[SOLR-8197] Make zero counts in heatmap PNG transparent

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: spatial
• Assignee: Unassigned
• Reporter: Neil Ireson
• Created: 23/Oct/15 21:37
• Updated: 04/Jan/18 14:54

Description

It would be useful to have transparent zero values so that I can overlay the image as a layer on a map.

The change just requires altering two methods in SpatialHeatmapFacets.java as follows:

static void writeCountAtColumnRow(BufferedImage image, int rows, int c, int r, int val)
{
      image.setRGB(c, rows - 1 - r, val == 0 ? 0 : val ^ 0xFF_00_00_00);
}

static int getCountAtColumnRow(BufferedImage image, int rows, int c, int r)
{
      int val = image.getRGB(c, rows - 1 - r);
      return val == 0 ? 0 : val ^ 0xFF_00_00_00;
}