Clip the start position when performing SVG text queries

If a text query straddles multiple line boxes, only the first would be considered, because |startPosition| would end up being negative. Instead clip the character range to [0) (the following functions will clip against the end position) and only reject ranges that are empty i.e. that appear before the current fragment (logically.) BUG=353462 Review URL: https://codereview.chromium.org/206663003 git-svn-id: svn://svn.chromium.org/blink/trunk@169682 bbb929c8-8fbe-4397-9dbb-9b2b20218538

Clip the start position when performing SVG text queries
If a text query straddles multiple line boxes, only the first would be considered, because |startPosition| would end up being negative. Instead clip the character range to [0) (the following functions will clip against the end position) and only reject ranges that are empty i.e. that appear before the current fragment (logically.) BUG=353462 Review URL: https://codereview.chromium.org/206663003 git-svn-id: svn://svn.chromium.org/blink/trunk@169682 bbb929c8-8fbe-4397-9dbb-9b2b20218538
e6858792 · fs@opera.com · 6c5b3194 · e6858792 · e6858792 · e6858792
Commit e6858792 authored Mar 20, 2014 by fs@opera.com
3 changed files
--- a/third_party/WebKit/LayoutTests/svg/text/text-getSubStringLength-expected.txt
+++ b/third_party/WebKit/LayoutTests/svg/text/text-getSubStringLength-expected.txt
+W3C نشاط
+AB
+ This is a testharness.js-based test.
+PASS SVGTextContentElement.getSubStringLength, BiDi. 
+PASS SVGTextContentElement.getSubStringLength, multiple text-chunks. 
+Harness: the test ran to completion.
+
--- a/third_party/WebKit/LayoutTests/svg/text/text-getSubStringLength.html
+++ b/third_party/WebKit/LayoutTests/svg/text/text-getSubStringLength.html
+<!DOCTYPE html>
+<title>SVGTextContentElement.getSubStringLength</title>
+<script src="../../resources/testharness.js"></script>
+<script src="../../resources/testharnessreport.js"></script>
+<div id=log></div>
+<div>
+  <svg xmlns="http://www.w3.org/2000/svg" width="100" height="100">
+    <text x="10" y="20">W3C &#x0646;&#x0634;&#x0627;&#x0637;</text>
+    <text x="10 50" y="40">AB</text>
+  </svg>
+</div>
+<script>
+test(function() {
+    var text = document.querySelector('text');
+    assert_equals(text.getNumberOfChars(), 8);
+    var lenFirst4 = text.getSubStringLength(0, 4);
+    var lenLast4 = text.getSubStringLength(4, 4);
+    var lenAll = text.getSubStringLength(0, 8);
+    assert_approx_equals(lenFirst4 + lenLast4, lenAll, 0.01, 'Sum of the parts equal the total.');
+}, document.title+', BiDi.');
+test(function() {
+    var text = document.querySelector('text + text');
+    assert_equals(text.getNumberOfChars(), 2);
+    var lenFirst = text.getSubStringLength(0, 1);
+    var lenLast = text.getSubStringLength(1, 1);
+    var lenAll = text.getSubStringLength(0, 2);
+    assert_approx_equals(lenFirst + lenLast, lenAll, 0.01, 'Sum of the parts equal the total.');
+}, document.title+', multiple text-chunks.');
+</script>
--- a/third_party/WebKit/Source/core/rendering/svg/SVGTextQuery.cpp
+++ b/third_party/WebKit/Source/core/rendering/svg/SVGTextQuery.cpp
@@ -141,7 +141,9 @@ bool SVGTextQuery::mapStartEndPositionsIntoFragmentCoordinates(Data* queryData,
    startPosition -= queryData->processedCharacters;
    endPosition -= queryData->processedCharacters;

-    if (startPosition >= endPosition || startPosition < 0 || endPosition < 0)
+    startPosition = max(0, startPosition);
+
+    if (startPosition >= endPosition)
        return false;

    modifyStartEndPositionsRespectingLigatures(queryData, startPosition, endPosition);