Refactor texture image filtering

- Support only `Linear` or `Nearest`
- Simplify `Layer` groups
- Move `FilterMethod` to `Image` and `image::Viewer`

core/src/image.rs

@@ -5,31 +5,11 @@ use std::hash::{Hash, Hasher as _};
 use std::path::PathBuf;
 use std::sync::Arc;
 
-/// Image filter method
-#[derive(Default, Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub enum FilterMethod {
-    /// Bilinear interpolation
-    #[default]
-    Linear,
-    /// Nearest Neighbor
-    Nearest,
-}
-
-/// Texture filter settings
-#[derive(Default, Debug, Clone, PartialEq, Eq, Hash)]
-pub struct TextureFilter {
-    /// Filter for scaling the image down.
-    pub min: FilterMethod,
-    /// Filter for scaling the image up.
-    pub mag: FilterMethod,
-}
-
 /// A handle of some image data.
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Handle {
     id: u64,
     data: Data,
-    filter: TextureFilter,
 }
 
 impl Handle {
@@ -76,7 +56,6 @@ impl Handle {
         Handle {
             id: hasher.finish(),
             data,
-            filter: TextureFilter::default(),
         }
     }
 
@@ -89,17 +68,6 @@ impl Handle {
     pub fn data(&self) -> &Data {
         &self.data
     }
-
-    /// Returns a reference to the [`TextureFilter`].
-    pub fn filter(&self) -> &TextureFilter {
-        &self.filter
-    }
-
-    /// Sets the texture filtering methods.
-    pub fn set_filter(mut self, filter: TextureFilter) -> Self {
-        self.filter = filter;
-        self
-    }
 }
 
 impl<T> From<T> for Handle
@@ -196,6 +164,16 @@ impl std::fmt::Debug for Data {
     }
 }
 
+/// Image filtering strategy.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
+pub enum FilterMethod {
+    /// Bilinear interpolation.
+    #[default]
+    Linear,
+    /// Nearest neighbor.
+    Nearest,
+}
+
 /// A [`Renderer`] that can render raster graphics.
 ///
 /// [renderer]: crate::renderer
@@ -210,5 +188,10 @@ pub trait Renderer: crate::Renderer {
 
     /// Draws an image with the given [`Handle`] and inside the provided
     /// `bounds`.
-    fn draw(&mut self, handle: Self::Handle, bounds: Rectangle);
+    fn draw(
+        &mut self,
+        handle: Self::Handle,
+        filter_method: FilterMethod,
+        bounds: Rectangle,
+    );
 }

examples/tour/src/main.rs

@@ -1,4 +1,4 @@
-use iced::alignment;
+use iced::alignment::{self, Alignment};
 use iced::theme;
 use iced::widget::{
     checkbox, column, container, horizontal_space, image, radio, row,
@@ -126,7 +126,10 @@ impl Steps {
                 Step::Toggler {
                     can_continue: false,
                 },
-                Step::Image { width: 300 },
+                Step::Image {
+                    width: 300,
+                    filter_method: image::FilterMethod::Linear,
+                },
                 Step::Scrollable,
                 Step::TextInput {
                     value: String::new(),
@@ -195,6 +198,7 @@ enum Step {
     },
     Image {
         width: u16,
+        filter_method: image::FilterMethod,
     },
     Scrollable,
     TextInput {
@@ -215,6 +219,7 @@ pub enum StepMessage {
     TextColorChanged(Color),
     LanguageSelected(Language),
     ImageWidthChanged(u16),
+    ImageUseNearestToggled(bool),
     InputChanged(String),
     ToggleSecureInput(bool),
     ToggleTextInputIcon(bool),
@@ -265,6 +270,15 @@ impl<'a> Step {
                     *width = new_width;
                 }
             }
+            StepMessage::ImageUseNearestToggled(use_nearest) => {
+                if let Step::Image { filter_method, .. } = self {
+                    *filter_method = if use_nearest {
+                        image::FilterMethod::Nearest
+                    } else {
+                        image::FilterMethod::Linear
+                    };
+                }
+            }
             StepMessage::InputChanged(new_value) => {
                 if let Step::TextInput { value, .. } = self {
                     *value = new_value;
@@ -330,7 +344,10 @@ impl<'a> Step {
             Step::Toggler { can_continue } => Self::toggler(*can_continue),
             Step::Slider { value } => Self::slider(*value),
             Step::Text { size, color } => Self::text(*size, *color),
-            Step::Image { width } => Self::image(*width),
+            Step::Image {
+                width,
+                filter_method,
+            } => Self::image(*width, *filter_method),
             Step::RowsAndColumns { layout, spacing } => {
                 Self::rows_and_columns(*layout, *spacing)
             }
@@ -525,16 +542,25 @@ impl<'a> Step {
             )
     }
 
