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Ticket #537 applied 
Patch for QgsRasterLayer to allow stretching in DrawMultiColorBand, DrawSingleBandGray
With thanks to Pete



git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@6435 c8812cc2-4d05-0410-92ff-de0c093fc19c
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timlinux committed Jan 15, 2007
1 parent 1d8725d commit 59bb6ed
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Showing 2 changed files with 189 additions and 9 deletions.
186 changes: 177 additions & 9 deletions src/core/raster/qgsrasterlayer.cpp
View file
Expand Up @@ -377,6 +377,10 @@ QgsRasterLayer::QgsRasterLayer(QString const & path, QString const & baseName)
dataProvider(0)

{
userDefinedColorMinMax = false; //defaults needed to bypass stretch
userDefinedGrayMinMax = false;
setColorScalingAlgorithm(QgsRasterLayer::NO_STRETCH); //defaults needed to bypass stretch

// Initialise the affine transform matrix
adfGeoTransform[0] = 0;
adfGeoTransform[1] = 1;
Expand Down Expand Up @@ -1335,7 +1339,7 @@ void QgsRasterLayer::draw (QPainter * theQPainter,
void QgsRasterLayer::drawSingleBandGray(QPainter * theQPainter, QgsRasterViewPort * theRasterViewPort, QgsMapToPixel * theQgsMapToPixel, int theBandNoInt)
{
QgsDebugMsg("QgsRasterLayer::drawSingleBandGray called for layer " + QString::number(theBandNoInt));
QgsRasterBandStats myRasterBandStats = getRasterBandStats(theBandNoInt);
//QgsRasterBandStats myRasterBandStats = getRasterBandStats(theBandNoInt);
GDALRasterBand *myGdalBand = gdalDataset->GetRasterBand(theBandNoInt);
GDALDataType myDataType = myGdalBand->GetRasterDataType();
void *myGdalScanData = readData ( myGdalBand, theRasterViewPort );
Expand All @@ -1345,34 +1349,85 @@ void QgsRasterLayer::drawSingleBandGray(QPainter * theQPainter, QgsRasterViewPor
myQImage.setAlphaBuffer(true);
myQImage.fill(qRgba(255,255,255,0 )); // fill transparent

double myRangeDouble = myRasterBandStats.rangeDouble;
//double myRangeDouble = myRasterBandStats.rangeDouble;
QgsRasterBandStats myGrayBandStats;
/*
* If stDevsToPlotDouble is set it will override any user defined Min Max values
*/
if(QgsRasterLayer::NO_STRETCH != getColorScalingAlgorithm() && (!userDefinedGrayMinMax || stdDevsToPlotDouble > 0))
{
myGrayBandStats = getRasterBandStats(theBandNoInt);

/*
* This may upset some, but these values are set directly so that the userDefinedColorMinMax variable is not set,
* though it really does not matter by this point.
*/
if(stdDevsToPlotDouble > 0)
{
minGrayDouble = myGrayBandStats.meanDouble - (stdDevsToPlotDouble * myGrayBandStats.stdDevDouble);
maxGrayDouble = myGrayBandStats.meanDouble + (stdDevsToPlotDouble * myGrayBandStats.stdDevDouble);
}
else
{
minGrayDouble = myGrayBandStats.minValDouble;
maxGrayDouble = myGrayBandStats.maxValDouble;
}
}

/*
* Check for invalid min max value based on GDALDataType.
* Invalid values can happen if the user uses stdDevs to set min and max
* TODO:Needs to be expanded for all GDALDataTypes
*/
if(GDT_Byte == myDataType)
{
if(minGrayDouble < 0.0)
minGrayDouble = 0.0;
if(maxGrayDouble > 255.0)
maxGrayDouble = 255.0;
}

// print each point in myGdalScanData with equal parts R, G ,B o make it show as gray
for (int myColumnInt = 0; myColumnInt < theRasterViewPort->drawableAreaYDimInt; ++myColumnInt)
{
for (int myRowInt = 0; myRowInt < theRasterViewPort->drawableAreaXDimInt; ++myRowInt)
{
double myGrayValDouble = readValue ( myGdalScanData, myDataType,
double myGrayValueDouble = readValue ( myGdalScanData, myDataType,
myColumnInt * theRasterViewPort->drawableAreaXDimInt + myRowInt );

