DrawOnAnImage
VTKExamples/Cxx/Images/DrawOnAnImage
Description¶
This example draws a circle in the center of the input image using {{class|vtkImageCanvasSource2D}}'s DrawCircle
method.
Code¶
DrawOnAnImage.cxx
#include <vtkSmartPointer.h> #include <vtkRenderWindow.h> #include <vtkRenderWindowInteractor.h> #include <vtkRenderer.h> #include <vtkJPEGReader.h> #include <vtkImageData.h> #include <vtkImageMapper3D.h> #include <vtkImageViewer2.h> #include <vtkImageCanvasSource2D.h> #include <vtkImageBlend.h> int main ( int argc, char* argv[] ) { //Verify input arguments if ( argc != 2 ) { std::cout << "Usage: " << argv[0] << " InputFilename(jpg)" << std::endl; return EXIT_FAILURE; } // Parse input arguments std::string inputFilename = argv[1]; // Read the image vtkSmartPointer<vtkJPEGReader> jPEGReader = vtkSmartPointer<vtkJPEGReader>::New(); jPEGReader->SetFileName ( inputFilename.c_str() ); jPEGReader->Update(); vtkImageData* image = jPEGReader->GetOutput(); // Find center of image int center[2]; center[0] = (image->GetExtent()[1] + image->GetExtent()[0]) / 2; center[1] = (image->GetExtent()[3] + image->GetExtent()[2]) / 2; // Pick a radius for the circle int radius; radius = (image->GetExtent()[1] < image->GetExtent()[3]) ? image->GetExtent()[1] * 2 / 5 : image->GetExtent()[3] * 2 / 5; // Draw a circle in the center of the image vtkSmartPointer<vtkImageCanvasSource2D> drawing = vtkSmartPointer<vtkImageCanvasSource2D>::New(); drawing->SetNumberOfScalarComponents(3); drawing->SetScalarTypeToUnsignedChar(); drawing->SetExtent(image->GetExtent()); drawing->SetDrawColor(0.0, 0.0, 0.0); drawing->FillBox(image->GetExtent()[0], image->GetExtent()[1], image->GetExtent()[2], image->GetExtent()[3]); drawing->SetDrawColor(255.0, 255.0, 255.0); drawing->DrawCircle(center[0], center[1], radius); // Combine the images (blend takes multiple connections on the 0th // input port) vtkSmartPointer<vtkImageBlend> blend = vtkSmartPointer<vtkImageBlend>::New(); blend->AddInputConnection(jPEGReader->GetOutputPort()); blend->AddInputConnection(drawing->GetOutputPort()); blend->SetOpacity(0,.6); blend->SetOpacity(1,.4); // Display the result vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = vtkSmartPointer<vtkRenderWindowInteractor>::New(); vtkSmartPointer<vtkImageViewer2> imageViewer = vtkSmartPointer<vtkImageViewer2>::New(); imageViewer->SetInputConnection(blend->GetOutputPort()); imageViewer->SetSize(640, 512); imageViewer->SetupInteractor(renderWindowInteractor); imageViewer->GetRenderer()->ResetCamera(); imageViewer->GetRenderer()->SetBackground(1,0,0); //red renderWindowInteractor->Initialize(); renderWindowInteractor->Start(); return EXIT_SUCCESS; }
CMakeLists.txt¶
cmake_minimum_required(VERSION 2.8) PROJECT(DrawOnAnImage) find_package(VTK REQUIRED) include(${VTK_USE_FILE}) add_executable(DrawOnAnImage MACOSX_BUNDLE DrawOnAnImage.cxx) target_link_libraries(DrawOnAnImage ${VTK_LIBRARIES})
Download and Build DrawOnAnImage¶
Danger
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Click here to download DrawOnAnImage and its CMakeLists.txt file. Once the tarball DrawOnAnImage.tar has been downloaded and extracted,
cd DrawOnAnImage/build
If VTK is installed:
cmake ..
If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:
cmake -DVTK_DIR:PATH=/home/me/vtk_build ..
Build the project:
make
and run it:
./DrawOnAnImage
WINDOWS USERS PLEASE NOTE: Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.