Move ggez example to tour

examples/tour/renderer/image.rs

@@ -0,0 +1,51 @@
+use super::Renderer;
+
+use ggez::{graphics, nalgebra};
+use iced::image;
+
+impl image::Renderer<graphics::Image> for Renderer<'_> {
+    fn node(
+        &self,
+        style: iced::Style,
+        image: &graphics::Image,
+        width: Option<u16>,
+        height: Option<u16>,
+        _source: Option<iced::Rectangle<u16>>,
+    ) -> iced::Node {
+        let aspect_ratio = image.width() as f32 / image.height() as f32;
+
+        let style = match (width, height) {
+            (Some(width), Some(height)) => style.width(width).height(height),
+            (Some(width), None) => style
+                .width(width)
+                .height((width as f32 / aspect_ratio).round() as u16),
+            (None, Some(height)) => style
+                .height(height)
+                .width((height as f32 * aspect_ratio).round() as u16),
+            (None, None) => style.width(image.width()).height(image.height()),
+        };
+
+        iced::Node::new(style)
+    }
+
+    fn draw(
+        &mut self,
+        image: &graphics::Image,
+        bounds: iced::Rectangle,
+        _source: Option<iced::Rectangle<u16>>,
+    ) {
+        // We should probably use batches to draw images efficiently and keep
+        // draw side-effect free, but this is good enough for the example.
+        graphics::draw(
+            self.context,
+            image,
+            graphics::DrawParam::new()
+                .dest(nalgebra::Point2::new(bounds.x, bounds.y))
+                .scale(nalgebra::Vector2::new(
+                    bounds.width / image.width() as f32,
+                    bounds.height / image.height() as f32,
+                )),
+        )
+        .expect("Draw image");
+    }
+}