From e07b5c7e102020110d4ded59710e1d41c63039ad Mon Sep 17 00:00:00 2001
From: holoeye-photonics <github-developer@holoeye.com>
Date: Tue, 2 May 2017 11:59:19 +0200
Subject: [PATCH] Added function core::captureWindow() to capture the current
 screen into a ImageData object. Also added a function overload to save it to
 a png file.

---
 oxygine/src/core/gl/oxgl.cpp |  4 +++
 oxygine/src/core/gl/oxgl.h   |  6 +++-
 oxygine/src/core/oxygine.cpp | 57 ++++++++++++++++++++++++++++++++++++
 oxygine/src/core/oxygine.h   |  6 ++++
 4 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/oxygine/src/core/gl/oxgl.cpp b/oxygine/src/core/gl/oxgl.cpp
index 9b00b5590..3fcfee874 100644
--- a/oxygine/src/core/gl/oxgl.cpp
+++ b/oxygine/src/core/gl/oxgl.cpp
@@ -120,6 +120,8 @@ extern "C"
     {}
     GLAPI GLint APIENTRY def_glGetAttribLocation(GLuint program, const GLchar* name)
     {return 0;}
+    GLAPI void APIENTRY def_glReadPixels(GLint x​, GLint y​, GLsizei width​, GLsizei height​, GLenum format​, GLenum type​, GLvoid * data​)
+    {}
 //!--defgl-end--!
 
 //!--_gl-begin--!
@@ -171,6 +173,7 @@ extern "C"
     PFNGLBLENDFUNCSEPARATEPROC _glBlendFuncSeparate = 0;
     PFNGLBLENDEQUATIONSEPARATEPROC _glBlendEquationSeparate = 0;
     PFNGLGETATTRIBLOCATIONPROC _glGetAttribLocation = 0;
+    PFNGLREADPIXELSPROC _glReadPixels = 0;
 //!--_gl-end--!
 }
 
@@ -230,6 +233,7 @@ int initGLExtensions(myGetProcAdress func)
     GETFUNC(_glBlendFuncSeparate, def_glBlendFuncSeparate, PFNGLBLENDFUNCSEPARATEPROC, "glBlendFuncSeparate");
     GETFUNC(_glBlendEquationSeparate, def_glBlendEquationSeparate, PFNGLBLENDEQUATIONSEPARATEPROC, "glBlendEquationSeparate");
     GETFUNC(_glGetAttribLocation, def_glGetAttribLocation, PFNGLGETATTRIBLOCATIONPROC, "glGetAttribLocation");
+    GETFUNC(_glReadPixels, def_glReadPixels, PFNGLREADPIXELSPROC, "glReadPixels");
 //!--getfunc-end--!
 
     return missing;
diff --git a/oxygine/src/core/gl/oxgl.h b/oxygine/src/core/gl/oxgl.h
index 4f01870bf..5d2421559 100644
--- a/oxygine/src/core/gl/oxgl.h
+++ b/oxygine/src/core/gl/oxgl.h
@@ -23,6 +23,8 @@
 
 #   define GL_ETC1_RGB8_OES                                        0x8D64
 
+typedef void (APIENTRYP PFNGLREADPIXELSPROC) (GLint x​, GLint y​, GLsizei width​, GLsizei height​, GLenum format​, GLenum type​, GLvoid * data​);
+
 extern "C"
 {
 //!--pfngl-begin--!
@@ -74,6 +76,7 @@ extern "C"
     extern PFNGLBLENDFUNCSEPARATEPROC _glBlendFuncSeparate;
     extern PFNGLBLENDEQUATIONSEPARATEPROC _glBlendEquationSeparate;
     extern PFNGLGETATTRIBLOCATIONPROC _glGetAttribLocation;
+    extern PFNGLREADPIXELSPROC _glReadPixels;
 //!--pfngl-end--!
 }
 
@@ -179,6 +182,7 @@ extern "C"
 #define oxglBlendFuncSeparate DECLARE_GLEXT(glBlendFuncSeparate)
 #define oxglBlendEquationSeparate DECLARE_GLEXT(glBlendEquationSeparate)
 #define oxglGetAttribLocation DECLARE_GLEXT(glGetAttribLocation)
+#define oxglReadPixels DECLARE_GLEXT(glReadPixels)
 //!--oxgl-end--!
 
 
@@ -191,4 +195,4 @@ namespace oxygine {void checkGLError();}
 
 typedef void*  (*myGetProcAdress)(const char*);
 /**returns number of missing functions/extensions*/
-int initGLExtensions(myGetProcAdress);
\ No newline at end of file
+int initGLExtensions(myGetProcAdress);
diff --git a/oxygine/src/core/oxygine.cpp b/oxygine/src/core/oxygine.cpp
index 618392264..d0a79b6c5 100644
--- a/oxygine/src/core/oxygine.cpp
+++ b/oxygine/src/core/oxygine.cpp
@@ -549,6 +549,63 @@ namespace oxygine
         }
 #endif
 
+        void captureWindow(ImageData &image)
+        {
+            Point size = core::getDisplaySize();
+
+            size_t memsize = size.x * size.y * 4;
+
+            image = ImageData(size.x, size.y, size.y * 4, TF_R8G8B8A8, malloc(memsize));
+
+            memset(image.data, 0, memsize);
+
+            oxglReadPixels(0, 0, size.x, size.y, GL_RGBA, GL_UNSIGNED_BYTE, image.data);
+        }
+
+#ifdef OX_HAVE_LIBPNG
+        bool captureWindow(const char *pngFilename)
+        {
+            FILE *fp = fopen(pngFilename, "wb");
+
+            if(fp == NULL)
+                return false;
+
+            ImageData data;
+
+            captureWindow(data);
+
+            png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+            png_infop info_ptr = png_create_info_struct(png_ptr);
+
+            OX_ASSERT(png_ptr != NULL);
+            OX_ASSERT(info_ptr != NULL);
+
+            setjmp(png_jmpbuf(png_ptr));
+
+            png_set_IHDR(png_ptr, info_ptr, data.w, data.h,
+                     8, PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
+                     PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+            png_init_io(png_ptr, fp);
+
+            png_write_info(png_ptr, info_ptr);
+
+            for(int r = 0; r < data.h; ++r)
+                png_write_row(png_ptr, data.data + ((data.h - r - 1) * data.w * 4));
+
+            png_write_end(png_ptr, NULL);
+
+            fclose(fp);
+
+            png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
+            png_destroy_write_struct(&png_ptr, (png_infopp)NULL);
+
+            free(data.data);
+
+            return true;
+        }
+#endif
+
         void reset()
         {
             log::messageln("core::reset()");
diff --git a/oxygine/src/core/oxygine.h b/oxygine/src/core/oxygine.h
index 06383cc4c..660a1f38c 100644
--- a/oxygine/src/core/oxygine.h
+++ b/oxygine/src/core/oxygine.h
@@ -118,6 +118,12 @@ namespace oxygine
         SDL_Window*     getWindow();
 #endif
 
+        void captureWindow(ImageData &image);
+
+#ifdef OX_HAVE_LIBPNG
+        bool captureWindow(const char *pngFilename);
+#endif
+
         enum
         {
             EVENT_SYSTEM = sysEventID('c', 'S', 'y'), //events from SDL