[Openmcl-devel] Need Some ObjC Bridge Help

Brent Fulgham bfulg at pacbell.net
Wed Mar 21 05:09:16 UTC 2007


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Hi,

I'm trying to determine the width of a string based on a specific  
font (eventually it will default to the current system font, but  
first I want to get this case working).

Based on the Apple documentation, something like this should work:

NSFont* font = [NSFont fontWithName: @"Helvetica" size: 16];
NSString* text = [[NSString alloc] initWithString: @"Hello"];

NSDictionary* fontAttrs = [[NSDictionary dictionaryWithObjects:  
[NSArray arrayWithObjects:  font, nil]
                                                                         
   forKeys:                          [NSArray arrayWithObjects:   
NSFontAttributeName, nil]] copy]

NSSize extent = [text sizeWithAttributes: fontAttrs];


I'm attempting to perform the same with OpenMCL:

;;
;;  Some AD3D stuff.  A Font-Spec is a list:  (list "font-name" font- 
size :font-style)
;;       e.g., ("helvetica" 16 :plain)
;;
(defun STRING-WIDTH (String &optional Font-Spec)
   "Returns the width in pixels of String, as if it were displayed in  
the font,
    size, and style of font-spec."
   (if (null font-spec)
       (format t "No spec!")
       ;; NSDictionary* attributes = [NSDictionary  
dictionaryWithObjectsAndKeys: font, nil];
       ;; NSString foo = String;
       ;; Size = foo :sizeWithAttributes attributes
       (let ((size (float (second font-spec))))
         (with-cstrs ((c-font-name (first font-spec))
                      (c-string    String))
           (with-autorelease-pool
              (let* ((tempname   (ccl::send (@class ns- 
string) :string-with-c-string c-font-name))
                       (fontname   (ccl::send tempname 'capitalized- 
string))
                       (nsstring   (ccl::send (@class ns- 
string) :string-with-c-string c-string))
                       (font       (ccl::send (@class ns- 
font)   :font-with-name fontname :size size)))
                (ccl::%stack-block ((paramptrs (ash 1 target::word- 
shift)))
                   (setf (ccl::%get-ptr paramptrs 0) font)
                   (let ((val-array (ccl::send (ccl::send (@class  
"NSArray") 'alloc) :init-with-objects paramptrs :count 1)))
                        (rlet ((glyph-size :<NSS>ize))
                          (let ((dict (ccl::send (@class ns- 
dictionary) :dictionary-with-objects-and-keys val-array)))
                             (ccl::send/stret glyph-size  
nsstring :size-with-attributes dict)
                             (let ((width (ccl::pref glyph- 
size :<NSS>ize.width)))
                                width)))))))))))


This crashes horribly:

? (string-width "Hello" (list "Helvetica" 16 :plain))
Unhandled exception 11 at 0xfffeff18, context->regs at #xf0135478
Read operation to unmapped address 0xbad00020
In foreign code at address 0xfffeff18
? for help
[26533] OpenMCL kernel debugger: b
current thread: tcr = 0x301ab0, native thread ID = 0x3603, interrupts  
enabled


(#xf0135960) #x90A411D4 : _objc_msgSend + 244
(#xf0135a00) #x92BCCCA4 : +[NSDictionary  
dictionaryWithObjectsAndKeys:] + 480
(#xf0135ac0) #x00006654 : _SPpoweropen_ffcall + 204
(#xF0135B00) #x08CD4C2C : #<Function STRING-WIDTH #x08cd4f16> + 3632
(#xf0135b10) #x00000000 : (null) + 0
(#xF0135B60) #x08CD4C54 : #<Function STRING-WIDTH #x08cd4f16> + 3672
(#xF0135B70) #x08CD4A54 : #<Function STRING-WIDTH #x08cd4f16> + 3160
(#xF0135B80) #x08CD3F20 : #<Function STRING-WIDTH #x08cd4f16> + 292
(#xF0135B90) #x000060F8 : (subprimitive _ret1valn)
(#xF0135BA0) #x0426179C : #<Function CALL-CHECK-REGS #x081c97ae> + 72
(#xF0135BB0) #x000060F8 : (subprimitive _ret1valn)

I'm clearly passing something non-kosher to the cocoa API, but I'm  
not sure how to get it to do what I want.

Does anyone have a better alternative, or can see anything obvious  
I'm doing wrong?

Thanks,

- -Brent
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