From: "Kalum Somaratna aka Grendel" To: djgpp AT delorie DOT com Date: Sun, 2 Jan 2000 19:37:33 +0600 MIME-Version: 1.0 Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT Subject: Re: transparent bitmaps In-reply-to: <84nbap$gdo$1@planja.arnes.si> X-mailer: Pegasus Mail for Win32 (v3.12) Message-ID: <94685661201@out.newmail.net> Reply-To: djgpp AT delorie DOT com X-Mailing-List: djgpp AT delorie DOT com X-Unsubscribes-To: listserv AT delorie DOT com Precedence: bulk On 2 Jan 00, at 12:03, Matej wrote: > > Just pick a color that you want to be transparent, most people > > choose 255 or just 0, and make a BMP displayer that skips the pixels > > with that value. > > > Yes, but how to do it? Can you give me an example? > Thanks Hi!, I am not quite sure whether you are asking about how to create transparent images or how to write a blitting routine that handles transparent pixels. If you want to create transparent images like the ones you see on the web pages then then I hope the following helps you. GIF files support transparency. This is how you do it, If you load a GIF file to your paint program there should be a menu option which would allow you to select a single colour from your image which would be marked as transparent. So if your 256 colour image had a background of purple and if purple was palette entry 15 (of the total 256 palette entries) you would select purple from the palette and you've got a transparent GIF. All the pixels in the GIF which are drawn with entry 15 (purple in this case) would not be drawn by the program which draws the GIF (like Netscape etc if your thinking of a web page). So since this pixels are not drawn your background will show through these areas and you've got your transparency. Actually some paint programs allow you to just simply select the transparent colour using a color picker from the image. I use Gif Constructionset Professional from alchemy mindworks to create my GIF's. It's Never expiring shareware so you might try getting it. (I've forgotten the URL, Please do a search). Hope This Help's Kalum