[librsvg: 2/5] New ToPixel trait

[Marge Bot <marge-bot src gnome org>]

commit 3ba831aa4fd97ab126697478a0871e6938f56b03
Author: Federico Mena Quintero <federico gnome org>
Date:   Tue Sep 21 12:22:15 2021 -0500

    New ToPixel trait
    
    Use it where we convert GdkPixbuf pixels to our own Pixel for premultiplication.
    
    Part-of: <https://gitlab.gnome.org/GNOME/librsvg/-/merge_requests/592>

 src/surface_utils/mod.rs            | 32 ++++++++++++++++++++++++++++++++
 src/surface_utils/shared_surface.rs |  5 +++--
 2 files changed, 35 insertions(+), 2 deletions(-)
---
diff --git a/src/surface_utils/mod.rs b/src/surface_utils/mod.rs
index 93d3b4f7..58953e6a 100644
--- a/src/surface_utils/mod.rs
+++ b/src/surface_utils/mod.rs
@@ -25,6 +25,9 @@ pub type CairoARGB = ARGB8;
 /// GdkPixbuf's endian-independent RGBA8 pixel layout.
 pub type GdkPixbufRGBA = rgb::RGBA8;
 
+/// GdkPixbuf's packed RGB pixel layout.
+pub type GdkPixbufRGB = rgb::RGB8;
+
 /// Analogous to `rgb::FromSlice`, to convert from `[T]` to `[CairoARGB]`
 #[allow(clippy::upper_case_acronyms)]
 pub trait AsCairoARGB<T: Copy> {
@@ -68,6 +71,11 @@ pub trait ToGdkPixbufRGBA {
     fn to_pixbuf_rgba(&self) -> GdkPixbufRGBA;
 }
 
+/// Trait to convert pixels in various formats to our own Pixel layout.
+pub trait ToPixel {
+    fn to_pixel(&self) -> Pixel;
+}
+
 impl ToGdkPixbufRGBA for Pixel {
     #[inline]
     fn to_pixbuf_rgba(&self) -> GdkPixbufRGBA {
@@ -80,6 +88,30 @@ impl ToGdkPixbufRGBA for Pixel {
     }
 }
 
+impl ToPixel for GdkPixbufRGBA {
+    #[inline]
+    fn to_pixel(&self) -> Pixel {
+        Pixel {
+            r: self.r,
+            g: self.g,
+            b: self.b,
+            a: self.a,
+        }
+    }
+}
+
+impl ToPixel for GdkPixbufRGB {
+    #[inline]
+    fn to_pixel(&self) -> Pixel {
+        Pixel {
+            r: self.r,
+            g: self.g,
+            b: self.b,
+            a: 255,
+        }
+    }
+}
+
 /// Extension methods for `cairo::ImageSurfaceData`.
 pub trait ImageSurfaceDataExt: DerefMut<Target = [u8]> {
     /// Sets the pixel at the given coordinates. Assumes the `ARgb32` format.
diff --git a/src/surface_utils/shared_surface.rs b/src/surface_utils/shared_surface.rs
index 476a6f77..9fa9a2e1 100644
--- a/src/surface_utils/shared_surface.rs
+++ b/src/surface_utils/shared_surface.rs
@@ -16,6 +16,7 @@ use crate::util::clamp;
 use super::{
     iterators::{PixelRectangle, Pixels},
     AsCairoARGB, CairoARGB, EdgeMode, ImageSurfaceDataExt, Pixel, PixelOps, ToGdkPixbufRGBA,
+    ToPixel,
 };
 
 /// Types of pixel data in a `ImageSurface`.
@@ -304,13 +305,13 @@ impl ImageSurface<Shared> {
                 .map(|row| row.as_rgba())
                 .zip(surf.rows_mut())
                 .flat_map(|(src_row, dest_row)| src_row.iter().zip(dest_row.iter_mut()))
-                .for_each(|(src, dest)| *dest = src.premultiply().into());
+                .for_each(|(src, dest)| *dest = src.to_pixel().premultiply().into());
         } else {
             pixbuf_rows
                 .map(|row| row.as_rgb())
                 .zip(surf.rows_mut())
                 .flat_map(|(src_row, dest_row)| src_row.iter().zip(dest_row.iter_mut()))
-                .for_each(|(src, dest)| *dest = src.alpha(0xff).into());
+                .for_each(|(src, dest)| *dest = src.to_pixel().into());
         }
 
         if let (Some(content_type), Some(bytes)) = (content_type, mime_data) {