lava · alexdewar · Nov 6, 2018 · Nov 6, 2018 · May 8, 2019 · Nov 6, 2018
diff --git a/Makefile b/Makefile
@@ -1,4 +1,4 @@
-examples: minimal basic modern animation nonblock xkcd quiver bar surface fill_inbetween fill update
+examples: minimal basic modern animation nonblock xkcd quiver bar surface fill_inbetween fill update imshow
 
 minimal: examples/minimal.cpp matplotlibcpp.h
 	cd examples && g++ -DWITHOUT_NUMPY minimal.cpp -I/usr/include/python2.7 -lpython2.7 -o minimal -std=c++11
@@ -32,9 +32,12 @@ fill_inbetween: examples/fill_inbetween.cpp matplotlibcpp.h
 
 fill: examples/fill.cpp matplotlibcpp.h
 	cd examples && g++ fill.cpp -I/usr/include/python2.7 -lpython2.7 -o fill -std=c++11
-	
+
 update: examples/update.cpp matplotlibcpp.h
 	cd examples && g++ update.cpp -I/usr/include/python2.7 -lpython2.7 -o update -std=c++11
 
+imshow: examples/imshow.cpp matplotlibcpp.h
+	cd examples && g++ imshow.cpp -I/usr/include/python2.7 -lpython2.7 -o imshow -std=c++11
+
 clean:
-	rm -f examples/{minimal,basic,modern,animation,nonblock,xkcd,quiver,bar,surface,fill_inbetween,fill,update}
+	rm -f examples/{minimal,basic,modern,animation,nonblock,xkcd,quiver,bar,surface,fill_inbetween,fill,update,imshow}
diff --git a/examples/imshow.cpp b/examples/imshow.cpp
@@ -0,0 +1,27 @@
+#define _USE_MATH_DEFINES
+#include <cmath>
+#include "../matplotlibcpp.h"
+
+using namespace std;
+namespace plt = matplotlibcpp;
+
+int main()
+{
+    // Prepare data
+    int ncols = 500, nrows = 300;
+    std::vector<float> z(ncols * nrows);
+    for (int j=0; j<nrows; ++j) {
+        for (int i=0; i<ncols; ++i) {
+            z.at(ncols * j + i) = std::sin(std::hypot(i - ncols/2, j - nrows/2));
+        }
+    }
+
+    const float* zptr = &(z[0]);
+    const int colors = 1;
+
+    plt::title("My matrix");
+    plt::imshow(zptr, nrows, ncols, colors);
+
+    // Show plots
+    plt::save("imshow.png");
+}
diff --git a/matplotlibcpp.h b/matplotlibcpp.h
@@ -15,6 +15,10 @@
 #ifndef WITHOUT_NUMPY
 #  define NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION
 #  include <numpy/arrayobject.h>
+
+#  ifdef WITH_OPENCV
+#  include <opencv2/opencv.hpp>
+#  endif // WITH_OPENCV
 #endif // WITHOUT_NUMPY
 
 #if PY_MAJOR_VERSION >= 3
@@ -45,6 +49,7 @@ struct _interpreter {
     PyObject *s_python_function_fill;
     PyObject *s_python_function_fill_between;
     PyObject *s_python_function_hist;
+    PyObject *s_python_function_imshow;
     PyObject *s_python_function_scatter;
     PyObject *s_python_function_subplot;
     PyObject *s_python_function_legend;
@@ -165,6 +170,9 @@ struct _interpreter {
         s_python_function_fill = PyObject_GetAttrString(pymod, "fill");
         s_python_function_fill_between = PyObject_GetAttrString(pymod, "fill_between");
         s_python_function_hist = PyObject_GetAttrString(pymod,"hist");
+#ifndef WITHOUT_NUMPY
+        s_python_function_imshow = PyObject_GetAttrString(pymod, "imshow");
+#endif
         s_python_function_scatter = PyObject_GetAttrString(pymod,"scatter");
         s_python_function_subplot = PyObject_GetAttrString(pymod, "subplot");
         s_python_function_legend = PyObject_GetAttrString(pymod, "legend");
@@ -211,6 +219,9 @@ struct _interpreter {
             || !s_python_function_axis
             || !s_python_function_xlabel
             || !s_python_function_ylabel
+#ifndef WITHOUT_NUMPY
+            || !s_python_function_imshow
+#endif
             || !s_python_function_grid
             || !s_python_function_xlim
             || !s_python_function_ion
@@ -246,6 +257,9 @@ struct _interpreter {
             || !PyFunction_Check(s_python_function_legend)
             || !PyFunction_Check(s_python_function_annotate)
             || !PyFunction_Check(s_python_function_ylim)
+#ifndef WITHOUT_NUMPY
+            || !PyFunction_Check(s_python_function_imshow)
+#endif
             || !PyFunction_Check(s_python_function_title)
             || !PyFunction_Check(s_python_function_axis)
             || !PyFunction_Check(s_python_function_xlabel)
@@ -623,6 +637,78 @@ bool hist(const std::vector<Numeric>& y, long bins=10,std::string color="b",
     return res;
 }
 
