On Dec 1, 2007, at 20:34 , Pete wrote:
Hi, I'm new to Smalltalk, coming from C++ and Java.
I find Squeak very interesting, especially the
features for rapid prototyping.
I tried learning on the job, started with the
Games-Chess class category, as I'm was formerly
experienced in chess programming.
My problem is that I dont understand how Bitmaps for
Forms are defined:
blackKingImage
^((Color yxForm
extent: [EMAIL PROTECTED]
depth: 2
fromArray: #( 0 0 0 0 0 0 0 0 0 0 4194304 0 0
22020096 0 0 4194304 0 0 89391104 0 0 111411200 0
1398016 107216981 1426063360 22369600 107218261
1430257664 22456660 107222362 2772434944 89740885
111416741 1498415104 90527125 1162892885 1448083456
93672805 1095850325 1448083456 362108249 1431656790
2522087424 362190169 1435854230 2522087424 362190422
1452643686 2522087424 362112598 1431672169 1448345600
362112597 2505463146 2522087424 93760085 2505463145
1448083456 93678165 2526434665 1448083456 93673045
1704351141 1498415104 90527317 1700353429 1498415104
23418261 1700353429 1497366528 22631829 1499027029
1497366528 22631829 1503221333 1698693120 5657957
1503222101 1694498816 1463653 1499026773 2483027968
1414485 1499026774 1409286144 354986 2841291433
1342177280 87381 1431655765 1073741824 21845
1431655765 0 5802 2863311508 0 6485 1431655780 0 6485
1521046884 0 6485 1431655780 0 6826 2863311524 0 5461
1431655764 0 0 0 0 0 0 0)
offset: [EMAIL PROTECTED])
colorsFromArray: #(#( ) #(0.0 0.0 0.032) #(1.0 1.0
1.0) #( ) ))
I searched the whole Web for an explanation, but found
none. It's also not clear to me why this array is
size of 120, when we have an rectangular region of
40x40, and what is the difference of depth 1,2,4 ...
Depth is the number of bits per pixel. Depth 2 means 2 bits per
pixel, hence 4 colors.
The array stores 32 bits per element. So at depth 2 you get 16 pixels
per element. You need 3 elements per row for 40 pixels. 40 rows times
3 words per row is 120. Mystery solved.
FYI, pixels are stored big-endian by default.
And I'm pretty sure Form even has a class comment, as should Bitmap.
- Bert -
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