Refactor ImageBrush to use generic type for image data and simplify ImageBrushRef implementation (#133)

Making `ImageBrush` generic over `ImageData` allows us to simplify
`ImageBrushRef`, because `ImageBrushRef<'a> = ImageBrush<&'a
ImageData>`. My main usecase for generic `ImageBrush` is recording: you
register image outside of draw command and reference it using newtype
(this will be converted to `ImageBrushRef` when actually used).

Next version of #122

---------

Signed-off-by: sagudev <[email protected]>

Author: sagudev

src/image.rs

@@ -181,35 +181,19 @@ impl ImageSampler {
 
 /// Describes the image content of a filled or stroked shape.
 ///
-/// See also [`ImageBrushRef`] which can be used to avoid reference counting overhead.
-#[derive(Clone, PartialEq, Debug)]
+/// This type is generic over the storage used for the image data.
+/// By default, the generic parameter is [`ImageData`], which is a shared image with dynamic lifetime.
+/// However, different renderers can use different types here, such as a pre-registered id.
+#[derive(Copy, Clone, PartialEq, Debug)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
-pub struct ImageBrush {
+pub struct ImageBrush<D = ImageData> {
     /// The image to render.
-    pub image: ImageData,
+    pub image: D,
     /// Parameters which specify how to sample from the image during rendering.
     pub sampler: ImageSampler,
 }
 
-impl ImageBrush {
-    /// Creates a new `ImageBrush` for the specified `ImageData` with default `ImageSampler`.
-    #[must_use]
-    pub fn new(image: ImageData) -> Self {
-        Self {
-            image,
-            sampler: ImageSampler::default(),
-        }
-    }
-
-    /// Converts an owned `ImageBrush` into a borrowed `ImageBrushRef`.
-    #[must_use]
-    pub fn as_ref(&self) -> ImageBrushRef<'_> {
-        ImageBrushRef {
-            image: &self.image,
-            sampler: self.sampler,
-        }
-    }
-
+impl<D> ImageBrush<D> {
     /// Builder method for setting the image [extend mode](Extend) in both
     /// directions.
     #[must_use]
@@ -269,89 +253,36 @@ impl ImageBrush {
     }
 }
 
-/// Borrowed version of [`ImageBrush`] for avoiding reference counting overhead.
-#[derive(Copy, Clone, PartialEq, Debug)]
-pub struct ImageBrushRef<'a> {
-    /// The image to render.
-    pub image: &'a ImageData,
-    /// Parameters which specify how to sample from the image during rendering.
-    pub sampler: ImageSampler,
-}
-
-impl ImageBrushRef<'_> {
-    /// Creates a new image with the given data, [format](ImageFormat) and dimensions.
+impl ImageBrush {
+    /// Creates a new `ImageBrush` for the specified `ImageData` with default `ImageSampler`.
     #[must_use]
-    pub fn new<'a>(image: &'a ImageData) -> ImageBrushRef<'a> {
-        ImageBrushRef {
+    pub fn new(image: ImageData) -> Self {
+        Self {
             image,
             sampler: ImageSampler::default(),
         }
     }
 
-    /// Converts the `ImageBrushRef` to an owned `ImageBrush`.
+    /// Converts an owned `ImageBrush` into a borrowed `ImageBrushRef`.
     #[must_use]
-    pub fn to_owned(&self) -> ImageBrush {
+    pub fn as_ref(&'_ self) -> ImageBrushRef<'_> {
         ImageBrush {
-            image: (*self.image).clone(),
+            image: &self.image,
             sampler: self.sampler,
         }
     }
+}
 
-    /// Builder method for setting the image [extend mode](Extend) in both
-    /// directions.
-    #[must_use]
-    pub fn with_extend(mut self, mode: Extend) -> Self {
-        self.sampler.x_extend = mode;
-        self.sampler.y_extend = mode;
-        self
-    }
-
-    /// Builder method for setting the image [extend mode](Extend) in the
-    /// horizontal direction.
-    #[must_use]
-    pub fn with_x_extend(mut self, mode: Extend) -> Self {
-        self.sampler.x_extend = mode;
-        self
-    }
-
-    /// Builder method for setting the image [extend mode](Extend) in the
-    /// vertical direction.
-    #[must_use]
-    pub fn with_y_extend(mut self, mode: Extend) -> Self {
-        self.sampler.y_extend = mode;
-        self
-    }
-
-    /// Builder method for setting a hint for the desired image [quality](ImageQuality)
-    /// when rendering.
-    #[must_use]
-    pub fn with_quality(mut self, quality: ImageQuality) -> Self {
-        self.sampler.quality = quality;
-        self
-    }
-
-    /// Returns the image with the alpha multiplier set to `alpha`.
-    #[must_use]
-    #[track_caller]
-    pub fn with_alpha(mut self, alpha: f32) -> Self {
-        debug_assert!(
-            alpha.is_finite() && alpha >= 0.0,
-            "A non-finite or negative alpha ({alpha}) is meaningless."
-        );
-        self.sampler.alpha = alpha;
-        self
-    }
+/// Borrowed version of [`ImageBrush`] for avoiding reference counting overhead.
+pub type ImageBrushRef<'a> = ImageBrush<&'a ImageData>;
 
-    /// Returns the image with the alpha multiplier multiplied again by `alpha`.
-    /// The behaviour of this transformation is undefined if `alpha` is negative.
+impl ImageBrushRef<'_> {
+    /// Converts the `ImageBrushRef` to an owned `ImageBrush`.
     #[must_use]
-    #[track_caller]
-    pub fn multiply_alpha(mut self, alpha: f32) -> Self {
-        debug_assert!(
-            alpha.is_finite() && alpha >= 0.0,
-            "A non-finite or negative alpha ({alpha}) is meaningless."
-        );
-        self.sampler.alpha *= alpha;
-        self
+    pub fn to_owned(&self) -> ImageBrush {
+        ImageBrush {
+            image: (*self.image).clone(),
+            sampler: self.sampler,
+        }
     }
 }