// If noDataValueDouble is 'nan', the comparison
// against myGrayValDouble will always fail ( nan==nan always
// returns false, by design), hence the slightly odd comparison
// of myGrayValDouble against itself.
if ( myGrayValDouble == noDataValueDouble ||
myGrayValDouble != myGrayValDouble)
if ( myGrayValueDouble == noDataValueDouble ||
myGrayValueDouble != myGrayValueDouble)
{

myQImage.setPixel(myRowInt, myColumnInt, qRgba(255,255,255,0 ));
continue;
}

int myGrayValInt = static_cast < int >( (myGrayValDouble-myRasterBandStats.minValDouble)
* (255/myRangeDouble));
if(QgsRasterLayer::NO_STRETCH != getColorScalingAlgorithm())
{
if(QgsRasterLayer::CLIP_TO_MINMAX == getColorScalingAlgorithm() || QgsRasterLayer::STRETCH_AND_CLIP_TO_MINMAX == getColorScalingAlgorithm())
if(myGrayValueDouble < minGrayDouble || myGrayValueDouble > maxGrayDouble) continue;

if(QgsRasterLayer::STRETCH_TO_MINMAX == getColorScalingAlgorithm() || QgsRasterLayer::STRETCH_AND_CLIP_TO_MINMAX == getColorScalingAlgorithm())
myGrayValueDouble = ((myGrayValueDouble - minGrayDouble)/(maxGrayDouble - minGrayDouble))*255;

//Check for out of range pixel values
if(myGrayValueDouble < 0.0)
myGrayValueDouble = 0.0;
else if(myGrayValueDouble > 255.0)
myGrayValueDouble = 255.0;
}

int myGrayValInt = static_cast < int > ( myGrayValueDouble);
//int myGrayValInt = static_cast < int >( (myGrayValDouble-myRasterBandStats.minValDouble) * (255/myRangeDouble));

if (invertHistogramFlag)
{
myGrayValDouble = 255 - myGrayValDouble;
myGrayValInt = 255 - myGrayValInt;
}
myQImage.setPixel(myRowInt, myColumnInt, qRgba(myGrayValInt, myGrayValInt, myGrayValInt, mTransparencyLevel));
}
Expand Down Expand Up @@ -2235,6 +2290,80 @@ void QgsRasterLayer::drawMultiBandColor(QPainter * theQPainter, QgsRasterViewPor
//myQImage.fill(0);
myQImage.setAlphaBuffer(true);
myQImage.fill(qRgba(255,255,255,0 )); // fill transparent

QgsRasterBandStats myRedBandStats;
QgsRasterBandStats myGreenBandStats;
QgsRasterBandStats myBlueBandStats;
/*
* If a stetch is requested and there are no user defined Min Max values
* we need to get these values from the bands themselves.
* If stDevsToPlotDouble is set it will override any user defined Min Max values
*
* NOTE: If the user only set minRedDouble this next block would be skipped
* and all the other variables could have garbage (they are not initialized in the constructor)
* This may want to be updated so that each Min Max is check to be sure it was set and if one is missing
* the get the QgsRasterBandStats for that band.
*/
if(QgsRasterLayer::NO_STRETCH != getColorScalingAlgorithm() && (!userDefinedColorMinMax || stdDevsToPlotDouble > 0))
{
myRedBandStats = getRasterBandStats(myRedBandNoInt);
myGreenBandStats = getRasterBandStats(myGreenBandNoInt);
myBlueBandStats = getRasterBandStats(myBlueBandNoInt);

/*
* This may upset some, but these values are set directly so that the userDefinedColorMinMax variable is not set,
* though it really does not matter at this point. Also insignificantly faster.
*/
if(stdDevsToPlotDouble > 0)
{
minRedDouble = myRedBandStats.meanDouble - (stdDevsToPlotDouble * myRedBandStats.stdDevDouble);
maxRedDouble = myRedBandStats.meanDouble + (stdDevsToPlotDouble * myRedBandStats.stdDevDouble);
minGreenDouble = myGreenBandStats.meanDouble - (stdDevsToPlotDouble * myGreenBandStats.stdDevDouble);
maxGreenDouble = myGreenBandStats.meanDouble + (stdDevsToPlotDouble * myGreenBandStats.stdDevDouble);
minBlueDouble = myBlueBandStats.meanDouble - (stdDevsToPlotDouble * myBlueBandStats.stdDevDouble);
maxBlueDouble = myBlueBandStats.meanDouble + (stdDevsToPlotDouble * myBlueBandStats.stdDevDouble);
}
else
{
minRedDouble = myRedBandStats.minValDouble;
maxRedDouble = myRedBandStats.maxValDouble;
minGreenDouble = myGreenBandStats.minValDouble;
maxGreenDouble = myGreenBandStats.maxValDouble;
minBlueDouble = myBlueBandStats.minValDouble;
maxBlueDouble = myBlueBandStats.maxValDouble;
}
}

