<Swing Dev> [10] RFR JDK-8187957:Tab Size does not work correctly in JTextArea

Semyon Sadetsky semyon.sadetsky at oracle.com
Mon Nov 13 21:00:44 UTC 2017


+1

--Semyon


On 11/13/2017 12:52 AM, Prasanta Sadhukhan wrote:
> Hi Semyon,
>
> Please find the modified webrev for automated test.
> http://cr.openjdk.java.net/~psadhukhan/8187957/webrev.01/
>
> Regards
> Prasanta
> On 11/9/2017 11:36 PM, Semyon Sadetsky wrote:
>> Hi Prasanta,
>>
>>
>> On 11/09/2017 01:56 AM, Prasanta Sadhukhan wrote:
>>> I guess by "manual implementation", Sergey was mentioning about 
>>> programmer doing the calculation rather than using system api to do 
>>> the job for us.
>>>
>>> Anyway, I saw using Math.ceil and no "nTabs+1", alignment does not work
>>>
>>> This is because
>>> For ex, if x = 66.0, tabSize = 48.0, tabBase = 0, then nTabs = 
>>> ceil(66/48) = 2 and tabStop=tabBase + ntabs * tabSize=96
>>> Now, nextTabStop is called from Utilities.getTabbedTextWidth() in a 
>>> loop passing the same value which it gets as return value from 
>>> nextTabStop, for "x"
>>> so x = 96.0, tabSize=48.0,ntabs = ceil(96/48)=2 and tabStop=96 again 
>>> and it go on getting same tabStop.
>>>
>>> With
>>> int ntabs = (int) ((x - tabBase) / tabSize);
>>>         return tabBase + ((ntabs + 1) * tabSize);
>>>
>>> we get proper alignment
>>> x 66.0 tabSize 48.0 ntabs 1 tabstop 96.0
>>> x 96.0 tabSize 48.0 ntabs 2 tabstop 144.0
>>> x 144.0 tabSize 48.0 ntabs 3 tabstop 192.0
>>>
>>> So, I guess, as Semyon suggested, making the "result of the sentence 
>>> should be  truncated to int, not its members" should be the way to go.
>>>
>>> Lastly, could you please suggest as to how to automate this test?
>> I think the easiest way is to set the caret in the corresponding 
>> position and read its coordinates.
>>
>> --Semyon
>>>
>>> Regards
>>> Prasanta
>>> On 11/9/2017 8:36 AM, semyon.sadetsky at oracle.com wrote:
>>>> On 11/8/17 12:24 PM, Sergey Bylokhov wrote:
>>>>
>>>>> On 08/11/2017 11:38, Semyon Sadetsky wrote:
>>>>>>> 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.
>>>>>> There may not be negative values here, so Math.ceil() is redundant.
>>>>>
>>>>> I do not see a reason why standard function can be redundant, and 
>>>>> why manual implementation is better. Since even in the first 
>>>>> version of the fix there is an issues in manual implementation.
>>>> I don't see it standard, just redundant in the case. What did you 
>>>> mean under "manual implementation"?
>>>>
>>>> --Semyon
>>>>>
>>>>>>
>>>>>> --Semyon
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> 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 <https://bugs.openjdk.java.net/browse/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.
>>>>>>>>>>
>>>>>>>>>> Regards
>>>>>>>>>> Prasanta
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>




More information about the swing-dev mailing list