Add image filters

Signed-off-by: trivernis <trivernis@protonmail.com>

README.md

@@ -270,7 +270,7 @@ Hide a section (including subsections) in the TOC
 #[toc-hidden] Section
 
 Set the size of an image
-!(url)[width = 42% height=auto]
+!(url)[width = 42%, height=auto, grayscale, brightness=10, contrast=1.2]
 
 Set the source of a quote
 [author=Me date=[[date]] display="{{author}} - {{date}}"]> It's me

src/elements/mod.rs

@@ -710,6 +710,8 @@ impl Placeholder {
 pub trait Metadata {
     fn get_bool(&self, key: &str) -> bool;
     fn get_string(&self, key: &str) -> Option<String>;
+    fn get_float(&self, key: &str) -> Option<f64>;
+    fn get_integer(&self, key: &str) -> Option<i64>;
     fn get_string_map(&self) -> HashMap<String, String>;
 }
 
@@ -730,6 +732,24 @@ impl Metadata for InlineMetadata {
         }
     }
 
+    fn get_float(&self, key: &str) -> Option<f64> {
+        if let Some(MetadataValue::Float(f)) = self.data.get(key) {
+            Some(*f)
+        } else if let Some(MetadataValue::Integer(i)) = self.data.get(key) {
+            Some(*i as f64)
+        } else {
+            None
+        }
+    }
+
+    fn get_integer(&self, key: &str) -> Option<i64> {
+        if let Some(MetadataValue::Integer(i)) = self.data.get(key) {
+            Some(*i)
+        } else {
+            None
+        }
+    }
+
     fn get_string_map(&self) -> HashMap<String, String> {
         let mut string_map = HashMap::new();
         for (k, v) in &self.data {

src/parser/inline.rs

@@ -140,21 +140,24 @@ impl ParseInline for Parser {
         self.ctm.seek_one()?;
 
         if let Ok(url) = self.parse_url(true) {
-            let metadata = if let Ok(meta) = self.parse_inline_metadata() {
-                Some(meta)
-            } else {
-                None
-            };
+            let metadata = self.parse_inline_metadata().ok();
+
             let path = url.url.clone();
+            let pending_image = self
+                .options
+                .document
+                .images
+                .lock()
+                .add_image(PathBuf::from(path));
+
+            if let Some(meta) = &metadata {
+                pending_image.lock().assign_from_meta(meta)
+            }
+
             Ok(Image {
                 url,
                 metadata,
-                image_data: self
-                    .options
-                    .document
-                    .images
-                    .lock()
-                    .add_image(PathBuf::from(path)),
+                image_data: pending_image,
             })
         } else {
             Err(self.ctm.rewind_with_error(start_index))
@@ -502,6 +505,7 @@ impl ParseInline for Parser {
 
         self.ctm.seek_any(&INLINE_WHITESPACE)?;
         let mut value = MetadataValue::Bool(true);
+
         if self.ctm.check_char(&EQ) {
             self.ctm.seek_one()?;
             self.ctm.seek_any(&INLINE_WHITESPACE)?;

src/utils/image_converting.rs

@@ -1,3 +1,4 @@
+use crate::elements::Metadata;
 use crate::utils::caching::CacheStorage;
 use crate::utils::downloads::download_path;
 use image::imageops::FilterType;
@@ -60,6 +61,9 @@ pub struct PendingImage {
     pub data: Option<Vec<u8>>,
     cache: CacheStorage,
     pub mime: Mime,
+    brightness: Option<i32>,
+    contrast: Option<f32>,
+    grayscale: bool,
 }
 
 impl PendingImage {
@@ -71,9 +75,22 @@ impl PendingImage {
             data: None,
             cache: CacheStorage::new(),
             mime,
+            brightness: None,
+            contrast: None,
+            grayscale: false,
         }
     }
 
+    pub fn assign_from_meta<M: Metadata>(&mut self, meta: &M) {
+        if let Some(brightness) = meta.get_integer("brightness") {
+            self.brightness = Some(brightness as i32);
+        }
+        if let Some(contrast) = meta.get_float("contrast") {
+            self.contrast = Some(contrast as f32);
+        }
+        self.grayscale = meta.get_bool("grayscale");
+    }
+
     /// Converts the image to the specified target format (specified by target_extension)
     pub fn convert(
         &mut self,
@@ -87,6 +104,7 @@ impl PendingImage {
                     .and_then(|extension| ImageFormat::from_extension(extension))
             })
             .unwrap_or(ImageFormat::Png);
+
         let output_path = self.get_output_path(format, target_size);
         self.mime = get_mime(&output_path);
 
@@ -118,6 +136,18 @@ impl PendingImage {
                 image = image.resize(width, height, FilterType::Lanczos3);
             }
         }
+
+        if let Some(brightness) = self.brightness {
+            image = image.brighten(brightness);
+        }
+
+        if let Some(contrast) = self.contrast {
+            image = image.adjust_contrast(contrast);
+        }
+        if self.grayscale {
+            image = image.grayscale();
+        }
+
         let data = Vec::new();
         let mut writer = Cursor::new(data);
 
@@ -155,7 +185,14 @@ impl PendingImage {
         if let Some(target_size) = target_size {
             file_name += &*format!("-{}-{}", target_size.0, target_size.1);
         }
-        file_name += format!("-{}-converted", type_name).as_str();
+        if let Some(b) = self.brightness {
+            file_name += &*format!("-{}", b);
+        }
+        if let Some(c) = self.contrast {
+            file_name += &*format!("-{}", c);
+        }
+
+        file_name += format!("-{}", type_name).as_str();
         path.set_file_name(file_name);
         path.set_extension(extension);