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| Title | Animate a moving picture in VB .NET |
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| Description | This example shows how to animate a moving picture in VB .NET. When a Timer fires, it moves the image slightly. This example shows how to make parts of a picture transparent. |
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| Keywords | animate, animation, multimedia |
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| Categories | Multimedia, Graphics, VB.NET |
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Thanks to Graeme Summers.
When the tmrFly Timer fires, the program redraws the part of the background image that is currently covered by the image it is animating. It then updates the object's position and calls MakeTransparent to draw the object in its new location.
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Private Sub tmrFly_Tick(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles tmrFly.Tick
' Rerdaw area covered in the last frame.
' section of background to copy
Dim RectCopy As New Rectangle(X, Y, 64, 35)
' draw this section over the butterfly
objCanvas.DrawImage(FormBackground, X, Y, RectCopy, _
GraphicsUnit.Pixel)
' Wrap around.
If X > Me.Width Then X = -picShip.Width
X += 10 + Rnd() * 10
Y = 100 + Rnd() * 50 - 25
MakeTransparent(objCanvas, picShip.Image, X, Y)
End Sub
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Subroutine MakeTransparent copies the object's image and calls the Bitmap object's MakeTransparent method to make the background pixels transparent. It then draws the image at the correct position on the form's background.
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Public Sub MakeTransparent(ByVal Canvas As Graphics, ByVal _
ImageSent As Image, ByVal X As Integer, ByVal Y As _
Integer)
' Create a bitmap from the image sent
Dim myBitmap As New Bitmap(ImageSent)
' Get the color of a background pixel.
Dim backColor As Color = myBitmap.GetPixel(1, 1)
' Make backColor transparent for myBitmap.
myBitmap.MakeTransparent(backColor)
' Draw the transparent bitmap to the canvas
Canvas.DrawImage(myBitmap, X, Y, myBitmap.Width, _
myBitmap.Height)
End Sub
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