Android Question Canvas Draw Text Center Is Not Centering

[Mahares]

Below is my full project. I would like to use ‘CENTER’ for ‘World Cup 2018’ in cvs.DrawText line, but the only way I can do it is to manipulate the position x and use LEFT. How can I use ‘CENTER’ and achieve a horizontally centered text. I only want to make use of the core lib. I do not wish to use XUI lib.
Thank you

Sub Activity_Resume
    CreateBitmap
End Sub

Sub Activity_Pause (UserClosed As Boolean)
    If UserClosed Then Activity.Finish
End Sub

Sub Activity_Create(FirstTime As Boolean)  
End Sub

Sub CreateBitmap As Canvas
   Dim bmp As Bitmap
   bmp.InitializeMutable(200dip, 200dip)
   Dim cvs As Canvas
   cvs.Initialize2(bmp)
   Dim r As Rect
   r.Initialize(0, 0, bmp.Width, bmp.Height)
   cvs.DrawRect(r, Colors.Transparent, False, 5dip)
   DrawBitmap(cvs, LoadBitmap(File.DirAssets, "worldcuprussia2018.png"))
    cvs.DrawText("World Cup 2018",0,cvs.Bitmap.Height/2,Typeface.DEFAULT_BOLD,12,Colors.blue,"CENTER")
'   cvs.DrawText("World Cup 2018",0,cvs.Bitmap.Height/2,Typeface.DEFAULT_BOLD,12,Colors.blue,"LEFT")
   Activity.SetBackgroundImage(cvs.Bitmap)
   Return cvs
End Sub

Sub DrawBitmap (cvs As Canvas, bmp As Bitmap)
   Dim r As Rect
   r.Initialize(0, 0, cvs.Bitmap.Width, cvs.Bitmap.Height)
   cvs.DrawBitmap(bmp, Null, r)
End Sub

 

[Jeffrey Cameron]

The drawing alignment parameters only specify how the text is drawn beginning at the x/y position specified.

This post might be helpful in answering your question: https://www.b4x.com/android/forum/threads/drawtext-alignment-right-does-not-work.7028/

 

[Mahares]

This post might be helpful in answering your question

The link is quite old from 2010 and does not address the 'CENTER' position. I am attaching the full project. Perhaps someone can figure it out.

 

[stevel05]

As Jeffrey said, the alignment in relation to drawing on a canvas defines how the text is positioned relative to the specified x point.

You would need to change

cvs.DrawText("World Cup 2018",0,cvs.Bitmap.Height/2,Typeface.DEFAULT_BOLD,12,Colors.blue,"CENTER")

to

cvs.DrawText("World Cup 2018",cvs.Bitmap.Width/2,cvs.Bitmap.Height/2,Typeface.DEFAULT_BOLD,12,Colors.blue,"CENTER")

The text will then be drawn centered on the x position (cvs.Bitmap.Width/2), which is at the center of the bitmap,

To test it, change the Alignment from "CENTER" to "LEFT" or "RIGHT" to see the difference.

 

[Jeffrey Cameron]

The link is quite old from 2010 and does not address the 'CENTER' position.

Correct, but it did nicely illustrate the origin point of the drawtext method which is what I was attempting to emphasize.

It should also be noted that the text is drawn starting from the origin point, UP and left/right from the origin point. So, if you wish to correctly center the text on the Y axis you should add 1/2 of the text height to your Y value (see Canvas.MeasureStringHeight).

 

[Erel]

I only want to make use of the core lib. I do not wish to use XUI lib.

This is a large mistake. There is no reason not to use the XUI library. You only make things more complicated.

The best text measurements methods are available in B4XCanvas.