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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Dear fellow vtk fans:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I’m trying to read a 255x1 24-bit bitmap and convert
it into a lookup table so I don’t have to manually input 255 rgb values.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> vtkLookupTable *lut = vtkLookupTable::New; //
or no ::New(): doesn’t seem to matter<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> vtkBMPReader *bmpReader = vtkBMPReader::New();<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> char bmpFileName[] = "topo-bathy255x1.bmp";<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> bmpReader->SetFileName(bmpFileName);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> lut = bmpReader->GetLookupTable();<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> //lut->Build(); // ????????<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>This doesn’t do it, because nothing is forcing the reader to execute
reading the file. I could write a subclass of </span></font><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>vtkBMPReader
and call the parent class’s protected Execute() method in a public function,
but that’s at best a kludge. When I look at lut, it’s got its
default 256-element size and all the r, g, and b values are 0. How can I
force a read? <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>The more general question is: why are we restricted to
employing this lazy evaluation approach? What are the drawbacks to
providing a public ReadFile() method for vtkBMPReader (as a specific example)? Thanks,
both for helping me to see what may be an obvious solution to my immediate
problem, and for helping me to understand the underlying rationale.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>-Steve</span></font><o:p></o:p></p>
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