Android Question rotate a non square bitmap with transparent parts

[Toni]

Hello,
I tried out everything I found in the forum but no code example works for me.
I flipped the bitmap of an non square and partly transparent imageview and it works fine. I've tried to translate this to
a rotating sub to do in the same manor, but find no working solution. I tried also out a DestRec with dip values thatare
explicit larger than a 45° rotated bitmap of my imageview, but at the end even when I change width and height for the
imageview the dimension stay as initial values. For rotating square bitmaps the code works fine. I know that I have to
recalculate left and top for non square bitmaps but that should be a peace of cake, even for me
Any hints please? Thanks in advance!

Sub Gesture_onPointerDown(ptrIndex As Int, PID As Int, MotionEvent As Object)
    ' flipp image works fine
    Dim i As ImageView
    i=Sender
    Dim j As Int=i.tag  

    Dim vert As Boolean, hor As Boolean
    Dim bmp As Bitmap=i.bitmap
    Dim bmpflip As Bitmap
    bmpflip.InitializeMutable(bmp.width, bmp.height)
    Dim cv As Canvas
    cv.Initialize2(bmpflip)  
    cv.DrawColor(Colors.ARGB(0, 0, 0, 0))                                   ' 0 means fully transparent
    If bmp.Width>bmp.Height Then
        vert=True
        hor=False
    Else
        vert=False
        hor=True
    End If
    Dim DestRect As Rect
    DestRect.Initialize(0dip, 0dip, bmp.Width, bmp.height)
    cv.DrawBitmapFlipped(bmp, Null, DestRect, vert, hor) 
    i.Bitmap=bmpflip
    i.Invalidate
End Sub

Sub Gesture_onDoubleTap(X As Float, Y As Float, MotionEvent As Object)
' rotating  the bitmap works not
    Dim i As ImageView
    i=Sender
    Dim j As Int=i.tag   
    Dim bmp As Bitmap=i.bitmap
    Dim bmprot As Bitmap
    bmprot.InitializeMutable(bmp.width, bmp.height)
    Dim cv As Canvas
    cv.Initialize2(bmprot)
    cv.DrawColor(Colors.ARGB(0, 0, 0, 0))                           ' 0 means fully transparent
    Dim DestRect As Rect
    DestRect.Initialize(0dip, 0dip, bmp.Width, bmp.height)            ' also tried changing width and height, 210dip x 210dip or added a multiplyer to  width and height
    cv.DrawBitmaprotated(bmp, Null, DestRect, 90)
    i.Bitmap=bmprot                                           ' also tried setLayoutAnimated(0, i.left, i.top, new width, new height)
    i.Invalidate
end sub

 

[klaus]

You can make an animated rotation with an additional ImageView for the rotation.

' --- Coherent rotation ---
Sub Gesture_onDoubleTap(X As Float, Y As Float, MotionEvent As Object)
    Dim imv As ImageView = Sender
    Dim j As Int = imv.Tag

    Dim bmp As B4XBitmap = imv.Bitmap
    Dim rotated As B4XBitmap = RotateBitmapJO(bmp, 90)
   
    Private imvd As ImageView    
    imvd.Initialize("")
    imvd.Gravity = Gravity.FILL
    imvd.Bitmap = bmp
    imv.Parent.As(B4XView).AddView(imvd, imv.Left, imv.Top, imv.Width, imv.Height)
    
    imv.Visible = False
    imv.Bitmap = rotated
    
    For a = 0 To 90 Step 5
        imvd.As(B4XView).Rotation = a
        Sleep(20)
    Next
    
    imv.Visible = True
    imvd.Visible = False
    imvd.RemoveView
    
    Dim tmp As Int = BaseW(j)
    BaseW(j) = BaseH(j)
    BaseH(j) = tmp

    ' applies the current scale
    Dim w As Int = Round(BaseW(j) * Scale(j))
    Dim h As Int = Round(BaseH(j) * Scale(j))
    Dim cx As Float = imv.Left + imv.Width / 2
    Dim cy As Float = imv.Top + imv.Height / 2
    Dim newLeft As Int = Round(cx - w / 2)
    Dim newTop As Int = Round(cy - h / 2)

    imv.SetLayoutAnimated(0, newLeft, newTop, w, h)
End Sub

 

[zed]

Always effective. Perfect