Android Question Gradients and circles/ovals

BitmapCreator currently doesn't support drawing ovals so Klaus used B4XCanvas for this.

The "pure" way to draw a circle with gradient fill is to create a BCBrush with the gradient fill and then to use it to draw a circle:

Code:

Sub Globals

   Private GradientBrush As BCBrush
   Private xui As XUI
   Private ActivityBC As BitmapCreator
   Private ImageView1 As ImageView
End Sub

Sub Activity_Create(FirstTime As Boolean)
   Activity.LoadLayout("1")
   'create the brush (create it once and reuse it when needed)
   Dim bc As BitmapCreator
   bc.Initialize(100dip, 100dip)
   bc.FillGradient(Array As Int(xui.Color_Red, xui.Color_Blue), bc.TargetRect, "TL_BR")
   GradientBrush = bc.CreateBrushFromBitmapCreator(bc)
   'Create the bc that will be used for the drawings
   ActivityBC.Initialize(100%x, 100%y)
End Sub

Sub Activity_Touch (Action As Int, X As Float, Y As Float)
   GradientBrush.SrcOffsetX = x - 50dip 'Need to set the brush offsets to make it start in the top left corner
   GradientBrush.SrcOffsetY = y - 50dip
   ActivityBC.DrawCircle2(X, Y, 50dip, GradientBrush, True, 0)
   ActivityBC.SetBitmapToImageView(ActivityBC.Bitmap, ImageView1) 'ImageView1 covers the activity
End Sub

Note that you can use any drawing you like for the brush:

Code:

Sub Activity_Create(FirstTime As Boolean)
   Activity.LoadLayout("1")
   ActivityBC.Initialize(100%x, 100%y)
   GradientBrush = ActivityBC.CreateBrushFromBitmap(LoadBitmapResize(File.DirAssets, "10039.jpg", 100dip, 100dip, True))
End Sub

Sub Activity_Touch (Action As Int, X As Float, Y As Float)
   GradientBrush.SrcOffsetX = x - 50dip 'Need to set the brush offsets to make it start in the top left corner
   GradientBrush.SrcOffsetY = y - 50dip
   ActivityBC.DrawCircle2(X, Y, 50dip, GradientBrush, True, 0)
   ActivityBC.SetBitmapToImageView(ActivityBC.Bitmap, ImageView1) 'ImageView1 covers the activity
End Sub

 

BTW, if you don't set the bitmap SrcOffset it will look like this:

 

No. BitmapCreator doesn't support drawing ovals so you need to use B4XCanvas for this. If you only need to draw circles (or other supported shapes) then you don't need the canvas.