How to determine the maximum number of characters on a button

Question

I have a combination of strings and depending on the maximum number of characters that will fit on the button I want to adapt the length of the individual strings. How do I get the max number of characters on a button:

Button foo=(Button)findViewById(R.id.foobutton);
String a="longtext";
String b="longtext";
String c="longtext";
foo.setText(a+b+c);

But if a+b+c won't fit, I want to cut off for example String b.

I tried the following, but it gives more characters than actually fit:

 int maxpix=foo.getLayout().getEllipsizedWidth();

          float textlengthinpix=foo.getPaint().measureText(a+b+c);
          float pixperchar=textlengthinpix/((a+b+c).length());
          int maxcharsinview=(int) (maxchars/pixperchar);

[How to get string width on Android](http://stackoverflow.com/questions/3630086/how-to-get-string-width-on-android) will help since then you'll know if it fits or not. — , Nov 04 '14 at 03:53
By default the button will grow to accommodate all the text, how do you determine if it won't fit? If the button width is bigger than the parent view width? — momo, Nov 04 '14 at 03:56
Getting the size and wrapping point of any given laid out text is one of the best kept secrets in the Android SDK. I wish Google gave more access to lower level APIs for text rendering *ahem* OGL *ahem*. — MLProgrammer-CiM, Nov 04 '14 at 03:58
@MLProgrammer-CiM, are you saying I can't get the maximum number of characters that would fit on a button if, like momo said, the text will be bigger than the parent view width. — Diego, Nov 04 '14 at 04:05
I haven't touched this for a while, but this doc page is a good starting point http://developer.android.com/reference/android/text/Layout.html — MLProgrammer-CiM, Nov 04 '14 at 04:07
Related: http://developer.android.com/reference/android/widget/TextView.html#getPaint() — MLProgrammer-CiM, Nov 04 '14 at 04:08
Related too: http://developer.android.com/reference/android/widget/TextView.html#getLayout() — MLProgrammer-CiM, Nov 04 '14 at 04:10
So, I'm guessing foo.getLayout().getEllipsizedWidth() returns the pixels, since it's 243. How can I translate those pixels to actual characters in a String? — Diego, Nov 04 '14 at 04:17
http://developer.android.com/reference/android/text/TextUtils.html ellipsize methods with the paint from the button — MLProgrammer-CiM, Nov 04 '14 at 04:19
Please confirm it was like that so I can fav this question and never forget the answer. — MLProgrammer-CiM, Nov 04 '14 at 04:28
I guess I can check whether it fits or not: Returns the original text if it fits in the specified width given the properties of the specified Paint, or, if it does not fit, a truncated copy with ellipsis character added at the specified edge or center - but if it doesn't fit, I still don't know how many chars would fit - or am I wrong? — Diego, Nov 04 '14 at 04:38

score 0 · Answer 1 · answered Nov 04 '14 at 05:22

0

try adding

android:maxLength="10" //say max length set to 10 character

property with the button widget...

answered Nov 04 '14 at 05:22

Angad Tiwari

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Thing is, I don't want to limit the length, I want to use the maximum number of chars and adapt my string accordingly – Diego Nov 05 '14 at 17:30

score 0 · Answer 2 · edited Nov 11 '14 at 08:26

I managed to do it as follows:

int maxcharspix=0;
float textlengthinpix=0;
float pixperchar=0;
String longstring="verylongstring";
try {
  maxcharspix=btn.getLayout().getEllipsizedWidth();
  textlengthinpix=btn.getPaint().measureText(longstring)*btn.getPaint().getTextScaleX();
  pixperchar=textlengthinpix/(longstring.length());

} catch (Exception e){
  e.printStackTrace();
}

int maxcharsinview=(int) (maxcharspix/pixperchar);

if (maxcharsinview<btn.length()){
//string is too long for button              
}

btn.setText(adaptedlongstring);

How to determine the maximum number of characters on a button

2 Answers2