Support the new Python 3 buffer interface to get the Agg renderer buffer.

Supported by Sage Days 29

Author: astropy-buildbot

CXX/Python3/ExtensionTypeBase.hxx

@@ -121,7 +121,8 @@ namespace Py
         virtual Object number_power( const Object &, const Object & );
 
         // Buffer
-        // QQQ need to add py3 interface
+        virtual int buffer_get( Py_buffer *, int flags );
+        virtual int buffer_release( Py_buffer *buf );
 
     public:
         // helper functions to call function fn_name with 0 to 9 args

CXX/Python3/cxx_extensions.cxx

@@ -262,7 +262,8 @@ extern "C"
     static PyObject *number_power_handler( PyObject *, PyObject *, PyObject * );
 
     // Buffer
-    // QQQ
+    static int buffer_get_handler( PyObject *, Py_buffer *, int );
+    static void buffer_release_handler( PyObject *, Py_buffer * );
 }
 
 extern "C" void standard_dealloc( PyObject *p )
@@ -345,8 +346,8 @@ PythonType &PythonType::supportBufferType()
         buffer_table = new PyBufferProcs;
         memset( buffer_table, 0, sizeof( PyBufferProcs ) );   // ensure new fields are 0
         table->tp_as_buffer = buffer_table;
-        // QQQ bf_getbuffer
-        // QQQ bf_releasebuffer
+        buffer_table->bf_getbuffer = buffer_get_handler;
+        buffer_table->bf_releasebuffer = buffer_release_handler;
     }
     return *this;
 }
@@ -1099,6 +1100,25 @@ extern "C" PyObject *number_power_handler( PyObject *self, PyObject *x1, PyObjec
 }
 
 // Buffer
+extern "C" int buffer_get_handler( PyObject *self, Py_buffer *buf, int flags )
+{
+    try
+    {
+        PythonExtensionBase *p = getPythonExtensionBase( self );
+        return p->buffer_get( buf, flags );
+    }
+    catch( Py::Exception & )
+    {
+        return -1;    // indicate error
+    }
+}
+
+extern "C" void buffer_release_handler( PyObject *self, Py_buffer *buf )
+{
+    PythonExtensionBase *p = getPythonExtensionBase( self );
+    p->buffer_release( buf );
+    // NOTE: No way to indicate error to Python
+}
 
 //================================================================================
 //
@@ -1454,7 +1474,18 @@ Py::Object PythonExtensionBase::number_power( const Py::Object &, const Py::Obje
 
 
 // Buffer
-// QQQ
+int PythonExtensionBase::buffer_get( Py_buffer *buf, int flags )
+{
+    missing_method( buffer_get );
+    return -1;
+}
+
+int PythonExtensionBase::buffer_release( Py_buffer *buf )
+{
+    /* This method is optional and only required if the buffer's
+       memory is dynamic. */
+    return 0;
+}
 
 //--------------------------------------------------------------------------------
 //

examples/pylab_examples/agg_buffer_to_array.py

@@ -10,7 +10,7 @@
 fig.canvas.draw()
 
 # grab rhe pixel buffer and dumpy it into a numpy array
-buf = fig.canvas.buffer_rgba(0,0)
+buf = fig.canvas.buffer_rgba()
 l, b, w, h = fig.bbox.bounds
 X = np.frombuffer(buf, np.uint8)
 X.shape = h,w,4

lib/matplotlib/backends/backend_agg.py

@@ -249,10 +249,10 @@ def tostring_argb(self):
                                      'debug-annoying')
         return self._renderer.tostring_argb()
 
-    def buffer_rgba(self,x,y):
+    def buffer_rgba(self):
         if __debug__: verbose.report('RendererAgg.buffer_rgba',
                                      'debug-annoying')
-        return self._renderer.buffer_rgba(x,y)
+        return self._renderer.buffer_rgba()
 
     def clear(self):
         self._renderer.clear()
@@ -421,10 +421,10 @@ def tostring_argb(self):
                                      'debug-annoying')
         return self.renderer.tostring_argb()
 
-    def buffer_rgba(self,x,y):
+    def buffer_rgba(self):
         if __debug__: verbose.report('FigureCanvasAgg.buffer_rgba',
                                      'debug-annoying')
-        return self.renderer.buffer_rgba(x,y)
+        return self.renderer.buffer_rgba()
 
     def get_default_filetype(self):
         return 'png'
@@ -447,7 +447,7 @@ def print_png(self, filename_or_obj, *args, **kwargs):
         renderer.dpi = self.figure.dpi
         if is_string_like(filename_or_obj):
             filename_or_obj = open(filename_or_obj, 'wb')
-        _png.write_png(renderer._renderer.buffer_rgba(0, 0),
+        _png.write_png(renderer._renderer.buffer_rgba(),
                        renderer.width, renderer.height,
                        filename_or_obj, self.figure.dpi)
         renderer.dpi = original_dpi
@@ -457,7 +457,7 @@ def print_to_buffer(self):
         renderer = self.get_renderer()
         original_dpi = renderer.dpi
         renderer.dpi = self.figure.dpi
-        result = (renderer._renderer.buffer_rgba(0, 0),
+        result = (renderer._renderer.buffer_rgba(),
                   (int(renderer.width), int(renderer.height)))
         renderer.dpi = original_dpi
         return result

lib/matplotlib/backends/backend_cocoaagg.py

@@ -144,7 +144,7 @@ def updatePlot(self):
         self.image_.setSize_((w,h))
 
