Android Question XUI - B4XCanvas

[LucaMs]

How to set anti aliasing for B4XCanvas?

I tried this example:
https://www.b4x.com/android/forum/threads/b4x-xui-create-a-round-image.85102/

and the result is bad - both circle and image.

 

[Erel]

It is set internally.

 

[LucaMs]

It is set internally.

Are you sure? Is it set correctly?

On the left, the standard canvas, with anti aliasing.
On the right, XUICanvas (code snippet mentioned in the first post).

 

[Erel]

It probably happens because of the clipping. Try to draw a circle with B4XCanvas.

 

[LucaMs]

It probably happens because of the clipping. Try to draw a circle with B4XCanvas.

Yes, it is the clipping. DrawBitmap also has this problem:

Left: standard canvas
Center: the snippet
Right: B4XCanvas DrawCircle

 

[Erel]

You should compare it to clipping with the standard canvas. The result should be the same.

 

[LucaMs]

You should compare it to clipping with the standard canvas. The result should be the same.

You make me work too much!

Does this mean that clipping (standard or XUI) has this problem?

 

[Erel]

This is not exactly a problem. You need to understand how anti aliasing works...

The way to solve it in this case is to draw the circle after you remove the clipping.

 

[LucaMs]

This is not exactly a problem. You need to understand how anti aliasing works...

The way to solve it in this case is to draw the circle after you remove the clipping.

But the bitmap will be drawn anyway without anti-aliasing... or not?

 

[Erel]

The issue with the bitmap drawing is not related to anti aliasing but rather to the way the bitmap is resized.

This code should provide better results:

Sub CreateRoundBitmap (Input As B4XBitmap, Size As Int) As B4XBitmap
   If Input.Width <> Input.Height Then
       'if the image is not square then we crop it to be a square.
       Dim l As Int = Min(Input.Width, Input.Height)
       Input = Input.Crop(Input.Width / 2 - l / 2, Input.Height / 2 - l / 2, l, l)
   End If
   Dim c As B4XCanvas
   Dim xview As B4XView = xui.CreatePanel("")
   xview.SetLayoutAnimated(0, 0, 0, Size, Size)
   c.Initialize(xview)
   Dim path As B4XPath
   path.InitializeOval(c.TargetRect)
   c.ClipPath(path)
   c.DrawBitmap(Input.Resize(Size, Size, False), c.TargetRect)
   c.RemoveClip
   c.DrawCircle(c.TargetRect.CenterX, c.TargetRect.CenterY, c.TargetRect.Width / 2 - 2dip, xui.Color_White, False, 5dip) 'comment this line to remove the border
   c.Invalidate
   Dim res As B4XBitmap = c.CreateBitmap
   c.Release
   Return res
End Sub

 

[LucaMs]

This code should provide better results

Much better!