Face-on stellar density distribution at four different times, denoting different phases of the bar evolution (for details, see the text). The black dashed lines denote the contours of constant density. The yellow dashed lines denote the bar major-axis whereas the cyan dashed lines denote the bar minor-axis, respectively. The white dashed circle denotes the bar length (R_bar, 1), measured from the constancy of the phase-angle of the m = 2 Fourier moment. For details, we refer to the text.