static pdf_material *
+pdf_drop_material(fz_context *ctx, pdf_material *mat)
+{
+	if (mat->colorspace)
+		fz_drop_colorspace(ctx, mat->colorspace);
+	if (mat->pattern)
+		pdf_drop_pattern(ctx, mat->pattern);
+	if (mat->shade)
+		fz_drop_shade(ctx, mat->shade);
+	return mat;
+}
+
+static void
+copy_state(pdf_gstate *gs, pdf_gstate *old)
+{
+	gs->stroke = old->stroke;
+	gs->fill = old->fill;
+	gs->font = old->font;
+	gs->softmask = old->softmask;
+
+	pdf_keep_material(&gs->stroke);
+	pdf_keep_material(&gs->fill);
+	if (gs->font)
+		pdf_keep_font(gs->font);
+	if (gs->softmask)
+		pdf_keep_xobject(gs->softmask);
+}
+
+
 static pdf_csi *
-pdf_new_csi(pdf_xref *xref, fz_device *dev, fz_matrix ctm, char *event, fz_cookie *cookie)
+pdf_new_csi(pdf_xref *xref, fz_device *dev, fz_matrix ctm, char *event, fz_cookie *cookie, pdf_gstate *gstate)
 {
 	pdf_csi *csi;
 	fz_context *ctx = dev->ctx;
@@ -896,6 +974,8 @@ pdf_new_csi(pdf_xref *xref, fz_device *dev, fz_matrix ctm, char *event, fz_cooki
 
 		csi->top_ctm = ctm;
 		pdf_init_gstate(&csi->gstate[0], ctm);
+		if (gstate)
+			copy_state(&csi->gstate[0], gstate);
 		csi->gtop = 0;
 
 		csi->cookie = cookie;
@@ -927,30 +1007,6 @@ pdf_clear_stack(pdf_csi *csi)
 	csi->top = 0;
 }
 
-static pdf_material *
-pdf_keep_material(pdf_material *mat)
-{
-	if (mat->colorspace)
-		fz_keep_colorspace(mat->colorspace);
-	if (mat->pattern)
-		pdf_keep_pattern(mat->pattern);
-	if (mat->shade)
-		fz_keep_shade(mat->shade);
-	return mat;
-}
-
-static pdf_material *
-pdf_drop_material(fz_context *ctx, pdf_material *mat)
-{
-	if (mat->colorspace)
-		fz_drop_colorspace(ctx, mat->colorspace);
-	if (mat->pattern)
-		pdf_drop_pattern(ctx, mat->pattern);
-	if (mat->shade)
-		fz_drop_shade(ctx, mat->shade);
-	return mat;
-}
-
 static void
 pdf_gsave(pdf_csi *csi)
 {
@@ -962,12 +1018,11 @@ pdf_gsave(pdf_csi *csi)
 		csi->gstate = fz_resize_array(ctx, csi->gstate, csi->gcap*2, sizeof(pdf_gstate));
 		csi->gcap *= 2;
 	}
-	gs = csi->gstate + csi->gtop;
 
 	memcpy(&csi->gstate[csi->gtop + 1], &csi->gstate[csi->gtop], sizeof(pdf_gstate));
 
-	csi->gtop ++;
-
+	csi->gtop++;
+	gs = &csi->gstate[csi->gtop];
 	pdf_keep_material(&gs->stroke);
 	pdf_keep_material(&gs->fill);
 	if (gs->font)
@@ -1419,16 +1474,26 @@ pdf_run_extgstate(pdf_csi *csi, fz_obj *rdb, fz_obj *extgstate)
 
 		else if (!strcmp(s, "LC"))
 		{
+			csi->dev->flags &= ~(FZ_DEVFLAG_STARTCAP_UNDEFINED | FZ_DEVFLAG_DASHCAP_UNDEFINED | FZ_DEVFLAG_ENDCAP_UNDEFINED);
 			gstate->stroke_state.start_cap = fz_to_int(val);
 			gstate->stroke_state.dash_cap = fz_to_int(val);
 			gstate->stroke_state.end_cap = fz_to_int(val);
 		}
 		else if (!strcmp(s, "LW"))
+		{
+			csi->dev->flags &= ~FZ_DEVFLAG_LINEWIDTH_UNDEFINED;
 			gstate->stroke_state.linewidth = fz_to_real(val);
+		}
 		else if (!strcmp(s, "LJ"))
+		{
+			csi->dev->flags &= ~FZ_DEVFLAG_LINEJOIN_UNDEFINED;
 			gstate->stroke_state.linejoin = fz_to_int(val);
+		}
 		else if (!strcmp(s, "ML"))
+		{
+			csi->dev->flags &= ~FZ_DEVFLAG_MITERLIMIT_UNDEFINED;
 			gstate->stroke_state.miterlimit = fz_to_real(val);
+		}
 
