transparentblt() paint into picture box from a picture that is not visible

I have found some code to paint with transparency from a picturebox into another. The intent is to
make a virtual volume control fader. The fader cap moves with mouse over. Problem is, that my source picturebox needs to be not visible on the screen. this code works when picture1 is visible

Code:

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TransparentBlt Picture2(i).hdc, 18, position(i), Picture1.ScaleWidth, Picture1.ScaleHeight, Picture1.hdc, 0, 0, Picture1.ScaleWidth, Picture1.ScaleHeight, vbRed

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is there a way to substitute picture1 with a stdpicture object, or any other way besides Picture1 visible on the form? TIA for any help or suggestions Attachment 34825