Merge trunk

1 files changed, 125 insertions, 11 deletions

diff --git a/generic/tkCanvArc.c b/generic/tkCanvArc.c
index 57f5835..880d313 100644
--- a/generic/tkCanvArc.c
+++ b/generic/tkCanvArc.c
@@ -62,6 +62,12 @@ typedef struct ArcItem {
 				 * start (see ComputeArcOutline). */
     double center2[2];		/* Coordinates of center of arc outline at
 				 * start+extent (see ComputeArcOutline). */
+    double height;              /* Distance from the arc's chord to its
+				 * mid-point. */
+    double startPoint[2];       /* Start point of arc used when specifying
+				 * height. */
+    double endPoint[2];         /* End point of arc used when specifying
+				 * height. */
 } ArcItem;
 
 /*
@@ -140,6 +146,8 @@ static const Tk_ConfigSpec configSpecs[] = {
 	"90", offsetof(ArcItem, extent), TK_CONFIG_DONT_SET_DEFAULT, NULL},
     {TK_CONFIG_COLOR, "-fill", NULL, NULL,
 	NULL, offsetof(ArcItem, fillColor), TK_CONFIG_NULL_OK, NULL},
+    {TK_CONFIG_DOUBLE, "-height", NULL, NULL,
+	0, offsetof(ArcItem, height), TK_CONFIG_DONT_SET_DEFAULT, NULL},
     {TK_CONFIG_CUSTOM, "-offset", NULL, NULL,
 	"0,0", offsetof(ArcItem, tsoffset),
 	TK_CONFIG_DONT_SET_DEFAULT, &offsetOption},
@@ -175,6 +183,7 @@ static void		ComputeArcBbox(Tk_Canvas canvas, ArcItem *arcPtr);
 static int		ConfigureArc(Tcl_Interp *interp,
 			    Tk_Canvas canvas, Tk_Item *itemPtr, int objc,
 			    Tcl_Obj *const objv[], int flags);
+static void		ComputeArcFromHeight(ArcItem *arcPtr);
 static int		CreateArc(Tcl_Interp *interp,
 			    Tk_Canvas canvas, struct Tk_Item *itemPtr,
 			    int objc, Tcl_Obj *const objv[]);
@@ -291,6 +300,7 @@ CreateArc(
     arcPtr->disabledFillStipple = None;
     arcPtr->style = PIESLICE_STYLE;
     arcPtr->fillGC = None;
+    arcPtr->height = 0;
 
     /*
      * Process the arguments to fill in the item record.
@@ -351,8 +361,8 @@ ArcCoords(
 	objs[2] = Tcl_NewDoubleObj(arcPtr->bbox[2]);
 	objs[3] = Tcl_NewDoubleObj(arcPtr->bbox[3]);
 	Tcl_SetObjResult(interp, Tcl_NewListObj(4, objs));
-    } else if ((objc == 1)||(objc == 4)) {
-	if (objc==1) {
+    } else if ((objc == 1) || (objc == 4)) {
+	if (objc == 1) {
 	    if (Tcl_ListObjGetElements(interp, objv[0], &objc,
 		    (Tcl_Obj ***) &objv) != TCL_OK) {
 		return TCL_ERROR;
@@ -374,6 +384,17 @@ ArcCoords(
 			&arcPtr->bbox[3]) != TCL_OK)) {
 	    return TCL_ERROR;
 	}
+
+	/*
+	 * Store bbox as start and end points so they can be used if either
+	 * radius or height is specified.
+	 */
+
+	arcPtr->startPoint[0] = arcPtr->bbox[0];
+	arcPtr->startPoint[1] = arcPtr->bbox[1];
+	arcPtr->endPoint[0] = arcPtr->bbox[2];
+	arcPtr->endPoint[1] = arcPtr->bbox[3];
+
 	ComputeArcBbox(canvas, arcPtr);
     } else {
 	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
@@ -447,6 +468,23 @@ ConfigureArc(
 	itemPtr->redraw_flags &= ~TK_ITEM_STATE_DEPENDANT;
     }
 
