Quote: "...or look for a command to fit the bill and set the transparent colours manually"
Unfortunately, DBC only accepts black as a transparent color.
Quote: "Although I save the .gif images with a transparent background, when I loud them into DarkBASIC it puts a black square around the animation"
Like BN2 suggested, if the transparent areas of your GIFs are true black,
then use SET SPRITE to turn on transparency:
rem load the sprite
load image "myimage.gif",1
rem make the sprite
rem transparency for black areas
rem SET SPRITE Sprite Number, BackSave State, Transparency State
set sprite 1,1,1
Just a note: if you set BackSave State to 0 you will get better performance. You will just have to control the clearing and redrawing of the screen yourself. The BackSave state flag allows the sprite to refresh itself regardless of what the background is doing. However, this adds some processing overhead.
Another tip on performance:
With the backsave state off (zero), you can keep all of your sprites hidden at all times. Whenever you need to display your sprites, you use PASTE SPRITE . This will make a "rubber stamp" of the sprite wherever you choose complete with transparency if set as described previously. This will also increase performance and it will also allow you to still use sprite collision detection.
Enjoy your day.