Halting first steps towards encoding .pngs.

vtkm/rendering/CMakeLists.txt

@@ -51,6 +51,7 @@ set(headers
   ConnectivityProxy.h
   Cylinderizer.h
   DecodePNG.h
+  EncodePNG.h
   LineRenderer.h
   MatrixHelpers.h
   Scene.h
@@ -85,6 +86,7 @@ set(sources
   Camera.cxx
   Color.cxx
   DecodePNG.cxx
+  EncodePNG.cxx
   raytracing/Logger.cxx
   )
 

vtkm/rendering/Canvas.cxx

@@ -14,6 +14,7 @@
 #include <vtkm/cont/TryExecute.h>
 #include <vtkm/rendering/BitmapFontFactory.h>
 #include <vtkm/rendering/DecodePNG.h>
+#include <vtkm/rendering/EncodePNG.h>
 #include <vtkm/rendering/LineRenderer.h>
 #include <vtkm/rendering/TextRenderer.h>
 #include <vtkm/rendering/WorldAnnotator.h>
@@ -568,11 +569,40 @@ void Canvas::SetViewToScreenSpace(const vtkm::rendering::Camera& vtkmNotUsed(cam
 void Canvas::SaveAs(const std::string& fileName) const
 {
   this->RefreshColorBuffer();
-  std::ofstream of(fileName.c_str(), std::ios_base::binary | std::ios_base::out);
+  auto ends_with = [](std::string const& value, std::string const& ending) {
+    if (ending.size() > value.size())
+    {
+      return false;
+    }
+    return std::equal(ending.rbegin(), ending.rend(), value.rbegin());
+  };
+
+  ColorBufferType::ReadPortalType colorPortal = GetColorBuffer().ReadPortal();
   vtkm::Id width = GetWidth();
   vtkm::Id height = GetHeight();
+
+  if (ends_with(fileName, ".png"))
+  {
+    std::vector<unsigned char> img(static_cast<size_t>(width * height));
+    for (vtkm::Id yIndex = height - 1; yIndex >= 0; yIndex--)
+    {
+      for (vtkm::Id xIndex = 0; xIndex < width; xIndex++)
+      {
+        vtkm::Vec4f_32 tuple = colorPortal.Get(yIndex * width + xIndex);
+        size_t idx = static_cast<size_t>(4 * width * yIndex + 4 * xIndex);
+        img[idx + 0] = (unsigned char)(tuple[0] * 255);
+        img[idx + 1] = (unsigned char)(tuple[1] * 255);
+        img[idx + 2] = (unsigned char)(tuple[2] * 255);
+        img[idx + 3] = (unsigned char)(tuple[3] * 255);
+      }
+    }
+
+    SavePNG(fileName, img, static_cast<unsigned long>(width), static_cast<unsigned long>(height));
+    return;
+  }
+
+  std::ofstream of(fileName.c_str(), std::ios_base::binary | std::ios_base::out);
   of << "P6" << std::endl << width << " " << height << std::endl << 255 << std::endl;
-  ColorBufferType::ReadPortalType colorPortal = GetColorBuffer().ReadPortal();
   for (vtkm::Id yIndex = height - 1; yIndex >= 0; yIndex--)
   {
     for (vtkm::Id xIndex = 0; xIndex < width; xIndex++)

vtkm/rendering/DecodePNG.cxx

@@ -14,8 +14,6 @@
 #include <vtkm/internal/Configure.h>
 
 VTKM_THIRDPARTY_PRE_INCLUDE
-#define LODEPNG_NO_COMPILE_ENCODER
-#define LODEPNG_NO_COMPILE_DISK
 #include <vtkm/thirdparty/lodepng/vtkmlodepng/lodepng.cpp>
 VTKM_THIRDPARTY_PRE_INCLUDE
 

vtkm/rendering/EncodePNG.cxx

@@ -0,0 +1,69 @@
+//============================================================================
+//  Copyright (c) Kitware, Inc.
+//  All rights reserved.
+//  See LICENSE.txt for details.
+//
+//  This software is distributed WITHOUT ANY WARRANTY; without even
+//  the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+//  PURPOSE.  See the above copyright notice for more information.
+//============================================================================
+#include <algorithm> // for std::equal
+#include <vtkm/rendering/EncodePNG.h>
+
+#include <vtkm/cont/Logging.h>
+#include <vtkm/internal/Configure.h>
+
+VTKM_THIRDPARTY_PRE_INCLUDE
+#include <vtkm/thirdparty/lodepng/vtkmlodepng/lodepng.cpp>
+VTKM_THIRDPARTY_PRE_INCLUDE
+
+namespace vtkm
+{
+namespace rendering
+{
+
+vtkm::UInt32 EncodePNG(std::vector<unsigned char> const& image,
+                       unsigned long width,
+                       unsigned long height,
+                       std::vector<unsigned char>& output_png)
+{
+  // The default is 8 bit RGBA; does anyone care to have more options?
+  vtkm::UInt32 error = vtkm::png::lodepng::encode(output_png, image, width, height);
+  if (error)
+  {
+    // TODO: Use logging framework instead:
+    std::cerr << "PNG Encoder error number " << error << ": " << png::lodepng_error_text(error)
+              << "\n";
+  }
+  return error;
+}
+
+
+vtkm::UInt32 SavePNG(std::string const& filename,
+                     std::vector<unsigned char> const& image,
+                     unsigned long width,
+                     unsigned long height)
+{
+  auto ends_with = [](std::string const& value, std::string const& ending) {
+    if (ending.size() > value.size())
+    {
+      return false;
+    }
+    return std::equal(ending.rbegin(), ending.rend(), value.rbegin());
+  };
+
+  if (!ends_with(filename, ".png"))
+  {
+    std::cerr << "PNG filename must end with .png\n";
+  }
+
+  std::vector<unsigned char> output_png;
+  vtkm::UInt32 error = EncodePNG(image, width, height, output_png);
+  if (!error)
+  {
+    vtkm::png::lodepng::save_file(output_png, filename);
+  }
+  return error;
+}
+}
+} // namespace vtkm::rendering

vtkm/rendering/EncodePNG.h

@@ -0,0 +1,39 @@
+//============================================================================
+//  Copyright (c) Kitware, Inc.
+//  All rights reserved.
+//  See LICENSE.txt for details.
+//
+//  This software is distributed WITHOUT ANY WARRANTY; without even
+//  the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+//  PURPOSE.  See the above copyright notice for more information.
+//============================================================================
+#ifndef vtk_m_rendering_EncodePNG_h
+#define vtk_m_rendering_EncodePNG_h
+
+#include <vtkm/Types.h>
+#include <vtkm/rendering/vtkm_rendering_export.h>
+
+#include <vector>
+
+namespace vtkm
+{
+namespace rendering
+{
+
+//
+VTKM_RENDERING_EXPORT
+vtkm::UInt32 EncodePNG(std::vector<unsigned char> const& image,
+                       unsigned long width,
+                       unsigned long height,
+                       unsigned char* out_png,
+                       std::size_t out_size);
+
+VTKM_RENDERING_EXPORT
+vtkm::UInt32 SavePNG(std::string filename,
+                     std::vector<unsigned char> const& image,
+                     unsigned long width,
+                     unsigned long height);
+}
+} // vtkm::rendering
+
+#endif //vtk_m_rendering_EncodePNG_h