-    fn image(width: u16) -> Column<'a, StepMessage> {
+    fn image(
+        width: u16,
+        filter_method: image::FilterMethod,
+    ) -> Column<'a, StepMessage> {
         Self::container("Image")
             .push("An image that tries to keep its aspect ratio.")
-            .push(ferris(width))
+            .push(ferris(width, filter_method))
             .push(slider(100..=500, width, StepMessage::ImageWidthChanged))
             .push(
                 text(format!("Width: {width} px"))
                     .width(Length::Fill)
                     .horizontal_alignment(alignment::Horizontal::Center),
             )
+            .push(checkbox(
+                "Use nearest interpolation",
+                filter_method == image::FilterMethod::Nearest,
+                StepMessage::ImageUseNearestToggled,
+            ))
+            .align_items(Alignment::Center)
     }
 
     fn scrollable() -> Column<'a, StepMessage> {
@@ -555,7 +581,7 @@ impl<'a> Step {
                     .horizontal_alignment(alignment::Horizontal::Center),
             )
             .push(vertical_space(4096))
-            .push(ferris(300))
+            .push(ferris(300, image::FilterMethod::Linear))
             .push(
                 text("You made it!")
                     .width(Length::Fill)
@@ -646,7 +672,10 @@ impl<'a> Step {
     }
 }
 
-fn ferris<'a>(width: u16) -> Container<'a, StepMessage> {
+fn ferris<'a>(
+    width: u16,
+    filter_method: image::FilterMethod,
+) -> Container<'a, StepMessage> {
     container(
         // This should go away once we unify resource loading on native
         // platforms
@@ -655,6 +684,7 @@ fn ferris<'a>(width: u16) -> Container<'a, StepMessage> {
         } else {
             image(format!("{}/images/ferris.png", env!("CARGO_MANIFEST_DIR")))
         }
+        .filter_method(filter_method)
         .width(width),
     )
     .width(Length::Fill)

graphics/src/primitive.rs

@@ -68,6 +68,8 @@ pub enum Primitive<T> {
     Image {
         /// The handle of the image
         handle: image::Handle,
+        /// The filter method of the image
+        filter_method: image::FilterMethod,
         /// The bounds of the image
         bounds: Rectangle,
     },

graphics/src/renderer.rs

@@ -215,8 +215,17 @@ where
         self.backend().dimensions(handle)
     }
 
-    fn draw(&mut self, handle: image::Handle, bounds: Rectangle) {
-        self.primitives.push(Primitive::Image { handle, bounds });
+    fn draw(
+        &mut self,
+        handle: image::Handle,
+        filter_method: image::FilterMethod,
+        bounds: Rectangle,
+    ) {
+        self.primitives.push(Primitive::Image {
+            handle,
+            filter_method,
+            bounds,
+        });
     }
 }
 

renderer/src/lib.rs

@@ -214,8 +214,13 @@ impl<T> crate::core::image::Renderer for Renderer<T> {
         delegate!(self, renderer, renderer.dimensions(handle))
     }
 
-    fn draw(&mut self, handle: crate::core::image::Handle, bounds: Rectangle) {
-        delegate!(self, renderer, renderer.draw(handle, bounds));
+    fn draw(
+        &mut self,
+        handle: crate::core::image::Handle,
+        filter_method: crate::core::image::FilterMethod,
+        bounds: Rectangle,
+    ) {
+        delegate!(self, renderer, renderer.draw(handle, filter_method, bounds));
     }
 }
 

tiny_skia/src/backend.rs

@@ -445,7 +445,11 @@ impl Backend {
                 );
             }
             #[cfg(feature = "image")]
-            Primitive::Image { handle, bounds } => {
+            Primitive::Image {
+                handle,
+                filter_method,
+                bounds,
+            } => {
                 let physical_bounds = (*bounds + translation) * scale_factor;
 
                 if !clip_bounds.intersects(&physical_bounds) {
@@ -461,8 +465,14 @@ impl Backend {
                 )
                 .post_scale(scale_factor, scale_factor);
 
-                self.raster_pipeline
-                    .draw(handle, *bounds, pixels, transform, clip_mask);
+                self.raster_pipeline.draw(
+                    handle,
+                    *filter_method,
+                    *bounds,
+                    pixels,
+                    transform,
+                    clip_mask,
+                );
             }
             #[cfg(not(feature = "image"))]
             Primitive::Image { .. } => {

tiny_skia/src/raster.rs

@@ -28,6 +28,7 @@ impl Pipeline {
     pub fn draw(
         &mut self,
         handle: &raster::Handle,
+        filter_method: raster::FilterMethod,
         bounds: Rectangle,
         pixels: &mut tiny_skia::PixmapMut<'_>,
         transform: tiny_skia::Transform,
@@ -39,7 +40,7 @@ impl Pipeline {
 
             let transform = transform.pre_scale(width_scale, height_scale);
 
-            let quality = match handle.filter().mag {
+            let quality = match filter_method {
                 raster::FilterMethod::Linear => {
                     tiny_skia::FilterQuality::Bilinear
                 }