Introduce dynamic `opacity` support for `Image` and `Svg`

18 files changed, 142 insertions, 33 deletions

diff --git a/core/src/image.rs b/core/src/image.rs
index 91a7fd36..82ecdd0f 100644
--- a/core/src/image.rs
+++ b/core/src/image.rs
@@ -174,5 +174,6 @@ pub trait Renderer: crate::Renderer {
         filter_method: FilterMethod,
         bounds: Rectangle,
         rotation: Radians,
+        opacity: f32,
     );
 }
diff --git a/core/src/renderer/null.rs b/core/src/renderer/null.rs
index 91519b40..e8709dbc 100644
--- a/core/src/renderer/null.rs
+++ b/core/src/renderer/null.rs
@@ -173,6 +173,7 @@ impl image::Renderer for () {
         _filter_method: image::FilterMethod,
         _bounds: Rectangle,
         _rotation: Radians,
+        _opacity: f32,
     ) {
     }
 }
@@ -188,6 +189,7 @@ impl svg::Renderer for () {
         _color: Option<Color>,
         _bounds: Rectangle,
         _rotation: Radians,
+        _opacity: f32,
     ) {
     }
 }
diff --git a/core/src/svg.rs b/core/src/svg.rs
index 01f102e3..946b8156 100644
--- a/core/src/svg.rs
+++ b/core/src/svg.rs
@@ -101,5 +101,6 @@ pub trait Renderer: crate::Renderer {
         color: Option<Color>,
         bounds: Rectangle,
         rotation: Radians,
+        opacity: f32,
     );
 }
diff --git a/examples/ferris/src/main.rs b/examples/ferris/src/main.rs
index 13d746dd..1d0e9181 100644
--- a/examples/ferris/src/main.rs
+++ b/examples/ferris/src/main.rs
@@ -17,6 +17,7 @@ pub fn main() -> iced::Result {
 
 struct Image {
     width: f32,
+    opacity: f32,
     rotation: Rotation,
     content_fit: ContentFit,
     spin: bool,
@@ -26,6 +27,7 @@ struct Image {
 #[derive(Debug, Clone, Copy)]
 enum Message {
     WidthChanged(f32),
+    OpacityChanged(f32),
     RotationStrategyChanged(RotationStrategy),
     RotationChanged(Degrees),
     ContentFitChanged(ContentFit),
@@ -39,6 +41,9 @@ impl Image {
             Message::WidthChanged(width) => {
                 self.width = width;
             }
+            Message::OpacityChanged(opacity) => {
+                self.opacity = opacity;
+            }
             Message::RotationStrategyChanged(strategy) => {
                 self.rotation = match strategy {
                     RotationStrategy::Floating => {
@@ -97,6 +102,7 @@ impl Image {
                 .width(self.width)
                 .content_fit(self.content_fit)
                 .rotation(self.rotation)
+                .opacity(self.opacity)
             )
             .explain(Color::WHITE),
             "I am Ferris!"
@@ -117,14 +123,15 @@ impl Image {
                 Message::ContentFitChanged
             )
             .width(Length::Fill),
-            column![
+            with_value(
                 slider(100.0..=500.0, self.width, Message::WidthChanged),
-                text(format!("Width: {}px", self.width))
-                    .size(12)
-                    .line_height(1.0)
-            ]
-            .spacing(2)
-            .align_items(Alignment::Center)
+                format!("Width: {}px", self.width)
+            ),
+            with_value(
+                slider(0.0..=1.0, self.opacity, Message::OpacityChanged)
+                    .step(0.01),
+                format!("Opacity: {:.2}", self.opacity)
+            )
         ]
         .spacing(10)
         .align_items(Alignment::End);
@@ -139,7 +146,7 @@ impl Image {
                 Message::RotationStrategyChanged,
             )
             .width(Length::Fill),
-            column![
+            with_value(
                 row![
                     slider(
                         Degrees::RANGE,
@@ -153,15 +160,8 @@ impl Image {
                 ]
                 .spacing(10)
                 .align_items(Alignment::Center),
-                text(format!(
-                    "Rotation: {:.0}°",
-                    f32::from(self.rotation.degrees())
-                ))
-                .size(12)
-                .line_height(1.0)
-            ]
-            .spacing(2)
-            .align_items(Alignment::Center)
+                format!("Rotation: {:.0}°", f32::from(self.rotation.degrees()))
+            )
         ]
         .spacing(10)
         .align_items(Alignment::End);
@@ -176,6 +176,7 @@ impl Default for Image {
     fn default() -> Self {
         Self {
             width: 300.0,
+            opacity: 1.0,
             rotation: Rotation::default(),
             content_fit: ContentFit::default(),
             spin: false,
@@ -198,3 +199,13 @@ impl std::fmt::Display for RotationStrategy {
         })
     }
 }
+
+fn with_value<'a>(
+    control: impl Into<Element<'a, Message>>,
+    value: String,
+) -> Element<'a, Message> {
+    column![control.into(), text(value).size(12).line_height(1.0)]
+        .spacing(2)
+        .align_items(Alignment::Center)
+        .into()
+}
diff --git a/graphics/src/image.rs b/graphics/src/image.rs
index 9d09bf4c..318592be 100644
--- a/graphics/src/image.rs
+++ b/graphics/src/image.rs
@@ -18,8 +18,11 @@ pub enum Image {
         /// The bounds of the image.
         bounds: Rectangle,
 
