  We present an analysis of CCD photometric observations of the eclipsing
novalike cataclysmic variable DW UMa obtained in two different luminosity
states: high and intermediate. The star presents eclipses with very different
depth: ~1.2 mag in the high and ~3.4 mag in the intermediate state. Eclipse
mapping reveals that this difference is almost entirely due to the changes in
the accretion disc radius: from ~0.5RL1 in the intermediate state to ~0.75RL1
in the high state (RL1 is the distance from the white dwarf to the first
Lagrangian point). In the intermediate state, the entire disc is eclipsed while
in the high state, its outer part remains visible. We also find that the
central intensity of the disc is nearly the same in the two luminosity states
and that it is the increase of the disc radius that is responsible for the
final rise from the 1999/2000 low state. We find that the intensity profile of
the disc is rather flat and suggest a possible explanation. We also discuss the
effect of using a more realistic limb-darkening law on the disc temperatures
inferred from eclipse mapping experiments. Periodogram analysis of the high
state data reveals "positive superhumps" with a period of 0.1455 in 2002 and
0.1461 in 2003, in accord with the results of Patterson et al. However, we
cannot confirm the quasi-periodic oscillations reported by these authors. We
obtain an updated orbital ephemeris of DW UMa:
Tmin[HJD]=2446229.00687(9)+0.136606527(3)E.
