1 files changed, 92 insertions, 89 deletions
diff --git a/lib/output/assets-inliner.js b/lib/output/assets-inliner.js
index 9733505..b5d076e 100644
--- a/lib/output/assets-inliner.js
+++ b/lib/output/assets-inliner.js
@@ -2,7 +2,7 @@ var util = require('util');
 var path = require('path');
 var crc = require('crc');
 
-var FolderOutput = require('./folder');
+var FolderOutput = require('./folder')();
 var Promise = require('../utils/promise');
 var fs = require('../utils/fs');
 var imagesUtil = require('../utils/images');
@@ -11,123 +11,126 @@ var location = require('../utils/location');
 var DEFAULT_ASSETS_FOLDER = 'assets';
 
 /*
-Utility mixin to inline all the assets in a book:
+Mixin to inline all the assets in a book:
     - Outline <svg> tags
     - Download remote images
     - Convert .svg images as png
 */
 
-function AssetsInliner() {
-    FolderOutput.apply(this, arguments);
+module.exports = function assetsInliner(Base) {
+    Base = Base || FolderOutput;
 
-    // Map of svg already converted
-    this.svgs = {};
-    this.inlineSvgs = {};
+    function AssetsInliner() {
+        Base.apply(this, arguments);
 
-    // Map of images already downloaded
-    this.downloaded = {};
-}
-util.inherits(AssetsInliner, FolderOutput);
+        // Map of svg already converted
+        this.svgs = {};
+        this.inlineSvgs = {};
 
-// Output a SVG buffer as a file
-AssetsInliner.prototype.onOutputSVG = function(page, svg) {
-    this.log.debug.ln('output svg from', page.path);
+        // Map of images already downloaded
+        this.downloaded = {};
+    }
+    util.inherits(AssetsInliner, Base);
 
-    // Convert svg buffer to a png file
-    return this.convertSVGBuffer(svg)
+    // Output a SVG buffer as a file
+    AssetsInliner.prototype.onOutputSVG = function(page, svg) {
+        this.log.debug.ln('output svg from', page.path);
 
-        // Return relative path from the page
-        .then(function(filename) {
-            return page.relative('/' + filename);
-        });
-};
+        // Convert svg buffer to a png file
+        return this.convertSVGBuffer(svg)
 
+            // Return relative path from the page
+            .then(function(filename) {
+                return page.relative('/' + filename);
+            });
+    };
 
-// Output an image as a file
-AssetsInliner.prototype.onOutputImage = function(page, src) {
-    var that = this;
 
-    return Promise()
+    // Output an image as a file
+    AssetsInliner.prototype.onOutputImage = function(page, src) {
+        var that = this;
 
-    // Download file if external
-    .then(function() {
-        if (!location.isExternal(src)) return;
+        return Promise()
 
-        return that.downloadAsset(src)
-        .then(function(_asset) {
-            src = '/' + _asset;
-        });
+        // Download file if external
+        .then(function() {
+            if (!location.isExternal(src)) return;
 
-    })
-    .then(function() {
-        if (path.extname(src).toLowerCase() != '.svg') {
-            return src;
-        }
+            return that.downloadAsset(src)
+            .then(function(_asset) {
+                src = '/' + _asset;
+            });
 
-        // Convert SVG to PNG
-        return that.convertSVGFile(that.resolveForPage(page, src));
-    })
+        })
+        .then(function() {
+            if (path.extname(src).toLowerCase() != '.svg') {
+                return src;
+            }
 
-    // Return relative path from the page
-    .then(function(filename) {
-        return page.relative('/' + filename);
-    });
-};
+            // Convert SVG to PNG
+            return that.convertSVGFile(that.resolveForPage(page, src));
+        })
 
-// Download an asset if not already download; returns the output file
-AssetsInliner.prototype.downloadAsset = function(src) {
-    if (this.downloaded[src]) return Promise(this.downloaded[src]);
+        // Return relative path from the page
+        .then(function(filename) {
+            return page.relative('/' + filename);
+        });
+    };
 