 		else if (!strcmp(s, "D"))
 		{
@@ -1655,12 +1720,16 @@ static void pdf_run_cs_imp(pdf_csi *csi, fz_obj *rdb, int what)
 
 static void pdf_run_CS(pdf_csi *csi, fz_obj *rdb)
 {
+	csi->dev->flags &= ~FZ_DEVFLAG_STROKECOLOR_UNDEFINED;
+
 	pdf_run_cs_imp(csi, rdb, PDF_STROKE);
 	/* RJW: "cannot set colorspace" */
 }
 
 static void pdf_run_cs(pdf_csi *csi, fz_obj *rdb)
 {
+	csi->dev->flags &= ~FZ_DEVFLAG_FILLCOLOR_UNDEFINED;
+
 	pdf_run_cs_imp(csi, rdb, PDF_FILL);
 	/* RJW: "cannot set colorspace" */
 }
@@ -1774,6 +1843,7 @@ static void pdf_run_F(pdf_csi *csi)
 
 static void pdf_run_G(pdf_csi *csi)
 {
+	csi->dev->flags &= ~FZ_DEVFLAG_STROKECOLOR_UNDEFINED;
 	pdf_set_colorspace(csi, PDF_STROKE, fz_device_gray);
 	pdf_set_color(csi, PDF_STROKE, csi->stack);
 }
@@ -1781,6 +1851,7 @@ static void pdf_run_G(pdf_csi *csi)
 static void pdf_run_J(pdf_csi *csi)
 {
 	pdf_gstate *gstate = csi->gstate + csi->gtop;
+	csi->dev->flags &= ~(FZ_DEVFLAG_STARTCAP_UNDEFINED | FZ_DEVFLAG_DASHCAP_UNDEFINED | FZ_DEVFLAG_ENDCAP_UNDEFINED);
 	gstate->stroke_state.start_cap = csi->stack[0];
 	gstate->stroke_state.dash_cap = csi->stack[0];
 	gstate->stroke_state.end_cap = csi->stack[0];
@@ -1788,6 +1859,7 @@ static void pdf_run_J(pdf_csi *csi)
 
 static void pdf_run_K(pdf_csi *csi)
 {
+	csi->dev->flags &= ~FZ_DEVFLAG_STROKECOLOR_UNDEFINED;
 	pdf_set_colorspace(csi, PDF_STROKE, fz_device_cmyk);
 	pdf_set_color(csi, PDF_STROKE, csi->stack);
 }
@@ -1795,6 +1867,7 @@ static void pdf_run_K(pdf_csi *csi)
 static void pdf_run_M(pdf_csi *csi)
 {
 	pdf_gstate *gstate = csi->gstate + csi->gtop;
+	csi->dev->flags &= ~FZ_DEVFLAG_MITERLIMIT_UNDEFINED;
 	gstate->stroke_state.miterlimit = csi->stack[0];
 }
 
@@ -1809,6 +1882,7 @@ static void pdf_run_Q(pdf_csi *csi)
 
 static void pdf_run_RG(pdf_csi *csi)
 {
+	csi->dev->flags &= ~FZ_DEVFLAG_STROKECOLOR_UNDEFINED;
 	pdf_set_colorspace(csi, PDF_STROKE, fz_device_rgb);
 	pdf_set_color(csi, PDF_STROKE, csi->stack);
 }
@@ -1880,6 +1954,7 @@ static void pdf_run_SC_imp(pdf_csi *csi, fz_obj *rdb, int what, pdf_material *ma
 static void pdf_run_SC(pdf_csi *csi, fz_obj *rdb)
 {
 	pdf_gstate *gstate = csi->gstate + csi->gtop;
+	csi->dev->flags &= ~FZ_DEVFLAG_STROKECOLOR_UNDEFINED;
 	pdf_run_SC_imp(csi, rdb, PDF_STROKE, &gstate->stroke);
 	/* RJW: "cannot set color and colorspace" */
 }
@@ -1887,6 +1962,7 @@ static void pdf_run_SC(pdf_csi *csi, fz_obj *rdb)
 static void pdf_run_sc(pdf_csi *csi, fz_obj *rdb)
 {
 	pdf_gstate *gstate = csi->gstate + csi->gtop;
+	csi->dev->flags &= ~FZ_DEVFLAG_FILLCOLOR_UNDEFINED;
 	pdf_run_SC_imp(csi, rdb, PDF_FILL, &gstate->fill);
 	/* RJW: "cannot set color and colorspace" */
 }
@@ -2070,12 +2146,20 @@ static void pdf_run_d(pdf_csi *csi)
 
 static void pdf_run_d0(pdf_csi *csi)
 {
-	csi->dev->flags |= FZ_CHARPROC_COLOR;
+	csi->dev->flags |= FZ_DEVFLAG_COLOR;
 }
 
