From ae31f18a9dc1eb5da3582f232e057498ca90322e Mon Sep 17 00:00:00 2001
From: NotsayJustdo <709444814@qq.com>
Date: Wed, 3 Apr 2019 16:08:15 +0800
Subject: [PATCH] specify fontFamily to filter fonts

if many fonts in stylesheets, dom-to-image will download all fonts, it will cause some problems: 1. waiting long time to load all fonts  2. use large computer memories, maybe make the browser breakdown. I suggest to add fontFamily option for user, user can specify they use fontFamily, it will avoid that problems!
---
 src/dom-to-image.js | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/dom-to-image.js b/src/dom-to-image.js
index 27201ac9..ed42631f 100644
--- a/src/dom-to-image.js
+++ b/src/dom-to-image.js
@@ -135,6 +135,8 @@
     }
 
     function copyOptions(options) {
+        // get user specifiy fontFamily
+        domtoimage.impl.options.fontFamily = options.fontFamily || []
         // Copy options to impl options for use in impl
         if(typeof(options.imagePlaceholder) === 'undefined') {
             domtoimage.impl.options.imagePlaceholder = defaultOptions.imagePlaceholder;
@@ -677,9 +679,24 @@
 
             function getCssRules(styleSheets) {
                 var cssRules = [];
+                let flag = false;
                 styleSheets.forEach(function (sheet) {
                     try {
-                        util.asArray(sheet.cssRules || []).forEach(cssRules.push.bind(cssRules));
+                        util.asArray(sheet.cssRules || []).forEach(rule => {
+                            flag = false
+                            if (rule.cssText.indexOf('@font-face') !== -1) {
+                                // filter fonts by specific fontFamily to void download all fonts
+                                for (let i = 0; domtoimage.impl.options.fontFamily[i]; i++) {
+                                    if (rule.cssText.indexOf(domtoimage.impl.options.fontFamily[i]) !== -1) {
+                                        flag = true
+                                        break
+                                    }
+                                }
+                            }
+                            if (flag) {
+                                cssRules.push(rule)
+                            }
+                        });
                     } catch (e) {
                         console.log('Error while reading CSS rules from ' + sheet.href, e.toString());
                     }