Bug 694794: Fix blendmode use in pdf device.

Previously we were setting blendmode in the created form XObjects
transparency group definition. This didn't work as PDF readers don't
look for it there.

Now we set it in the calling stream's resources, and set it before
calling the group.

1 files changed, 22 insertions, 8 deletions

diff --git a/source/pdf/pdf-device.c b/source/pdf/pdf-device.c
index 9877782f..05c6f456 100644
--- a/source/pdf/pdf-device.c
+++ b/source/pdf/pdf-device.c
@@ -63,7 +63,6 @@ typedef struct group_entry_s group_entry;
 
 struct group_entry_s
 {
-	int blendmode;
 	int alpha;
 	int isolated;
 	int knockout;
@@ -767,7 +766,7 @@ pdf_dev_end_text(pdf_device *pdev)
 }
 
 static int
-pdf_dev_new_form(pdf_obj **form_ref, pdf_device *pdev, const fz_rect *bbox, int isolated, int knockout, int blendmode, float alpha, fz_colorspace *colorspace)
+pdf_dev_new_form(pdf_obj **form_ref, pdf_device *pdev, const fz_rect *bbox, int isolated, int knockout, float alpha, fz_colorspace *colorspace)
 {
 	fz_context *ctx = pdev->ctx;
 	pdf_document *doc = pdev->doc;
@@ -782,7 +781,7 @@ pdf_dev_new_form(pdf_obj **form_ref, pdf_device *pdev, const fz_rect *bbox, int
 	for(num = 0; num < pdev->num_groups; num++)
 	{
 		group_entry *g = &pdev->groups[num];
-		if (g->isolated == isolated && g->knockout == knockout && g->blendmode == blendmode && g->alpha == alpha && g->colorspace == colorspace)
+		if (g->isolated == isolated && g->knockout == knockout && g->alpha == alpha && g->colorspace == colorspace)
 		{
 			group_ref = pdev->groups[num].ref;
 			break;
@@ -803,7 +802,6 @@ pdf_dev_new_form(pdf_obj **form_ref, pdf_device *pdev, const fz_rect *bbox, int
 		pdev->num_groups++;
 		pdev->groups[num].isolated = isolated;
 		pdev->groups[num].knockout = knockout;
-		pdev->groups[num].blendmode = blendmode;
 		pdev->groups[num].alpha = alpha;
 		pdev->groups[num].colorspace = fz_keep_colorspace(ctx, colorspace);
 		pdev->groups[num].ref = NULL;
@@ -814,7 +812,6 @@ pdf_dev_new_form(pdf_obj **form_ref, pdf_device *pdev, const fz_rect *bbox, int
 			pdf_dict_puts_drop(group, "S", pdf_new_name(doc, "Transparency"));
 			pdf_dict_puts_drop(group, "K", pdf_new_bool(doc, knockout));
 			pdf_dict_puts_drop(group, "I", pdf_new_bool(doc, isolated));
-			pdf_dict_puts_drop(group, "BM", pdf_new_name(doc, fz_blendmode_name(blendmode)));
 			if (!colorspace)
 			{}
 			else if (colorspace->n == 1)
@@ -1098,7 +1095,7 @@ pdf_dev_begin_mask(fz_device *dev, const fz_rect *bbox, int luminosity, fz_color
 	pdf_dev_end_text(pdev);
 
 	/* Make a new form to contain the contents of the softmask */
-	pdf_dev_new_form(&form_ref, pdev, bbox, 0, 0, 0, 1, colorspace);
+	pdf_dev_new_form(&form_ref, pdev, bbox, 0, 0, 1, colorspace);
 
 	fz_try(ctx)
 	{
@@ -1169,17 +1166,34 @@ pdf_dev_begin_group(fz_device *dev, const fz_rect *bbox, int isolated, int knock
 {
 	pdf_device *pdev = (pdf_device *)dev->user;
 	fz_context *ctx = pdev->ctx;
+	pdf_document *doc = pdev->doc;
 	int num;
 	pdf_obj *form_ref;
 	gstate *gs;
 
 	pdf_dev_end_text(pdev);
 
-	num = pdf_dev_new_form(&form_ref, pdev, bbox, isolated, knockout, blendmode, alpha, NULL);
+	num = pdf_dev_new_form(&form_ref, pdev, bbox, isolated, knockout, alpha, NULL);
+
+	/* Do we have an appropriate blending extgstate already? */
+	{
+		char text[32];
+		pdf_obj *obj;
+		snprintf(text, sizeof(text), "ExtGState/BlendMode%d", blendmode);
+		obj = pdf_dict_getp(pdev->resources, text);
+		if (obj == NULL)
+		{
+			/* No, better make one */
+			obj = pdf_new_dict(pdev->doc, 2);
+			pdf_dict_puts_drop(obj, "Type", pdf_new_name(doc, "ExtGState"));
+			pdf_dict_puts_drop(obj, "BM", pdf_new_name(doc, fz_blendmode_name(blendmode)));
+			pdf_dict_putp_drop(pdev->resources, text, obj);
+		}
+	}
 
 	/* Add the call to this group */
 	gs = CURRENT_GSTATE(pdev);
-	fz_buffer_printf(dev->ctx, gs->buf, "/Fm%d Do\n", num);
+	fz_buffer_printf(dev->ctx, gs->buf, "/BlendMode%d gs /Fm%d Do\n", blendmode, num);
 
 	/* Now, everything we get until the end of group needs to go into a
 	 * new buffer, which will be the stream contents for the form. */