B4J Question Shift a bitmap vertically

kimstudio said:

B4J Internal library jBitmapCreator has pixel random-access function GetColor/ARGB and SetColor/ARGB.

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yo3ggx said:

I know, but working at pixel level is not fast enough.

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Sub Class_Globals
    Private Root As B4XView
    Private xui As XUI
    Private ImageView1 As B4XView
    Private bc1 As BitmapCreator
End Sub

Public Sub Initialize
End Sub

'This event will be called once, before the page becomes visible.
Private Sub B4XPage_Created (Root1 As B4XView)
    Root = Root1
    Root.LoadLayout("MainPage")
    Dim bmp As B4XBitmap = xui.LoadBitmap(File.DirAssets, "33472.jpg")
    bc1.Initialize(bmp.Width, bmp.Height)
    bc1.CopyPixelsFromBitmap(bmp)
    bc1.SetBitmapToImageView(bc1.Bitmap, ImageView1)
End Sub

Private Sub Button1_Click
    ShiftUpRow(bc1, 10)
    bc1.SetBitmapToImageView(bc1.Bitmap, ImageView1)
End Sub

Private Sub ShiftUpRow (bc As BitmapCreator, NumberOfRows As Int)
    Bit.ArrayCopy(bc.Buffer, bc.mWidth * 4 * NumberOfRows, bc.Buffer, 0, bc.mWidth * 4 * (bc.mHeight - NumberOfRows))
End Sub

JordiCP said:

(Only if you are using Windows...)

Get the first example from HERE (jOpenCV_Sample01_ImageProcessing) open any picture (first icon: folder), and play with it.
...
Once you have it running I can guide you to add any line to the bitmap based on arbitrary data.

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Erel said:

BitmapCreator is very fast when used correctly.
It takes 0ms to shift an image vertically.

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    Private imgSpec As B4XView
    Dim bmc As BitmapCreator
    Dim linePixels() As Int
    Dim bc as ByteConverter

bc.LittleEndian = True
Bit.ArrayCopy(bmc.Buffer, bmc.mWidth * 4, bmc.Buffer, 0, bmc.mWidth * 4 * (bmc.mHeight - 1))    
Bit.ArrayCopy(bc.IntsToBytes(linePixels),0,bmc.buffer,bmc.mWidth * 4 * (bmc.mHeight - 1),bmc.mWidth * 4)             
bmc.SetBitmapToImageView(bmc.Bitmap,imgSpec)

yo3ggx said:

Using now a B4XView instead of an B4XImageView, how can i force the bitmap to fill the B4XView?

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Erel said:

I didn't use B4XImageView in my code. It is an ImageView declared as B4XView.

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