TweetFollow Us on Twitter

June 95 - Newton Q & A: Ask the Llama

Newton Q & A: Ask the Llama

Newton Developer Tecchnical Support

Q When I try to print or fax something, the Newton usually runs out of memory. I'm sending a lot of data to my print format, but it seems that the fields frame passed to SetupRoutingSlip should have only a reference to the data. What am I doing wrong?

A Unfortunately, you're missing one important step in the process of printing. The fields frame is eventually placed in the outbox soup. Thus all references are followed, which means that all the data you placed in the fields frame is duplicated. The duplication occurs in the soup:Add call.

In other words, you probably have a large data structure (or view, or proto) in your application. You put a reference to this structure in the fields frame in SetupRoutingSlip. When the user accepts the item to be printed (or faxed, beamed, or whatever), the fields frame is placed in the outbox soup, causing your structure to be duplicated.

Ideally, you should pass as little data as possible in the fields frame. As an example, assume that your data is all in a soup. You would pass information that allowed you to construct a query that returned the soup data of interest. This may be the index to search on plus the key to search for. You may even pass the query frame itself. Note that any changes made from the time the print request is made to the time the printing occurs will be reflected in the printed items. This may not be what you want. As in most cases, there are tradeoffs.

Q I'd like to have something like a viewIdleScript in my communications endpoint. The endpoint proto doesn't contain a way to do this. What's a good way to do it?

A One solution is to include your endpoint in a view object, such as a clView. You can then treat the whole clView as the communications object. You can use the view messages associated with opening a view to manage the control of your endpoint. Similar things can be done with viewQuitScript. And of course you can use a viewIdleScript.

Also note that using a view gives you a way to provide visual feedback (assuming it makes sense). Take a look at protoLlamaTalk in the LlamaTalk sample on this issue's CD for an example.

Q How do I get a text view to redraw itself with a new font?

A Simply use SetValue on the viewFont slot:

SetValue(theParaView,
	'viewFont,
	{family: 'espy, face: kFaceBold, size: 12});

Q I'm trying to use a view that has vfFillGray as the background. I've found that it looks really bad. Why is this?

A The pattern vfFillGray is an alternating on/off checkerboard pattern of pixels (that is, 50% gray). With the current state of the technology, all passive LCDs have problems displaying large areas of 50% gray (or large areas of black). The problem (called crosstalk ) is worse when you have alternating on and off pixels. Basically, the LCD freaks out. You should avoid using large areas of 50% gray where possible.Q When I try to add an index to my soup I sometimes get an exception -48019, but not always. What's going on?

A That particular exception indicates that an entry in your soup has a value of NIL in the slot you're trying to create an index for (that is, the entry contains the slot with a value of NIL). You can easily recreate this error by trying to add an index on the bday slot in the names file. Here's some code that you can type in the inspector:

call func()
begin
	local nameSoup := GetStores()[0]:GetSoup(ROM_cardfilesoupname);
	nameSoup:AddIndex(
		{structure: 'slot, path: 'bday, type: 'Int});
end with ();

In this case the error occurs because the default cardfile entry has a value of NIL for the bday slot. The solution is to make sure that there are no soup entries with a value of NIL for the slot that you want to use for the new index. This is best done in the design of your soup data.

If this isn't possible, the only solution is to make sure that all entries in the soup either have a valid value for the new index slot or do not contain the new index slot. Unfortunately, you don't know in advance if the new index will fail. In this case you can wrap the code that adds the index in a try/onexception clause. If an exception occurs that has the -48019 error number, you know that you have to iterate through the soup and fix entries.

Also note that you may want to keep a list of those "fixed" entries around since you may have to unfix them after the index has been added. In other words, it's OK for an entry to have a NIL value in an indexed slot after the index has been added to the soup.

Q I have a protoA2Z_TDS controlling a protoTextList. There are two things this combination doesn't do: (1) As the protoTextList contents are scrolled, the protoA2Z_TDS doesn't update the current letter, and (2) when the user clicks on a letter in the protoA2Z_TDS, I want to scroll the protoTextList to the appropriate place. How do I do these things?