/*
* Check for invalid min max value based on GDALDataType.
* Invalid values can happen if the user uses stdDevs to set min and max
* TODO:Needs to be expanded for all GDALDataTypes
*/
if(GDT_Byte == myRedType)
{
if(minRedDouble < 0.0)
minRedDouble = 0.0;
if(maxRedDouble > 255.0)
maxRedDouble = 255.0;
}

if(GDT_Byte == myGreenType)
{
if(minGreenDouble < 0.0)
minGreenDouble = 0.0;
if(maxGreenDouble > 255.0)
maxGreenDouble = 255.0;
}

if(GDT_Byte == myBlueType)
{
if(minBlueDouble < 0.0)
minBlueDouble = 0.0;
if(maxBlueDouble > 255.0)
maxBlueDouble = 255.0;
}

//Read and display pixels
for (int myColumnInt = 0; myColumnInt < theRasterViewPort->drawableAreaYDimInt; ++myColumnInt)
{
for (int myRowInt = 0; myRowInt < theRasterViewPort->drawableAreaXDimInt; ++myRowInt)
Expand Down Expand Up @@ -2263,6 +2392,44 @@ void QgsRasterLayer::drawMultiBandColor(QPainter * theQPainter, QgsRasterViewPor
continue;
}

/*
* Stretch RBG values based on selected color scaling algoritm
* NOTE: NO_STRETCH enum will help eliminte the need to call QgsRasterBandStats when an image is initially loaded
*/

if(QgsRasterLayer::NO_STRETCH != getColorScalingAlgorithm())
{
/*
* Currently if any one band is outside of min max range for the band the pixel is discarded,
* this can easily be updated so that all band have to be ouside of the min max range
*/
if(QgsRasterLayer::CLIP_TO_MINMAX == getColorScalingAlgorithm() || QgsRasterLayer::STRETCH_AND_CLIP_TO_MINMAX == getColorScalingAlgorithm())
{
if(myRedValueDouble < minRedDouble || myRedValueDouble > maxRedDouble) continue;
if(myGreenValueDouble < minRedDouble || myGreenValueDouble > maxRedDouble) continue;
if(myBlueValueDouble < minBlueDouble || myBlueValueDouble > maxBlueDouble) continue;
}
if(QgsRasterLayer::STRETCH_TO_MINMAX == getColorScalingAlgorithm() || QgsRasterLayer::STRETCH_AND_CLIP_TO_MINMAX == getColorScalingAlgorithm())
{
myRedValueDouble = ((myRedValueDouble - minRedDouble)/(maxRedDouble - minRedDouble))*255;
myGreenValueDouble = ((myGreenValueDouble - minGreenDouble)/(maxGreenDouble - minGreenDouble))*255;
myBlueValueDouble = ((myBlueValueDouble - minBlueDouble)/(maxBlueDouble - minBlueDouble))*255;
}
//Check for out of range pixel values
if(myRedValueDouble < 0.0)
myRedValueDouble = 0.0;
else if(myRedValueDouble > 255.0)
myRedValueDouble = 255.0;
if(myGreenValueDouble < 0.0)
myGreenValueDouble = 0.0;
else if(myGreenValueDouble > 255.0)
myGreenValueDouble = 255.0;
if(myBlueValueDouble < 0.0)
myBlueValueDouble = 0.0;
else if(myBlueValueDouble > 255.0)
myBlueValueDouble = 255.0;
}

int myRedValueInt = static_cast < int > ( myRedValueDouble );
int myGreenValueInt = static_cast < int > ( myGreenValueDouble );
int myBlueValueInt = static_cast < int > ( myBlueValueDouble );
Expand All @@ -2273,6 +2440,7 @@ void QgsRasterLayer::drawMultiBandColor(QPainter * theQPainter, QgsRasterViewPor
myGreenValueInt = 255 - myGreenValueInt;
myBlueValueInt = 255 - myBlueValueInt;
}

