Hello, I’m trying to implement The CoreGraphics CGAffineTransform functions via declares and am having some trouble (I’m new to declares.)
Reference for CGAffineTransform: Apple Developer Documentation
I have a class with a structure that maps to CGAffineTransform:
This should be correct: 48 bytes (6 doubles), column-major format. I’m only running 64-bit code.
My class has a property, “Matrix as CGAffineTransform”, and initializes it to the identity transform:
Me.Matrix.a = 1.0
Me.Matrix.d = 1.0
I’ve also set up a log method:
Dim s As String = EndOfLine
s = s + Me.Matrix.a.ToString("0.0") + " " + Me.Matrix.b.ToString("0.0") + EndOfLine
s = s + Me.Matrix.c.ToString("0.0") + " " + Me.Matrix.d.ToString("0.0") + EndOfLine
s = s + Me.Matrix.tx.ToString("0.0") + " " + Me.Matrix.ty.ToString("0.0") + EndOfLine
System.DebugLog(s)
If I log the output of the identity matrix I get the expected result:
1.0 0.0
0.0 1.0
0.0 0.0
I’m writing and calling my declare like this:
Declare Function CGAffineTransformTranslate Lib CoreGraphics (t As CGAffineTransform, tx As CGFloat, ty As CGFloat) As CGAffineTransform
Me.Matrix = CGAffineTransformTranslate(Me.Matrix, tx, ty)
Reference for the CoreGraphics function: Apple Developer Documentation
But the result not correct:
1.0 0.0
0.0 4.0
0.0 0.0
To verify, this is an Objective-C version:
#import <Foundation/Foundation.h>
#import <CoreGraphics/CoreGraphics.h>
int main(int argc, char *argv[]) {
@autoreleasepool {
CGAffineTransform t = CGAffineTransformIdentity;
int s = sizeof(CGAffineTransform);
NSLog(@"sizeof CGAffineTransform: %i\n\n", s);
NSLog(@"%f %f", t.a, t.b);
NSLog(@"%f %f", t.c, t.d);
NSLog(@"%f %f\n\n", t.tx, t.ty);
t = CGAffineTransformTranslate(t, 3, 6);
NSLog(@"%f %f", t.a, t.b);
NSLog(@"%f %f", t.c, t.d);
NSLog(@"%f %f\n\n", t.tx, t.ty);
}
}
…which produces the output:
sizeof CGAffineTransform: 48
1.000000 0.000000
0.000000 1.000000
0.000000 0.000000
1.000000 0.000000
0.000000 1.000000
3.000000 6.000000
Any tips would be appreciated!
John
