setColumnSelection method
Implementation
void setColumnSelection(Offset pos1, Offset pos2) {
final x1 = min(pos1.dx, pos2.dx);
final x2 = max(pos1.dx, pos2.dx);
final column1 =
binarySearch(columnOffsets, x1, 0, columnOffsets.length - 1);
final column2 =
binarySearch(columnOffsets, x2, 0, columnOffsets.length - 1);
clear();
indexWithFocus = Index(-1, -1);
for (int j = column1; j <= column2; j++) {
addColumnSelection(j);
}
}