[librsvg] Start draining RsvgHandlePrivate into a Rust struct

[Federico Mena Quintero <federico src gnome org>]

commit f20724acf0ee4fda3ed78e58fcd159c8935af43c
Author: Federico Mena Quintero <federico gnome org>
Date:   Mon Nov 26 12:25:23 2018 -0600

    Start draining RsvgHandlePrivate into a Rust struct

 librsvg/rsvg-handle.c        | 10 ++++++++++
 librsvg/rsvg-private.h       | 16 ++++++++++++++++
 rsvg_internals/src/handle.rs | 24 ++++++++++++++++++++++++
 rsvg_internals/src/lib.rs    |  2 +-
 4 files changed, 51 insertions(+), 1 deletion(-)
---
diff --git a/librsvg/rsvg-handle.c b/librsvg/rsvg-handle.c
index 86ee8066..eab2d59b 100644
--- a/librsvg/rsvg-handle.c
+++ b/librsvg/rsvg-handle.c
@@ -173,6 +173,8 @@ rsvg_handle_init (RsvgHandle * self)
     self->priv->font_config_for_testing = NULL;
     self->priv->font_map_for_testing = NULL;
 #endif
+
+    self->priv->rust_handle = rsvg_handle_rust_new();
 }
 
 static void
@@ -199,6 +201,8 @@ rsvg_handle_dispose (GObject *instance)
 
     g_clear_object (&self->priv->cancellable);
 
+    g_clear_pointer (&self->priv->rust_handle, rsvg_handle_rust_free);
+
     G_OBJECT_CLASS (rsvg_handle_parent_class)->dispose (instance);
 }
 
@@ -986,6 +990,12 @@ rsvg_handle_get_defs (RsvgHandle *handle)
     return handle->priv->defs;
 }
 
+RsvgHandleRust *
+rsvg_handle_get_rust (RsvgHandle *handle)
+{
+    return handle->priv->rust_handle;
+}
+
 RsvgCssStyles *
 rsvg_handle_get_css_styles (RsvgHandle *handle)
 {
diff --git a/librsvg/rsvg-private.h b/librsvg/rsvg-private.h
index f8ff9186..b79e3f53 100644
--- a/librsvg/rsvg-private.h
+++ b/librsvg/rsvg-private.h
@@ -85,6 +85,9 @@ typedef struct RsvgTree RsvgTree;
 
 typedef struct RsvgCssStyles RsvgCssStyles;
 
+/* Defined in rsvg_internals/src/handle.rs */
+typedef struct RsvgHandleRust RsvgHandleRust;
+
 struct RsvgHandlePrivate {
     RsvgHandleFlags flags;
 
@@ -118,6 +121,8 @@ struct RsvgHandlePrivate {
     FcConfig *font_config_for_testing;
     PangoFontMap *font_map_for_testing;
 #endif
+
+    RsvgHandleRust *rust_handle;
 };
 
 /* Implemented in rust/src/node.rs */
@@ -245,6 +250,9 @@ RsvgNode *rsvg_defs_lookup (const RsvgDefs * defs, RsvgHandle *handle, const cha
 G_GNUC_INTERNAL
 RsvgDefs *rsvg_handle_get_defs (RsvgHandle *handle);
 
+G_GNUC_INTERNAL
+RsvgHandleRust *rsvg_handle_get_rust (RsvgHandle *handle);
+
 G_GNUC_INTERNAL
 RsvgCssStyles *rsvg_handle_get_css_styles (RsvgHandle *handle);
 
@@ -256,6 +264,14 @@ G_GNUC_INTERNAL
 char *rsvg_handle_resolve_uri (RsvgHandle *handle,
                                const char *uri);
 
+/* Implemented in rsvg_internals/src/handle.rs */
+G_GNUC_INTERNAL
+RsvgHandleRust *rsvg_handle_rust_new (void);
+
+/* Implemented in rsvg_internals/src/handle.rs */
+G_GNUC_INTERNAL
+void rsvg_handle_rust_free (RsvgHandleRust *raw_handle);
+
 G_GNUC_INTERNAL
 RsvgHandle *rsvg_handle_load_extern (RsvgHandle *handle,
                                      const char *uri);
diff --git a/rsvg_internals/src/handle.rs b/rsvg_internals/src/handle.rs
index d978fa4a..ed53bc79 100644
--- a/rsvg_internals/src/handle.rs
+++ b/rsvg_internals/src/handle.rs
@@ -18,6 +18,10 @@ use util::utf8_cstr;
 
 pub enum RsvgHandle {}
 
+pub enum RsvgHandleRust {}
+
+struct Handle {}
+
 #[allow(improper_ctypes)]
 extern "C" {
     fn rsvg_handle_get_defs(handle: *const RsvgHandle) -> *const RsvgDefs;
@@ -54,6 +58,8 @@ extern "C" {
         handle: *mut RsvgHandle,
         href: *const libc::c_char,
     ) -> glib_sys::gboolean;
+
+    fn rsvg_handle_get_rust(handle: *const RsvgHandle) -> *mut RsvgHandleRust;
 }
 
 pub fn get_defs<'a>(handle: *const RsvgHandle) -> &'a mut Defs {
@@ -243,3 +249,21 @@ pub unsafe extern "C" fn rsvg_handle_load_css(handle: *mut RsvgHandle, href: *co
     let href = utf8_cstr(href);
     load_css(handle, href);
 }
+
+#[no_mangle]
+pub unsafe extern "C" fn rsvg_handle_rust_new() -> *mut RsvgHandleRust {
+    Box::into_raw(Box::new(Handle {})) as *mut RsvgHandleRust
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn rsvg_handle_rust_free(raw_handle: *mut RsvgHandleRust) {
+    assert!(!raw_handle.is_null());
+
+    Box::from_raw(raw_handle as *mut Handle);
+}
+
+fn get_rust_handle(handle: *const RsvgHandle) -> *mut Handle {
+    unsafe {
+        rsvg_handle_get_rust(handle) as *mut Handle
+    }
+}
diff --git a/rsvg_internals/src/lib.rs b/rsvg_internals/src/lib.rs
index 0c7a888b..56a80575 100644
--- a/rsvg_internals/src/lib.rs
+++ b/rsvg_internals/src/lib.rs
@@ -46,7 +46,7 @@ pub use drawing_ctx::{
     rsvg_drawing_ctx_new,
 };
 
-pub use handle::rsvg_handle_load_css;
+pub use handle::{rsvg_handle_load_css, rsvg_handle_rust_free, rsvg_handle_rust_new};
 
 pub use io::{
     rsvg_decode_data_uri,