[librsvg/rustification] Wrap some more RsvgDrawingCtx functions in Rust

[Federico Mena Quintero <federico src gnome org>]

commit efb58406c1cfb38218583c500c0c5c063308e683
Author: Federico Mena Quintero <federico gnome org>
Date:   Wed Nov 30 18:08:50 2016 -0600

    Wrap some more RsvgDrawingCtx functions in Rust

 rsvg-cairo-draw.h       |    1 +
 rust/src/bbox.rs        |    6 +++---
 rust/src/drawing_ctx.rs |   35 +++++++++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+), 3 deletions(-)
---
diff --git a/rsvg-cairo-draw.h b/rsvg-cairo-draw.h
index 286f0c5..aff07c6 100644
--- a/rsvg-cairo-draw.h
+++ b/rsvg-cairo-draw.h
@@ -37,6 +37,7 @@ PangoContext    *rsvg_cairo_create_pango_context    (RsvgDrawingCtx *ctx);
 G_GNUC_INTERNAL
 void         rsvg_cairo_render_pango_layout        (RsvgDrawingCtx *ctx, PangoLayout *layout, 
                                                  double x, double y);
+
 G_GNUC_INTERNAL
 void         rsvg_cairo_render_path_builder     (RsvgDrawingCtx *ctx, 
                                                  RsvgPathBuilder *builder);
diff --git a/rust/src/bbox.rs b/rust/src/bbox.rs
index 9e34596..a2ed3da 100644
--- a/rust/src/bbox.rs
+++ b/rust/src/bbox.rs
@@ -5,9 +5,9 @@ use self::cairo::MatrixTrait;
 /* Keep this in sync with ../../rsvg-private.h:RsvgBbox */
 #[repr(C)]
 pub struct RsvgBbox {
-    rect:   cairo::Rectangle,
-    affine: cairo::Matrix,
-    virgin: bool
+    pub rect:   cairo::Rectangle,
+    pub affine: cairo::Matrix,
+    pub virgin: bool
 }
 
 #[no_mangle]
diff --git a/rust/src/drawing_ctx.rs b/rust/src/drawing_ctx.rs
index 01da0b0..0eba6fc 100644
--- a/rust/src/drawing_ctx.rs
+++ b/rust/src/drawing_ctx.rs
@@ -1,5 +1,10 @@
+extern crate glib;
+extern crate cairo;
+extern crate cairo_sys;
 extern crate libc;
 
+use self::glib::translate::*;
+
 use state::RsvgState;
 use path_builder::RsvgPathBuilder;
 
@@ -16,12 +21,20 @@ extern "C" {
                                            out_x: *mut f64,
                                            out_y: *mut f64);
 
+    fn rsvg_drawing_ctx_push_view_box (draw_ctx: *const RsvgDrawingCtx,
+                                       width:     f64,
+                                       height:    f64);
+
+    fn rsvg_drawing_ctx_pop_view_box (draw_ctx: *const RsvgDrawingCtx);
+
     fn rsvg_state_reinherit_top (draw_ctx: *const RsvgDrawingCtx,
                                  state: *mut RsvgState,
                                  dominate: libc::c_int);
 
     fn rsvg_render_path_builder (draw_ctx: *const RsvgDrawingCtx,
                                  builder: *const RsvgPathBuilder);
+
+    fn rsvg_cairo_get_cairo_context (draw_ctx: *const RsvgDrawingCtx) -> *mut cairo_sys::cairo_t;
 }
 
 pub fn get_dpi (draw_ctx: *const RsvgDrawingCtx) -> (f64, f64) {
@@ -47,6 +60,17 @@ pub fn get_view_box_size (draw_ctx: *const RsvgDrawingCtx) -> (f64, f64) {
     (w, h)
 }
 
+pub fn push_view_box (draw_ctx: *const RsvgDrawingCtx,
+                      width:     f64,
+                      height:    f64)
+{
+    unsafe { rsvg_drawing_ctx_push_view_box (draw_ctx, width, height); }
+}
+
+pub fn pop_view_box (draw_ctx: *const RsvgDrawingCtx) {
+    unsafe { rsvg_drawing_ctx_pop_view_box (draw_ctx); }
+}
+
 pub fn state_reinherit_top (draw_ctx: *const RsvgDrawingCtx,
                             state: *mut RsvgState,
                             dominate: i32) {
@@ -58,3 +82,14 @@ pub fn render_path_builder (draw_ctx: *const RsvgDrawingCtx,
 {
     unsafe { rsvg_render_path_builder (draw_ctx, builder); }
 }
+
+pub fn get_cairo_context (draw_ctx: *const RsvgDrawingCtx) -> cairo::Context
+{
+    unsafe {
+        let raw_cr = rsvg_cairo_get_cairo_context (draw_ctx);
+
+        let cr = cairo::Context::from_glib_none (raw_cr);
+
+        cr
+    }
+}