-        /// The rotation of the image in radians
+        /// The rotation of the image.
         rotation: Radians,
+
+        /// The opacity of the image.
+        opacity: f32,
     },
     /// A vector image.
     Vector {
@@ -32,8 +35,11 @@ pub enum Image {
         /// The bounds of the image.
         bounds: Rectangle,
 
-        /// The rotation of the image in radians
+        /// The rotation of the image.
         rotation: Radians,
+
+        /// The opacity of the image.
+        opacity: f32,
     },
 }
 
diff --git a/renderer/src/fallback.rs b/renderer/src/fallback.rs
index a077031b..6a169692 100644
--- a/renderer/src/fallback.rs
+++ b/renderer/src/fallback.rs
@@ -155,11 +155,18 @@ where
         filter_method: image::FilterMethod,
         bounds: Rectangle,
         rotation: Radians,
+        opacity: f32,
     ) {
         delegate!(
             self,
             renderer,
-            renderer.draw_image(handle, filter_method, bounds, rotation)
+            renderer.draw_image(
+                handle,
+                filter_method,
+                bounds,
+                rotation,
+                opacity
+            )
         );
     }
 }
@@ -179,11 +186,12 @@ where
         color: Option<Color>,
         bounds: Rectangle,
         rotation: Radians,
+        opacity: f32,
     ) {
         delegate!(
             self,
             renderer,
-            renderer.draw_svg(handle, color, bounds, rotation)
+            renderer.draw_svg(handle, color, bounds, rotation, opacity)
         );
     }
 }
diff --git a/tiny_skia/src/engine.rs b/tiny_skia/src/engine.rs
index 544ff614..028b304f 100644
--- a/tiny_skia/src/engine.rs
+++ b/tiny_skia/src/engine.rs
@@ -551,6 +551,7 @@ impl Engine {
                 filter_method,
                 bounds,
                 rotation,
+                opacity,
             } => {
                 let physical_bounds = *bounds * _transformation;
 
@@ -574,6 +575,7 @@ impl Engine {
                     handle,
                     *filter_method,
                     *bounds,
+                    *opacity,
                     _pixels,
                     transform,
                     clip_mask,
@@ -585,6 +587,7 @@ impl Engine {
                 color,
                 bounds,
                 rotation,
+                opacity,
             } => {
                 let physical_bounds = *bounds * _transformation;
 
@@ -608,6 +611,7 @@ impl Engine {
                     handle,
                     *color,
                     physical_bounds,
+                    *opacity,
                     _pixels,
                     transform,
                     clip_mask,
diff --git a/tiny_skia/src/layer.rs b/tiny_skia/src/layer.rs
index c907c93c..48fca1d8 100644
--- a/tiny_skia/src/layer.rs
+++ b/tiny_skia/src/layer.rs
@@ -122,12 +122,14 @@ impl Layer {
         bounds: Rectangle,
         transformation: Transformation,
         rotation: Radians,
+        opacity: f32,
     ) {
         let image = Image::Raster {
             handle,
             filter_method,
             bounds: bounds * transformation,
             rotation,
+            opacity,
         };
 
         self.images.push(image);
@@ -140,12 +142,14 @@ impl Layer {
         bounds: Rectangle,
         transformation: Transformation,
         rotation: Radians,
+        opacity: f32,
     ) {
         let svg = Image::Vector {
             handle,
             color,
             bounds: bounds * transformation,
             rotation,
+            opacity,
         };
 
