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Date Posted: 07:11:44 05/25/00 Thu
Author: Michel
Subject: Re: Big black rectangle
In reply to: Andy Radchenko 's message, "Big black rectangle" on 17:39:09 05/24/00 Wed

Dear Andy,

Unfortunately there is not any easy solution to this. The API StretchDiBits may fail after reaching a certain size threshold. There is more information on this at,

<a rel=nofollow target=_blank href="http://www.efg2.com/lab/Graphics/VeryLargeBitmap.htm">http://www.efg2.com/lab/Graphics/VeryLargeBitmap.htm</a>

You'll probably need to do an extra step to reduce the size of your graphic when displaying it on screen. The DPI of a screen is usally 72 or 96, so it may be reasonable to reduce its dimensions with the TResizeTransform. If the TResizeTransform fails with Interpolated = False, you may need to set it to True, to prevent using StretchDiBits.

Best regards,


> I'm having problem viewing large b/w image zoomed to
> fit image scroll box width. What is shown is a black
> filled rectangle. If I maximize window to full screen,
> image is shown properly, however with any other window
> size its still a BBR. Image is a drawing 36"x24"
> scanned at 400 dpi compressed with CCITT group 4
> compression. Any suggestions?
> Another thing, I have some wishes:
> 1. Being able to abort image loading.
> 2. To be able to show user a progress of the image
> loading.
> How about it?
> Andy

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