gorm/gitbook/lib/output/assets-inliner.js
2016-02-26 22:05:59 +08:00

141 lines
4.0 KiB
JavaScript

var util = require('util');
var path = require('path');
var crc = require('crc');
var FolderOutput = require('./folder')();
var Promise = require('../utils/promise');
var fs = require('../utils/fs');
var imagesUtil = require('../utils/images');
var location = require('../utils/location');
var DEFAULT_ASSETS_FOLDER = 'assets';
/*
Mixin to inline all the assets in a book:
- Outline <svg> tags
- Download remote images
- Convert .svg images as png
*/
module.exports = function assetsInliner(Base) {
Base = Base || FolderOutput;
function AssetsInliner() {
Base.apply(this, arguments);
// Map of svg already converted
this.svgs = {};
this.inlineSvgs = {};
// Map of images already downloaded
this.downloaded = {};
}
util.inherits(AssetsInliner, Base);
// Output a SVG buffer as a file
AssetsInliner.prototype.onOutputSVG = function(page, svg) {
this.log.debug.ln('output svg from', page.path);
// 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()
// Download file if external
.then(function() {
if (!location.isExternal(src)) return;
return that.downloadAsset(src)
.then(function(_asset) {
src = '/' + _asset;
});
})
.then(function() {
// Resolve src to a relative filepath to the book's root
src = page.resolveLocal(src);
// Already a PNG/JPG/.. ?
if (path.extname(src).toLowerCase() != '.svg') {
return src;
}
// Convert SVG to PNG
return that.convertSVGFile(that.resolve(src));
})
// Return relative path from the page
.then(function(filename) {
return page.relative(filename);
});
};
// 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]);
var that = this;
var ext = path.extname(src);
var hash = crc.crc32(src).toString(16);
// Create new file
return this.createNewFile(DEFAULT_ASSETS_FOLDER, hash + ext)
.then(function(filename) {
that.downloaded[src] = filename;
that.log.debug.ln('downloading asset', src);
return fs.download(src, that.resolve(filename))
.thenResolve(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]);
var that = this;
var hash = crc.crc32(src).toString(16);
// Create new file
return this.createNewFile(DEFAULT_ASSETS_FOLDER, hash + '.png')
.then(function(filename) {
that.svgs[src] = filename;
return imagesUtil.convertSVGToPNG(src, that.resolve(filename))
.thenResolve(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);
// Already converted?
if (this.inlineSvgs[hash]) return Promise(this.inlineSvgs[hash]);
return this.createNewFile(DEFAULT_ASSETS_FOLDER, hash + '.png')
.then(function(filename) {
that.inlineSvgs[hash] = filename;
return imagesUtil.convertSVGBufferToPNG(buf, that.resolve(filename))
.thenResolve(filename);
});
};
return AssetsInliner;
};