🎉 Add dominat color extractor

src/DominantColorExtractor.js

@@ -0,0 +1,177 @@
+//////////////////////////////////////////////////////////////////////////////////////////
+//          )                                                   (                       //
+//       ( /(   (  (               )    (       (  (  (         )\ )    (  (            //
+//       )\()) ))\ )(   (         (     )\ )    )\))( )\  (    (()/( (  )\))(  (        //
+//      ((_)\ /((_|()\  )\ )      )\  '(()/(   ((_)()((_) )\ )  ((_)))\((_)()\ )\       //
+//      | |(_|_))( ((_)_(_/(    _((_))  )(_))  _(()((_|_)_(_/(  _| |((_)(()((_|(_)      //
+//      | '_ \ || | '_| ' \))  | '  \()| || |  \ V  V / | ' \)) _` / _ \ V  V (_-<      //
+//      |_.__/\_,_|_| |_||_|   |_|_|_|  \_, |   \_/\_/|_|_||_|\__,_\___/\_/\_//__/      //
+//                                 |__/                                                 //
+//                       Copyright (c) 2021 Simon Schneegans                            //
+//          Released under the GPLv3 or later. See LICENSE file for details.            //
+//////////////////////////////////////////////////////////////////////////////////////////
+
+'use strict';
+
+//////////////////////////////////////////////////////////////////////////////////////////
+// https://github.com/home-sweet-gnome/dash-to-panel/blob/master/utils.js#L669
+// DominantColorExtractor is adapted from https://github.com/micheleg/dash-to-dock
+//////////////////////////////////////////////////////////////////////////////////////////
+
+let themeLoader                = null;
+let iconCacheMap               = new Map();
+const MAX_CACHED_ITEMS         = 1000;
+const BATCH_SIZE_TO_DELETE     = 50;
+const DOMINANT_COLOR_ICON_SIZE = 64;
+
+var DominantColorExtractor = class {
+
+  constructor(app) {
+    this._app = app;
+  }
+
+  // Try to get the pixel buffer for the current icon, if not fail gracefully
+  _getIconPixBuf() {
+    let iconTexture = this._app.create_icon_texture(16);
+
+    if (themeLoader === null) {
+      let ifaceSettings = new Gio.Settings({schema: 'org.gnome.desktop.interface'});
+
+      themeLoader = new Gtk.IconTheme(),
+      themeLoader.set_custom_theme(
+        ifaceSettings.get_string('icon-theme'));  // Make sure the correct theme is loaded
+    }
+
+    // Unable to load the icon texture, use fallback
+    if (iconTexture instanceof St.Icon === false) {
+      return null;
+    }
+
+    iconTexture = iconTexture.get_gicon();
+
+    // Unable to load the icon texture, use fallback
+    if (iconTexture === null) {
+      return null;
+    }
+
+    if (iconTexture instanceof Gio.FileIcon) {
+      // Use GdkPixBuf to load the pixel buffer from the provided file path
+      return GdkPixbuf.Pixbuf.new_from_file(iconTexture.get_file().get_path());
+    }
+
+    // Get the pixel buffer from the icon theme
+    if (iconTexture instanceof Gio.ThemedIcon) {
+      let icon_info =
+        themeLoader.lookup_icon(iconTexture.get_names()[0], DOMINANT_COLOR_ICON_SIZE, 0);
+      if (icon_info !== null) return icon_info.load_icon();
+    }
+
+    return null;
+  }
+
+  // The backlight color choosing algorithm was mostly ported to javascript from the
+  // Unity7 C++ source of Canonicals:
+  // https://bazaar.launchpad.net/~unity-team/unity/trunk/view/head:/launcher/LauncherIcon.cpp
+  // so it more or less works the same way.
