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Thread: [VB6] Creation of GIF-animation with the transparent background.

  1. #1

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    [VB6] Creation of GIF-animation with the transparent background.

    Hi everyone!
    This project allows to create an GIF animations with the transparent background. As far as i know the GDI+ doesn't allow to set the property of "Disposal Method" in the "Graphic Control Extension" block, therefore each next frame is overlayed to the previous frame. For the opaque frames it's doesn't matter. In order to solve this issue i decide to change the needed bytes manually in the raw GIF file.
    It allows to prevent the restrictions of the transparent frames. Also this example contains the oct-tree class, which calculates the optimal palette for the each frame. There are the ability of the additional settings: threshold of the transparency, duration, and number of the loops for entire animation. For the disabling of the transparency enough set the threshold to zero. The greater the value of the threshold field the greater semitransparent pixels become transparent completely.

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    Кривоус Анатолий.
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  2. #2
    VB-aholic & Lovin' It LaVolpe's Avatar
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    Re: [VB6] Creation of GIF-animation with the transparent background.

    Setting the GIF frame structure to specifically define the disposal code is the right choice, I agree. A couple of other points of interest

    1. GdipGetImageThumbnail is ok, however, it can produce poor scaling. Just FYI

    2. GdipSaveAddImage does not work on earlier versions of GDI+ for GIFs. Maybe there should be a validation check?

    3. You may want to check to see a color table is being created for every frame. If it is, then the GIF can be much larger than needed. Without checking, I don't know if GdipSaveAddImage creates a local color table per frame or if it changes the pixel data to force using the global color table. In my projects, I build a color table that can be used by the most frames and set that color table as global and tell each of those frames to use the global. For the remaining frames that cannot use it, they keep their local color table.
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  3. #3

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    Re: [VB6] Creation of GIF-animation with the transparent background.

    LaVolpe, thanks for response.
    Quote Originally Posted by LaVolpe View Post
    1. GdipGetImageThumbnail is ok, however, it can produce poor scaling. Just FYI
    Ok, i didn't know. Thanks.
    Quote Originally Posted by LaVolpe View Post
    GdipSaveAddImage does not work on earlier versions of GDI+ for GIFs. Maybe there should be a validation check?
    Yes, as far as i know it doesn't work in XP. I was having my own code for the creation GIF frame, but it's written on C++. Maybe ever i'll update this code. Honestly, it is old project, i just posted it here.
    Quote Originally Posted by LaVolpe View Post
    You may want to check to see a color table is being created for every frame. If it is, then the GIF can be much larger than needed. Without checking, I don't know if GdipSaveAddImage creates a local color table per frame or if it changes the pixel data to force using the global color table. In my projects, I build a color table that can be used by the most frames and set that color table as global and tell each of those frames to use the global. For the remaining frames that cannot use it, they keep their local color table.
    In this example is created the palette for each frame. Just use oct-tree class, we can calculate the optimal palette for each frame and for entire animation.

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    Re: [VB6] Creation of GIF-animation with the transparent background.

    can not used in xp, can you fixed?thanks!

  5. #5
    PowerPoster Arnoutdv's Avatar
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    Re: [VB6] Creation of GIF-animation with the transparent background.

    It was already stated that this method doesn't work on XP...
    Yes, as far as i know it doesn't work in XP. I was having my own code for the creation GIF frame, but it's written on C++. Maybe ever i'll update this code. Honestly, it is old project, i just posted it here.

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    Re: [VB6] Creation of GIF-animation with the transparent background.

    thank you @the trick !

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    Re: [VB6] Creation of GIF-animation with the transparent background.

    does it work on xp yet
    Last edited by On Error Try Again; Jul 31st, 2016 at 02:41 PM.

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    Re: [VB6] Creation of GIF-animation with the transparent background.

    Don't you just hate it when someone says they'll do something and you never hear from them again
    Last edited by Code Dummy; Dec 26th, 2018 at 12:09 PM.

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    Super Moderator Shaggy Hiker's Avatar
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    Re: [VB6] Creation of GIF-animation with the transparent background.

    Don't know about that, but I sure do get aggravated by passive-aggressive voice.

    This is a forum of volunteers, many of whom are talented enough to be as busy as they want to be. People forget, or have other priorities, or just lose interest. There's no requirement on them, nor are they profiting from providing free code. You might ask them, if it matters that much.
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    Super Moderator Shaggy Hiker's Avatar
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    Re: [VB6] Creation of GIF-animation with the transparent background.

    Don't know about that, but I sure do get aggravated by passive-aggressive voice.

    This is a forum of volunteers, many of whom are talented enough to be as busy as they want to be. People forget, or have other priorities, or just lose interest. There's no requirement on them, nor are they profiting from providing free code. You might ask them, if it matters that much.
    My usual boring signature: Nothing

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