Custom Renderers

use iced_core::renderer;
use iced_core::{Background, Rectangle, Transformation};

pub struct MyRenderer {
    // Your renderer state
}

impl renderer::Renderer for MyRenderer {
    fn fill_quad(&mut self, quad: renderer::Quad, background: impl Into<Background>) {
        let background = background.into();
        // Draw a quad (rectangle) with the specified background
        // quad.bounds gives you the rectangle coordinates
        // quad.border gives you border radius and width
    }

    fn start_layer(&mut self, bounds: Rectangle) {
        // Begin a new clipping layer
        // Only content within 'bounds' should be visible
    }

    fn end_layer(&mut self) {
        // End the current clipping layer
    }

    fn start_transformation(&mut self, transformation: Transformation) {
        // Push a transformation matrix
        // Apply translation, rotation, and scaling
    }

    fn end_transformation(&mut self) {
        // Pop the transformation matrix
    }

    fn allocate_image(
        &mut self,
        handle: &iced_core::image::Handle,
        callback: impl FnOnce(Result<iced_core::image::Allocation, iced_core::image::Error>) + Send + 'static,
    ) {
        // Asynchronously load and allocate an image
        // Call the callback when done
    }

    fn hint(&mut self, scale_factor: f32) {
        // Hint about the current scale factor
        // Use for DPI-aware rendering
    }

    fn scale_factor(&self) -> Option<f32> {
        // Return the current scale factor if known
        None
    }

    fn tick(&mut self) {
        // Called once per frame
        // Use for resource management
    }

    fn reset(&mut self, new_bounds: Rectangle) {
        // Reset the renderer for a new frame
    }
}

use iced_core::text;
use iced_core::{Color, Font, Pixels, Point};

// Define your text types
pub struct MyParagraph {
    // Text layout information
}

pub struct MyEditor {
    // Text editor state
}

impl text::Renderer for MyRenderer {
    type Font = Font;
    type Paragraph = MyParagraph;
    type Editor = MyEditor;

    const ICON_FONT: Font = Font::with_name("Iced-Icons");
    const CHECKMARK_ICON: char = '\u{f00c}';
    const ARROW_DOWN_ICON: char = '\u{e800}';
    const ICED_LOGO: char = '\u{e801}';
    const SCROLL_UP_ICON: char = '\u{e802}';
    const SCROLL_DOWN_ICON: char = '\u{e803}';
    const SCROLL_LEFT_ICON: char = '\u{e804}';
    const SCROLL_RIGHT_ICON: char = '\u{e805}';

    fn default_font(&self) -> Self::Font {
        Font::default()
    }

    fn default_size(&self) -> Pixels {
        Pixels(16.0)
    }

    fn fill_paragraph(
        &mut self,
        paragraph: &Self::Paragraph,
        position: Point,
        color: Color,
        clip_bounds: Rectangle,
    ) {
        // Render a paragraph of text
    }

    fn fill_editor(
        &mut self,
        editor: &Self::Editor,
        position: Point,
        color: Color,
        clip_bounds: Rectangle,
    ) {
        // Render an editable text field
    }

    fn fill_text(
        &mut self,
        text: iced_core::Text,
        position: Point,
        color: Color,
        clip_bounds: Rectangle,
    ) {
        // Render simple text
    }
}

use iced_core::image;
use iced_core::{Image, Size};

impl image::Renderer for MyRenderer {
    type Handle = image::Handle;

    fn load_image(&self, handle: &Self::Handle) -> Result<image::Allocation, image::Error> {
        // Load image from handle (file path, bytes, etc.)
        // Return allocation ID for later use
    }

    fn measure_image(&self, handle: &Self::Handle) -> Option<Size<u32>> {
        // Return image dimensions
    }

    fn draw_image(
        &mut self,
        image: Image<Self::Handle>,
        bounds: Rectangle,
        clip_bounds: Rectangle,
    ) {
        // Draw the image within bounds
    }
}

use iced_core::svg;
use iced_core::Svg;

impl svg::Renderer for MyRenderer {
    fn measure_svg(&self, handle: &svg::Handle) -> Size<u32> {
        // Return SVG viewport dimensions
    }

    fn draw_svg(
        &mut self,
        svg: Svg,
        bounds: Rectangle,
        clip_bounds: Rectangle,
    ) {
        // Render SVG within bounds
    }
}

use iced_graphics::mesh;
use iced_graphics::Mesh;

