Move findMinMax

src/axis.js

@@ -578,4 +578,77 @@ c3_chart_internal_fn.getAxisData =  function(min, max, isAbscissa) {
     return axis;
 };
 
+c3.chart.internal.fn.findMinMax = function () {
+    var $$ = this, data = $$.data.targets;
+    var minY, maxY, minX, maxX;
+    var i,j, id;
+
+    var allData = $$.api.data();
+
+    allData.forEach(function(v){
+        var data;
+        if(v){
+            data = v.values;
+        } else {
+            data = {
+                length: 0
+            };
+        }
+
+        for(i = 0; i < data.length; i++) {
+            if (isUndefined(maxX) || data[i].x > maxX)
+                maxX = data[i].x;
+            if (isUndefined(minX) || data[i].x < minX)
+                minX = data[i].x;
+        }
+
+        var stacked = false;
+
+        var groups = $$.api.groups();
+
+        groups.forEach(function(elem){
+            if(elem.length){
+                stacked = true;
+            }
+        });
+
+        if(stacked){
+
+            data = $$.api.data();
+
+            var tmp = [];
+
+            for(i = 0; i < data.length; i++){
+                var tmp_seq = [];
+                var values = data[i].values;
+                values.forEach(function(value){
+                    tmp_seq.push(value);
+                });
+                tmp.push(tmp_seq);
+            }
+
+
+            for(i = 0; i < data.length; i++){
+                for(var j = 0; j < tmp[0].length; j++){
+                    var s = 0;
+                    for(var k = 0; k < tmp.length; k++){
+                        s += tmp[k][j].value;
+                    }
+                    if (isUndefined(maxY) || s > maxY)
+                    if (isUndefined(minY) || s < minY)
+                        minY = s;
+                }
+            }
+        } else {
+            for(i = 0; i < data.length; i++) {
+                if (isUndefined(maxY) || data[i].value > maxY)
+                    maxY = data[i].value;
+                if (isUndefined(minY) || data[i].value < minY)
+                    minY = data[i].value;
+            }
+        }
+    });
+
+    return {minY: minY, maxY: maxY, minX: minX, maxX: maxX};
+};