[librsvg: 1/2] Port default DPI tracking to Rust

[Federico Mena Quintero <federico src gnome org>]

commit d7ca2a9daf988e7efe7c88d04c70edb360b7f6b2
Author: Carlos Martín Nieto <cmn dwim me>
Date:   Thu Jan 3 23:24:06 2019 +0000

    Port default DPI tracking to Rust
    
    It's the only place from where we're accessing it already.

 librsvg/rsvg-base.c       | 34 ++++------------------------------
 librsvg/rsvg-private.h    |  6 ------
 rsvg_internals/src/dpi.rs | 29 +++++++++++++++++++++++------
 3 files changed, 27 insertions(+), 42 deletions(-)
---
diff --git a/librsvg/rsvg-base.c b/librsvg/rsvg-base.c
index 54d0601e..caf1453b 100644
--- a/librsvg/rsvg-base.c
+++ b/librsvg/rsvg-base.c
@@ -29,14 +29,8 @@
 #include "rsvg-private.h"
 #include "rsvg-css.h"
 
-/*
- * This is configurable at runtime
- */
-#define RSVG_DEFAULT_DPI_X 90.0
-#define RSVG_DEFAULT_DPI_Y 90.0
-
-static double rsvg_internal_dpi_x = RSVG_DEFAULT_DPI_X;
-static double rsvg_internal_dpi_y = RSVG_DEFAULT_DPI_Y;
+/* Implemented in rsvg_internals/src/dpi.rs */
+extern void rsvg_rust_set_default_dpi_x_y(double dpi_x, double dpi_y);
 
 /**
  * rsvg_error_quark:
@@ -70,7 +64,7 @@ rsvg_error_quark (void)
 void
 rsvg_set_default_dpi (double dpi)
 {
-    rsvg_set_default_dpi_x_y (dpi, dpi);
+    rsvg_rust_set_default_dpi_x_y (dpi, dpi);
 }
 
 /**
@@ -91,27 +85,7 @@ rsvg_set_default_dpi (double dpi)
 void
 rsvg_set_default_dpi_x_y (double dpi_x, double dpi_y)
 {
-    if (dpi_x <= 0.)
-        rsvg_internal_dpi_x = RSVG_DEFAULT_DPI_X;
-    else
-        rsvg_internal_dpi_x = dpi_x;
-
-    if (dpi_y <= 0.)
-        rsvg_internal_dpi_y = RSVG_DEFAULT_DPI_Y;
-    else
-        rsvg_internal_dpi_y = dpi_y;
-}
-
-double
-rsvg_get_default_dpi_x (void)
-{
-    return rsvg_internal_dpi_x;
-}
-
-double
-rsvg_get_default_dpi_y (void)
-{
-    return rsvg_internal_dpi_y;
+    rsvg_rust_set_default_dpi_x_y (dpi_x, dpi_y);
 }
 
 /**
diff --git a/librsvg/rsvg-private.h b/librsvg/rsvg-private.h
index 05c5cca7..add5f31c 100644
--- a/librsvg/rsvg-private.h
+++ b/librsvg/rsvg-private.h
@@ -60,12 +60,6 @@ typedef struct _RsvgNode RsvgNode;
 #define N_(X) X
 #endif
 
-G_GNUC_INTERNAL
-double rsvg_get_default_dpi_x (void);
-
-G_GNUC_INTERNAL
-double rsvg_get_default_dpi_y (void);
-
 G_GNUC_INTERNAL
 void rsvg_return_if_fail_warning (const char *pretty_function,
                                   const char *expression, GError ** error);
diff --git a/rsvg_internals/src/dpi.rs b/rsvg_internals/src/dpi.rs
index 6d4693ba..fcbe13cb 100644
--- a/rsvg_internals/src/dpi.rs
+++ b/rsvg_internals/src/dpi.rs
@@ -1,9 +1,11 @@
 use std::cell::Cell;
 
-extern "C" {
-    fn rsvg_get_default_dpi_y() -> f64;
-    fn rsvg_get_default_dpi_x() -> f64;
-}
+// This is configurable at runtime
+const DEFAULT_DPI_X: f64 = 90.0;
+const DEFAULT_DPI_Y: f64 = 90.0;
+
+static mut DPI_X: f64 = DEFAULT_DPI_X;
+static mut DPI_Y: f64 = DEFAULT_DPI_Y;
 
 #[derive(Debug, Clone, Default)]
 pub struct Dpi {
@@ -14,7 +16,7 @@ pub struct Dpi {
 impl Dpi {
     pub fn x(&self) -> f64 {
         if self.x.get() <= 0.0 {
-            unsafe { rsvg_get_default_dpi_x() }
+            unsafe { DPI_X }
         } else {
             self.x.get()
         }
@@ -26,7 +28,7 @@ impl Dpi {
 
     pub fn y(&self) -> f64 {
         if self.y.get() <= 0.0 {
-            unsafe { rsvg_get_default_dpi_y() }
+            unsafe { DPI_Y }
         } else {
             self.y.get()
         }
@@ -36,3 +38,18 @@ impl Dpi {
         self.y.set(dpi_y)
     }
 }
+
+#[no_mangle]
+pub unsafe extern "C" fn rsvg_rust_set_default_dpi_x_y(dpi_x: f64, dpi_y: f64) {
+    if dpi_x <= 0.0 {
+        DPI_X = DEFAULT_DPI_X;
+    } else {
+        DPI_X = dpi_x;
+    }
+
+    if dpi_y <= 0.0 {
+        DPI_Y = DEFAULT_DPI_Y;
+    } else {
+        DPI_Y = dpi_y;
+    }
+}