Improve rotation and padding calculation

src/core/core.scale.js

@@ -414,7 +414,7 @@ module.exports = Element.extend({
 		var options = me.options;
 		var tickOpts = options.ticks;
 		var ticks = me.getTicks();
-		var labelSizes, maxLabelWidth, maxLabelHeight, tickWidth, maxHeight, maxLabelDiagonal;
+		var labelSizes, maxLabelWidth, maxLabelHeight, maxWidth, tickWidth, maxHeight, maxLabelDiagonal;
 
 		var labelRotation = tickOpts.minRotation || 0;
 
@@ -427,10 +427,12 @@ module.exports = Element.extend({
 
 				// Estimate the width of each grid based on the canvas width, the maximum
 				// label width and the number of tick intervals
-				tickWidth = (me.chart.width - maxLabelWidth) / (ticks.length - 1);
+				maxWidth = Math.min(me.maxWidth, me.chart.width - maxLabelWidth);
+				tickWidth = options.offset ? me.maxWidth / ticks.length : maxWidth / (ticks.length - 1);
 
 				// Allow 3 pixels x2 padding either side for label readability
 				if (maxLabelWidth + 6 > tickWidth) {
+					tickWidth = maxWidth / (ticks.length - (options.offset ? 0.5 : 1));
 					maxHeight = me.maxHeight - getTickMarkLength(options.gridLines)
 						- tickOpts.padding - getScaleLabelHeight(options.scaleLabel);
 					maxLabelDiagonal = Math.sqrt(maxLabelWidth * maxLabelWidth + maxLabelHeight * maxLabelHeight);
@@ -529,8 +531,11 @@ module.exports = Element.extend({
 					paddingLeft = firstLabelSize.width / 2;
 					paddingRight = lastLabelSize.width / 2;
 				}
-				me.paddingLeft = Math.max(paddingLeft - offsetLeft, 0) + 3; // add 3 px to move away from canvas edges
-				me.paddingRight = Math.max(paddingRight - offsetRight, 0) + 3;
+
+				// Adjust padding taking into account changes in offsets
+				// and add 3 px to move away from canvas edges
+				me.paddingLeft = Math.max((paddingLeft - offsetLeft) * me.width / (me.width - offsetLeft), 0) + 3;
+				me.paddingRight = Math.max((paddingRight - offsetRight) * me.width / (me.width - offsetRight), 0) + 3;
 			} else {
 				// A vertical axis is more constrained by the width. Labels are the
 				// dominant factor here, so get that length first and account for padding