Calculation formula of Cgrectoffset and Cgrectinset

(1) cgrectinset
CGRect Cgrectinset (
CGRect Rect,
CGFloat DX,
cgfloat Dy
);
the application of the structure is centered on the original rect, and then referenced by the Dx,dy to zoom or enlarge.

Examples are as follows:

CGRect r1 = cgrectmake (100, 100, 50, 50);

CGRect R3 = Cgrectinset (r1, 10, 8);//The result should be: 110,108,30,34

/************* calculation works as follows ***************

R1.ORIGIN.X+=DX;//DX is a positive number is + =, negative is =

r1.size.width-=dx*2;

R1.origin.y+=dy;//dy is a positive number is + =, negative is =

r1.size.height-=dy*2;

****/

Apply Result:

r1.origin.x+=10;//Results for: 100+10

r1.size.width-=dx*2;//Results for: 50-10*2

r1.origin.y+=dy;//Results for: 100+8

r1.size.height-=dy*2;//Results for: 50-8*2

Output results

NSLog (@ "cgrectinset=%@\n", Nsstringfromcgrect (R3));

(2) Cgrectoffset
CGRect Cgrectoffset (
cgrect rect,
          CGFloat dx,
          cgfloat dy
offsets relative to the source rectangle Origin rect (the point at the upper-left corner) along the X-and Y-axes, and then on a rect basis along the X-and Y -axes

Examples are as follows:

Float offset =-50.0;

CGRect r1 = cgrectmake (100, 100, 50, 50);

CGRect r2 = cgrectoffset (r1, offset, offset);

/***

R1.origin.x+=offset;

R1.origin.y+=offset;

***/

NSLog (@ "cgrectoffset=%@\n", Nsstringfromcgrect (r2));

Calculation formula of Cgrectoffset and Cgrectinset