Ticket #1848: 0002-cairo-Rework-cairo_matrix_t-to-use-records.patch

cairo/0.1.18/cairo.scm

@@ -275 +275 @@
 
 ;; Matrix operations
 
-(define-foreign-type cairo_matrix_t (c-pointer "cairo_matrix_t")
-  values
-  (cut tag-pointer <> 'cairo-matrix))
+(define-foreign-variable sizeof-cairo-matrix int "sizeof(cairo_matrix_t)")
+
+;; see cairo-font/text-extents for the construction
+(define-record cairo-matrix-type buffer)
+(let ((maker make-cairo-matrix-type))
+  (set! make-cairo-matrix-type
+    (lambda () (maker (make-blob sizeof-cairo-matrix)))))
+
+(define-foreign-type cairo_matrix_t scheme-pointer cairo-matrix-type-buffer)
 
 (define (cairo-transform/matrix ctx v)
   (when (not (= (f64vector-length v) 6))
     (error "Vector size mismatch should be 6, is " (f64vector-length v)))
-  (cairo-transform ctx v))
+  (let ((matrix (make-cairo-matrix-type)))
+    (cairo-matrix-init matrix
+                       (f64vector-ref v 0)
+                       (f64vector-ref v 1)
+                       (f64vector-ref v 2)
+                       (f64vector-ref v 3)
+                       (f64vector-ref v 4)
+                       (f64vector-ref v 5))
+    (cairo-transform ctx matrix)))
 
-(define cairo-new-matrix
-  (make-f64vector 6 0))
 
 ; accessors for each element might be nice, but probably not
 ; immediately necessary