+#ifndef WITHOUT_NUMPY
+    namespace internal {
+        void imshow(void *ptr, const NPY_TYPES type, const int rows, const int columns, const int colors, const std::map<std::string, std::string> &keywords)
+        {
+            assert(type == NPY_UINT8 || type == NPY_FLOAT);
+            assert(colors == 1 || colors == 3 || colors == 4);
+
+            detail::_interpreter::get();    //interpreter needs to be initialized for the numpy commands to work
+
+            // construct args
+            npy_intp dims[3] = { rows, columns, colors };
+            PyObject *args = PyTuple_New(1);
+            PyTuple_SetItem(args, 0, PyArray_SimpleNewFromData(colors == 1 ? 2 : 3, dims, type, ptr));
+
+            // construct keyword args
+            PyObject* kwargs = PyDict_New();
+            for(std::map<std::string, std::string>::const_iterator it = keywords.begin(); it != keywords.end(); ++it)
+            {
+                PyDict_SetItemString(kwargs, it->first.c_str(), PyUnicode_FromString(it->second.c_str()));
+            }
+
+            PyObject *res = PyObject_Call(detail::_interpreter::get().s_python_function_imshow, args, kwargs);
+            Py_DECREF(args);
+            Py_DECREF(kwargs);
+            if (!res)
+                throw std::runtime_error("Call to imshow() failed");
+            Py_DECREF(res);
+        }
+    }
+
+    void imshow(const unsigned char *ptr, const int rows, const int columns, const int colors, const std::map<std::string, std::string> &keywords = {})
+    {
+        internal::imshow((void *) ptr, NPY_UINT8, rows, columns, colors, keywords);
+    }
+
+    void imshow(const float *ptr, const int rows, const int columns, const int colors, const std::map<std::string, std::string> &keywords = {})
+    {
+        internal::imshow((void *) ptr, NPY_FLOAT, rows, columns, colors, keywords);
+    }
+
+#ifdef WITH_OPENCV
+    void imshow(const cv::Mat &image, const std::map<std::string, std::string> &keywords = {})
+    {
+        // Convert underlying type of matrix, if needed
+        cv::Mat image2;
+        NPY_TYPES npy_type = NPY_UINT8;
+        switch (image.type() & CV_MAT_DEPTH_MASK) {
+        case CV_8U:
+            image2 = image;
+            break;
+        case CV_32F:
+            image2 = image;
+            npy_type = NPY_FLOAT;
+            break;
+        default:
+            image.convertTo(image2, CV_MAKETYPE(CV_8U, image.channels()));
+        }
+
+        // If color image, convert from BGR to RGB
+        switch (image2.channels()) {
+        case 3:
+            cv::cvtColor(image2, image2, CV_BGR2RGB);
+            break;
+        case 4:
+            cv::cvtColor(image2, image2, CV_BGRA2RGBA);
+        }
+
+        internal::imshow(image2.data, npy_type, image2.rows, image2.cols, image2.channels(), keywords);
+    }
+#endif
+#endif
+
 template<typename NumericX, typename NumericY>
 bool scatter(const std::vector<NumericX>& x,
              const std::vector<NumericY>& y,