Zoom

[Tec-Nico]

Hello there, I was asked to make a program to zoom a picture based on an algorithm given by my professor.

The real problem here is that I have to get the array of Bytes of a picture, then manipulate them to get a new array of Bytes and then place this array in a picturebox...

I know how to get the array of Bytes from a PictureBox but I do not know how to Put an array of Bytes into a picture box... Could somebody tell me how to do this?

I also need to know on which pixel the user is clicking so I can know the area I am going to zoom in.

Other ideas are welcomed...

Thanks in Advance

[Sastraxi]

Well, on the MouseDown event there are X and Y values, so I suppose you could use those, or the GetCursorPos() API call. And look up SetBitmapBits or SetDIBits or something to that extent for selecting it into a DC.

[Tec-Nico]

And how would you use SetBitmapBits?

[Sastraxi]

I think vbaccelerator.com has a full class that you can change DIB sections with... I used it once, got like 20 fps on a 640x480 image It's pretty fast.

[Tec-Nico]

So.. What do you recommend?

I tried using the following code but it won't work. It will just show me a black rectangle... What am I doing wrong?

'--- Code in BmpModule ---
Private Type BitMap
    bmType As Long
    bmWidth As Long
    bmHeight As Long
    bmWidthBytes As Long
    bmPlanes As Integer
    bmBitsPixel As Integer
    bmBits As Long
End Type
 
Public StartPosX As Single
Public StartPosY As Single
Public EndPosX As Single
Public EndPosY As Single
 
Private Declare Function GetBitmapBits Lib "gdi32" (ByVal hBitmap As Long, ByVal dwCount As Long, lpBits As Any) As Long
Private Declare Function SetBitmapBits Lib "gdi32" (ByVal hBitmap As Long, ByVal dwCount As Long, lpBits As Any) As Long
Private Declare Function GetObject Lib "gdi32" Alias "GetObjectA" (ByVal hObject As Long, ByVal nCount As Long, lpObject As Any) As Long
Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long
 
Public Sub GetPart(Picture1 As PictureBox, Picture2 As PictureBox)
Dim bmWidth As Long
Dim bmHeight As Long
Dim bmSize As Long
Dim NewbmSize As Long
Dim bmBits() As Byte
 
Dim bmZoomWidth As Long
Dim bmZoomHeight As Long
 
'Get picture's Width and Height
bmWidth = Picture1.Width
bmHeight = Picture1.Height
 
bmZoomWidth = EndPosX - StartPosX
bmZoomHeight = EndPosY - StartPosY
 
'ReDefine Bit array to hold all pixels from picture box
ReDim Bits(0 To bmWidth - 1, 0 To bmHeight - 1) As Byte
'ReDim BitsZoom(0 To bmZoomWidth - 1, 0 To bmZoomHeight - 1) As Byte
ReDim BitsZoom(StartPosX To EndPosX - 1, StartPosY To EndPosY - 1) As Byte
 
'Store size of bitmap in total pixels
bmSize = bmWidth * bmHeight
 
'Grab picture's pixels and load to Bit array
GetBitmapBits Picture1.Image, bmSize, Bits(0, 0)
    
'Get Bits Selected
Dim Y As Long
Dim X As Long
 
For Y = StartPosY To EndPosY - 1
 For X = StartPosX To EndPosX - 1
  BitsZoom(X - StartPosX, Y - StartPosY) = Bits(X, Y)
 Next X
Next Y
 
'Load Bit array to picture box
Picture2.Width = bmZoomWidth
Picture2.Height = bmZoomHeight
 
NewbmSize = bmZoomWidth * bmZoomHeight
 
SetBitmapBits Picture2.Image, NewbmSize, BitsZoom(0, 0)
 
'Redraw
Picture2.Refresh
End Sub
 
'--- Form's Code ---
Private Sub Picture1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
StartPosX = X
StartPosY = Y
 
'The Shape thing is to provide a sensation of selection
With Shape1
 .Left = X
 .Top = Y
 .Width = 0
 .Height = 0
 .BorderStyle = 5
 .Visible = True
 .Tag = ""
End With
End Sub
 
Private Sub Picture1_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
With Shape1
 If Shape1.Visible = True And .Tag = "" Then
  .Width = Abs(StartPosX - X)
  .Height = Abs(StartPosY - Y)
 End If
End With
End Sub
 
Private Sub Picture1_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
EndPosX = X
EndPosY = Y
Shape1.Tag = "Selected"
End Sub
 
Private Sub CmdCopyAll_Click()
StartPosY = 0
EndPosY = Picture1.Height
StartPosX = 0
EndPosX = Picture1.Width
 
GetPart Picture1, Picture2
End Sub
 
Private Sub CmdGetPart_Click()
If Shape1.Visible = False Then
 StartPosY = 0
 EndPosY = Picture1.Height
 StartPosX = 0
 EndPosX = Picture1.Width
Else
 Shape1.Visible = False
End If
 
Me.MousePointer = vbHourglass
GetPart Picture1, Picture2
Me.MousePointer = vbDefault
End Sub

[Valkan]

Go take a look at your other post about this