Two new options: "inset" and "fromCenter"

src/core.js

@@ -179,6 +179,8 @@ $.fn.powerTip.defaults = {
 	placement: 'n',
 	smartPlacement: false,
 	offset: 10,
+	inset: 20,
+	fromCenter: 1.0,
 	mouseOnToPopup: false,
 	manual: false,
 	openEvents: [ 'mouseenter', 'focus' ],

src/csscoordinates.js

@@ -32,4 +32,13 @@ function CSSCoordinates() {
 			me[property] = Math.round(value);
 		}
 	};
+
+	/**
+	 * Check if a property is set
+	 * @private
+	 * @param {string} property The name of the property.
+	 */
+	me.isSet = function(property) {
+		return $.isNumeric(me[property]);
+	};
 }

src/placementcalculator.js

@@ -21,18 +21,23 @@ function PlacementCalculator() {
 	 * @param {string} placement The placement for the tooltip.
 	 * @param {number} tipWidth Width of the tooltip element in pixels.
 	 * @param {number} tipHeight Height of the tooltip element in pixels.
-	 * @param {number} offset Distance to offset tooltips in pixels.
+	 * @param {number} options.offset Distance to offset tooltips in pixels.
+	 * @param {number} options.fromCenter Distance along line from center (0) to boundary (1).
+	 * @param {number} options.inset Distance from corner of tooltip to object for ne, nw, se, sw.
 	 * @return {CSSCoordinates} A CSSCoordinates object with the position.
 	 */
-	function computePlacementCoords(element, placement, tipWidth, tipHeight, offset) {
+	function computePlacementCoords(element, placement, tipWidth, tipHeight, options ) {
 		var placementBase = placement.split('-')[0], // ignore 'alt' for corners
+			offset = options.offset,
+			fromCenter = options.fromCenter,
+			inset = options.inset,
 			coords = new CSSCoordinates(),
 			position;
 
 		if (isSvgElement(element)) {
-			position = getSvgPlacement(element, placementBase);
+			position = getSvgPlacement(element, placementBase, fromCenter);
 		} else {
-			position = getHtmlPlacement(element, placementBase);
+			position = getHtmlPlacement(element, placementBase, fromCenter);
 		}
 
 		// calculate the appropriate x and y position in the document
@@ -55,14 +60,14 @@ function PlacementCalculator() {
 			break;
 		case 'nw':
 			coords.set('bottom', session.windowHeight - position.top + offset);
-			coords.set('right', session.windowWidth - position.left - 20);
+			coords.set('right', session.windowWidth - position.left - inset);
 			break;
 		case 'nw-alt':
 			coords.set('left', position.left);
 			coords.set('bottom', session.windowHeight - position.top + offset);
 			break;
 		case 'ne':
-			coords.set('left', position.left - 20);
+			coords.set('left', position.left - inset);
 			coords.set('bottom', session.windowHeight - position.top + offset);
 			break;
 		case 'ne-alt':
@@ -71,14 +76,14 @@ function PlacementCalculator() {
 			break;
 		case 'sw':
 			coords.set('top', position.top + offset);
-			coords.set('right', session.windowWidth - position.left - 20);
+			coords.set('right', session.windowWidth - position.left - inset);
 			break;
 		case 'sw-alt':
 			coords.set('left', position.left);
 			coords.set('top', position.top + offset);
 			break;
 		case 'se':
-			coords.set('left', position.left - 20);
+			coords.set('left', position.left - inset);
 			coords.set('top', position.top + offset);
 			break;
 		case 'se-alt':
@@ -90,20 +95,36 @@ function PlacementCalculator() {
 		return coords;
 	}
 
+	/**
+	 * Finds the weighted average of two values
+	 * @private
+	 * @param {number} a the first value (returned if weight=0)
+	 * @param {number} b the second value (returned if weight=1)
+	 * @param {number} weight the weight (0 <= weight <= 1)
+	 */
+	function weightedAvg(a, b, weight) {
+		return Math.round( b * weight + a * (1.0 - weight) );
+	}
+
 	/**
 	 * Finds the tooltip attachment point in the document for a HTML DOM element
 	 * for the specified placement.
 	 * @private
 	 * @param {jQuery} element The element that the tooltip should target.
 	 * @param {string} placement The placement for the tooltip.
+	 * @param {number} fromCenter The relative distance between center and boundary
 	 * @return {Object} An object with the top,left position values.
 	 */
-	function getHtmlPlacement(element, placement) {
+	function getHtmlPlacement(element, placement, fromCenter) {
 		var objectOffset = element.offset(),
 			objectWidth = element.outerWidth(),
 			objectHeight = element.outerHeight(),
 			left,
-			top;
+			top,
+			objectCenter = {
+				top: objectOffset.top + objectHeight / 2,
+				left: objectOffset.left + objectWidth / 2
+			};
 
 		// calculate the appropriate x and y position in the document
 		switch (placement) {
@@ -142,8 +163,8 @@ function PlacementCalculator() {
 		}
 
 		return {
-			top: top,
-			left: left
+			top: weightedAvg(objectCenter.top, top, fromCenter),
+			left: weightedAvg(objectCenter.left, left, fromCenter)
 		};
 	}
 
@@ -153,9 +174,10 @@ function PlacementCalculator() {
 	 * @private
 	 * @param {jQuery} element The element that the tooltip should target.
 	 * @param {string} placement The placement for the tooltip.
+	 * @param {number} fromCenter The relative distance between center and boundary
 	 * @return {Object} An object with the top,left position values.
 	 */
-	function getSvgPlacement(element, placement) {
+	function getSvgPlacement(element, placement, fromCenter) {
 		var svgElement = element.closest('svg')[0],
 			domElement = element[0],
 			point = svgElement.createSVGPoint(),
@@ -166,6 +188,7 @@ function PlacementCalculator() {
 			placements = [],
 			placementKeys = ['nw', 'n', 'ne', 'e', 'se', 's', 'sw', 'w'],
 			coords,
+						center = svgElement.createSVGPoint(),
 			rotation,
 			steps,
 			x;
@@ -174,9 +197,12 @@ function PlacementCalculator() {
 			placements.push(point.matrixTransform(matrix));
 		}
 
-		// get bounding box corners and midpoints
+		// Get bounding box corners and midpoints
 		point.x = boundingBox.x;
 		point.y = boundingBox.y;
+		center.x = point.x + halfWidth;
+		center.y = point.y + halfHeight;
+		center = center.matrixTransform(matrix);
 		pushPlacement();
 		point.x += halfWidth;
 		pushPlacement();
@@ -197,6 +223,7 @@ function PlacementCalculator() {
 		if (placements[0].y !== placements[1].y || placements[0].x !== placements[7].x) {
 			rotation = Math.atan2(matrix.b, matrix.a) * RAD2DEG;
 			steps = Math.ceil(((rotation % 360) - 22.5) / 45);
+			center = center.matrixTransform(matrix);
 			if (steps < 1) {
 				steps += 8;
 			}
@@ -214,8 +241,8 @@ function PlacementCalculator() {
 		}
 
 		return {
-			top: coords.y + session.scrollTop,
-			left: coords.x + session.scrollLeft
+			top: weightedAvg(center.y, coords.y, fromCenter) + session.scrollTop,
+			left: weightedAvg(center.x, coords.x, fromCenter) + session.scrollLeft
 		};
 	}
 

src/tooltipcontroller.js

@@ -339,7 +339,7 @@ function TooltipController(options) {
 				placement,
 				tipWidth,
 				tipHeight,
-				options.offset
+				options
 			);
 
 			// place the tooltip