+  _getColorPalette() {
+    if (iconCacheMap.get(this._app.get_id())) {
+      // We already know the answer
+      return iconCacheMap.get(this._app.get_id());
+    }
+
+    let pixBuf = this._getIconPixBuf();
+    if (pixBuf == null) return null;
+
+    let pixels = pixBuf.get_pixels(), offset = 0;
+
+    let total = 0, rTotal = 0, gTotal = 0, bTotal = 0;
+
+    let resample_y = 1, resample_x = 1;
+
+    // Resampling of large icons
+    // We resample icons larger than twice the desired size, as the resampling
+    // to a size s
+    // DOMINANT_COLOR_ICON_SIZE < s < 2*DOMINANT_COLOR_ICON_SIZE,
+    // most of the case exactly DOMINANT_COLOR_ICON_SIZE as the icon size is tipycally
+    // a multiple of it.
+    let width  = pixBuf.get_width();
+    let height = pixBuf.get_height();
+
+    // Resample
+    if (height >= 2 * DOMINANT_COLOR_ICON_SIZE)
+      resample_y = Math.floor(height / DOMINANT_COLOR_ICON_SIZE);
+
+    if (width >= 2 * DOMINANT_COLOR_ICON_SIZE)
+      resample_x = Math.floor(width / DOMINANT_COLOR_ICON_SIZE);
+
+    if (resample_x !== 1 || resample_y !== 1)
+      pixels = this._resamplePixels(pixels, resample_x, resample_y);
+
+    // computing the limit outside the for (where it would be repeated at each iteration)
+    // for performance reasons
+    let limit = pixels.length;
+    for (let offset = 0; offset < limit; offset += 4) {
+      let r = pixels[offset], g = pixels[offset + 1], b = pixels[offset + 2],
+          a = pixels[offset + 3];
+
+      let saturation = (Math.max(r, g, b) - Math.min(r, g, b));
+      let relevance  = 0.1 * 255 * 255 + 0.9 * a * saturation;
+
+      rTotal += r * relevance;
+      gTotal += g * relevance;
+      bTotal += b * relevance;
+
+      total += relevance;
+    }
+
+    total = total * 255;
+
+    let r = rTotal / total, g = gTotal / total, b = bTotal / total;
+
+    let hsv = ColorUtils.RGBtoHSV(r * 255, g * 255, b * 255);
+
+    if (hsv.s > 0.15) hsv.s = 0.65;
+    hsv.v = 0.90;
+
+    let rgb = ColorUtils.HSVtoRGB(hsv.h, hsv.s, hsv.v);
+
+    // Cache the result.
+    let backgroundColor = {
+      lighter: ColorUtils.colorLuminance(rgb.r, rgb.g, rgb.b, 0.2),
+      original: ColorUtils.colorLuminance(rgb.r, rgb.g, rgb.b, 0),
+      darker: ColorUtils.colorLuminance(rgb.r, rgb.g, rgb.b, -0.5)
+    };
+
+    if (iconCacheMap.size >= MAX_CACHED_ITEMS) {
+      // delete oldest cached values (which are in order of insertions)
+      let ctr = 0;
+      for (let key of iconCacheMap.keys()) {
+        if (++ctr > BATCH_SIZE_TO_DELETE) break;
+        iconCacheMap.delete(key);
+      }
+    }
+
+    iconCacheMap.set(this._app.get_id(), backgroundColor);
+
+    return backgroundColor;
+  }
+
+  // Downsample large icons before scanning for the backlight color to
+  // improve performance.
+  _resamplePixels(pixels, resampleX, resampleY) {
+    let resampledPixels = [];
+    // computing the limit outside the for (where it would be repeated at each iteration)
+    // for performance reasons
+    let limit = pixels.length / (resampleX * resampleY) / 4;
+    for (let i = 0; i < limit; i++) {
+      let pixel = i * resampleX * resampleY;
+
+      resampledPixels.push(pixels[pixel * 4]);
+      resampledPixels.push(pixels[pixel * 4 + 1]);
+      resampledPixels.push(pixels[pixel * 4 + 2]);
+      resampledPixels.push(pixels[pixel * 4 + 3]);
+    }
+
+    return resampledPixels;
+  }
+};