Pass rect and matrix by value in geometry functions.

Several things irk me about passing values as const pointers:

* They can be NULL, which is not a valid value.
* They require explicit temporary variables for storage.
* They don't compose easily in a legible manner, requiring
  weird pointer passing semantics where the variable being assigned
  is hidden as an argument in the innermost function call.
* We can't change the value through the pointer, requiring yet more
  local variables to hold copies of the input value.

In the device interface where we pass a matrix to a function, we often
find ourselves making a local copy of the matrix so we can concatenate
other transforms to it. This copying is a lot of unnecessary busywork
that I hope to eventually avoid by laying the groundwork with this
commit.

This is a rather large API change, so I apologize for the inconvenience,
but I hope the end result and gain in legibility will be worth the pain.

1 files changed, 18 insertions, 21 deletions

diff --git a/source/xps/xps-link.c b/source/xps/xps-link.c
index 59b4d1a5..9da2e5e2 100644
--- a/source/xps/xps-link.c
+++ b/source/xps/xps-link.c
@@ -7,11 +7,11 @@
 /* Quick parsing of document to find links. */
 
 static void
-xps_load_links_in_element(fz_context *ctx, xps_document *doc, const fz_matrix *ctm,
+xps_load_links_in_element(fz_context *ctx, xps_document *doc, fz_matrix ctm,
 		char *base_uri, xps_resource *dict, fz_xml *node, fz_link **link);
 
 static void
-xps_add_link(fz_context *ctx, xps_document *doc, const fz_rect *area, char *base_uri, char *target_uri, fz_link **head)
+xps_add_link(fz_context *ctx, xps_document *doc, fz_rect area, char *base_uri, char *target_uri, fz_link **head)
 {
 	fz_link *link = fz_new_link(ctx, area, doc, target_uri);
 	link->next = *head;
@@ -19,7 +19,7 @@ xps_add_link(fz_context *ctx, xps_document *doc, const fz_rect *area, char *base
 }
 
 static void
-xps_load_links_in_path(fz_context *ctx, xps_document *doc, const fz_matrix *ctm,
+xps_load_links_in_path(fz_context *ctx, xps_document *doc, fz_matrix ctm,
 		char *base_uri, xps_resource *dict, fz_xml *root, fz_link **link)
 {
 	char *navigate_uri_att = fz_xml_att(root, "FixedPage.NavigateUri");
@@ -33,13 +33,12 @@ xps_load_links_in_path(fz_context *ctx, xps_document *doc, const fz_matrix *ctm,
 
 		fz_path *path = NULL;
 		int fill_rule;
-		fz_matrix local_ctm;
 		fz_rect area;
 
 		xps_resolve_resource_reference(ctx, doc, dict, &data_att, &data_tag, NULL);
 		xps_resolve_resource_reference(ctx, doc, dict, &transform_att, &transform_tag, NULL);
 
-		xps_parse_transform(ctx, doc, transform_att, transform_tag, &local_ctm, ctm);
+		ctm = xps_parse_transform(ctx, doc, transform_att, transform_tag, ctm);
 
 		if (data_att)
 			path = xps_parse_abbreviated_geometry(ctx, doc, data_att, &fill_rule);
@@ -47,15 +46,15 @@ xps_load_links_in_path(fz_context *ctx, xps_document *doc, const fz_matrix *ctm,
 			path = xps_parse_path_geometry(ctx, doc, dict, data_tag, 0, &fill_rule);
 		if (path)
 		{
-			fz_bound_path(ctx, path, NULL, &local_ctm, &area);
+			area = fz_bound_path(ctx, path, NULL, ctm);
 			fz_drop_path(ctx, path);
-			xps_add_link(ctx, doc, &area, base_uri, navigate_uri_att, link);
+			xps_add_link(ctx, doc, area, base_uri, navigate_uri_att, link);
 		}
 	}
 }
 
 static void
-xps_load_links_in_glyphs(fz_context *ctx, xps_document *doc, const fz_matrix *ctm,
+xps_load_links_in_glyphs(fz_context *ctx, xps_document *doc, fz_matrix ctm,
 		char *base_uri, xps_resource *dict, fz_xml *root, fz_link **link)
 {
 	char *navigate_uri_att = fz_xml_att(root, "FixedPage.NavigateUri");
@@ -76,14 +75,13 @@ xps_load_links_in_glyphs(fz_context *ctx, xps_document *doc, const fz_matrix *ct
 
 		int is_sideways = 0;
 		int bidi_level = 0;
-		fz_matrix local_ctm;
 		fz_font *font;
 		fz_text *text;
 		fz_rect area;
 
 		xps_resolve_resource_reference(ctx, doc, dict, &transform_att, &transform_tag, NULL);
 
