refactor: restructure project into a workspace by introducing a plugin API crate and modularizing individual plugin definitions.

plugins/image-ascii/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "convertis-image-ascii"
+build = "../../plugin-build.rs"
+version.workspace = true
+edition.workspace = true
+authors.workspace = true
+license.workspace = true
+repository.workspace = true
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+convertis-plugin-api.workspace = true
+image.workspace = true

plugins/image-ascii/src/lib.rs

@@ -0,0 +1,96 @@
+// Copyright (C) 2026 Elias Wendland <eliaswendland@pm.me>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, version 3 exclusively.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+use convertis_plugin_api::{Conversion, ConversionRequest, OptionSpec, Plugin, PluginMetadata};
+const FORMATS: &[&str] = &["png", "jpeg", "gif", "webp", "bmp", "tiff", "ico"];
+struct ImageAscii;
+
+impl Plugin for ImageAscii {
+    fn metadata(&self) -> PluginMetadata {
+        PluginMetadata {
+            id: "image-ascii".into(),
+            package: "convertis-image-ascii".into(),
+            description: "Render images as ASCII text".into(),
+            conversions: FORMATS
+                .iter()
+                .map(|from| Conversion::file(from, "text", (255, 180, 230)))
+                .collect(),
+            options: vec![
+                OptionSpec {
+                    name: "width".into(),
+                    help: "Output width in characters".into(),
+                    default: Some("80".into()),
+                },
+                OptionSpec {
+                    name: "characters".into(),
+                    help: "Dark-to-light character ramp".into(),
+                    default: Some("@%#*+=-:. ".into()),
+                },
+                OptionSpec {
+                    name: "invert".into(),
+                    help: "Reverse the character ramp".into(),
+                    default: Some("false".into()),
+                },
+            ],
+        }
+    }
+
+    fn convert(&self, request: &ConversionRequest) -> Result<(), String> {
+        let image = image::open(&request.input).map_err(|error| error.to_string())?;
+        let width: u32 = request
+            .options
+            .get("width")
+            .map(String::as_str)
+            .unwrap_or("80")
+            .parse()
+            .map_err(|_| "width must be a positive integer")?;
+        if width == 0 {
+            return Err("width must be greater than zero".into());
+        }
+        let height = ((image.height() as f32 / image.width() as f32) * width as f32 * 0.5)
+            .round()
+            .max(1.0) as u32;
+        let grayscale = image
+            .resize_exact(width, height, image::imageops::FilterType::Triangle)
+            .to_luma8();
+        let mut ramp: Vec<char> = request
+            .options
+            .get("characters")
+            .map(String::as_str)
+            .unwrap_or("@%#*+=-:. ")
+            .chars()
+            .collect();
+        if ramp.len() < 2 {
+            return Err("characters must contain at least two characters".into());
+        }
+        if request
+            .options
+            .get("invert")
+            .is_some_and(|value| value == "true")
+        {
+            ramp.reverse();
+        }
+        let mut output = String::with_capacity((width as usize + 1) * height as usize);
+        for y in 0..height {
+            for x in 0..width {
+                let value = grayscale.get_pixel(x, y)[0] as usize;
+                output.push(ramp[value * (ramp.len() - 1) / 255]);
+            }
+            output.push('\n');
+        }
+        std::fs::write(&request.output, output).map_err(|error| error.to_string())
+    }
+}
+
+convertis_plugin_api::export_plugin!(ImageAscii, "image-ascii");