[interfacekit] Re: programming problems


Ingo Weinhold wrote: 
  How do you know witch resize mode a view is using???
  'Cause (ResizingMode() & B_FOLLOW_BOTTOM) or any other "FOLLOW" is
not working!

  First of all, let me rephrase that:
  How do you know which resize mode a view is using???

PS: Look into View.h !

Anything special there? 
  Uh, gee, nothing special... just what you need to give me a good
answer!?!?!??

const uint32 _VIEW_TOP_         = 1UL;
const uint32 _VIEW_LEFT_        = 2UL;
const uint32 _VIEW_BOTTOM_      = 3UL;
const uint32 _VIEW_RIGHT_       = 4UL;
const uint32 _VIEW_CENTER_      = 5UL;

inline uint32 _rule_(uint32 r1, uint32 r2, uint32 r3, uint32 r4)
        { return ((r1 << 12) | (r2 << 8) | (r3 << 4) | r4); }

#define B_FOLLOW_NONE 0
#define B_FOLLOW_ALL_SIDES              _rule_(_VIEW_TOP_, _VIEW_LEFT_,
_VIEW_BOTTOM_, _VIEW_RIGHT_)
#define B_FOLLOW_ALL                    B_FOLLOW_ALL_SIDES

#define B_FOLLOW_LEFT                   _rule_(0, _VIEW_LEFT_, 0, _VIEW_LEFT_)
#define B_FOLLOW_RIGHT                  _rule_(0, _VIEW_RIGHT_, 0, _VIEW_RIGHT_)
#define B_FOLLOW_LEFT_RIGHT             _rule_(0, _VIEW_LEFT_, 0, _VIEW_RIGHT_)
#define B_FOLLOW_H_CENTER               _rule_(0, _VIEW_CENTER_, 0, 
_VIEW_CENTER_)

#define B_FOLLOW_TOP                    _rule_(_VIEW_TOP_, 0, _VIEW_TOP_, 0)
#define B_FOLLOW_BOTTOM                 _rule_(_VIEW_BOTTOM_, 0, _VIEW_BOTTOM_, 
0)
#define B_FOLLOW_TOP_BOTTOM             _rule_(_VIEW_TOP_, 0, _VIEW_BOTTOM_, 0)
#define B_FOLLOW_V_CENTER               _rule_(_VIEW_CENTER_, 0, _VIEW_CENTER_, 
0)

That's not surprising, given how the constants are constructed. Apparently it is possible to individually specify for each side whether it shall follow the top, left, bottom, right, center (or nothing) of the parent view.
Apparently, this is written in BeBook, so we already know that!

Anyway you can decompose the resizing mode like that:

        uint32 mode = ResizingMode();
        uint32 topMode = (mode >> 12) & 0xf;
        uint32 leftMode = (mode >> 8) & 0xf;
        uint32 bottomMode = (mode >> 4) & 0xf;
        uint32 rightMode = mode & 0xf;

And then analyze the value for each side:

// top side follows...
switch (topMode) {
case 0:
// ... nothing
break;
case _VIEW_TOP_:
// ... parent's top
break;
case _VIEW_LEFT_:
// ... parent's left? -- meaning?
break;
case _VIEW_BOTTOM_:
// ... parent's bottom
break;
case _VIEW_RIGHT_:
// ... parent's right? -- meaning?
break;
case _VIEW_CENTER_:
// ... parent's vertical center
break;
} 
  Did you read the hole email I previously sent?
  I said:
"and I've come upon a problem at witch I want an easy answer, answer
that I failed to find so far."

  Easy Ingo, easy! I'm not going to write all those structures for a
simple point.Set(x,y)!

Anyway, I had a solution but I was not fond of it. In the mean time it
appears I've found one:

                // resize/move horizontaly
        if ((rmask & 0x00000f00UL)>>8 == _VIEW_LEFT_
                        && (rmask & 0x0000000fUL)>>0 == _VIEW_RIGHT_){
                printf("1\n");
        }
        else if ((rmask & 0x00000f00UL)>>8 == _VIEW_LEFT_){
                printf("2\n");
        }
        else if ((rmask & 0x0000000fUL)>>0 == _VIEW_RIGHT_){
                printf("3\n");
        }
        else if ((rmask & 0x00000f00UL)>>8 == _VIEW_CENTER_){
                printf("4\n");
        }
        else { // illegal flag. Do nothing.
                printf("5\n");
        }

                // resize/move verticaly
        if ((rmask & 0x0000f000UL)>>12 == _VIEW_TOP_
                        && (rmask & 0x000000f0UL)>>4 == _VIEW_BOTTOM_){
                printf("1\n");
        }
        else if ((rmask & 0x0000f000UL)>>12 == _VIEW_TOP_){
                printf("2\n");
        }
        else if ((rmask & 0x000000f0UL)>>4 == _VIEW_BOTTOM_){
                printf("3\n");
        }
        else if ((rmask & 0x0000f000UL)>>12 == _VIEW_CENTER_){
                printf("4\n");
        }
        else { // illegal flag. Do nothing.
                printf("5\n");
        }

  I did tried to use B_FOLLOW_* flags but they lead to a very ugly
looking code. So I adopted those 5 undocumented flags with the help of
which the code seems more readable, but still not easy!

NOW, I have an idea!
...
And this what it came out:

Ingo Weinhold wrote:
> On 2004-02-01 at 23:06:23 [+0100], Andrew Bachmann wrote:
>>Assuming that the constants are multi-bit, I think the most reliable way to
>>test would be to use a
>>construct like this:
>>
>>if (ResizingMode() & B_FOLLOW_LEFT_RIGHT == B_FOLLOW_LEFT_RIGHT)
>>....
>>if (ResizingMode() & B_FOLLOW_LEFT == B_FOLLOW_LEFT)
>>....
>>if (ResizingMode() & B_FOLLOW_RIGHT == B_FOLLOW_RIGHT)
>>....
>
>
> This won't work in general, since it holds for instance:
> B_FOLLOW_BOTTOM & B_FOLLOW_TOP == B_FOLLOW_TOP
But will work if placed in the proper order!
Had tried that before, but it is only now I got inspired. :-)

And, that order is:
                // resize/move horizontaly
        if ((rmask & B_FOLLOW_H_CENTER) == B_FOLLOW_H_CENTER){
                printf("1\n");
        }
        else if ((rmask & B_FOLLOW_LEFT_RIGHT) == B_FOLLOW_LEFT_RIGHT){
                printf("2\n");
        }
        else if ((rmask & B_FOLLOW_RIGHT) == B_FOLLOW_RIGHT){
                printf("3\n");
        }
        else if ((rmask & B_FOLLOW_LEFT) == B_FOLLOW_LEFT){
                printf("4\n");
        }
        else { // illegal flag. Do nothing.
                printf("5\n");
        }

                // resize/move verticaly
        if ((rmask & B_FOLLOW_V_CENTER) == B_FOLLOW_V_CENTER){
                printf("1\n");
        }
        else if ((rmask & B_FOLLOW_BOTTOM) == B_FOLLOW_BOTTOM){
                printf("2\n");
        }
        else if ((rmask & B_FOLLOW_TOP_BOTTOM) == B_FOLLOW_TOP_BOTTOM){
                printf("3\n");
        }
        else if ((rmask & B_FOLLOW_TOP) == B_FOLLOW_TOP){
                printf("4\n");
        }
        else { // illegal flag. Do nothing.
                printf("5\n");
        }

I think we shall make this public. Others may have the same problem.


Adi.





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