Transparent - Flicker-free scrolling text
I am making a marquee desktop application in VB...
The requirement is,
I hv a configuration form, on which the user has the options to decide different
parameters(i.e. select the picture,select the direction of scrolling the text....left to
right....right to left....top to bottom etc.,center,stretch,tile options for backgroung image
etc.)
The user can define the text of his own from configuration form....he can change it anytime.
When he decides to execute the marquee....a second form...without the top bar is displayed,
having the background picture and the text scrolling in the direction , he selected.
The problem is,
1>We have to keep the control containing the text, transparent so that the whole area around
the text is transparent showing the picture beneath it and also move it in the direction
specified by the user.
Now if I put the text in the label control...I can make it transparent...but when I move it
on the screen with the help of timer...then it has a lot of flicker.
If I use the textbox control to display the text...and move it then there is no flicker but
it is not transparent..I mean the text is displayed in an opaque rectangular strip....
BitBlt API is used in animations to remove flicker in VC & VB, using the concept of back
buffering...but it requires hDC (handle of device context)...which is not present for the
Label (i.e. Graphic) control.
Second method I came to know is using double buffering thro' OpenGL programming...but I don't
know how to program it and whether the problem can really be solved by this method.
The solution can be in any language as far as we can make a DLL of it so that it can be
called in VB thro' API.
2>The same flicker problem is there when I tile the background picture with the help of
PaintPicture method and the Picturebox control containing the picture to be tiled and then scroll
the label control.
Hope somebody can give me any solution.....
