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fix errors reported by pixman for meter redraws (and add more comments to help the coordinate challenged

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This commit is contained in:
Paul Davis 2016-09-28 13:37:19 -05:00
parent 67e415e14c
commit c8ae41d598
1 changed files with 54 additions and 14 deletions
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68
libs/canvas/meter.cc
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@ -140,9 +140,6 @@ Meter::init (int clr0, int clr1, int clr2, int clr3,
_stp[2] = stp2;
_stp[3] = stp3;
pixrect.x = 1;
pixrect.y = 1;
if (!len) {
len = 250;
}
@ -159,8 +156,16 @@ Meter::init (int clr0, int clr1, int clr2, int clr3,
bgpattern = horizontal_background (pixwidth + 2, pixheight + 2, _bgc, false);
}
pixrect.width = pixwidth;
pixrect.height = pixheight;
pixrect.x = 1;
if (orientation == Vertical) {
pixrect.width = pixwidth;
pixrect.y = pixheight; /* bottom of meter, so essentially "show zero" */
} else {
pixrect.width = 0; /* right of meter, so essentially "show zero" */
pixrect.y = 1;
}
}
void
@ -519,10 +524,17 @@ Meter::vertical_expose (ArdourCanvas::Rect const & area, Cairo::RefPtr<Cairo::Co
top_of_meter = (gint) floor (pixheight * current_level);
/* reset the height & origin of the rect that needs to show the pixbuf
/* reset the height & origin of the rect that needs to show the meter pattern
*/
pixrect.height = top_of_meter;
/* X/cairo coordinates; y grows down so y origin of pixrect (pattern
fill area) is the TOP of the pattern area, which we compute like this:
- start at 1
- go to bottom of meter (pixheight)
- back up by current meter height (top_of_meter)
*/
pixrect.y = 1 + pixheight - top_of_meter;
background.x = 1;
@ -728,19 +740,47 @@ Meter::queue_vertical_redraw (float old_level)
{
Cairo::RectangleInt rect;
gint new_top = (gint) floor (pixheight * current_level);
gint new_height = (gint) floor (pixheight * current_level);
/* this is the nominal area that needs to be filled by the meter
* pattern
*/
rect.x = 1;
rect.width = pixwidth;
rect.height = new_top;
rect.y = 1 + pixheight - new_top;
/* compute new top of meter (rect.y) by starting at one (border
* offset), go down the full height of the meter (X/Cairo coordinates
* grow down) to get to the bottom coordinate, then back up by the
* height of the patterned area.
*/
rect.y = 1 + pixheight - new_height;
/* remember: height extends DOWN thanks to X/Cairo */
rect.height = new_height;
/* now lets optimize redrawing by figuring out which part needs to be
actually redrawn (i.e. re-use the last drawn state).
*/
if (current_level > old_level) {
/* colored/pixbuf got larger, just draw the new section */
/* rect.y stays where it is because of X coordinates */
/* height of invalidated area is between new.y (smaller) and old.y
(larger).
X coordinates just make my brain hurt.
/* filled area got taller, just draw the new section */
/* rect.y (new y origin) is smaller or equal to pixrect.y (old
* y origin) because the top of the meter is higher (X/Cairo:
* coordinates grow down).
*
* Leave rect.y alone, and recompute the height to be just the
* difference between the new bottom and the top of the previous
* pattern area.
*
* The old pattern area extended DOWN from pixrect.y to
* pixrect.y + pixrect.height.
*
* The new pattern area extends DOWN from rect.y to
* rect.y + rect.height
*
* The area needing to be drawn is the difference between the
* old top (pixrect.y) and the new top (rect.y)
*/
rect.height = pixrect.y - rect.y;
} else {