Merge pull request matplotlib#3806 from mdboom/image-orientation-macosx

OSX backend. 2D histograms are flipped vertically

Author: jenshnielsen

src/_macosx.m

@@ -3222,9 +3222,15 @@ static void _data_provider_release(void* info, const void* data, size_t size)
 
     CGFloat deviceScale = _get_device_scale(cr);
 
-    CGContextDrawImage(cr, CGRectMake(x, y, ncols/deviceScale, nrows/deviceScale), bitmap);
+    CGContextSaveGState(cr);
+    CGContextTranslateCTM(cr, 0, y + nrows/deviceScale);
+    CGContextScaleCTM(cr, 1.0, -1.0);
+
+    CGContextDrawImage(cr, CGRectMake(x, 0, ncols/deviceScale, nrows/deviceScale), bitmap);
     CGImageRelease(bitmap);
 
+    CGContextRestoreGState(cr);
+
     Py_INCREF(Py_None);
     return Py_None;
 }