//set the pixel based on the above color mappings
myQImage.setPixel ( myRowInt, myColumnInt,
qRgba(myRedValueInt, myGreenValueInt, myBlueValueInt, mTransparencyLevel) );
Expand Down Expand Up @@ -2315,7 +2483,7 @@ void QgsRasterLayer::drawMultiBandColor(QPainter * theQPainter, QgsRasterViewPor
/ theQgsMapToPixel->mapUnitsPerPixel()
* fabs(adfGeoTransform[5])
);
}
}

QgsDebugMsg("QgsRasterLayer::drawSingleBandGray: painting image to canvas from source NW"\
+ QString::number(paintXoffset) + ", " + QString::number(paintYoffset)\
Expand Down
12 changes: 12 additions & 0 deletions src/core/raster/qgsrasterlayer.h
View file
Expand Up @@ -460,6 +460,7 @@ class CORE_EXPORT QgsRasterLayer : public QgsMapLayer
* that falls outside the clipping range.*/
void setMinRedDouble(double theDouble)
{
userDefinedColorMinMax = true;
minRedDouble=theDouble;
};
/** \brief Accessor for maximum clipping range for red.
Expand All @@ -478,6 +479,7 @@ class CORE_EXPORT QgsRasterLayer : public QgsMapLayer
* that falls outside the clipping range.*/
void setMaxRedDouble(double theDouble)
{
userDefinedColorMinMax = true;
maxRedDouble=theDouble;
};
//
Expand All @@ -499,6 +501,7 @@ class CORE_EXPORT QgsRasterLayer : public QgsMapLayer
* that falls outside the clipping range.*/
void setMinGreenDouble(double theDouble)
{
userDefinedColorMinMax = true;
minGreenDouble=theDouble;
};
/** \brief Accessor for maximum clipping range for green.
Expand All @@ -517,6 +520,7 @@ class CORE_EXPORT QgsRasterLayer : public QgsMapLayer
* that falls outside the clipping range.*/
void setMaxGreenDouble(double theDouble)
{
userDefinedColorMinMax = true;
maxGreenDouble=theDouble;
};
//
Expand All @@ -539,6 +543,7 @@ class CORE_EXPORT QgsRasterLayer : public QgsMapLayer
* that falls outside the clipping range.*/
void setMinBlueDouble(double theDouble)
{
userDefinedColorMinMax = true;
minBlueDouble=theDouble;
};
/** \brief Accessor for maximum clipping range for blue.
Expand All @@ -557,6 +562,7 @@ class CORE_EXPORT QgsRasterLayer : public QgsMapLayer
* that falls outside the clipping range.*/
void setMaxBlueDouble(double theDouble)
{
userDefinedColorMinMax = true;
maxBlueDouble=theDouble;
};
//
Expand All @@ -578,6 +584,7 @@ class CORE_EXPORT QgsRasterLayer : public QgsMapLayer
* that falls outside the clipping range.*/
void setMinGrayDouble(double theDouble)
{
userDefinedGrayMinMax = true;
minGrayDouble=theDouble;
};
/** \brief Accessor for maximum clipping range for gray.
Expand All @@ -596,12 +603,14 @@ class CORE_EXPORT QgsRasterLayer : public QgsMapLayer
* that falls outside the clipping range.*/
void setMaxGrayDouble(double theDouble)
{
userDefinedGrayMinMax = true;
maxGrayDouble=theDouble;
};
//
/** \brief This enumerator describes the types of histogram scaling algorithms that can be used. */
enum COLOR_SCALING_ALGORITHM
{
NO_STRETCH, //this should be the default color scaling algorithm, will allow for the display of images without calling QgsRasterBandStats unless needed
STRETCH_TO_MINMAX, //linear histogram stretch
STRETCH_AND_CLIP_TO_MINMAX,
CLIP_TO_MINMAX
Expand Down Expand Up @@ -998,6 +1007,9 @@ public slots:
double maxGrayDouble;
/** \brief Whether this raster has overviews / pyramids or not */
bool hasPyramidsFlag;
//Since QgsRasterBandStats deos not set the minRedDouble maxRedDouble etc., it is benificial to know if the user as set these values. Default = false
bool userDefinedColorMinMax;
bool userDefinedGrayMinMax;
/** \brief This list holds a series of RasterPyramid structs
* which store infomation for each potential pyramid level for this raster.*/
RasterPyramidList mPyramidList;
Expand Down

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