Zoom for categoryAxisRenderer: manage the zoom - fix jqPlot#187

Copy of orignal ticks and data is done in order to be able to restore them on zoom out.
Change of the ticks and the data to match the selected area.
Implementation of restoration on zoom out.

This code only works for x axis.
This code may be unefficient for large data (to be tested).

src/plugins/jqplot.cursor.js

@@ -316,7 +316,9 @@
 
     $.jqplot.Cursor.prototype.resetZoom = function(plot, cursor) {
         var axes = plot.axes;
+        var series = plot.series;
         var cax = cursor._zoom.axes;
+        var cser = cursor._data_series;
         if (!plot.plugins.cursor.zoomProxy && cursor._zoom.isZoomed) {
             for (var ax in axes) {
                 // axes[ax]._ticks = [];
@@ -326,12 +328,18 @@
                 // axes[ax].tickInterval = cax[ax].tickInterval;
                 // // for date axes
                 // axes[ax].daTickInterval = cax[ax].daTickInterval;
+                axes[ax].ticks = cax[ax].ticks;
                 axes[ax].reset();
                 axes[ax]._ticks = [];
                 // fake out tick creation algorithm to make sure original auto
                 // computed format string is used if _overrideFormatString is true
                 axes[ax]._autoFormatString = cax[ax].tickFormatString;
             }
+            if (cser){
+                for (var idxSerie=0 ; idxSerie < series.length; idxSerie++) {
+                    series[idxSerie].data = cser[idxSerie];
+                }
+            }
             plot.redraw();
             cursor._zoom.isZoomed = false;
         }
@@ -350,6 +358,7 @@
     $.jqplot.Cursor.prototype.doZoom = function (gridpos, datapos, plot, cursor) {
         var c = cursor;
         var axes = plot.axes;
+        var series = plot.series;
         var zaxes = c._zoom.axes;
         var start = zaxes.start;
         var end = zaxes.end;
@@ -363,6 +372,7 @@
                     // make a copy of the original axes to revert back.
                     if (c._zoom.axes[ax] == undefined) {
                         c._zoom.axes[ax] = {};
+                        c._zoom.axes[ax].ticks = axes[ax].ticks;
                         c._zoom.axes[ax].numberTicks = axes[ax].numberTicks;
                         c._zoom.axes[ax].tickInterval = axes[ax].tickInterval;
                         // for date axes...
@@ -371,6 +381,13 @@
                         c._zoom.axes[ax].max = axes[ax].max;
                         c._zoom.axes[ax].tickFormatString = (axes[ax].tickOptions != null) ? axes[ax].tickOptions.formatString :  '';
                     }
+                    // make a copy of the original data to revert back.
+                    if (c._data_series == undefined){
+                        c._data_series = new Array();
+                        for (var idxSerie=0 ; idxSerie < series.length; idxSerie++) {
+                            c._data_series.push(series[idxSerie].data);
+                        }
+                    }
 
 
                     if ((c.constrainZoomTo == 'none') || (c.constrainZoomTo == 'x' && ax.charAt(0) == 'x') || (c.constrainZoomTo == 'y' && ax.charAt(0) == 'y')) {   
@@ -400,8 +417,34 @@
                                     _numberTicks = plot.axes.yaxis.numberTicks;
                                 }
                             }
-
-                            if (this.looseZoom && (axes[ax].renderer.constructor === $.jqplot.LinearAxisRenderer || axes[ax].renderer.constructor === $.jqplot.LogAxisRenderer )) { //} || axes[ax].renderer.constructor === $.jqplot.DateAxisRenderer)) {
+
+                            if (axes[ax].renderer.constructor === $.jqplot.CategoryAxisRenderer && curax.name === "xaxis") {  // only managed for x
+                                var tickDelta = axes[ax].max / axes[ax].ticks.length;
+                                var currentValue = 0;
+                                var currentData = new Array();
+                                var newTicks = new Array();
+                                // only get the relevant ticks and filter data
+                                for (var idxTick=0 ; idxTick < axes[ax].ticks.length; idxTick++) {
+                                    if (currentValue >= newmin && currentValue <= newmax){
+                                        newTicks.push(axes[ax].ticks[idxTick]);
+                                        for (var idxSerie=0 ; idxSerie < series.length; idxSerie++) {
+                                            if (currentData.length <= idxSerie) currentData.push(new Array());
+                                            currentData[idxSerie].push(
+                                                [newTicks.length, series[idxSerie].data[idxTick][1]]);
+                                        }
+                                    }
+                                    currentValue += tickDelta;
+                                }
+                                if (newTicks.length){
+                                    axes[ax].min = newmin;
+                                    axes[ax].max = newmax;
+                                    axes[ax].ticks = newTicks;
+                                    for (var idxSerie=0 ; idxSerie < series.length; idxSerie++) {
+                                        series[idxSerie].data = currentData[idxSerie];
+                                    }
+                                }
+                            }
+                            else if (this.looseZoom && (axes[ax].renderer.constructor === $.jqplot.LinearAxisRenderer || axes[ax].renderer.constructor === $.jqplot.LogAxisRenderer )) { //} || axes[ax].renderer.constructor === $.jqplot.DateAxisRenderer)) {
 
                                 ret = $.jqplot.LinearTickGenerator(newmin, newmax, curax._scalefact, _numberTicks);
 
@@ -423,7 +466,6 @@
                                     ret[0] += ret[4];
                                     ret[2] -= 1;
                                 }
-
                                 axes[ax].min = ret[0];
                                 axes[ax].max = ret[1];
                                 axes[ax]._autoFormatString = ret[3];