         brep = NSBitmapImageRep.alloc().initWithBitmapDataPlanes_pixelsWide_pixelsHigh_bitsPerSample_samplesPerPixel_hasAlpha_isPlanar_colorSpaceName_bytesPerRow_bitsPerPixel_(
-            (self.canvas.buffer_rgba(0,0),'','','',''), # Image data
+            (self.canvas.buffer_rgba(),'','','',''), # Image data
             w, # width
             h, # height
             8, # bits per pixel

lib/matplotlib/backends/backend_fltkagg.py

@@ -108,7 +108,7 @@ def draw(self):
             self._source.resize(newsize)
             self._source.draw()
         t1,t2,w,h = self._source.figure.bbox.bounds
-        Fltk.fl_draw_image(self._source.buffer_rgba(0,0),0,0,int(w),int(h),4,0)
+        Fltk.fl_draw_image(self._source.buffer_rgba(),0,0,int(w),int(h),4,0)
         self.redraw()
 
     def blit(self,bbox=None):
@@ -118,7 +118,7 @@ def blit(self,bbox=None):
            t1o,t2o,wo,ho = self._source.figure.bbox.bounds
            t1,t2,w,h = bbox.bounds
         x,y=int(t1),int(t2)
-        Fltk.fl_draw_image(self._source.buffer_rgba(x,y),x,y,int(w),int(h),4,int(wo)*4)
+        Fltk.fl_draw_image(self._source.buffer_rgba(),x,y,int(w),int(h),4,int(wo)*4)
         #self.redraw()
 
     def handle(self, event):

lib/matplotlib/backends/backend_gtkagg.py

@@ -76,7 +76,7 @@ def _render_figure(self, pixmap, width, height):
         if DEBUG: print('FigureCanvasGTKAgg.render_figure pixmap', pixmap)
         #agg_to_gtk_drawable(pixmap, self.renderer._renderer, None)
 
-        buf = self.buffer_rgba(0,0)
+        buf = self.buffer_rgba()
         ren = self.get_renderer()
         w = int(ren.width)
         h = int(ren.height)

lib/matplotlib/backends/backend_wxagg.py

@@ -160,7 +160,7 @@ def _convert_agg_to_wx_bitmap(agg, bbox):
     if bbox is None:
         # agg => rgba buffer -> bitmap
         return wx.BitmapFromBufferRGBA(int(agg.width), int(agg.height),
-            agg.buffer_rgba(0, 0))
+            agg.buffer_rgba())
     else:
         # agg => rgba buffer -> bitmap => clipped bitmap
         return _WX28_clipped_agg_as_bitmap(agg, bbox)
@@ -177,7 +177,7 @@ def _WX28_clipped_agg_as_bitmap(agg, bbox):
     t = b + height
 
     srcBmp = wx.BitmapFromBufferRGBA(int(agg.width), int(agg.height),
-        agg.buffer_rgba(0, 0))
+        agg.buffer_rgba())
     srcDC = wx.MemoryDC()
     srcDC.SelectObject(srcBmp)
 

src/_backend_agg.cpp

@@ -2191,19 +2191,13 @@ RendererAgg::buffer_rgba(const Py::Tuple& args)
 
     _VERBOSE("RendererAgg::buffer_rgba");
 
-    args.verify_length(2);
-    int startw = Py::Int(args[0]);
-    int starth = Py::Int(args[1]);
-    int row_len = width * 4;
-    int start = row_len * starth + startw * 4;
+    args.verify_length(0);
 
     #if PY3K
-    Py_buffer view;
-    PyBuffer_FillInfo(&view, NULL, (void *)((const char *)pixBuffer + start),
-                      row_len*height - start, 1, PyBUF_SIMPLE);
-    return Py::asObject(PyMemoryView_FromBuffer(&view));
+    return Py::asObject(this);
     #else
-    return Py::asObject(PyBuffer_FromMemory(pixBuffer + start, row_len*height - start));
+    int row_len = width * 4;
+    return Py::asObject(PyBuffer_FromMemory(pixBuffer, row_len*height));
     #endif
 }
 
@@ -2318,6 +2312,14 @@ RendererAgg::points_to_pixels(const Py::Object& points)
     return p * dpi / 72.0;
 }
 
+#if PY3K
+int
+RendererAgg::buffer_get( Py_buffer* buf, int flags )
+{
+    return PyBuffer_FillInfo(buf, this, pixBuffer, width * height * 4, 1,
+                             PyBUF_SIMPLE);
+}
+#endif
 
 RendererAgg::~RendererAgg()
 {
@@ -2439,6 +2441,10 @@ void RendererAgg::init_type()
                        "restore_region(region)");
     add_varargs_method("restore_region2", &RendererAgg::restore_region2,
                        "restore_region(region, x1, y1, x2, y2, x3, y3)");
+
+    #if PY3K
+    behaviors().supportBufferType();
+    #endif
 }
 
 PyMODINIT_FUNC

src/_backend_agg.h

@@ -195,6 +195,10 @@ class RendererAgg: public Py::PythonExtension<RendererAgg>
     Py::Object restore_region(const Py::Tuple & args);
     Py::Object restore_region2(const Py::Tuple & args);
 
+    #if PY3K
+    virtual int buffer_get( Py_buffer *, int flags );
+    #endif
+
     virtual ~RendererAgg();
 
     static const size_t PIXELS_PER_INCH;