         self.images.push(svg);
diff --git a/tiny_skia/src/lib.rs b/tiny_skia/src/lib.rs
index e0cbfa0d..1aabff00 100644
--- a/tiny_skia/src/lib.rs
+++ b/tiny_skia/src/lib.rs
@@ -378,6 +378,7 @@ impl core::image::Renderer for Renderer {
         filter_method: core::image::FilterMethod,
         bounds: Rectangle,
         rotation: core::Radians,
+        opacity: f32,
     ) {
         let (layer, transformation) = self.layers.current_mut();
         layer.draw_image(
@@ -386,6 +387,7 @@ impl core::image::Renderer for Renderer {
             bounds,
             transformation,
             rotation,
+            opacity,
         );
     }
 }
@@ -405,9 +407,17 @@ impl core::svg::Renderer for Renderer {
         color: Option<Color>,
         bounds: Rectangle,
         rotation: core::Radians,
+        opacity: f32,
     ) {
         let (layer, transformation) = self.layers.current_mut();
-        layer.draw_svg(handle, color, bounds, transformation, rotation);
+        layer.draw_svg(
+            handle,
+            color,
+            bounds,
+            transformation,
+            rotation,
+            opacity,
+        );
     }
 }
 
diff --git a/tiny_skia/src/raster.rs b/tiny_skia/src/raster.rs
index 907fce7c..c40f55b2 100644
--- a/tiny_skia/src/raster.rs
+++ b/tiny_skia/src/raster.rs
@@ -31,6 +31,7 @@ impl Pipeline {
         handle: &raster::Handle,
         filter_method: raster::FilterMethod,
         bounds: Rectangle,
+        opacity: f32,
         pixels: &mut tiny_skia::PixmapMut<'_>,
         transform: tiny_skia::Transform,
         clip_mask: Option<&tiny_skia::Mask>,
@@ -56,6 +57,7 @@ impl Pipeline {
                 image,
                 &tiny_skia::PixmapPaint {
                     quality,
+                    opacity,
                     ..Default::default()
                 },
                 transform,
diff --git a/tiny_skia/src/vector.rs b/tiny_skia/src/vector.rs
index 8e3463f2..bbe08cb8 100644
--- a/tiny_skia/src/vector.rs
+++ b/tiny_skia/src/vector.rs
@@ -34,6 +34,7 @@ impl Pipeline {
         handle: &Handle,
         color: Option<Color>,
         bounds: Rectangle,
+        opacity: f32,
         pixels: &mut tiny_skia::PixmapMut<'_>,
         transform: Transform,
         clip_mask: Option<&tiny_skia::Mask>,
@@ -47,7 +48,10 @@ impl Pipeline {
                 bounds.x as i32,
                 bounds.y as i32,
                 image,
-                &tiny_skia::PixmapPaint::default(),
+                &tiny_skia::PixmapPaint {
+                    opacity,
+                    ..tiny_skia::PixmapPaint::default()
+                },
                 transform,
                 clip_mask,
             );
diff --git a/wgpu/src/image/mod.rs b/wgpu/src/image/mod.rs
index 285eb2f6..063822aa 100644
--- a/wgpu/src/image/mod.rs
+++ b/wgpu/src/image/mod.rs
@@ -137,16 +137,18 @@ impl Pipeline {
                             0 => Float32x2,
                             // Center
                             1 => Float32x2,
-                            // Image size
+                            // Scale
                             2 => Float32x2,
                             // Rotation
                             3 => Float32,
+                            // Opacity
+                            4 => Float32,
                             // Atlas position
-                            4 => Float32x2,
-                            // Atlas scale
                             5 => Float32x2,
+                            // Atlas scale
+                            6 => Float32x2,
                             // Layer
-                            6 => Sint32,
+                            7 => Sint32,
                         ),
                     }],
                 },
@@ -229,6 +231,7 @@ impl Pipeline {
                     filter_method,
                     bounds,
                     rotation,
+                    opacity,
                 } => {
                     if let Some(atlas_entry) =
                         cache.upload_raster(device, encoder, handle)
@@ -237,6 +240,7 @@ impl Pipeline {
                             [bounds.x, bounds.y],
                             [bounds.width, bounds.height],
                             f32::from(*rotation),
+                            *opacity,
                             atlas_entry,
                             match filter_method {
                                 crate::core::image::FilterMethod::Nearest => {
@@ -258,6 +262,7 @@ impl Pipeline {
                     color,
                     bounds,
                     rotation,
+                    opacity,
                 } => {
                     let size = [bounds.width, bounds.height];
 
