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axum_server/src/picture_generator/mod.rs

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+/*!
+This is going to be an attempt for creating HTML markup for serving and generating images
+for the most common PIXEL_DENSITIES.
+It should create `<picture>` elements with following features:
+
+- least amount of needed arguments
+- for each pixel density it should have a definition in `srcset`
+- create a `avif` type for the image for each pixel_density
+- create an image in the original format for each pixel_density
+- support case of `svg` therefore not doing any of the pixel_density logic
+
+These features might be considered later:
+- support case for art direction (different pictures for different screen sizes)
+
+
+TODO: figure wether `height` or `width` have to be known ahead of time
+
+## Usage
+
+It can be used from the rust code
+It should be used from the templates as well
+*/
+
+pub mod picture_markup_generator;

axum_server/src/picture_generator/picture_markup_generator.rs

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+use std::path::Path;
+
+
+pub const PIXEL_DENSITIES: [f64; 5] = [1., 1.5, 2., 3., 4.];
+
+#[derive(Debug, PartialEq)]
+pub enum ExportFormat {
+    JPG,
+    AVIF,
+    SVG,
+    PNG,
+}
+
+pub fn generate_picture_markup(orig_img_path: &str, width: u32, height: u32) -> String {
+    let exported_formats = get_export_formats(&orig_img_path);
+
+    for export_format in exported_formats {
+
+        // TODO get original img resolution and determine how many exports are going to be needed
+        // let orig_img_resolution = 
+        // let resolutions = get_resolutions(width, height);
+
+        let resolutions = vec![(300, 200), (450, 300), (600, 400), (900, 600), (1200, 800)];
+        let generated_paths = get_generated_paths(orig_img_path, resolutions);
+        
+    }
+    let result = format!("<picture></picture>");
+    result
+}
+
+fn get_generated_paths(orig_img_path: &str, &resolutions: Vec<(i32, i32)>) -> Vec<String> {
+    
+}
+
+#[test]
+fn test_get_generated_paths {
+    let orig_img_path = "./images/uploads/img_name.jpg";
+    let resolutions = vec![(300, 200), (450, 300), (600, 400), (900, 600), (1200, 800)];
+    assert_eq!(get_generated_paths(orig_img_path,&resolutions), vec![])
+}
+
+
+// TODO get original img resolution and determine how many exports are going to be needed
+fn get_resolutions(orig_width: i32, orig_height: i32, width: i32, height: i32) -> Vec<(i32, i32)> {
+    todo!("get original img resolution and determine how many exports are going to be needed")
+}
+
+fn generate_srcset(new_path: &str, width: u32, height: u32) -> &str {
+    todo!("generate srcset")
+}
+
+fn get_export_formats(orig_img_path: &str) -> Vec<ExportFormat> {
+    let path = Path::new(&orig_img_path).extension().and_then(|ext| ext.to_str());
+
+    match path {
+        Some("jpg" | "jpeg") => vec![ExportFormat::AVIF, ExportFormat::JPG]
+        Some("png") => vec![ExportFormat::AVIF, ExportFormat::PNG]
+        Some(_) | None => vec![]
+    }
+}
+
+#[test]
+fn test_get_export_formats {
+    assert_eq!(get_export_formats("./images/uploads/img_name.jpg"), vec![ExportFormat::AVIF, ExportFormat::JPG])
+}
+#[test]
+fn test_generate_srcset() {
+    let width = 400;
+    let height = 200;
+    let orig_img_path = "./images/uploads/img_name.jpg";
+    let result = "./generated_images/images/uploads/img_name_400x200.avif 1x, ./generated_images/images/uploads/img_name_500x300.avif 1.5x, ./generated_images/images/uploads/img_name_800x400.avif 2x, ./generated_images/images/uploads/img_name_1200x600.avif 3x, ./generated_images/images/uploads/img_name_1600x800.avif 4x";
+    assert_eq!(generate_srcset(orig_img_path, width, height), result)
+}
+
+#[test]
+fn test_generate_picture_markup() {
+    let width = 300;
+    let height = 200;
+    let orig_img_path = "./images/uploads/img_name.jpg";
+    let result = r#"""
+        <picture>
+            <source
+                srcset="./generated_images/images/uploads/img_name_300x200.avif 1x, ./generated_images/images/uploads/img_name_450x300.avif 1.5x, ./generated_images/images/uploads/img_name_600x400.avif 2x, ./generated_images/images/uploads/img_name_900x600.avif 3x, ./generated_images/images/uploads/img_name_1200x800.avif 4x"
+                type="image/avif"
+            > 
+            <source
+                srcset="./generated_images/images/uploads/img_name_300x200.jpg 1x, ./generated_images/images/uploads/img_name_450x300.jpg 1.5x, ./generated_images/images/uploads/img_name_600x400.jpg 2x, ./generated_images/images/uploads/img_name_900x600.jpg 3x, ./generated_images/images/uploads/img_name_1200x800.jpg 4x"
+                type="image/jpeg"
+            >
+            <img
+                src="./generated_images/images/uploads/img_name_300x200.jpg"
+                width="300"
+                height="200"
+            >
+        </picture>
+    """#;
+    assert_eq!(
+        generate_picture_markup(orig_img_path, width, height),
+        result
+    );
+}