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more changes for rectangle outlining

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This commit is contained in:
Paul Davis 2014-10-31 10:56:03 -04:00
parent a942493565
commit 90872c2b31
1 changed files with 32 additions and 33 deletions
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65
libs/canvas/rectangle.cc
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@ -88,53 +88,52 @@ Rectangle::render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) con
setup_outline_context (context);
/* the goal here is that if the border is 1 pixel
* thick, it will precisely align with the corner
* coordinates of the rectangle. So if the rectangle
* has a left edge at 0 and a right edge at 10, then
* the left edge must span -0.5..+0.5, the right edge
* must span 9.5..10.5 (i.e. the single full color
* pixel is precisely aligned with 0 and 10
* respectively).
*
* we have to shift left/up in all cases, which means
* subtraction along both axes (i.e. edge at
* N, outline must start at N-0.5).
*
* see the cairo FAQ on single pixel lines to see why we do
* the 0.5 pixel additions.
*/
self = self.translate (Duple (-0.5, -0.5));
std::cerr << "Outline using " << self << " from " << _rect << std::endl;
if (_outline_what == What (LEFT|RIGHT|BOTTOM|TOP)) {
context->rectangle (self.x0 + 0.5, self.y0 + 0.5, self.width() - 1.0, self.height() - 1.0);
context->rectangle (self.x0, self.y0, self.width(), self.height());
} else {
/* the goal here is that if the border is 1 pixel
* thick, it will precisely align with the corner
* coordinates of the rectangle. So if the rectangle
* has a left edge at 0 and a right edge at 10, then
* the left edge must span -0.5..+0.5, the right edge
* must span 9.5..10.5 (i.e. the single full color
* pixel is precisely aligned with 0 and 10
* respectively).
*
* we have to shift left/up in all cases, which means
* subtraction along both axes (i.e. edge at
* N, outline must start at N-0.5).
*
* see the cairo FAQ on single pixel lines to see why we do
* the 0.5 pixel additions.
*/
if (_outline_what & LEFT) {
/* vertical line: move x-coordinate left by 0.5 pixels */
context->move_to (self.x0 - 0.5, self.y0);
context->line_to (self.x0 - 0.5, self.y1);
context->move_to (self.x0, self.y0);
context->line_to (self.x0, self.y1);
}
if (_outline_what & TOP) {
/* horizontal line: move y-coordinate up by 0.5 pixels */
context->move_to (self.x0, self.y0 - 0.5);
context->line_to (self.x1, self.y0 - 0.5);
context->move_to (self.x0, self.y0);
context->line_to (self.x1, self.y0);
}
if (_outline_what & BOTTOM) {
/* horizontal line: move y-coordinate up by 0.5 pixels */
context->move_to (self.x0, self.y1 - 0.5);
context->line_to (self.x1, self.y1 - 0.5);
context->move_to (self.x0, self.y1);
context->line_to (self.x1, self.y1);
}
if (_outline_what & RIGHT) {
/* vertical line: move x-coordinate left by 0.5 pixels */
context->move_to (self.x1 - 0.5, self.y0);
context->line_to (self.x1 - 0.5, self.y1);
context->move_to (self.x1, self.y0);
context->line_to (self.x1, self.y1);
}
}
context->stroke ();
@ -146,12 +145,12 @@ Rectangle::compute_bounding_box () const
{
if (!_rect.empty()) {
Rect r = _rect.fix ();
/* take into acount the 0.5 addition to the bounding
box for the right and bottom edges, see ::render() above
*/
r.x1 += 1.0; // XXX this makes no sense but is necessary
r.y1 += 0.5;
r = r.expand (1.0);
_bounding_box = r;
}