B4J Code Snippet Measure Multiline Text Height

Erel

Administrator
Staff member
Licensed User
Measuring the length of multiline text is simple in B4A with StringUtils.MeasureMultilineTextHeight and in B4i by setting the width of a multiline Label and calling SizeToFit.

There is no similar method available in B4J. One option is to add a label to an AnchorPane and wait for the layout to be set: https://www.b4x.com/android/forum/threads/measure-text.45750/#post-311358

Another option is to call a non-public API with the following code:
B4X:
Sub MeasureMultilineTextHeight (Font As Font, Width As Double, Text As String) As Double
   Dim jo As JavaObject = Me
   Return jo.RunMethod("MeasureMultilineTextHeight", Array(Font, Text, Width))
End Sub

#if Java
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import javafx.scene.text.Font;
import javafx.scene.text.TextBoundsType;
public static double MeasureMultilineTextHeight(Font f, String text, double width) throws Exception {
  Method m = Class.forName("com.sun.javafx.scene.control.skin.Utils").getDeclaredMethod("computeTextHeight",
  Font.class, String.class, double.class, TextBoundsType.class);
  m.setAccessible(true);
  return (Double)m.invoke(null, f, text, width, TextBoundsType.LOGICAL_VERTICAL_CENTER);
  }
#End If
Usage example:
B4X:
Dim height As Double = MeasureMultilineTextHeight(fx.DefaultFont(20), 100, $" jskldf jslkd fjlk wel;fk we;lfk we;lf k
erg
erg
erg
er
gsdfj lksdf jlksd fjlksd f"$)
Log(height)
Note that if you want to add it to a class then you need to remove the 'static' modifier from the Java code.

As this is a non-public API it might change in the future. It does work with Java 8 and Java 9 so it is probably be quite safe to use.
 
Last edited:

Misterbates

Active Member
Licensed User
Would this also work in B4A? Would remove the dependency on StringUtils :)
Or is there some equivalent code that could be used for MeasureText?
 
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