<Swing Dev>  RFR JDK-8187957:Tab Size does not work correctly in JTextArea
Sergey.Bylokhov at oracle.com
Wed Nov 8 19:28:24 UTC 2017
On 08/11/2017 10:39, Semyon Sadetsky wrote:
> It also may be written as
> int ntabs = (int)((x - tabBase) / tabSize);
> return tabBase + (ntabs + 1) * tabSize
Yes "(int)+1" is also can be used for positive values, but the "ceil()"
is better since this purpose of this method, and in general it works for
negative values as well.
> On 11/08/2017 10:24 AM, Sergey Bylokhov wrote:
>> Hi, Prasanta.
>> Is it possible that dropping the float part of "tabSize" and "x" will
>> cause Off-by-one error? For example:
>> float tabSize=3.99f;
>> float x=21.9f;
>> int tabBase=0;
>> 649 int ntabs = ((int) x - tabBase) / (int)tabSize;
>> 650 return tabBase + ((ntabs + 1) * tabSize);
>> The result is: ntabs=7 -> 31.92 which is not correct.
>> I guess you will need something like this:
>> int ntabs = (int) Math.ceil((x - tabBase) / tabSize);
>> return tabBase + ntabs * tabSize;
>> The result is: ntabs=6 -> 23.94
>> On 08/11/2017 03:25, Prasanta Sadhukhan wrote:
>>> Hi All,
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8187957
>>> webrev: http://cr.openjdk.java.net/~psadhukhan/8187957/webrev.00/
>>> Please review a fix for an issue where it is seen string with "tab"
>>> in them are not aligned properly.
>>> This is because while calculating tab stop postion, it is calculating
>>> number of tabs in float value (an aftereffect of JDK-8156217
>>> so next tab stop location is coming out wrong.
>>> Fix is to use "number of tabs" as an integer value in order to
>>> calculate the tab position correctly.
Best regards, Sergey.
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