Nov 98 Tips
Volume Number: 14
Issue Number: 11
Column Tag: Tips & Tidbits
Nov 98 Tips & Tidbits
by Jeff Clites
Strings and Numbers - The Twain Shall Meet
String and numbers are different animals, but programmers are constantly faced with
the need to translate back and forth between the two. For integers, it is easy:
StringToNum() and NumToString() to the job nicely. But for floating-point numbers,
things get a little more tricky, because there are a myriad of choices about how to
format them. Apple has provided StringToExtended() and ExtendedToString() to give
you complete control over the process - too much control, you might say. Sometimes,
you don't want the hassle of the page of code needed, and a simple solution would be
appreciated. The classic solution in C is to use sprintf(), but this can wastefully
increase the size of your executable if this is the only Standard Library function you
need, and it doesn't respect localization settings. The following clever solution
convinces the Apple Event Manager to do the work for you:
OSErr ConvertDoubleToString( double inValue, AEDesc *outResult )
OSErr theErr = noErr;
theErr = AECoercePtr( typeFloat, // input data
type--'doub'
(const void *) &inValue, // pointer to input data.
(Size) (sizeof(double)), // size of input data
typeChar, // desired 'want' type is character
outResult ); // pointer to AEDesc for output data
return theErr; // the error returned by the
coercion.
}
The returned AEDescriptor will contain a descriptor type of typeChar ('TEXT') and a
Handle to a block of text (use GetHandleSize() to determine the resulting string
length). Of course, don't forget to AEDispose() the AEDescriptor returned by this call.
Stephen L. Reid
sreid@ti.com
______________________________
Loading a Graphics File with QuickTime
QuickTime makes it easy to load a graphics file into an offscreen GWorld, but as simple
as the process is, it can be hard to track down sample code to show you how it is done.
The following simple snippet illustrates the process nicely, and has two of my favorite
characteristics in a snippet: it doesn't omit error checking, and once you have looked it
over it is so intuitive that you will be able to recreate it when you need it, without
digging up the actual example:
FSSpec fsp;
ComponentInstance gi;
Rect r;
ImageDescriptionHandle idH;
GWorldPtr outGWp;
OSErr errCode = noErr;
// fill in the FSSpec
if(noErr == errCode){ errCode = GetGraphicsImporterForFile(fsp, &gi);
}
if(noErr == errCode){ errCode = GraphicsImportGetImageDescription(gi,
&idH); }
if(noErr == errCode){
r.left = 0;
r.top = 0;
r.right = (**idH).width;
r.bottom = (**idH).height;
errCode = NewGWorld(&outGWp,(**idH).depth, &r, nil, nil,0);
errCode = NewGWorld(&outGWp, (**idH).depth, &r, nil, nil,
useTempMem);
}
}
CGrafPtr savePort;
GDHandle saveGD;
GetGWorld(&savePort, &saveGD);
SetGWorld(outGWp, nil);
EraseRect(&r); // in case PICT has transparent
areas
GraphicsImportSetBoundsRect(gi, &r);
GraphicsImportSetGWorld(gi, outGWp, nil);
errCode = GraphicsImportDraw(gi);
SetGWorld(savePort, saveGD);
}
if(noErr != errCode && nil != outGWp){ // error occurred
DisposeGWorld(outGWp);
outGWp = nil;
}
DisposeHandle(reinterpret_cast(idH));
}
if(nil != gi){
CloseComponent(gi);
}
If outGWp is not nil, it is a GWorld of the file.
David Phillip Oster
oster@netcom.com