A For those who may not know, protoA2Z_TDS is sample code provided by PIE Developer Technical Support. In answer to the first question, all you need to do is set the curIndex to the correct value, where A is 0 and Z is 25. If you use SetValue, the display will update for you. So if your protoA2Z_TDS was declared as indexer, and you wanted to change it to the letter B, you would do this:

SetValue(indexer, 'curIndex, 1);

You could also write a method of the protoA2Z_TDS that would update the display based on a character:

SetIndex := func(newChar)
begin
	local newIndex := Ord(Upcase(newChar)) - 65;
	if newIndex < 0 then newIndex := 0;
	if newIndex >= numIndices then newIndex := numIndices - 1;
		SetValue(self, 'curIndex, newIndex);
end;

Note that this function will try to do the right thing with weird input. However, if you're expecting the full range of Unicode values, you'll have to change the function to accommodate multibyte characters. Now let's tackle question number 2. You need to know about three things in the protoTextList that aren't yet documented in the Newton Programmer's Guide :

  1. There's a slot named lineHeight that contains the height of each line in pixels.
  2. The protoTextList uses SetOrigin to scroll. Therefore, the slot viewOriginY contains the number of pixels that the view is scrolled (and viewOriginY DIV lineHeight is the line number of the top displayed line).
  3. There's a method DoScrollScript(offset) that scrolls from the current position by the specified offset (in pixels).

Given these three pieces of information, here's a method for a protoTextList that will highlight a particular row and make it visible:

protoTextList.HiliteRow := func(index)
begin
	// highlight this item
	SetValue(self, 'selection, index);
	// scroll as necessary
	local topItem := viewOriginY DIV lineHeight;
	if index < topItem or (index >= topItem + viewLines) then begin
		// we need to scroll so that the index is the first item
		:DoScrollScript(-(topItem - index) * lineHeight);
	end;
end

Of course you still have to calculate what index to pass to the function. But that should be fairly straightforward. The protoA2Z_TDS will give you the first letter, which you can then find in your listItems array in the protoTextList. Note that if the listItems array is sorted, you can use a binary search to find the correct index.

Q What is the origin of the llama?

A The first evidence of llamas dates back to the llama raptor discovered by Dr. Leakey in the jungles of the Amazon. This find was dated back to the late "Jurassic Park" period. Early llamas are thought to have been both more violent and more intelligent than today's breeds. Cave paintings from the hills of Venezuela clearly depict early humans in use as pack animals for tribes of llamas.


The llama is the unofficial mascot of the Developer Technical Support group in Apple's Personal Interactive Electronics (PIE) division. Send your Newton-related questions to NewtonMail DRLLAMA or AppleLink DR.LLAMA. The first time we use a question from you, we'll send you a T-shirt. *

Thanks to Erik York and our PIE Partners for the questions used in this column, and to Bob Ebert, J. Christopher Bell, Mike Engber, Neil Rhodes, Kent Sandvik, Jim Schram, Maurice Sharp, and Bruce Thompson for the answers. *

Have more questions? Need more answers? Take a look at PIE Developer Info on AppleLink. *

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

The beginner's guide to Warbits
Warbits is a turn-based strategy that's clearly inspired by Nintendo's Advance Wars series. Since turn-based strategy games can be kind of tricky to dive into, see below for a few tips to help you in the beginning. Positioning is crucial [Read... | Read more »
How to upgrade your character in Spellsp...
So you’ve mastered the basics of Spellspire. By which I mean you’ve realised it’s all about spelling things in a spire. What next? Well you’re going to need to figure out how to toughen up your character. It’s all well and good being able to spell... | Read more »
5 slither.io mash-ups we'd love to...
If there's one thing that slither.io has proved, it's that the addictive gameplay of Agar.io can be transplanted onto basically anything and it will still be good fun. It wouldn't be surprising if we saw other developers jumping on the bandwagon,... | Read more »
How to navigate the terrain in Sky Charm...
Sky Charms is a whimsical match-'em up adventure that uses creative level design to really ramp up the difficulty. [Read more] | Read more »
Victorious Knight (Games)
Victorious Knight 1.3 Device: iOS Universal Category: Games Price: $1.99, Version: 1.3 (iTunes) Description: New challenges awaits you! Experience fresh RPG experience with a unique combat mechanic, packed with high quality 3D... | Read more »
Agent Gumball - Roguelike Spy Game (Gam...
Agent Gumball - Roguelike Spy Game 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Someone’s been spying on Gumball. What the what?! Two can play at that game! GO UNDERCOVERSneak past enemy... | Read more »
Runaway Toad (Games)
Runaway Toad 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: It ain’t easy bein’ green! Tap, hold, and swipe to help Toad hop to safety in this gorgeous new action game from the creators of... | Read more »
PsyCard (Games)
PsyCard 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: From the makers och Card City Nights, Progress To 100 and Ittle Dew PSYCARD is a minesweeper-like game set in a cozy cyberpunk... | Read more »
Sago Mini Robot Party (Education)
Sago Mini Robot Party 1.0 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0 (iTunes) Description: -- Children's Technology Review Editor's Choice -- | Read more »
Egz – The Origin of the Universe (Games...
Egz – The Origin of the Universe 1.0.2 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0.2 (iTunes) Description: ►►► Special offer until 2nd may : get the game at 2.99€ instead of 3.99€ ! ◄◄◄ Egz is a mesmerizing mix... | Read more »

