Author: toshok
Date: 2008-01-24 18:23:26 -0500 (Thu, 24 Jan 2008)
New Revision: 93858
Modified:
trunk/moon/src/ChangeLog
trunk/moon/src/stylus.cpp
Log:
2008-01-24 Chris Toshok <[EMAIL PROTECTED]>
* stylus.cpp (Stroke::HitTestEndcapSegment): implement.
(calc_perpendicular_intersection_points): new method.
(Stroke::HitTestSegmentSegment): use
calc_perpendicular_intersection_points to give us the end points
of the outer line segments, and use those for hit testing.
Modified: trunk/moon/src/ChangeLog
===================================================================
--- trunk/moon/src/ChangeLog 2008-01-24 23:22:04 UTC (rev 93857)
+++ trunk/moon/src/ChangeLog 2008-01-24 23:23:26 UTC (rev 93858)
@@ -1,3 +1,11 @@
+2008-01-24 Chris Toshok <[EMAIL PROTECTED]>
+
+ * stylus.cpp (Stroke::HitTestEndcapSegment): implement.
+ (calc_perpendicular_intersection_points): new method.
+ (Stroke::HitTestSegmentSegment): use
+ calc_perpendicular_intersection_points to give us the end points
+ of the outer line segments, and use those for hit testing.
+
2008-01-24 Jeffrey Stedfast <[EMAIL PROTECTED]>
* media.cpp (UpdateProgress): When switching to Buffering mode,
Modified: trunk/moon/src/stylus.cpp
===================================================================
--- trunk/moon/src/stylus.cpp 2008-01-24 23:22:04 UTC (rev 93857)
+++ trunk/moon/src/stylus.cpp 2008-01-24 23:23:26 UTC (rev 93858)
@@ -13,6 +13,7 @@
#include <config.h>
#include <stdlib.h>
+#include <math.h>
#include "stylus.h"
#include "collection.h"
@@ -151,7 +152,27 @@
p2.x, p2.y);
#endif
- return false;
+
+ double m = (p2.x - p1.x)/p2.y - p1.y;
+ double b_ = p1.y - m * p1.x;
+
+ double a, b;
+ if (w > h) {
+ a = w / 2;
+ b = h / 2;
+ }
+ else {
+ a = h / 2;
+ b = w / 2;
+ }
+
+ double aq = (m*m) / (b*b) + 1 / (a*a);
+ double cq = b_ * b_ - b * b;
+
+ double discr = -4 * aq * cq;
+
+ /* discr == 0 means 1 intersection point, discr > 0 means 2 */
+ return discr >= 0;
}
static bool
@@ -178,6 +199,61 @@
return false;
}
+// given the line segment between @p1 and @p2, with an ellipse with
+// width = @w and height = @h centered at point @p, return the left
+// (lesser x coordinate if the x's are different, and lesser y
+// coordinate if they're the same) and right (greater x coordinate, or
+// greater y coordinate) intersection points of the line through the
+// same point @p but perpendicular to line @p2 - @p1.
+static void
+calc_perpendicular_intersection_points (Point p1, Point p2,
+ Point p,
+ double w, double h,
+ Point *left_point, Point *right_point)
+{
+ if (p2.y == p1.y) { // horizontal line
+ *left_point = Point (p.x, p.y - h / 2);
+ *right_point = Point (p.x, p.y + h / 2);
+ }
+ else if (p2.x == p1.x) { // vertical line
+ *left_point = Point (p.x - w / 2, p.y);
+ *right_point = Point (p.x + w / 2, p.y);
+ }
+ else {
+ // slope of the perpendicular line
+ double m = -(p2.x - p1.x)/p2.y - p1.y;
+
+ double a, b;
+ if (w > h) {
+ a = w / 2;
+ b = h / 2;
+ }
+ else {
+ a = h / 2;
+ b = w / 2;
+ }
+
+ double aq = (m*m) / (b*b) + 1 / (a*a);
+
+ double discr = 4 * aq;
+
+ if (discr <= 0) {
+ g_warning ("should never happen, there should always be
two roots");
+ *left_point = p;
+ *right_point = p;
+ }
+ else {
+ double sqrt_discr = sqrt (discr);
+
+ double root = (sqrt_discr) / (2 * aq);
+
+ *left_point = Point (-root + p.x, (-root * m) + p.y);
+ *right_point = Point (root + p.x, (root * m) + p.y);
+ }
+
+ }
+}
+
bool
Stroke::HitTestSegmentSegment (Point stroke_p1, Point stroke_p2,
double w, double h,
@@ -191,11 +267,18 @@
p1.x, p1.y,
p2.x, p2.y);
#endif
- bool rv = intersect_line_2d (stroke_p1, stroke_p2, p1, p2);
-#if DEBUG_HITTEST
- printf (" + %s\n", rv ? "TRUE" : "FALSE");
-#endif
- return rv;
+ Point left_stroke_p1, right_stroke_p1;
+ Point left_stroke_p2, right_stroke_p2;
+
+ calc_perpendicular_intersection_points (stroke_p1, stroke_p2,
stroke_p1, w, h, &left_stroke_p1, &right_stroke_p1);
+ calc_perpendicular_intersection_points (stroke_p1, stroke_p2,
stroke_p2, w, h, &left_stroke_p2, &right_stroke_p2);
+
+ if (intersect_line_2d (left_stroke_p1, left_stroke_p2, p1, p2))
+ return true;
+ if (intersect_line_2d (right_stroke_p1, right_stroke_p2, p1, p2))
+ return true;
+
+ return false;
}
bool
_______________________________________________
Mono-patches maillist - [email protected]
http://lists.ximian.com/mailman/listinfo/mono-patches
