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, 3 insertions, 7 deletions

diff --git a/source/svg/svg-doc.c b/source/svg/svg-doc.c
index a651c9ae..89ff148c 100644
--- a/source/svg/svg-doc.c
+++ b/source/svg/svg-doc.c
@@ -23,19 +23,15 @@ svg_count_pages(fz_context *ctx, fz_document *doc_)
 	return 1;
 }
 
-static fz_rect *
-svg_bound_page(fz_context *ctx, fz_page *page_, fz_rect *rect)
+static fz_rect
+svg_bound_page(fz_context *ctx, fz_page *page_)
 {
 	svg_page *page = (svg_page*)page_;
 	svg_document *doc = page->doc;
 
 	svg_parse_document_bounds(ctx, doc, fz_xml_root(doc->xml));
 
-	rect->x0 = 0;
-	rect->y0 = 0;
-	rect->x1 = doc->width;
-	rect->y1 = doc->height;
-	return rect;
+	return fz_make_rect(0, 0, doc->width, doc->height);
 }
 
 static void