qgspseudocolorshader.cpp

一个非常好的GIS开源新版本

/* **************************************************************************
                qgspseudocolorshader.cpp -  description
                       -------------------
begin                : Fri Dec 28 2007
copyright            : (C) 2007 by Peter J. Ersts
email                : [e-mail]

This class contains code that was originally part of the larger QgsRasterLayer 
class originally created circa 2004 by T.Sutton, Gary E.Sherman, Steve Halasz
****************************************************************************/

/* **************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#include <QDebug>

#include "qgspseudocolorshader.h"

QgsPseudoColorShader::QgsPseudoColorShader(double theMinimumValue, double theMaximumValue) : QgsRasterShaderFunction(theMinimumValue, theMaximumValue)
{
  setClassBreaks();
}


bool QgsPseudoColorShader::generateShadedValue(double theValue, int* theReturnRedValue, int* theReturnGreenValue, int* theReturnBlueValue)
{
  double myPixelValue = theValue;
  
  //double check that myInt >= min and <= max
  //this is relevant if we are plotting within stddevs
  if ( myPixelValue < mMinimumValue )
  {
    myPixelValue = mMinimumValue;
  }
  if ( myPixelValue > mMaximumValue)
  {
    myPixelValue = mMaximumValue;
  }
        
  //check if we are in the first class break
  if ((myPixelValue >= mClassBreakMin1) && (myPixelValue < mClassBreakMax1))
  {
    *theReturnRedValue = 0;
    *theReturnGreenValue = static_cast < int >( ( (255 / mMinimumMaximumRange) * (myPixelValue - mClassBreakMin1) ) * 3 );
    *theReturnBlueValue = 255;
  }
  //check if we are in the second class break
  else if ( (myPixelValue >= mClassBreakMin2) && (myPixelValue < mClassBreakMax2) )
  {
    *theReturnRedValue = static_cast < int >( ( (255 / mMinimumMaximumRange) * ((myPixelValue - mClassBreakMin2) / 1)) * 3);
    *theReturnGreenValue = 255;
    *theReturnBlueValue = static_cast < int >(255 - ( ( (255 / mMinimumMaximumRange) * ((myPixelValue - mClassBreakMin2) / 1)) * 3));
  }
  //otherwise we must be in the third classbreak
  else
  {
    *theReturnRedValue = 255;
    *theReturnGreenValue = static_cast < int >(255 - ( ( (255 / mMinimumMaximumRange) * ((myPixelValue - mClassBreakMin3) / 1) * 3)));
    *theReturnBlueValue = 0;
  }
  
  return true;
}

bool QgsPseudoColorShader::generateShadedValue(double theRedValue, double theGreenValue, double theBlueValue, int* theReturnRedValue, int* theReturnGreenValue, int* theReturnBlueValue)
{
  *theReturnRedValue = 0;
  *theReturnGreenValue = 0;
  *theReturnBlueValue = 0;
  
  return false;
}

void QgsPseudoColorShader::setClassBreaks()
{
  //set up the three class breaks for pseudocolour mapping
  mBreakSize = mMinimumMaximumRange / 3;
  mClassBreakMin1 = mMinimumValue;
  mClassBreakMax1 = mClassBreakMin1 + mBreakSize;
  mClassBreakMin2 = mClassBreakMax1;
  mClassBreakMax2 = mClassBreakMin2 + mBreakSize;
  mClassBreakMin3 = mClassBreakMax2;
}

/**
    Set the maximum value for the raster shader. 
    
    @param theValue The new maximum value
*/
void QgsPseudoColorShader::setMaximumValue(double theValue)
{
  mMaximumValue = theValue;
  mMinimumMaximumRange = mMaximumValue - mMinimumValue;
  setClassBreaks();
}

/**
    Set the maximum value for the raster shader
    
    @param theValue The new minimum value
*/
void QgsPseudoColorShader::setMinimumValue(double theValue)
{
  mMinimumValue = theValue;
  mMinimumMaximumRange = mMaximumValue - mMinimumValue;
  setClassBreaks();
}