[librsvg: 17/32] Move the HandleIsNotLoaded error to c_api

[Federico Mena Quintero <federico src gnome org>]

commit b55a5b1cb18678e5d9df09627a67ffc89d949aab
Author: Federico Mena Quintero <federico gnome org>
Date:   Thu Nov 26 15:48:23 2020 -0600

    Move the HandleIsNotLoaded error to c_api
    
    This is just for RsvgHandle's state keeping.

 src/c_api/handle.rs | 57 +++++++++++++++++++++++++++++++++++++----------------
 src/error.rs        |  4 ----
 2 files changed, 40 insertions(+), 21 deletions(-)
---
diff --git a/src/c_api/handle.rs b/src/c_api/handle.rs
index 140f84fe..c17fb73c 100644
--- a/src/c_api/handle.rs
+++ b/src/c_api/handle.rs
@@ -24,6 +24,7 @@
 
 use std::cell::{Cell, Ref, RefCell, RefMut};
 use std::ffi::{CStr, CString};
+use std::fmt;
 use std::ops;
 use std::path::PathBuf;
 use std::ptr;
@@ -53,9 +54,7 @@ use glib::types::instance_of;
 
 use gobject_sys::{GEnumValue, GFlagsValue};
 
-use crate::api::{
-    CairoRenderer, IntrinsicDimensions, Loader, LoadingError, RenderingError, SvgHandle,
-};
+use crate::api::{self, CairoRenderer, IntrinsicDimensions, Loader, LoadingError, SvgHandle};
 
 use crate::{
     length::RsvgLength,
@@ -70,6 +69,30 @@ use super::sizing::LegacySize;
 
 include!(concat!(env!("OUT_DIR"), "/version.rs"));
 
+// This is basically the same as api::RenderingError but with extra cases for
+// the peculiarities of the C API.
+enum RenderingError {
+    RenderingError(api::RenderingError),
+
+    // The RsvgHandle is created, but hasn't been loaded yet.
+    HandleIsNotLoaded,
+}
+
+impl<T: Into<api::RenderingError>> From<T> for RenderingError {
+    fn from(e: T) -> RenderingError {
+        RenderingError::RenderingError(e.into())
+    }
+}
+
+impl fmt::Display for RenderingError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            RenderingError::RenderingError(ref e) => e.fmt(f),
+            RenderingError::HandleIsNotLoaded => write!(f, "SVG data is not loaded into handle"),
+        }
+    }
+}
+
 mod handle_flags {
     // The following is entirely stolen from the auto-generated code
     // for GBindingFlags, from gtk-rs/glib/src/gobject/auto/flags.rs
@@ -859,7 +882,7 @@ impl CHandle {
 
     fn has_sub(&self, id: &str) -> Result<bool, RenderingError> {
         let handle = self.get_handle_ref()?;
-        handle.has_element_with_id(id)
+        Ok(handle.has_element_with_id(id)?)
     }
 
     fn get_dimensions_or_empty(&self) -> RsvgDimensionData {
@@ -954,12 +977,12 @@ impl CHandle {
         let renderer = self.make_renderer(&handle);
 
         match id {
-            Some(id) => renderer.geometry_for_layer(Some(id), &unit_rectangle()),
+            Some(id) => Ok(renderer.geometry_for_layer(Some(id), &unit_rectangle())?),
 
-            None => renderer.legacy_document_size_in_pixels().map(|(w, h)| {
+            None => Ok(renderer.legacy_document_size_in_pixels().map(|(w, h)| {
                 let rect = cairo::Rectangle::from_size(w, h);
                 (rect, rect)
-            }),
+            })?),
         }
     }
 
@@ -1004,7 +1027,7 @@ impl CHandle {
         let dimensions = self.get_dimensions_sub(None)?;
 
         if dimensions.width == 0 || dimensions.height == 0 {
-            return empty_pixbuf();
+            return Ok(empty_pixbuf()?);
         }
 
         let surface = cairo::ImageSurface::create(
@@ -1020,7 +1043,7 @@ impl CHandle {
 
         let surface = SharedImageSurface::wrap(surface, SurfaceType::SRgb)?;
 
-        pixbuf_from_surface(&surface)
+        Ok(pixbuf_from_surface(&surface)?)
     }
 
     fn render_document(
@@ -1033,7 +1056,7 @@ impl CHandle {
         let handle = self.get_handle_ref()?;
 
         let renderer = self.make_renderer(&handle);
-        renderer.render_document(cr, viewport)
+        Ok(renderer.render_document(cr, viewport)?)
     }
 
     fn get_geometry_for_layer(
@@ -1044,9 +1067,9 @@ impl CHandle {
         let handle = self.get_handle_ref()?;
         let renderer = self.make_renderer(&handle);
 
-        renderer
+        Ok(renderer
             .geometry_for_layer(id, viewport)
-            .map(|(i, l)| (RsvgRectangle::from(i), RsvgRectangle::from(l)))
+            .map(|(i, l)| (RsvgRectangle::from(i), RsvgRectangle::from(l)))?)
     }
 
     fn render_layer(
@@ -1061,7 +1084,7 @@ impl CHandle {
 
         let renderer = self.make_renderer(&handle);
 
-        renderer.render_layer(cr, id, viewport)
+        Ok(renderer.render_layer(cr, id, viewport)?)
     }
 
     fn get_geometry_for_element(
@@ -1072,9 +1095,9 @@ impl CHandle {
 
         let renderer = self.make_renderer(&handle);
 
-        renderer
+        Ok(renderer
             .geometry_for_element(id)
-            .map(|(i, l)| (RsvgRectangle::from(i), RsvgRectangle::from(l)))
+            .map(|(i, l)| (RsvgRectangle::from(i), RsvgRectangle::from(l)))?)
     }
 
     fn render_element(
@@ -1089,7 +1112,7 @@ impl CHandle {
 
         let renderer = self.make_renderer(&handle);
 
-        renderer.render_element(cr, id, element_viewport)
+        Ok(renderer.render_element(cr, id, element_viewport)?)
     }
 
     fn get_intrinsic_dimensions(&self) -> Result<IntrinsicDimensions, RenderingError> {
@@ -2157,7 +2180,7 @@ fn check_cairo_context(cr: &cairo::Context) -> Result<(), RenderingError> {
         );
 
         rsvg_g_warning(&msg);
-        Err(RenderingError::Cairo(status))
+        Err(RenderingError::from(status))
     }
 }
 
diff --git a/src/error.rs b/src/error.rs
index 7708c357..c535998c 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -147,9 +147,6 @@ pub enum RenderingError {
     /// Not enough memory was available for rendering.
     // FIXME: right now this is only returned from pixbuf_utils.rs
     OutOfMemory,
-
-    /// Cannot occur from librsvg_crate; this is just for the C API.
-    HandleIsNotLoaded,
 }
 
 impl From<DefsLookupErrorKind> for RenderingError {
@@ -168,7 +165,6 @@ impl fmt::Display for RenderingError {
         match *self {
             RenderingError::LimitExceeded(ref s) => write!(f, "limit exceeded: {}", s),
             RenderingError::OutOfMemory => write!(f, "out of memory"),
-            RenderingError::HandleIsNotLoaded => write!(f, "SVG data is not loaded into handle"),
             RenderingError::Cairo(ref status) => write!(f, "cairo error: {:?}", status),
             RenderingError::IdNotFound => write!(f, "element id not found"),
             RenderingError::InvalidId(ref s) => write!(f, "invalid id: {:?}", s),