impl mesh::Renderer for MyRenderer {
    fn draw_mesh(&mut self, mesh: Mesh) {
        // Draw triangle mesh
        // mesh.vertices() - vertex positions and colors
        // mesh.indices() - triangle indices
    }

    fn draw_mesh_cache(&mut self, cache: mesh::Cache) {
        // Draw cached mesh (for performance)
    }
}

use iced_graphics::compositor;
use iced_graphics::{Compositor, Viewport};

pub struct MyCompositor {
    // Compositor state
}

impl Compositor for MyCompositor {
    type Renderer = MyRenderer;
    type Surface = MySurface;

    async fn with_backend(
        settings: iced_graphics::Settings,
        display: impl compositor::Display + Clone,
        compatible_window: impl compositor::Window + Clone,
        shell: iced_graphics::Shell,
        backend: Option<&str>,
    ) -> Result<Self, iced_graphics::Error> {
        // Initialize your compositor
        // Return error if backend name doesn't match
        Ok(Self { /* ... */ })
    }

    fn create_renderer(&self) -> Self::Renderer {
        // Create a new renderer instance
        MyRenderer { /* ... */ }
    }

    fn create_surface<W: compositor::Window + Clone>(
        &mut self,
        window: W,
        width: u32,
        height: u32,
    ) -> Self::Surface {
        // Create a rendering surface for a window
        MySurface { /* ... */ }
    }

    fn configure_surface(&mut self, surface: &mut Self::Surface, width: u32, height: u32) {
        // Resize the surface
    }

    fn load_font(&mut self, font: std::borrow::Cow<'static, [u8]>) {
        // Load a font into the renderer
    }

    fn information(&self) -> compositor::Information {
        // Return backend information
        compositor::Information {
            adapter: "My Custom Renderer".to_string(),
            backend: "custom".to_string(),
        }
    }

    fn present(
        &mut self,
        renderer: &mut Self::Renderer,
        surface: &mut Self::Surface,
        viewport: &Viewport,
        background_color: iced_core::Color,
        on_pre_present: impl FnOnce(),
    ) -> Result<(), compositor::SurfaceError> {
        // Render the frame to the surface
        // Call on_pre_present before final present
        on_pre_present();
        // Present to screen
        Ok(())
    }

    fn screenshot(
        &mut self,
        renderer: &mut Self::Renderer,
        viewport: &Viewport,
        background_color: iced_core::Color,
    ) -> Vec<u8> {
        // Capture the current frame as RGBA bytes
        vec![]
    }
}

use iced_wgpu::Primitive;

impl iced_wgpu::primitive::Renderer for MyRenderer {
    fn draw_primitive(&mut self, bounds: Rectangle, primitive: impl Primitive) {
        // Execute custom shader primitive
        primitive.prepare(/* ... */);
        primitive.render(/* ... */);
    }
}

use iced_graphics::geometry;

impl geometry::Renderer for MyRenderer {
    type Geometry = MyGeometry;
    type Frame = MyFrame;

    fn new_frame(&self, bounds: Rectangle) -> Self::Frame {
        // Create a new drawing frame
        MyFrame::new(bounds)
    }

    fn draw_geometry(&mut self, geometry: Self::Geometry) {
        // Draw the geometry
    }
}

struct DrawBatch {
    quads: Vec<(Quad, Background)>,
    meshes: Vec<Mesh>,
}

impl MyRenderer {
    fn flush(&mut self) {
        // Draw all batched items at once
    }
}

use rustc_hash::FxHashMap;

struct MyRenderer {
    text_cache: FxHashMap<TextCacheKey, CachedText>,
    image_cache: FxHashMap<image::Handle, LoadedImage>,
}

impl MyRenderer {
    fn tick(&mut self) {
        self.text_cache.retain(|_, v| v.is_recently_used());
        self.image_cache.trim();
    }
}

use iced::{Element, Program};

fn main() -> iced::Result {
    iced::application("Custom Renderer Test", update, view)
        .run()
}

fn update(state: &mut State, message: Message) {
    // ...
}

fn view(state: &State) -> Element<Message> {
    // Test various widgets
    column![
        text("Hello, World!"),
        button("Click me"),
        // ...
    ].into()
}

impl iced_graphics::compositor::Default for MyRenderer {
    type Compositor = MyCompositor;
}

use iced::Program;

fn main() -> iced::Result {
    MyProgram::run(Settings::default())
}