add initial support for converting images (by url) to ascii

src/toascii/models/image.clj

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+(ns toascii.models.image
+  "Largely based on the Claskii library: https://github.com/LauJensen/Claskii"
+  (:import (java.awt Color RenderingHints Graphics2D Image)
+           (java.awt.image BufferedImage)
+           (javax.swing ImageIcon)
+           (javax.imageio ImageIO)
+           (java.io File)
+           (java.net URL URLEncoder URI))
+  (:require [cemerick.url :as url]
+            [toascii.util :refer [query-param-url->java-url]])
+  (:use hiccup.core))
+
+(def ascii-chars [\# \A \@ \% \$ \+ \= \* \: \, \. \space])
+
+(defmacro get-properties [obj & properties]
+  (let [target (gensym)]
+    `(let [~target ~obj]
+       (vector ~@(for [property properties]
+                   `(~property ~target))))))
+
+(defn scale-image
+  "takes a source image specified by the uri (a filename or a URL) and scales it proportionally
+   using the new width, returning the newly scaled image."
+  [url new-width]
+  (let [^Image image (ImageIO/read url)
+        new-height   (* (/ new-width (.getWidth image))
+                        (.getHeight image))
+        scaled-image (BufferedImage. new-width new-height BufferedImage/TYPE_INT_RGB)
+        gfx2d        (doto (.createGraphics scaled-image)
+                       (.setRenderingHint RenderingHints/KEY_INTERPOLATION
+                                          RenderingHints/VALUE_INTERPOLATION_BILINEAR)
+                       (.drawImage image 0 0 new-width new-height nil)
+                       (.dispose))]
+    scaled-image))
+
+(defn ascii [^BufferedImage img x y color?]
+  (let [[red green blue] (get-properties (Color. (.getRGB img x y))
+                                         .getRed .getGreen .getBlue)
+        peak    (apply max [red green blue])
+        idx     (if (zero? peak)
+                  (dec (count ascii-chars))
+                  (dec (int (+ 1/2 (* (count ascii-chars) (/ peak 255))))))
+        output  (nth ascii-chars (if (pos? idx) idx 0))	]
+    (if color?
+      (html [:span {:style (format "color: rgb(%s,%s,%s);" red green blue)} output])
+      output)))
+
+(defn convert-image [url w color?]
+  (let [java-url         (query-param-url->java-url url)
+        ^Image raw-image (scale-image java-url w)
+        ascii-image      (->> (for [y (range (.getHeight raw-image))
+                                    x (range (.getWidth  raw-image))]
+                                (ascii raw-image x y color?))
+                              (partition w))
+        output           (->> ascii-image
+                              (interpose (if color? "<BR/>" \newline))
+                              flatten)]
+    (if color?
+      (html [:pre {:style "font-size:5pt; letter-spacing:1px;
+                           line-height:4pt; font-weight:bold;"}
+             output])
+      (println output))))

src/toascii/routes/api/image.clj

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+(ns toascii.routes.api.image
+  (:require [clojure.string :as str]
+            [liberator.core :refer [defresource]]
+            [compojure.core :refer [ANY]]
+            [toascii.route-utils :refer [register-routes]]
+            [toascii.models.image :refer [convert-image]]))
+
+(defresource render-image [{:keys [url width color format] :as params}]
+  :media-type-available?
+  (fn [ctx]
+    (let [type (condp = format
+                 "html" "text/html"
+                 "text" "text/plain"
+                 "text/html")]
+      {:representation {:media-type type}}))
+  :malformed?
+  (fn [_]
+    (cond
+      (str/blank? url) {:error "Missing image url"}))
+  :handle-ok
+  (fn [ctx]
+    (let [rendered (convert-image url 64 true)]
+      (if (= "text/html" (get-in ctx [:representation :media-type]))
+        rendered
+        rendered)))
+  :handle-malformed
+  (fn [ctx]
+    (:error ctx)))
+
+(register-routes api-image-routes
+  (ANY "/api/image" {params :params} (render-image params)))