@@ -268,6 +273,7 @@ impl Pipeline {
                             [bounds.x, bounds.y],
                             size,
                             f32::from(*rotation),
+                            *opacity,
                             atlas_entry,
                             nearest_instances,
                         );
@@ -498,6 +504,7 @@ struct Instance {
     _center: [f32; 2],
     _size: [f32; 2],
     _rotation: f32,
+    _opacity: f32,
     _position_in_atlas: [f32; 2],
     _size_in_atlas: [f32; 2],
     _layer: u32,
@@ -517,6 +524,7 @@ fn add_instances(
     image_position: [f32; 2],
     image_size: [f32; 2],
     rotation: f32,
+    opacity: f32,
     entry: &atlas::Entry,
     instances: &mut Vec<Instance>,
 ) {
@@ -532,6 +540,7 @@ fn add_instances(
                 center,
                 image_size,
                 rotation,
+                opacity,
                 allocation,
                 instances,
             );
@@ -561,7 +570,8 @@ fn add_instances(
                 ];
 
                 add_instance(
-                    position, center, size, rotation, allocation, instances,
+                    position, center, size, rotation, opacity, allocation,
+                    instances,
                 );
             }
         }
@@ -574,6 +584,7 @@ fn add_instance(
     center: [f32; 2],
     size: [f32; 2],
     rotation: f32,
+    opacity: f32,
     allocation: &atlas::Allocation,
     instances: &mut Vec<Instance>,
 ) {
@@ -586,6 +597,7 @@ fn add_instance(
         _center: center,
         _size: size,
         _rotation: rotation,
+        _opacity: opacity,
         _position_in_atlas: [
             (x as f32 + 0.5) / atlas::SIZE as f32,
             (y as f32 + 0.5) / atlas::SIZE as f32,
diff --git a/wgpu/src/layer.rs b/wgpu/src/layer.rs
index e0242c59..9551311d 100644
--- a/wgpu/src/layer.rs
+++ b/wgpu/src/layer.rs
@@ -119,12 +119,14 @@ impl Layer {
         bounds: Rectangle,
         transformation: Transformation,
         rotation: Radians,
+        opacity: f32,
     ) {
         let image = Image::Raster {
             handle,
             filter_method,
             bounds: bounds * transformation,
             rotation,
+            opacity,
         };
 
         self.images.push(image);
@@ -137,12 +139,14 @@ impl Layer {
         bounds: Rectangle,
         transformation: Transformation,
         rotation: Radians,
+        opacity: f32,
     ) {
         let svg = Image::Vector {
             handle,
             color,
             bounds: bounds * transformation,
             rotation,
+            opacity,
         };
 
         self.images.push(svg);
diff --git a/wgpu/src/lib.rs b/wgpu/src/lib.rs
index eb600dde..4c168029 100644
--- a/wgpu/src/lib.rs
+++ b/wgpu/src/lib.rs
@@ -518,6 +518,7 @@ impl core::image::Renderer for Renderer {
         filter_method: core::image::FilterMethod,
         bounds: Rectangle,
         rotation: core::Radians,
+        opacity: f32,
     ) {
         let (layer, transformation) = self.layers.current_mut();
         layer.draw_image(
@@ -526,6 +527,7 @@ impl core::image::Renderer for Renderer {
             bounds,
             transformation,
             rotation,
+            opacity,
         );
     }
 }
@@ -542,9 +544,17 @@ impl core::svg::Renderer for Renderer {
         color_filter: Option<Color>,
         bounds: Rectangle,
         rotation: core::Radians,
+        opacity: f32,
     ) {
         let (layer, transformation) = self.layers.current_mut();
-        layer.draw_svg(handle, color_filter, bounds, transformation, rotation);
+        layer.draw_svg(
+            handle,
+            color_filter,
+            bounds,
+            transformation,
+            rotation,
+            opacity,
+        );
     }
 }
 
diff --git a/wgpu/src/shader/image.wgsl b/wgpu/src/shader/image.wgsl
index 71bf939c..accefc17 100644
--- a/wgpu/src/shader/image.wgsl
+++ b/wgpu/src/shader/image.wgsl
@@ -12,15 +12,17 @@ struct VertexInput {
     @location(1) center: vec2<f32>,
     @location(2) scale: vec2<f32>,
     @location(3) rotation: f32,
-    @location(4) atlas_pos: vec2<f32>,
-    @location(5) atlas_scale: vec2<f32>,
-    @location(6) layer: i32,
+    @location(4) opacity: f32,
+    @location(5) atlas_pos: vec2<f32>,
+    @location(6) atlas_scale: vec2<f32>,
+    @location(7) layer: i32,
 }
 
 struct VertexOutput {
     @builtin(position) position: vec4<f32>,
     @location(0) uv: vec2<f32>,
     @location(1) layer: f32, // this should be an i32, but naga currently reads that as requiring interpolation.
+    @location(2) opacity: f32,
 }
 
