| Pic.DrawFramesBack | Part of Pic module |
| Syntax | Pic.DrawFramesBack (picIds : array 1 .. * of int, x, y, mode : int,
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| Description | Pic.DrawFramesBack is very similar to
Pic.DrawFrames. The only
difference is that Pic.DrawFramesBack returns immediately
after being called and program execution continues while the frames
are being drawn. This allows you to continue to draw other graphics
while the frames are being drawn. For example, this procedure is necessary if you want to have two sets of frames being drawn simultaneously.
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| Details | If you are wish to have several sets of images displayed at the
same time, you must use Pic.DrawFramesBack to display each set
of images but the last and then use Pic.DrawFrames to display
the last set so that Turing will wait until they are completed before
continuing execution. If you want to draw the same set of frames continuously, do not use Pic.DrawFramesBack.
for i : 1 .. 20 If you do, Turing will attempt to run each of the calls at the same time, and the animation will appear to only run once.
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| Details | GIF files can contain multiple frames (pictures). Animated GIFs
function by each frame in the GIF one after another with a delay
between them.
Turing allows users to load multiple frame GIF images into a series of pictures into an array using the Pic.FileNewFrames procedure. The user can determine how many frames are found in the GIF file using Pic.Frames. The frames can be sequentially displayed using either Pic.DrawFrames or Pic.DrawFramesBack which display the images one at a time. (Pic.DrawFrames returns once all the images have been displayed, Pic.DrawFramesBack returns immediately allowing the program to continue execution while the frames are being displayed. Pic.Frames is a function which returns the number of frames found in the GIF. If it is used on a GIF that does not contain multiple images, or on a non-GIF image file, it returns 1.
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| Example | The program loads a multiple frame GIF called "globe.gif" and
displays it.
% Determine the number of frames in "globe.gif"
var numFrames := Pic.Frames ("globe.gif")
% Load the picture
var delayTime : int
var pics : array 1 .. numFrames of int
Pic.FileNewFrames ("globe.gif", pics, delayTime)
for i : 1 .. 50
Pic.DrawFramesBack (pics, 10, 10, picMerge, numFrames, 50, false)
Pic.DrawFramesBack (pics, 20 + Pic.Width (pics(1)), 10, picMerge, numFrames, 50, false)
% All 50 iterations will execute at once if the next call is
% Pic.DrawFramesBack, and not Pic.DrawFrames
Pic.DrawFrames (pics, 30 + 2 * Pic.Width (pics(1)), 10, picMerge, numFrames, 50, false)
end for
for i : 1 .. numFrames | |||||||||
| Execute | ||||||||||
| Status | Exported qualified. This means that you can only call the function by calling Pic.DrawFrames, not by calling DrawFrames.
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| See also | Pic.Frames for information on how
to determine the number of frames in a GIF image. Pic.FileNewFrames for information on how to load a GIF image with multiple frames into an array of ints. Pic.DrawFramesBack for information on how to sequentially display the images stored in array of pictures while continuing to execute the program.
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