Price Scanner via MacPrices.net

SanDisk Half-Terabyte SSD Optimized for Every...
SanDisk Corporation has announced the SanDisk Z410 SSD, a cost-competitive, half-terabyte solid state drive (SSD) that enables manufacturers to design for a broad range of desktop PCs and laptops.... Read more
Churchill Downs Racetrack Selects VenueNext t...
Churchill Downs Racetrack has announced an agreement with VenueNext to implement its technology platform for the start of Churchill Downs 2016 Spring Meet, which includes the 142nd running of the... Read more
Record 700 Million Pounds of CE Recycled in 2...
The Consumer Technology Association (CTA) reports that a record-setting 700 million pounds of consumer electronics (CE) have been recycled under the eCycling Leadership Initiative (ELI). According to... Read more
Price drops on clearance 12-inch Retina MacBo...
B&H Photo has dropped prices on leftover 2015 12″ Retina MacBooks with models now available starting at $999. Shipping is free, and B&H charges NY tax only: - 12″ 1.1GHz Gray Retina MacBook... Read more
15-inch Retina MacBook Pros available for $20...
B&H Photo has 15″ Retina MacBook Pros on sale for up to $210 off MSRP. Shipping is free, and B&H charges NY tax only: - 15″ 2.2GHz Retina MacBook Pro: $1799 $200 off MSRP - 15″ 2.5GHz Retina... Read more
Target offers Apple Watch Sport for $50 off M...
Target has Apple Watch Sports on sale for $50 off MSRP for a limited time. Choose free shipping or free local store pickup (if available). Sale prices for online orders only, in-store prices may vary... Read more
Apple restocks Certified Refurbished Mac mini...
Apple has restocked Certified Refurbished 2014 Mac minis, with models available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $... Read more
15-inch 2.2GHz Retina MacBook Pro on sale for...
Amazon.com has the 15″ 2.2GHz Retina MacBook Pro on sale for $1699.99 including free shipping. Their price is $300 off MSRP, and it’s the lowest price available for this model from any reseller (and... Read more
Apple Beats Microsoft at Own Game; Amazon Pri...
First quarter seasonality combined with an overall disinterested customer base led to an annual decline of 14.7% in worldwide tablet shipments during the first quarter of 2016 (1Q16). Worldwide... Read more
Tablets Had Worst Quarter Since 2012, says St...
The global tablet market began 2016 just as 2015 left off, down. Tablet shipments fell 10% to 46.5 million units during the Q1 2016, according to the new “Preliminary Global Tablet Shipments and... Read more

Jobs Board

Restaurant Manager (Neighborhood Captain) - A...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
Simply Mac *Apple* Specialist- Service Repa...
Simply Mac is the largest premier retailer of Apple products in the nation. In order to support our growing customer base, we are currently looking for a driven Read more
*Apple* Retail - Multiple Positions - Apple,...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Restaurant Manager (Neighborhood Captain) - A...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
Automotive Sales Consultant - Apple Ford Linc...
…you. The best candidates are smart, technologically savvy and are customer focused. Apple Ford Lincoln Apple Valley is different, because: $30,000 annual salary Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.