Dar, Jacque, et al:
Following is based on (a) what I've read about imageData from Rev
Dictionary, (b) what I've learned about imageData in personal
testing, and (c) what I THINK I know about imageData based on
conclusions drawn from (a) & (b):
* Rev. Dictionary: "Revolution supports GIF, JPEG, PNG, PICT, BMP,
PBM/PGM/PPM, and XBM/XPM/XWD formats, as well as its own internal
format". My presumption is (untested) the "internal format",
designated as "rle" in the image's paintCompression property, is the
format used for imageData [4 bytes per pixel: null, red, green,
blue].
* Rev Dictionary: "Because most picture formats include compression,
the content of an image is normally smaller than its imageData
property." My presumption is (untested) that if an image has never
been resized since created in rle format, the image's text &
imageData properties will be identical. [ I would also note the
Dictionary is likely to be incorrect if the image is displayed at
less than full size.]
* Rev Dictionary: "To manipulate each pixel (for example, to
brighten the image or remove the red channel), to examine the actual
screen appearance of the image, or to work with the picture data in a
format-independent way, use the imageData property." I think this
should read "use the rle format" instead of "use the imageData
property." [Though one could reference the imageData property to
convert images in other formats to rle.]
* Rev Dictionary, "To take advantage of the characteristics of a
particular format or to transfer picture data between objects, use
the image content." [Emphasis mine.]
So Jacque notes that "set the imageData of image id 12345 to
my32x32RLEString" should be functionally equivalent to "set the text
of image id 12345 to my32x32RLEString", and Dar suggests people work
with imageData because it's easier to decipher and manipulate
bit-by-bit than other Rev image formats.
1. Setting the text of an image automatically resets image
dimensions (among other properties); setting the imageData of an
image does NOT adjust dimensions and WILL cause image distortion if
the imageData does not contain exactly the number of pixels needed to
fill the screen space occupied by the image.
2. Changing image content via resetting the imageData property ONLY
works for data in rle format:
get URL "binfile:/Disk/Folder/image.jpg"
set the imageData of image id 12345 to it
will not display(or load?) the image correctly. So I feel it's bad
form to post solutions that change image content by changing the
imageData; since it only works for one of the eight image formats Rev
supports and does not update all the image properties that are
touched by "set the text of image id 12345 to it".
3. None of this means one cannot create and manipulate images rle
format, it just means once one has created the image string, one
should set the text of the image to it or put it into the image,
rather than setting the imageData of the image to it.
--
Rob Cozens
CCW, Serendipity Software Company
"And I, which was two fooles, do so grow three;
Who are a little wise, the best fooles bee."
from "The Triple Foole" by John Donne (1572-1631)
_______________________________________________
use-revolution mailing list
use-revolution@lists.runrev.com
Please visit this url to subscribe, unsubscribe and manage your subscription
preferences:
http://lists.runrev.com/mailman/listinfo/use-revolution
