Swing Hacks

Handling Dropped Picts on Mac OS X #68

Chapter 9, Drag-and-Drop

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349

HACK

Next is the QTJ stuff. It’s OK if you don’t totally understand it—QTJ code

is pretty twisted. That’s why there’s a whole book on it. First, you open a

QTSession

, which initializes QuickTime and allocates resources. You have to

do this before any QTJ call. It can throw a

QTException

, as can most other

QTJ calls, so the whole thing is wrapped in a

try

-

catch

block.

Next, you create a

Pict

object from the byte array and pass that to

DataRef

,

which is a sort of generic media reference. In this case, you pass in flags to tell

the

DataRef exactly what it’s pointing to. The second and third arguments

indicate that we’re using the old-style Mac OS file type and that its value is

PICT. You might be wondering why being a Pict object isn’t self-descriptive

enough. It’s because many QTJ objects are just pointers to blocks of memory

and the functions that work with them. The

DataRef signature used here

takes a

QTHandleRef as an argument. QTHandleRef is subclassed by Pict, but it

is little more than a pointer; the only level on which the

DataRef understands

the

Pict, in fact, is as a block of memory. My point here: QTJ code is weird

and often C-like.

Create a

GraphicsImporter for the Pict format, and point it to the DataRef.

You have now read the Pict “file” from memory. Now, you can get the size

of the imported image and create a

QTImageProducer, with ...