From c9a2092b9cb70ec7a7c7e5ebe087e99323f083f3 Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Thu, 3 Mar 2016 09:53:10 +0000
Subject: [PATCH] Fix image export on *nix.

Before this commit, trying to export image on *nix platforms yielded
a black rectangle, since since there is nowhere to render to
when we're not in a GUI toolkit draw callback.

On Windows, nothing changes: we do a repaint without the toolbar,
glReadPixels, export. On *nix, we create another offscreen rendering
context, render into it, then destroy it. As a bonus this avoids
some minor flickering that would happen if we reused the regular
rendering path.
---
 src/export.cpp           | 7 +++++++
 src/solvespace.h         | 1 +
 src/unix/gloffscreen.cpp | 2 ++
 3 files changed, 10 insertions(+)

diff --git a/src/export.cpp b/src/export.cpp
index 6bfb4b5..38d7642 100644
--- a/src/export.cpp
+++ b/src/export.cpp
@@ -7,6 +7,9 @@
 // Copyright 2008-2013 Jonathan Westhues.
 //-----------------------------------------------------------------------------
 #include "solvespace.h"
+#ifndef WIN32
+#include <unix/gloffscreen.h>
+#endif
 #include <png.h>
 
 void SolveSpaceUI::ExportSectionTo(const std::string &filename) {
@@ -1048,6 +1051,10 @@ void SolveSpaceUI::ExportAsPngTo(const std::string &filename) {
     // so repaint the scene. And hide the toolbar too.
     bool prevShowToolbar = SS.showToolbar;
     SS.showToolbar = false;
+#ifndef WIN32
+    std::unique_ptr<GLOffscreen> gloffscreen(new GLOffscreen);
+    gloffscreen->begin(w, h);
+#endif
     SS.GW.Paint();
     SS.showToolbar = prevShowToolbar;
 
diff --git a/src/solvespace.h b/src/solvespace.h
index d5ba6ac..c52733a 100644
--- a/src/solvespace.h
+++ b/src/solvespace.h
@@ -17,6 +17,7 @@
 #include <math.h>
 #include <limits.h>
 #include <algorithm>
+#include <memory>
 #include <string>
 #include <vector>
 #include <map>
diff --git a/src/unix/gloffscreen.cpp b/src/unix/gloffscreen.cpp
index 107721f..be836e2 100644
--- a/src/unix/gloffscreen.cpp
+++ b/src/unix/gloffscreen.cpp
@@ -27,6 +27,8 @@ GLOffscreen::GLOffscreen() : _pixels(NULL), _pixels_inv(NULL), _width(0), _heigh
 }
 
 GLOffscreen::~GLOffscreen() {
+    delete[] _pixels;
+    delete[] _pixels_inv;
     glDeleteRenderbuffersEXT(1, &_depth_renderbuffer);
     glDeleteRenderbuffersEXT(1, &_color_renderbuffer);
     glDeleteFramebuffersEXT(1, &_framebuffer);