private float getCenterYForRow(int row) {
        return paddingTop + row * squareHeight + squareHeight / 2f;
    }
Helper method to find the column x fallis into.

@param x The x coordinate.
@return The column that x falls in, or -1 if it falls in no column.
android-patternview/src/main/java/com/eftimoff/patternview/PatternView.java