// getBlankTileData returns zero 2d tile data with a given scaling and format.
func (d *Data) getBlankTileImage(uuid dvid.UUID, shape dvid.DataShape, scaling Scaling) (image.Image, error) {
levelSpec, found := d.Levels[scaling]
if !found {
return nil, fmt.Errorf("Could not extract tiles for unspecified scale level %d", scaling)
}
tileW, tileH, err := shape.GetSize2D(levelSpec.TileSize)
if err != nil {
return nil, err
}
source, err := datastore.GetDataByUUID(uuid, d.Source)
if err != nil {
return nil, err
}
src, ok := source.(*imageblk.Data)
if !ok {
return nil, fmt.Errorf("Data instance %q for uuid %q is not imageblk.Data", d.Source, uuid)
}
bytesPerVoxel := src.Values.BytesPerElement()
switch bytesPerVoxel {
case 1, 2, 4, 8:
numBytes := tileW * tileH * bytesPerVoxel
data := make([]byte, numBytes, numBytes)
return dvid.GoImageFromData(data, int(tileW), int(tileH))
default:
return nil, fmt.Errorf("Cannot construct blank tile for data %q with %d bytes/voxel",
d.Source, src.Values.BytesPerElement())
}
}
// getBlankTileData returns a background 2d tile data
func (d *Data) getBlankTileImage(tile *GoogleSubvolGeom) (image.Image, error) {
if tile == nil {
return nil, fmt.Errorf("Can't get blank tile for unknown tile spec")
}
if d.Scales == nil || len(d.Scales) <= int(tile.gi) {
return nil, fmt.Errorf("Scaled volumes for %d not suitable for tile spec", d.DataName())
}
// Generate the blank image
numBytes := tile.sizeWant[0] * tile.sizeWant[1] * tile.bytesPerVoxel
data := make([]byte, numBytes, numBytes)
return dvid.GoImageFromData(data, int(tile.sizeWant[0]), int(tile.sizeWant[1]))
}