From 4004c0cb0d6cb8f9980716e30f3544b4b02cf575 Mon Sep 17 00:00:00 2001
From: alexbrekken <brekkal@gmail.com>
Date: Fri, 20 Oct 2017 16:42:18 -0500
Subject: [PATCH] Added ability to partially un-highlight selected text.

---
 src/modules/rangy-highlighter.js | 37 ++++++++++++++++++
 test/highlightertests.js         | 67 +++++++++++++++++++++++++++++++-
 2 files changed, 103 insertions(+), 1 deletion(-)

diff --git a/src/modules/rangy-highlighter.js b/src/modules/rangy-highlighter.js
index 4527d5d6..3b7dfcfd 100644
--- a/src/modules/rangy-highlighter.js
+++ b/src/modules/rangy-highlighter.js
@@ -291,6 +291,43 @@ rangy.createModule("Highlighter", ["ClassApplier"], function(api, module) {
             }
         },
 
+        /**
+         * Removes all highlights for the currently selected text and preserves any existing highlights
+         * that were partially selected.
+         */
+        removeHighlightsFromSelection: function(containerElementId) {
+            var _self = this;
+            var doc = this.doc;
+            var currentSelection = api.getSelection(doc);
+            var scope = getContainerElement(currentSelection.win.document, containerElementId);
+            var charRanges = [];
+
+            forEach(currentSelection.getAllRanges(), function(range) {
+                var charRangeScoped = _self.converter.rangeToCharacterRange(range, scope);
+                charRanges.push(charRangeScoped);
+            });
+
+            var newHighlights = [];
+            var intersectingHighlights = this.getHighlightsInSelection(currentSelection);
+            if (intersectingHighlights.length > 0) {
+                forEach(charRanges, function(charRange) {
+                    //for each charRange in the selection, see if it intersects with any existing highlights
+                    //and preserve unselected portions of existing highlights
+                    forEach(intersectingHighlights, function(highlight) {
+                        var complements = highlight.characterRange.getComplements(charRange);
+                        forEach(complements, function(complement) {
+                            newHighlights.push(new Highlight(doc, complement, highlight.classApplier, _self.converter, null, containerElementId));
+                        });
+                    });
+                });
+            }
+            this.removeHighlights(intersectingHighlights);
+            forEach(newHighlights, function(highlight) {
+                highlight.apply();
+                _self.highlights.push(highlight);
+            });
+        },
+
         removeAllHighlights: function() {
             this.removeHighlights(this.highlights);
         },
diff --git a/test/highlightertests.js b/test/highlightertests.js
index d95162df..c21b5605 100644
--- a/test/highlightertests.js
+++ b/test/highlightertests.js
@@ -30,4 +30,69 @@ xn.test.suite("Highlighter module tests", function(s) {
         highlighter.highlightSelection("c1", { selection: rangy.getSelection() });
     });
 
-}, false);
+    s.test("partial unhighlight test", function(t) {
+        var applier = rangy.createClassApplier("yellow");
+        var highlighter = rangy.createHighlighter();
+        highlighter.addClassApplier(applier);
+
+        var testEl = document.getElementById("test");
+        var range = rangyTestUtils.createRangeInHtml(testEl, '[one two three four]');
+        range.select();
+
+        highlighter.highlightSelection("yellow");
+
+        t.assertEquals(highlighter.highlights[0].characterRange.start, 9);
+        t.assertEquals(highlighter.highlights[0].characterRange.end, 27);
+
+        var range2 = rangyTestUtils.createRangeInHtml(testEl, '[one two] three four');
+        range2.select();
+
+        highlighter.removeHighlightsFromSelection();
+
+        t.assertEquals(highlighter.highlights[0].characterRange.start, 16);
+        t.assertEquals(highlighter.highlights[0].characterRange.end, 27);
+    });
+
+    s.test("partial unhighlight test 2", function(t) {
+        var yellow = rangy.createClassApplier("yellow");
+        var green = rangy.createClassApplier("green");
+        var highlighter = rangy.createHighlighter();
+        highlighter.addClassApplier(yellow);
+        highlighter.addClassApplier(green);
+
+        var testEl = document.getElementById("test");
+        var range = rangyTestUtils.createRangeInHtml(testEl, '[one two three four]');
+        range.select();
+
+        highlighter.highlightSelection("yellow");
+
+        var range2 = rangyTestUtils.createRangeInHtml(testEl, '[one two] three four');
+        range2.select();
+        highlighter.highlightSelection("green");
+
+        //yellow
+        t.assertEquals(highlighter.highlights[0].classApplier.className, "yellow");
+        t.assertEquals(highlighter.highlights[0].characterRange.start, 16);
+        t.assertEquals(highlighter.highlights[0].characterRange.end, 27);
+        //green
+        t.assertEquals(highlighter.highlights[1].classApplier.className, "green");
+        t.assertEquals(highlighter.highlights[1].characterRange.start, 9);
+        t.assertEquals(highlighter.highlights[1].characterRange.end, 16);
+
+        var range3 = rangyTestUtils.createRangeInHtml(testEl, 'one [two three] four');
+        range3.select();
+
+        highlighter.removeHighlightsFromSelection();
+
+        //yellow
+        t.assertEquals(highlighter.highlights[0].classApplier.className, "yellow");
+        t.assertEquals(highlighter.highlights[0].characterRange.start, 22);
+        t.assertEquals(highlighter.highlights[0].characterRange.end, 27);
+        //green
+        t.assertEquals(highlighter.highlights[1].classApplier.className, "green");
+        t.assertEquals(highlighter.highlights[1].characterRange.start, 9);
+        t.assertEquals(highlighter.highlights[1].characterRange.end, 13);
+
+    });
+
+}, false);
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