Various translation problems

Philippe de Rochambeau pr1 at club-internet.fr
Mon Feb 23 16:49:47 UTC 1998


I am having problems translating the following snippets of code in the
"Duckling" example in Lalonde's "Inside Smalltalk II":

1) 

erase
	"I erase myself by whitening the area occupied by my icon."
	Display white: (position extent: icon extent).

should "white:" be replaced by "fillWhite:"?


2)

"Next, create a mother duck with a bigger icon."
	mother := self new. " mother icon: (ducklingIcon magnifyBy: 2 at 2).

what should I replace "magnifyBy" by?

3) [The following initialize method shows how duck bitmaps are created and
their extent defined during initialization. See below]

initialize
	"MotherDuck initialize"

	"Older implementation definitions"
	DuckIcons := (1 to: 7) collect: [:index |
		Cursor
			perform: (#(origin corner crossHair up down read write)
			at: index)].
	DuckIconMenuNames := ('left corner\right corner\cross hair\up arrow\',
		'down arrow\eyeglass\pen writing') withCRs.

	"Newer implementation definitions."
	DuckIcons := Array
		with: (Form extent: 50 at 50
			fromArray: #(0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0
				0 0 0 0 0 1536 0 0 0768 0 15 57344 896 0 31 61440 390 0 56 6144 204
				0 48 3072 220 0 97 33792 112 0 103 58550 240 0 480 512 176 0 1008
				768 432 0 3888 480 864 0 16368 496 544 0 7984 26 608 0 2032 15
				1568 0 510 5 33888 0 127 35840 60512 0 3 50688 14528 0 0 59136
				4544 0 0 29568 384 0 0 12672 384 0 0 12480 12672 0 0 6368 29056 0
				0 7291 50048 0 0 3135 33536 0 0 1567 1792 0 0 1792 1536 0 0 768
				3072 0 0 896 7168 0 0 449 61440 0 0 255 57344 0 0 63 0 0 0 6 0 0 0 6
				0 0 0 6 0 0 0 6 0 0 0 15 0 0 0 31 32768 0 0 58 49152 0 0 50
				24576 0 0 34 24576 0)
			offset: 0 at 0)
		with: (Form extent: 50 at 50
			fromArray: #(0 0 0 0 0 511 0 0 0 2047 49152 0 0 7681 6144 0 0 30720
				61440 0 1 49152 30720 0 3 32768 7198 0 7 0 3584 0 6 0 1536 0 6 0
				768 0 12 15360 768 0 24 65024 62336 0 25 50947 63872 0 57 37639
				7360 0 49 14726 20160 0 49 64900 59072 0 113 65415 63072 0 96
				1793 65120 0 96 0 3680 0 224 248 32 0 224 49151 32 0 199 63503
				57376 0 511 1 63536 0 504 0 15408 0 448 0 3888 0 384 0 944 0 128 0
				992 0 128 0 224 0 192 0 192 0 64 0 384 0 96 0 768 0 33 0 1536 0 49
				57408 3072 0 17 61560 6144 0 24 124 12288 0 24 0 24576 0 12 0
				3 49276 0 0 3 49368 0 0 6 24972 0 0 6 26380 0 0 12 15372 0 0 12
				14348 0 0 12 4100 0 0)
			offset: 0 at 0)

			[etc]

=======


the "quack" instance method contains the following line of code:

iconOffset := self icon extent // 2.

However, I get a "message not understood: extent" message at that point in the
code. Why? What is "extent" an instance variable of?

Many thanks.

Philippe de Rochambeau





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