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- Added additional color schemes
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- Added MooseEnum as the new way to select a color scheme
- Added additional comments to explain the code
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Samuel Tew committed Jul 4, 2019
1 parent 9f4246b commit b1d1ffc
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Showing 5 changed files with 111 additions and 47 deletions.
3 changes: 2 additions & 1 deletion framework/include/outputs/PNGOutput.h
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Expand Up @@ -15,6 +15,7 @@
#include <png.h>
// MOOSE includes
#include "FileOutput.h"
#include "MooseEnum.h"
// libmesh includes
#include "libmesh/mesh_function.h"
#include "libmesh/bounding_box.h"
Expand Down Expand Up @@ -57,7 +58,7 @@ class PNGOutput : public FileOutput
unsigned int _resolution;

// Way to specify color vs grayscale image creation.
bool _color;
MooseEnum _color;

/// Pointer the libMesh::MeshFunction object that the read data is stored
std::unique_ptr<MeshFunction> _mesh_function;
Expand Down
147 changes: 105 additions & 42 deletions framework/src/outputs/PNGOutput.C
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Expand Up @@ -21,7 +21,8 @@ validParams<PNGOutput>()
{
InputParameters params = validParams<FileOutput>();
params.addParam<unsigned int>("resolution", 2000, "The resolution of the image.");
params.addParam<bool>("color", false, "Show the image in color?");
MooseEnum color("GRAY BRYW BCR RWB BR");
params.addParam<MooseEnum>("color", color, "Choose the color scheme to use.");
params.addRangeCheckedParam<Real>("_out_bounds_shade",
.5,
"_out_bounds_shade>=0 & _out_bounds_shade<=1",
Expand All @@ -33,7 +34,7 @@ validParams<PNGOutput>()
PNGOutput::PNGOutput(const InputParameters & parameters)
: FileOutput(parameters),
_resolution(getParam<unsigned int>("resolution")),
_color(getParam<bool>("color")),
_color(parameters.get<MooseEnum>("color")),
_out_bounds_shade(getParam<Real>("_out_bounds_shade"))
{
}
Expand Down Expand Up @@ -61,6 +62,7 @@ PNGOutput::makeMeshFunc()
_mesh_function->enable_out_of_mesh_mode(reverseScale(_out_bounds_shade));
}

// Function to find the min and max values so that all the values can be scaled between the two.
void
PNGOutput::calculateRescalingValues()
{
Expand All @@ -81,24 +83,47 @@ PNGOutput::calculateRescalingValues()
_scaling_max += _shift_value;
}

// Function to apply the scale to the data points.
// Needed to be able to see accurate images that cover the appropriate color spectrum.
inline Real
PNGOutput::applyScale(Real value_to_scale)
{
return ((value_to_scale + _shift_value) / _scaling_max);
}

// Function to reverse the scaling that happens to a value.
// Needed to be able to accurately control the _out_bounds_shade.
inline Real
PNGOutput::reverseScale(Real value_to_unscale)
{
return ((value_to_unscale * _scaling_max) - _shift_value);
}

// Function that controls the colorization of the png image for non-grayscale images.
void
PNGOutput::setRGB(png_byte * rgb, Real selection)
{
// Using an RGB system with Red as 0 - 255, Green as 256 - 511 and
// Blue as 512 - 767 gives us our total colorSpectrum of 0 - 767.
const auto color_spectrum_max = 767;
// Depending on the color scheme we're using, we may want to use a subset
// of the colorSpectrum.
auto color_spectrum_max = 767;
switch (_color)
{
// BRYW. Keep the spectum as is.
case 1:
break;
// BCR. Change spectrum.
case 2:
// RWB. Change spectrum.
case 3:
color_spectrum_max = 511;
break;
case 4:
color_spectrum_max = 255;
break;
}

// We need to convert the
auto color = (int)(selection * color_spectrum_max);
// Make sure everything is within our colorSpectrum.
Expand All @@ -108,55 +133,91 @@ PNGOutput::setRGB(png_byte * rgb, Real selection)
color = 0;
auto magnitude = color % 256;

// Current color scheme: Blue->Red->Yellow->White
// Blue->Red
if (color < 256)
{
rgb[0] = magnitude;
rgb[1] = 0;
rgb[2] = 255 - magnitude;
}
// Red->Yellow
else if (color < 512)
{
rgb[0] = 255;
rgb[1] = magnitude;
rgb[2] = 0;
}
// Yellow->White
else
switch (_color)
{
rgb[0] = 255;
rgb[1] = 255;
rgb[2] = magnitude;
// Current color scheme: Blue->Red->Yellow->White
case 1:
// Blue->Red
if (color < 256)
{
rgb[0] = magnitude;
rgb[1] = 0;
rgb[2] = 255 - magnitude;
}
// Red->Yellow
else if (color < 512)
{
rgb[0] = 255;
rgb[1] = magnitude;
rgb[2] = 0;
}
// Yellow->White
else
{
rgb[0] = 255;
rgb[1] = 255;
rgb[2] = magnitude;
}
break;

