void DrawingView::UpdateGridBackground(void)
{
-//was: 128
-//#define BG_BRUSH_SPAN 72
-#define BG_BRUSH_SPAN (gridPixels)
// Transform the origin to Qt coordinates
Vector pixmapOrigin = Painter::CartesianToQtCoords(Vector());
int x = (int)pixmapOrigin.x;
int y = (int)pixmapOrigin.y;
// Use mod arithmetic to grab the correct swatch of background
- // Problem with mod 128: Negative numbers screw it up... [FIXED]
/*
Negative numbers still screw it up... Need to think about what we're
trying to do here. The fact that it worked with 72 seems to have been pure luck.
| | | |
Which means we need to grab the sample from x = 1. Which means we have to take
-the inverse of the modulus of gridPixels.
+the mirror of the modulus of gridPixels.
Doing a mod of a negative number is problematic: 1st, the compiler converts the
negative number to an unsigned int, then it does the mod. Gets you wrong answers
-most of the time, unless you use a power of 2. :-P
-
-This has been solved below:
-UGB: pmo=(2.000000,687.000000) X=2, X%48=2, new x=45
-UGB: pmo=(1.000000,687.000000) X=1, X%48=1, new x=46
-UGB: pmo=(0.000000,687.000000) X=0, X%48=0, new x=47
-UGB: pmo=(-1.000000,687.000000) X=-1, X%48=15, new x=1
-UGB: pmo=(-2.000000,686.000000) X=-2, X%48=14, new x=2
-UGB: pmo=(-3.000000,686.000000) X=-3, X%48=13, new x=3
-
-Problem with changing grid size causes x/y origin to be shown incorrectly:
-UGB: pmo=(10.000000,812.000000) X=10, X%12=10, new x=2
-UGB: pmo=(10.000000,812.000000) X=10, X%4=2, new x=2
-UGB: pmo=(3.333333,818.666667) X=3, X%48=3, new x=45
-UGB: pmo=(39.000000,782.000000) X=39, X%48=39, new x=9 <-- MMB move is here
-UGB: pmo=(39.000000,781.000000) X=39, X%48=39, new x=9
-
-
-
+most of the time, unless you use a power of 2. :-P So what we do here is just
+take the modulus of the negation, which means we don't have to worry about
+mirroring it later.
+
+The positive case looks gruesome (and it is) but it boils down to this: We take
+the modulus of the X coordinate, then mirror it by subtraction from the
+maximum (in this case, gridPixels). This gives us a number in the range of 1 to
+gridPixels. But we need the case where the result equalling gridPixels to be
+zero; so we do another modulus operation on the result to achieve this.
*/
-//printf("UGB: pmo=(%f,%f) X=%i, X%%%i=%i, ", pixmapOrigin.x, pixmapOrigin.y, x, BG_BRUSH_SPAN, x % BG_BRUSH_SPAN);
-// x = (x < 0 ? 0 : BG_BRUSH_SPAN - 1) - (x % BG_BRUSH_SPAN);
-// y = (y < 0 ? 0 : BG_BRUSH_SPAN - 1) - (y % BG_BRUSH_SPAN);
-// x = (BG_BRUSH_SPAN - 1) - (x % BG_BRUSH_SPAN);
-// y = (BG_BRUSH_SPAN - 1) - (y % BG_BRUSH_SPAN);
-// x = (x < 0 ? 0 : BG_BRUSH_SPAN - 1) - ((x < 0 ? -x : x) % BG_BRUSH_SPAN);
if (x < 0)
- x = -x % BG_BRUSH_SPAN;
+ x = -x % gridPixels;
else
- x = (BG_BRUSH_SPAN - (x % BG_BRUSH_SPAN)) % BG_BRUSH_SPAN;
+ x = (gridPixels - (x % gridPixels)) % gridPixels;
-// y = (y < 0 ? 0 : BG_BRUSH_SPAN - 1) - ((y < 0 ? -y : y) % BG_BRUSH_SPAN);
if (y < 0)
- y = -y % BG_BRUSH_SPAN;
+ y = -y % gridPixels;
else
- y = (BG_BRUSH_SPAN - (y % BG_BRUSH_SPAN)) % BG_BRUSH_SPAN;
-//printf("new x=%i\n", x);
+ y = (gridPixels - (y % gridPixels)) % gridPixels;
// Here we grab a section of the bigger pixmap, so that the background
// *looks* like it's scrolling...
- QPixmap pm = gridBackground.copy(x, y, BG_BRUSH_SPAN, BG_BRUSH_SPAN);
+ QPixmap pm = gridBackground.copy(x, y, gridPixels, gridPixels);
QPalette pal = palette();
pal.setBrush(backgroundRole(), QBrush(pm));
setAutoFillBackground(true);
}
-void DrawingView::resizeEvent(QResizeEvent * event)
+void DrawingView::resizeEvent(QResizeEvent * /*event*/)
{
Painter::screenSize = Vector(size().width(), size().height());
-// Painter::screenSize = Vector(event->size().width(), event->size().height());
-//printf("DrawingView::resizeEvent: new size:
UpdateGridBackground();
}