Recently, Karl Becker wrote:
> First off, does anyone know of any good ways to considerably speed up
> the displaying of large, high-quality images in MetaCard? I'm
> working with large jpeg files (around 1300 x 500 pixels) and bringing
> them up takes not just a wait, but usually a couple seconds before
> they display. Anyway to speed this up, other than to get a faster
> computer? (I'm on a Power Mac G3/333, which isn't an underpowered
> machine reallly...)
If your JPEGs are compressed, you could try reducing compression as low as
possible (meaning little or no compression). I would guess MC is
decompressing your JPEGs before displaying them. As a test comparison, you
might try using a BMP file (or PICT on MacOS) which I believe does not
incorporate any substantial compression and see if there is any difference
in display time.
Another issue is, at what point do you display the images? One way to
combat display lag is to "preload" your image before you display it, such as
at startup, or when moving between cards (by preload I mean setting the
fileName of an image, not actually importing it into the stack). A
technique I've adopted is to use a featureless button as the main display
control, and setting its icon to the ID of whatever images I've preloaded
into the stack (this process is identical in Supercard to setting the
pictureData of one grc to the pictureData of another).
Don't know if the following is of any use to you, but many of my projects
are CD-ROM based and load external graphics as needed while running from the
CD. After building a number of these, I've decided I don't like the slight
delay that is visible when switching between images (caused by slower CD
access time), so I've started "preloading" the necessary images during
preopenstack and preopencard handlers. This is a bit more work because, for
example, all the states of graphic button (off, over, on) must be brought
into the stack and held as separate images, but making these states
available in the stack (instead of reading them from disc) can significantly
decrease the button's response time.
With large images, you could run into some memory issues, but overall,
"preloading" only the necessary images might work in your situation.
Regards,
Scott
_____________________________________________________________________
Scott Rossi Tactile Media - Multimedia & Design
Creative Director Email: [EMAIL PROTECTED]
Web: www.tactilemedia.com
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