-		xps_parse_transform(ctx, doc, transform_att, transform_tag, &local_ctm, ctm);
+		ctm = xps_parse_transform(ctx, doc, transform_att, transform_tag, ctm);
 
 		if (is_sideways_att)
 			is_sideways = !strcmp(is_sideways_att, "true");
@@ -93,23 +91,22 @@ xps_load_links_in_glyphs(fz_context *ctx, xps_document *doc, const fz_matrix *ct
 		font = xps_lookup_font(ctx, doc, base_uri, font_uri_att, style_att);
 		if (!font)
 			return;
-		text = xps_parse_glyphs_imp(ctx, doc, &local_ctm, font, fz_atof(font_size_att),
+		text = xps_parse_glyphs_imp(ctx, doc, ctm, font, fz_atof(font_size_att),
 				fz_atof(origin_x_att), fz_atof(origin_y_att),
 				is_sideways, bidi_level, indices_att, unicode_att);
-		fz_bound_text(ctx, text, NULL, &local_ctm, &area);
+		area = fz_bound_text(ctx, text, NULL, ctm);
 		fz_drop_text(ctx, text);
 		fz_drop_font(ctx, font);
 
-		xps_add_link(ctx, doc, &area, base_uri, navigate_uri_att, link);
+		xps_add_link(ctx, doc, area, base_uri, navigate_uri_att, link);
 	}
 }
 
 static void
-xps_load_links_in_canvas(fz_context *ctx, xps_document *doc, const fz_matrix *ctm,
+xps_load_links_in_canvas(fz_context *ctx, xps_document *doc, fz_matrix ctm,
 		char *base_uri, xps_resource *dict, fz_xml *root, fz_link **link)
 {
 	xps_resource *new_dict = NULL;
-	fz_matrix local_ctm;
 	fz_xml *node;
 
 	char *navigate_uri_att = fz_xml_att(root, "FixedPage.NavigateUri");
@@ -129,20 +126,20 @@ xps_load_links_in_canvas(fz_context *ctx, xps_document *doc, const fz_matrix *ct
 
 	xps_resolve_resource_reference(ctx, doc, dict, &transform_att, &transform_tag, NULL);
 
-	xps_parse_transform(ctx, doc, transform_att, transform_tag, &local_ctm, ctm);
+	ctm = xps_parse_transform(ctx, doc, transform_att, transform_tag, ctm);
 
 	if (navigate_uri_att)
 		fz_warn(ctx, "FixedPage.NavigateUri attribute on Canvas element");
 
 	for (node = fz_xml_down(root); node; node = fz_xml_next(node))
-		xps_load_links_in_element(ctx, doc, &local_ctm, base_uri, dict, node, link);
+		xps_load_links_in_element(ctx, doc, ctm, base_uri, dict, node, link);
 
 	if (new_dict)
 		xps_drop_resource_dictionary(ctx, doc, new_dict);
 }
 
 static void
-xps_load_links_in_element(fz_context *ctx, xps_document *doc, const fz_matrix *ctm, char *base_uri, xps_resource *dict, fz_xml *node, fz_link **link)
+xps_load_links_in_element(fz_context *ctx, xps_document *doc, fz_matrix ctm, char *base_uri, xps_resource *dict, fz_xml *node, fz_link **link)
 {
 	if (fz_xml_is_tag(node, "Path"))
 		xps_load_links_in_path(ctx, doc, ctm, base_uri, dict, node, link);
@@ -159,7 +156,7 @@ xps_load_links_in_element(fz_context *ctx, xps_document *doc, const fz_matrix *c
 }
 
 static void
-xps_load_links_in_fixed_page(fz_context *ctx, xps_document *doc, const fz_matrix *ctm, xps_page *page, fz_link **link)
+xps_load_links_in_fixed_page(fz_context *ctx, xps_document *doc, fz_matrix ctm, xps_page *page, fz_link **link)
 {
 	fz_xml *root, *node, *resource_tag;
 	xps_resource *dict = NULL;
@@ -193,7 +190,7 @@ xps_load_links(fz_context *ctx, fz_page *page_)
 	xps_page *page = (xps_page*)page_;
 	fz_matrix ctm;
 	fz_link *link = NULL;
-	fz_scale(&ctm, 72.0f / 96.0f, 72.0f / 96.0f);
-	xps_load_links_in_fixed_page(ctx, page->doc, &ctm, page, &link);
+	ctm = fz_scale(72.0f / 96.0f, 72.0f / 96.0f);
+	xps_load_links_in_fixed_page(ctx, page->doc, ctm, page, &link);
 	return link;
 }