Update heatmap annotation text color logic to handle NaN values

Author: robertoffmoura

plotly/Test_plotlyfig.m

@@ -2686,5 +2686,31 @@ function testHeatmapAxisLabels(tc)
             tc.verifyEqual(p.layout.xaxis1.title.text, xLabelText);
             tc.verifyEqual(p.layout.yaxis1.title.text, yLabelText);
         end
+
+        function testHeatmapWithNaNValues(tc)
+            fig = figure("Visible","off");
+            data = [1 2 NaN; 4 NaN 6; 7 8 9];
+            heatmap(data);
+
+            p = plotlyfig(fig,"visible","off");
+
+            tc.verifyNumElements(p.data, 1);
+            heatmapData = p.data{1};
+            tc.verifyEqual(heatmapData.z, flip(data));
+        end
+
+        function testHeatmapAllNaNValues(tc)
+            fig = figure("Visible","off");
+            data = [NaN NaN; NaN NaN];
+            heatmap(data);
+
+            p = plotlyfig(fig,"visible","off");
+
+            tc.verifyNumElements(p.data, 1);
+            heatmapData = p.data{1};
+            tc.verifyEqual(heatmapData.z, flip(data));
+            tc.verifyTrue(all(isnan(heatmapData.z(:))));
+            tc.verifyTrue(all(isnan(heatmapData.text(:))));
+        end
     end
 end

plotly/plotlyfig_aux/handlegraphics/updateHeatmap.m

@@ -70,14 +70,15 @@
             ann.x = i-1;
             ann.y = j-1;
             ann.showarrow = false;
-            ratio = (cdata(j,i) - data.zmin) / (data.zmax - data.zmin);
-            colorIndex = 1 + clip(round(ratio*len), 0, len);
-            c = 255*cmap(colorIndex,:);
-            luminance = [0.299 0.587 0.114] * c'; % ITU-R BT.601 luminance standard
-            if luminance > 128
-                col = [0,0,0];
-            else
-                col = [255,255,255];
+            col = [255 255 255];
+            if isfinite(cdata(j,i))
+                ratio = (cdata(j,i) - data.zmin) / (data.zmax - data.zmin);
+                colorIndex = 1 + clip(round(ratio*len), 0, len);
+                c = 255*cmap(colorIndex,:);
+                luminance = [0.299 0.587 0.114] * c'; % ITU-R BT.601 luminance standard
+                if luminance > 128
+                    col = [0 0 0];
+                end
             end
             ann.font.color = getStringColor(col);
             annotations{(i-1)*n+j} = ann;