Geomap: fix scale calculations (#37375)

public/app/plugins/panel/geomap/dims/scale.test.ts

@@ -1,4 +1,5 @@
-import { validateScaleConfig } from './scale';
+import { ArrayVector, DataFrame, FieldType } from '@grafana/data';
+import { getScaledDimension, validateScaleConfig } from './scale';
 
 describe('scale dimensions', () => {
   it('should validate empty input', () => {
@@ -35,4 +36,33 @@ describe('scale dimensions', () => {
       }
     `);
   });
+
+  it('should support negative min values', () => {
+    const values = [-20, -10, -5, 0, 5, 10, 20];
+    const frame: DataFrame = {
+      name: 'a',
+      length: values.length,
+      fields: [
+        { name: 'time', type: FieldType.number, values: new ArrayVector(values), config: {} },
+        {
+          name: 'hello',
+          type: FieldType.number,
+          values: new ArrayVector(values),
+          config: {
+            min: -10,
+            max: 10,
+          },
+        },
+      ],
+    };
+
+    const supplier = getScaledDimension(frame, {
+      min: -1,
+      max: 1,
+      field: 'hello',
+      fixed: 0,
+    });
+    const scaled = frame.fields[0].values.toArray().map((k, i) => supplier.get(i));
+    expect(scaled).toEqual([-1, -1, -0.5, 0, 0.5, 1, 1]);
+  });
 });

public/app/plugins/panel/geomap/dims/scale.ts

@@ -34,6 +34,11 @@ export function getScaledDimension(frame: DataFrame, config: ScaleDimensionConfi
       if (value !== -Infinity) {
         percent = (value - info.min!) / info.delta;
       }
+      if (percent > 1) {
+        percent = 1;
+      } else if (percent < 0) {
+        percent = 0;
+      }
       return config.min + percent * delta;
     },
     field,