Apple Newton Utilities User's Guide download pdf (Page 265)

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CHAPTER 7

Controls and Other Protos

Scroller Protos 7-5

Scrolling in the Dates Application 7

Scrolling in the Dates application allows the user to see the 24 hours in a day, 7

hours at a time. When there is only interesting data in a certain range of the day,

the application sets the

dataRect for that time frame. This tells the scroller to

blacken a scroll arrow when the data time frame is not displayed in the viewRect,

providing additional visual feedback to the user.

scrollRect: SetBounds(0, 0, 0, 24) // 24 hours per day

viewRect: SetBounds(0, 0, 0, 7) // show 7 at a time

dataRect: SetBounds(0, 0, 0, 10) // meeting from 9-10

Scrolling In a Graphics Application 7

A ﬁnal example shows scrolling in a graphics application. This example shows a

total scrollable area of 200 pixels by 200 pixels, of which a 50 pixel by 50 pixel

area is shown at any one time. In this example, an object of interest (data) is

located at (100,100).

// total area is 200 by 200

scrollRect: SetBounds( 0, 0, 200, 200)

// show a 50 by 50 area at a time

viewRect: SetBounds( 0, 0, 50, 50)

// there’s something at location (100,100)

dataRect: SetBounds(100, 100, 110, 110)

Scroll Amounts 7

Whenever the ViewScroll2DScript method is called, the scroller proto

increments the

viewRect by 1. For example, in the Dates application example,

each time the user taps an arrow, the

viewRect is moved up or down by 1 hour.

In the graphics application example, each time the user taps an arrow, the viewRect

is moved up or down by 1 pixel. Since scrolling by 1 pixel at a time is too slow,

you need to be able to adjust the scrolling amount for certain applications. To do

so, you change the value of the

scrollAmounts slot, which is an array of three

values. The default value of this slot is:

[1, 1, 1]

The ﬁrst value in the scrollAmounts array speciﬁes the amount to scroll for a

single tap. The second value speciﬁes the amount to scroll when the user holds

down on the arrow (accelerated scrolling), and the third value speciﬁes the amount

to scroll for a double tap. For a typical graphics application, you can use values like

the following:

[10, 50, 50]

1 2 ... 260 261 262 263 264 265 266 267 268 269 270 ... 941 942

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Apple Newton Utilities User's Guide Page 265

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