 static void pdf_run_d1(pdf_csi *csi)
 {
-	csi->dev->flags |= FZ_CHARPROC_MASK;
+	csi->dev->flags |= FZ_DEVFLAG_MASK;
+	csi->dev->flags &= ~(FZ_DEVFLAG_FILLCOLOR_UNDEFINED |
+				FZ_DEVFLAG_STROKECOLOR_UNDEFINED |
+				FZ_DEVFLAG_STARTCAP_UNDEFINED |
+				FZ_DEVFLAG_DASHCAP_UNDEFINED |
+				FZ_DEVFLAG_ENDCAP_UNDEFINED |
+				FZ_DEVFLAG_LINEJOIN_UNDEFINED |
+				FZ_DEVFLAG_MITERLIMIT_UNDEFINED |
+				FZ_DEVFLAG_LINEWIDTH_UNDEFINED);
 }
 
 static void pdf_run_f(pdf_csi *csi)
@@ -2090,6 +2174,7 @@ static void pdf_run_fstar(pdf_csi *csi)
 
 static void pdf_run_g(pdf_csi *csi)
 {
+	csi->dev->flags &= ~FZ_DEVFLAG_FILLCOLOR_UNDEFINED;
 	pdf_set_colorspace(csi, PDF_FILL, fz_device_gray);
 	pdf_set_color(csi, PDF_FILL, csi->stack);
 }
@@ -2124,11 +2209,13 @@ static void pdf_run_i(pdf_csi *csi)
 static void pdf_run_j(pdf_csi *csi)
 {
 	pdf_gstate *gstate = csi->gstate + csi->gtop;
+	csi->dev->flags &= ~FZ_DEVFLAG_LINEJOIN_UNDEFINED;
 	gstate->stroke_state.linejoin = csi->stack[0];
 }
 
 static void pdf_run_k(pdf_csi *csi)
 {
+	csi->dev->flags &= ~FZ_DEVFLAG_FILLCOLOR_UNDEFINED;
 	pdf_set_colorspace(csi, PDF_FILL, fz_device_cmyk);
 	pdf_set_color(csi, PDF_FILL, csi->stack);
 }
@@ -2178,6 +2265,7 @@ static void pdf_run_re(pdf_csi *csi)
 
 static void pdf_run_rg(pdf_csi *csi)
 {
+	csi->dev->flags &= ~FZ_DEVFLAG_FILLCOLOR_UNDEFINED;
 	pdf_set_colorspace(csi, PDF_FILL, fz_device_rgb);
 	pdf_set_color(csi, PDF_FILL, csi->stack);
 }
@@ -2237,6 +2325,7 @@ static void pdf_run_w(pdf_csi *csi)
 {
 	pdf_gstate *gstate = csi->gstate + csi->gtop;
 	pdf_flush_text(csi); /* linewidth affects stroked text rendering mode */
+	csi->dev->flags &= ~FZ_DEVFLAG_LINEWIDTH_UNDEFINED;
 	gstate->stroke_state.linewidth = csi->stack[0];
 }
 
@@ -2607,7 +2696,7 @@ pdf_run_page_with_usage(pdf_xref *xref, pdf_page *page, fz_device *dev, fz_matri
 	if (page->transparency)
 		fz_begin_group(dev, fz_transform_rect(ctm, page->mediabox), 1, 0, 0, 1);
 
-	csi = pdf_new_csi(xref, dev, ctm, event, cookie);
+	csi = pdf_new_csi(xref, dev, ctm, event, cookie, NULL);
 	fz_try(ctx)
 	{
 		pdf_run_buffer(csi, page->resources, page->contents);
@@ -2649,7 +2738,7 @@ pdf_run_page_with_usage(pdf_xref *xref, pdf_page *page, fz_device *dev, fz_matri
 		if (!strcmp(event, "View") && (flags & (1 << 5))) /* NoView */
 			continue;
 
-		csi = pdf_new_csi(xref, dev, ctm, event, cookie);
+		csi = pdf_new_csi(xref, dev, ctm, event, cookie, NULL);
 		if (!pdf_is_hidden_ocg(fz_dict_gets(annot->obj, "OC"), csi, page->resources))
 		{
 			fz_try(ctx)
@@ -2676,9 +2765,9 @@ pdf_run_page(pdf_xref *xref, pdf_page *page, fz_device *dev, fz_matrix ctm, fz_c
 }
 
 void
-pdf_run_glyph(pdf_xref *xref, fz_obj *resources, fz_buffer *contents, fz_device *dev, fz_matrix ctm)
+pdf_run_glyph(pdf_xref *xref, fz_obj *resources, fz_buffer *contents, fz_device *dev, fz_matrix ctm, void *gstate)
 {
-	pdf_csi *csi = pdf_new_csi(xref, dev, ctm, "View", NULL);
+	pdf_csi *csi = pdf_new_csi(xref, dev, ctm, "View", NULL, gstate);
 	fz_context *ctx = xref->ctx;
 
 	fz_try(ctx)