-    var that = this;
-    var ext = path.extname(src);
-    var hash = crc.crc32(src).toString(16);
+    // Download an asset if not already download; returns the output file
+    AssetsInliner.prototype.downloadAsset = function(src) {
+        if (this.downloaded[src]) return Promise(this.downloaded[src]);
 
-    // Create new file
-    return this.createNewFile(DEFAULT_ASSETS_FOLDER, hash + ext)
-    .then(function(filename) {
-        that.downloaded[src] = filename;
+        var that = this;
+        var ext = path.extname(src);
+        var hash = crc.crc32(src).toString(16);
 
-        that.log.debug.ln('downloading asset', src);
-        return fs.download(src, that.resolve(filename))
-        .thenResolve(filename);
-    });
-};
+        // Create new file
+        return this.createNewFile(DEFAULT_ASSETS_FOLDER, hash + ext)
+        .then(function(filename) {
+            that.downloaded[src] = filename;
 
-// Convert a .svg into an .png
-// Return the output filename for the .png
-AssetsInliner.prototype.convertSVGFile = function(src) {
-    if (this.svgs[src]) return Promise(this.svgs[src]);
+            that.log.debug.ln('downloading asset', src);
+            return fs.download(src, that.resolve(filename))
+            .thenResolve(filename);
+        });
+    };
 
-    var that = this;
-    var hash = crc.crc32(src).toString(16);
+    // Convert a .svg into an .png
+    // Return the output filename for the .png
+    AssetsInliner.prototype.convertSVGFile = function(src) {
+        if (this.svgs[src]) return Promise(this.svgs[src]);
 
-    // Create new file
-    return this.createNewFile(DEFAULT_ASSETS_FOLDER, hash + '.png')
-    .then(function(filename) {
-        that.svgs[src] = filename;
+        var that = this;
+        var hash = crc.crc32(src).toString(16);
 
-        return imagesUtil.convertSVGToPNG(src, that.resolve(filename))
-        .thenResolve(filename);
-    });
-};
+        // Create new file
+        return this.createNewFile(DEFAULT_ASSETS_FOLDER, hash + '.png')
+        .then(function(filename) {
+            that.svgs[src] = filename;
 
-// Convert an inline svg into an .png
-// Return the output filename for the .png
-AssetsInliner.prototype.convertSVGBuffer = function(buf) {
-    var that = this;
-    var hash = crc.crc32(buf).toString(16);
+            return imagesUtil.convertSVGToPNG(src, that.resolve(filename))
+            .thenResolve(filename);
+        });
+    };
 
-    // Already converted?
-    if (this.inlineSvgs[hash]) return Promise(this.inlineSvgs[hash]);
+    // Convert an inline svg into an .png
+    // Return the output filename for the .png
+    AssetsInliner.prototype.convertSVGBuffer = function(buf) {
+        var that = this;
+        var hash = crc.crc32(buf).toString(16);
 
-    return this.createNewFile(DEFAULT_ASSETS_FOLDER, hash + '.png')
-    .then(function(filename) {
-        that.inlineSvgs[hash] = filename;
+        // Already converted?
+        if (this.inlineSvgs[hash]) return Promise(this.inlineSvgs[hash]);
 
-        return imagesUtil.convertSVGBufferToPNG(buf, that.resolve(filename))
-        .thenResolve(filename);
-    });
-};
+        return this.createNewFile(DEFAULT_ASSETS_FOLDER, hash + '.png')
+        .then(function(filename) {
+            that.inlineSvgs[hash] = filename;
 
+            return imagesUtil.convertSVGBufferToPNG(buf, that.resolve(filename))
+            .thenResolve(filename);
+        });
+    };
 
-module.exports = AssetsInliner;
+    return AssetsInliner;
+};