// Color Scheme: Blue->Cream->Red
case 2:
// Blue->Cream
if (color < 256)
{
rgb[0] = magnitude;
rgb[1] = magnitude - (5 / (256 - magnitude));
rgb[2] = 255 - (40 / (256 - magnitude));
}
// Cream->Red
else
{
rgb[0] = 255;
rgb[1] = (255 - (5 / (magnitude + 1))) - (magnitude + (5 / (magnitude + 1)));
rgb[2] = (255 - (40 / (magnitude + 1))) - (magnitude + (40 / (magnitude + 1)));
}
break;

// Red->White->Blue
case 3:
// Red->White
if (color < 256)
{
rgb[0] = 255;
rgb[1] = magnitude;
rgb[2] = magnitude;
}
// White->Blue
else
{
rgb[0] = 255 - magnitude;
rgb[1] = 255 - magnitude;
rgb[2] = 255;
}
break;

//Red->Blue
case 4:
// Red->Blue
rgb[0] = magnitude;
rgb[1] = 0;
rgb[2] = 255 - magnitude;
break;
}

// // Color Scheme: Blue->Cream->Red
// // Blue->Cream
// if (color < 256)
// {
// rgb[0] = magnitude - (40/(256-magnitude));
// rgb[1] = magnitude - (5/(256-magnitude));
// rgb[2] = 255 - (40/(256-magnitude));
// }
// // Cream->Red
// else
// {
// rgb[0] = 255 - (40/(256-magnitude));
// rgb[1] = (255 - (5/(magnitude+1))) - (magnitude + (5/(magnitude+1)));
// rgb[2] = (255 - (40/(magnitude+1))) - (magnitude + (40/(magnitude+1)));
// }
}

void
PNGOutput::output(const ExecFlagType & /*type*/)
{
makeMeshFunc();
_box = MeshTools::create_bounding_box(*_mesh_ptr);

// Make sure this happens on processor 0
if (processor_id() == 0)
makePNG();
}

// Function the writes the PNG out to the appropriate filename.
void
PNGOutput::makePNG()
{
Expand All @@ -173,15 +234,16 @@ PNGOutput::makePNG()
std::ostringstream png_file;
png_file << _file_base << "_" << std::setfill('0') << std::setw(3) << _t_step << ".png";

// libpng is built on C, so by default it takes FILE*.
FILE * fp = nullptr;
png_structrp pngp = nullptr;
png_infop infop = nullptr;
// Required depth for image clarity.
// Required depth for proper image clarity.
Real depth = 8;
Real width = dist_x * _resolution;
Real height = dist_y * _resolution;
// Allocate resources.
std::vector<png_byte> row ((width * 3) + 1);
std::vector<png_byte> row((width * 3) + 1);

// Check if we can open and write to the file.
MooseUtils::checkFileWriteable(png_file.str());
Expand All @@ -197,6 +259,7 @@ PNGOutput::makePNG()
if (!infop)
mooseError("Failed to make an info pointer for the png.");

// Initializes the IO for the png. Needs FILE* to compile.
png_init_io(pngp, fp);

// Set up the PNG header.
Expand All @@ -212,12 +275,12 @@ PNGOutput::makePNG()

png_write_info(pngp, infop);


// Initiallizing the point that will be used for populating the mesh values.
// Initializing x, y, z to zero so that we don't access the point before it's
// been set. z = 0 for all the png's.
Point pt(0, 0, 0);

// Dense vector that we can pass into the _mesh_function to fill with a value for a given point.
DenseVector<Number> dv(0);

// Loop through to create the image.
Expand Down
4 changes: 2 additions & 2 deletions test/tests/outputs/png/adv_diff_reaction_test.i
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Expand Up @@ -115,7 +115,7 @@
[Outputs]
[png]
type = PNGOutput
resolution = 500
color = true
resolution = 250
color = RWB
[]
[]
2 changes: 1 addition & 1 deletion test/tests/outputs/png/simple_transient_diffusion.i
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Expand Up @@ -50,6 +50,6 @@
[png]
type = PNGOutput
resolution = 250
color = false
color = RWB
[]
[]
2 changes: 1 addition & 1 deletion test/tests/outputs/png/wedge.i
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Expand Up @@ -73,6 +73,6 @@
[png]
type = PNGOutput
resolution = 250
color = false
color = RWB
[]
[]

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