+    /*
+     * If either the height is provided then the start and extent will be
+     * overridden.
+     */
+    if (arcPtr->height != 0) {
+	ComputeArcFromHeight(arcPtr);
+	ComputeArcBbox(canvas, arcPtr);
+    }
+
+    i = (int) (arcPtr->start/360.0);
+    arcPtr->start -= i*360.0;
+    if (arcPtr->start < 0) {
+	arcPtr->start += 360.0;
+    }
+    i = (int) (arcPtr->extent/360.0);
+    arcPtr->extent -= i*360.0;
+
     tsoffset = &arcPtr->outline.tsoffset;
     flags = tsoffset->flags;
     if (flags & TK_OFFSET_LEFT) {
@@ -464,14 +502,6 @@ ConfigureArc(
 	tsoffset->yoffset = (int) (arcPtr->bbox[2] + 0.5);
     }
 
-    i = (int) (arcPtr->start/360.0);
-    arcPtr->start -= i*360.0;
-    if (arcPtr->start < 0) {
-	arcPtr->start += 360.0;
-    }
-    i = (int) (arcPtr->extent/360.0);
-    arcPtr->extent -= i*360.0;
-
     mask = Tk_ConfigOutlineGC(&gcValues, canvas, itemPtr, &(arcPtr->outline));
     if (mask) {
 	gcValues.cap_style = CapButt;
@@ -509,7 +539,7 @@ ConfigureArc(
 	if (arcPtr->disabledFillStipple!=None) {
 	    stipple = arcPtr->disabledFillStipple;
 	}
-      }
+    }
 
     if (arcPtr->style == ARC_STYLE) {
 	newGC = None;
@@ -559,6 +589,90 @@ ConfigureArc(
 /*
  *--------------------------------------------------------------
  *
+ * ComputeArcFromHeight --
+ *
+ *	This function calculates the arc parameters given start-point,
+ *	end-point and height (!= 0).
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The height parameter is set to 0 on exit.
+ *
+ *--------------------------------------------------------------
+ */
+
+static void
+ComputeArcFromHeight(
+    ArcItem* arcPtr)
+{
+    double chordLen, chordDir[2], chordCen[2], arcCen[2], d, radToDeg, radius;
+
+    /*
+     * The chord.
+     */
+
+    chordLen = hypot(arcPtr->endPoint[1] - arcPtr->startPoint[1],
+	    arcPtr->startPoint[0] - arcPtr->endPoint[0]);
+    chordDir[0] = (arcPtr->endPoint[0] - arcPtr->startPoint[0]) / chordLen;
+    chordDir[1] = (arcPtr->endPoint[1] - arcPtr->startPoint[1]) / chordLen;
+    chordCen[0] = (arcPtr->startPoint[0] + arcPtr->endPoint[0]) / 2;
+    chordCen[1] = (arcPtr->startPoint[1] + arcPtr->endPoint[1]) / 2;
+
+    /*
+     * Calculate the radius (assumes height != 0).
+     */
+
+    radius = (4*pow(arcPtr->height, 2) + pow(chordLen, 2))
+	    / (8 * arcPtr->height);
+
+    /*
+     * The arc centre.
+     */
+
+    d = radius - arcPtr->height;
+    arcCen[0] = chordCen[0] - d * chordDir[1];
+    arcCen[1] = chordCen[1] + d * chordDir[0];
+
+    /*
+     * The arc start and span. Angles are negated because the coordinate
+     * system is left-handed.
+     */
+
+    radToDeg = 45 / atan(1);
+    arcPtr->start = atan2(arcCen[1] - arcPtr->startPoint[1],
+	    arcPtr->startPoint[0] - arcCen[0]) * radToDeg;
+    arcPtr->extent = -2 * asin(chordLen / (2 * radius)) * radToDeg;
+
+    /*
+     * Handle spans > 180.
+     */
+
+    if (fabs(2 * arcPtr->height) > chordLen) {
+	arcPtr->extent = arcPtr->extent > 0 ? (360 - arcPtr->extent)
+		: -(360 + arcPtr->extent);
+    }
+
+    /*
+     * Create the bounding box.
+     */
+
+    arcPtr->bbox[0] = arcCen[0] - radius;
+    arcPtr->bbox[1] = arcCen[1] - radius;
+    arcPtr->bbox[2] = arcCen[0] + radius;
+    arcPtr->bbox[3] = arcCen[1] + radius;
+
+    /*
+     * Set the height to 0 so that itemcget -height returns 0.
+     */
+
+    arcPtr->height = 0;
+}
+
+/*
+ *--------------------------------------------------------------
+ *
  * DeleteArc --
  *
  *	This function is called to clean up the data structure associated with