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Info-Mac 4
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Info_Mac IV CD-ROM (Pacific HiTech Inc.)(August 1994).iso
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RegionToRectangles Folder
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EachRegionRect.c
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1993-11-13
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2KB
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/* I was going to put "copyright (c)..." but that seemed
a bit presumptuous given that regions were designed by
Bill Atkinson. So,
Written by Hugh Fisher, March 1993.
This code is standard commercial quality: I think it
works, and I'll fix any bugs you find, but it's not
MY responsibility even if your computer melts.
*/
void EachRegionRect (RgnHandle r, void (* proc)(Rect *));
void EachRegionRect (RgnHandle r, void (* proc)(Rect *))
{
#define EndMark 32767
#define MaxY 32767
#define StackMax 1024
typedef struct {
short size;
Rect bbox;
short data[];
} ** Internal;
Internal region;
short width, xAdjust, y, index, x1, x2, x;
Rect box;
short stackStorage[1024];
short * buffer;
region = (Internal)r;
/* Check for plain rectangle */
if ((**region).size == 10) {
proc(&(**region).bbox);
return;
}
/* Got to scale x coordinates into range 0..something */
xAdjust = (**region).bbox.left;
width = (**region).bbox.right - xAdjust;
/* Most regions will be less than 1024 pixels wide */
if (width < StackMax)
buffer = stackStorage;
else {
buffer = (short *)NewPtr(width * 2);
if (buffer == NULL)
/* Truly humungous region or very low on memory.
Quietly doing nothing seems to be the
traditional Quickdraw response. */
return;
}
/* Initialise scan line list to bottom edges */
for (x = (**region).bbox.left; x < (**region).bbox.right; x++)
buffer[x - xAdjust] = MaxY;
index = 0;
/* Loop until we hit an empty scan line */
while ((**region).data[index] != EndMark) {
y = (**region).data[index];
index ++;
/* Loop through horizontal runs on this line */
while ((**region).data[index] != EndMark) {
x1 = (**region).data[index];
index ++;
x2 = (**region).data[index];
index ++;
x = x1;
while (x < x2) {
if (buffer[x - xAdjust] < y) {
/* We have a bottom edge - how long for? */
box.left = x;
box.top = buffer[x - xAdjust];
while (x < x2 && buffer[x - xAdjust] == box.top) {
buffer[x - xAdjust] = MaxY;
x ++;
}
/* Pass to client proc */
box.right = x;
box.bottom = y;
proc(&box);
} else {
/* This becomes a top edge */
buffer[x - xAdjust] = y;
x ++;
}
}
}
index ++;
}
/* Clean up after ourselves */
if (width >= StackMax)
DisposPtr((Ptr)buffer);
#undef EndMark
#undef MaxY
#undef StackMax
}