Resizing and rotating gifs

[r0ach]

Hi,

I want to resize a gif image to fit into a picture box, and turn it upside down. How can i do this?

[joefoulkes]

from vbsquare...

'// Make a New project. Add a module. To the form Add two picture boxes And a Command button.

'// Code:
'// Add this code To the module:

Declare Function SetPixel Lib "gdi32" Alias "SetPixelV" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long, ByVal crColor As Long) As Long
Declare Function GetPixel Lib "gdi32" (ByVal hdc As Long, ByVal x As Long, ByVal y As Long) As Long

'// Add this code To the form's General Declarations procedure:

Public Sub rotateimage()
	Dim x As Long
	Dim y As Long

	Picture2.Height = Picture1.Width
	Picture2.Width = Picture1.Height

	For x = 0 To Picture1.Width
		For y = 0 To Picture1.Height
			Call SetPixel(Picture2.hdc, y, x, GetPixel(Picture1.hdc, x, y))
		Next
			If x Mod 50 = 0 Then
			DoEvents

			Picture2.Refresh

			End If

	Next

	DoEvents

	Picture2.Refresh

End Sub

'// Add this code To the Command button:

Private Sub Command1_Click()
	Call RotateImage
End Sub

[Shrog]

There is another way - use the PaintPicture method.

Most controls with a graphic device context (hdc) has the PaintPicture method. That ioncludes Forms and PictureBoxes.

You simply pass it the picture and the coordinates and it renders the picture at that position on the control or form.

  'Place the picture in the top left corner of the picturebox
  Call picTest.PaintPicture(MyPicture, 0, 0)

But it has some hidden powers: By specifying the width and height, you can stretch or shrink the picture to fit the box.

  'fill the box with the picture
  Call picTest.PaintPicture(MyPicture, 0, 0, picTest.Width, picTest.Height)

By setting the x/y coordinates to the bottom right corner of the picture box, and the width and height as negative numbers, it flips the picture AND stretches it.

If you want to flip it only horizontally, make the width negative. For vertical, make the Height negative.

  'stretched and upside down
  With picTest
    Call .PaintPicture(MyPicture, 0, .ScaleHeight, .ScaleWidth, -.ScaleHeight)
  End With

Hope this helps.
Shrog

[r0ach]

Thanx.

Shrog's method worked better for my purpose, because the setpixel thing was just too slow. I needed BitBlt speed.

Thanx guys!

[r0ach]

OK. Another thing.
The transparent parts of the original gif, is now magenta in the copied pic. Any way around that?

[Shrog]

Alas, no. The moment you "re-draw" the picture, it is not a gif any more, and you lose the transparency.

There are ways around this, but they are not simple and they are not fast. VB does not actually cater for transparency very well. Sorry.

Shrog

[r0ach]

Never Mind...
I made a mask, and my Dest Pic's BGColor black.
Then I copied Src to Dest using vbSrcInvert (oh. Src's BGColor = White) and the copy mask to Dest using vbSrcAnd.

Works perfectly