improve new image mock and refactor scale function in calc

Author: archmoj

src/traces/image/calc.js

@@ -43,11 +43,9 @@ module.exports = function calc(gd, trace) {
     return [cd0];
 };
 
-function scale(zero, factor, min, max) {
+function scale(zero, ratio, min, max) {
     return function(c) {
-        c = (c - zero) * factor;
-        c = Lib.constrain(c, min, max);
-        return c;
+        return Lib.constrain((c - zero) * ratio, min, max);
     };
 }
 

test/image/baselines/image_non_numeric.png

@@ -4,13 +4,91 @@
     "hoverinfo": "all",
     "z": [
       [
-        [true, true, true],
-        [false, false, false]
+        [255, 0, 0],
+        [191, 0, 0],
+        [127, 0, 0]
+      ],
+      [
+        [0, 255, 0],
+        [0, 191, 0],
+        [0, 127, 0]
+      ],
+      [
+        [0, 0, 255],
+        [0, 0, 191],
+        [0, 0, 127]
+      ]
+    ]
+  }, {
+    "yaxis": "y2",
+    "xaxis": "x2",
+    "type": "image",
+    "hoverinfo": "all",
+    "z": [
+      [
+        [255, 0, 0],
+        [191, 0, null],
+        [127, 0, 0]
+      ],
+      [
+        [0, 255, 0],
+        [false, 191, 0],
+        [0, 127, 0]
+      ],
+      [
+        [0, 0, 255],
+        [0, true, 191],
+        [0, 0, 127]
+      ]
+    ]
+  }, {
+    "yaxis": "y3",
+    "xaxis": "x3",
+    "type": "image",
+    "hoverinfo": "all",
+    "z": [
+      [
+        [255, 0, 0],
+        [191, 0, 0],
+        [-10000, 0, 0]
+      ],
+      [
+        [0, 255, 0],
+        [0, "", 0],
+        [0, 127, 0]
+      ],
+      [
+        [0, 0, 10000],
+        [0, 0, 191],
+        [0, 0, 127]
       ]
     ]
+  }, {
+    "yaxis": "y4",
+    "xaxis": "x4",
+    "type": "image",
+    "hoverinfo": "all",
+    "z": [
+      [
+        [255, 0],
+        [191, 0, null],
+        [127, 0, ""]
+      ],
+      [
+        [true, 255, 0],
+        [false, 191, 0],
+        ["text", 127, 0]
+      ],
+      []
+    ]
   }],
   "layout": {
-    "width": 400,
-    "height": 400
+    "width": 600,
+    "height": 600,
+    "grid": {
+      "rows": 2,
+      "columns": 2,
+      "pattern": "independent"
+    }
   }
 }