 @vertex
@@ -33,6 +35,7 @@ fn vs_main(input: VertexInput) -> VertexOutput {
     // Map the vertex position to the atlas texture.
     out.uv = vec2<f32>(v_pos * input.atlas_scale + input.atlas_pos);
     out.layer = f32(input.layer);
+    out.opacity = input.opacity;
 
     // Calculate the vertex position and move the center to the origin
     v_pos = input.pos + v_pos * input.scale - input.center;
@@ -56,5 +59,5 @@ fn vs_main(input: VertexInput) -> VertexOutput {
 @fragment
 fn fs_main(input: VertexOutput) -> @location(0) vec4<f32> {
     // Sample the texture at the given UV coordinate and layer.
-    return textureSample(u_texture, u_sampler, input.uv, i32(input.layer));
+    return textureSample(u_texture, u_sampler, input.uv, i32(input.layer)) * vec4<f32>(1.0, 1.0, 1.0, input.opacity);
 }
diff --git a/widget/src/image.rs b/widget/src/image.rs
index 45209a91..80e17263 100644
--- a/widget/src/image.rs
+++ b/widget/src/image.rs
@@ -38,6 +38,7 @@ pub struct Image<Handle> {
     content_fit: ContentFit,
     filter_method: FilterMethod,
     rotation: Rotation,
+    opacity: f32,
 }
 
 impl<Handle> Image<Handle> {
@@ -50,6 +51,7 @@ impl<Handle> Image<Handle> {
             content_fit: ContentFit::default(),
             filter_method: FilterMethod::default(),
             rotation: Rotation::default(),
+            opacity: 1.0,
         }
     }
 
@@ -84,6 +86,15 @@ impl<Handle> Image<Handle> {
         self.rotation = rotation.into();
         self
     }
+
+    /// Sets the opacity of the [`Image`].
+    ///
+    /// It should be in the [0.0, 1.0] range—`0.0` meaning completely transparent,
+    /// and `1.0` meaning completely opaque.
+    pub fn opacity(mut self, opacity: impl Into<f32>) -> Self {
+        self.opacity = opacity.into();
+        self
+    }
 }
 
 /// Computes the layout of an [`Image`].
@@ -136,6 +147,7 @@ pub fn draw<Renderer, Handle>(
     content_fit: ContentFit,
     filter_method: FilterMethod,
     rotation: Rotation,
+    opacity: f32,
 ) where
     Renderer: image::Renderer<Handle = Handle>,
     Handle: Clone,
@@ -173,6 +185,7 @@ pub fn draw<Renderer, Handle>(
             filter_method,
             drawing_bounds,
             rotation.radians(),
+            opacity,
         );
     };
 
@@ -231,6 +244,7 @@ where
             self.content_fit,
             self.filter_method,
             self.rotation,
+            self.opacity,
         );
     }
 }
diff --git a/widget/src/image/viewer.rs b/widget/src/image/viewer.rs
index 5eb76452..8fe6f021 100644
--- a/widget/src/image/viewer.rs
+++ b/widget/src/image/viewer.rs
@@ -342,6 +342,7 @@ where
                         ..Rectangle::with_size(image_size)
                     },
                     Radians(0.0),
+                    1.0,
                 );
             });
         });
diff --git a/widget/src/svg.rs b/widget/src/svg.rs
index c1fccba1..4551bcad 100644
--- a/widget/src/svg.rs
+++ b/widget/src/svg.rs
@@ -30,6 +30,7 @@ where
     content_fit: ContentFit,
     class: Theme::Class<'a>,
     rotation: Rotation,
+    opacity: f32,
 }
 
 impl<'a, Theme> Svg<'a, Theme>
@@ -45,6 +46,7 @@ where
             content_fit: ContentFit::Contain,
             class: Theme::default(),
             rotation: Rotation::default(),
+            opacity: 1.0,
         }
     }
 
@@ -103,6 +105,15 @@ where
         self.rotation = rotation.into();
         self
     }
+
+    /// Sets the opacity of the [`Svg`].
+    ///
+    /// It should be in the [0.0, 1.0] range—`0.0` meaning completely transparent,
+    /// and `1.0` meaning completely opaque.
+    pub fn opacity(mut self, opacity: impl Into<f32>) -> Self {
+        self.opacity = opacity.into();
+        self
+    }
 }
 
 impl<'a, Message, Theme, Renderer> Widget<Message, Theme, Renderer>
@@ -204,6 +215,7 @@ where
                 style.color,
                 drawing_bounds,
                 self.rotation.radians(),
+                self.opacity,
             );
         };