py3k: Use new buffer protocol

Other ports have taken advantage of the fact that Python 3 has wrappers for
the old buffer protocol, but there's a significant disadvantage: you can't
let the buffered object know when you're done with it.

Since Python 2.6 supports the new protocol, we just go ahead and move to
it.

_imaging.c

@@ -103,19 +103,6 @@
 #define L16(p, i) ((((int)p[(i)+1]) << 8) + p[(i)])
 #define S16(v) ((v) < 32768 ? (v) : ((v) - 65536))
 
-#if PY_VERSION_HEX < 0x01060000
-#define PyObject_New PyObject_NEW
-#define PyObject_Del PyMem_DEL
-#endif
-
-#if PY_VERSION_HEX < 0x02050000
-#define Py_ssize_t int
-#define ssizeargfunc intargfunc
-#define ssizessizeargfunc intintargfunc
-#define ssizeobjargproc intobjargproc
-#define ssizessizeobjargproc intintobjargproc
-#endif
-
 /* -------------------------------------------------------------------- */
 /* OBJECT ADMINISTRATION						*/
 /* -------------------------------------------------------------------- */
@@ -243,43 +230,38 @@ void ImagingSectionLeave(ImagingSectionCookie* cookie)
 /* -------------------------------------------------------------------- */
 /* Python compatibility API */
 
-#if PY_VERSION_HEX < 0x02020000
-
-int PyImaging_CheckBuffer(PyObject *buffer)
-{
-    PyBufferProcs *procs = buffer->ob_type->tp_as_buffer;
-    if (procs && procs->bf_getreadbuffer && procs->bf_getsegcount &&
-        procs->bf_getsegcount(buffer, NULL) == 1)
-        return 1;
-    return 0;
-}
-
-int PyImaging_ReadBuffer(PyObject* buffer, const void** ptr)
-{
-    PyBufferProcs *procs = buffer->ob_type->tp_as_buffer;
-    return procs->bf_getreadbuffer(buffer, 0, ptr);
-}
-
-#else
-
 int PyImaging_CheckBuffer(PyObject* buffer)
 {
-    return PyObject_CheckReadBuffer(buffer);
+#if PY_VERSION_HEX >= 0x03000000
+    return PyObject_CheckBuffer(buffer);
+#else
+    return PyObject_CheckBuffer(buffer) || PyObject_CheckReadBuffer(buffer);
+#endif
 }
 
-int PyImaging_ReadBuffer(PyObject* buffer, const void** ptr)
+int PyImaging_GetBuffer(PyObject* buffer, Py_buffer *view)
 {
     /* must call check_buffer first! */
-#if PY_VERSION_HEX < 0x02050000
-    int n = 0;
+#if PY_VERSION_HEX >= 0x03000000
+    return PyObject_GetBuffer(buffer, view, PyBUF_SIMPLE);
 #else
-    Py_ssize_t n = 0;
-#endif
-    PyObject_AsReadBuffer(buffer, ptr, &n);
-    return (int) n;
-}
+    /* Use new buffer protocol if available
+       (mmap doesn't support this in 2.7, go figure) */
+    if (PyObject_CheckBuffer(buffer)) {
+        return PyObject_GetBuffer(buffer, view, PyBUF_SIMPLE);
+    }
 
+    /* Pretend we support the new protocol; PyBuffer_Release happily ignores
+       calling bf_releasebuffer on objects that don't support it */
+    *view = (Py_buffer) {0};
+    view->readonly = 1;
+
+    Py_INCREF(buffer);
+    view->obj = buffer;
+
+    return PyObject_AsReadBuffer(buffer, (void *) &view->buf, &view->len);
 #endif
+}
 
 /* -------------------------------------------------------------------- */
 /* EXCEPTION REROUTING                                                  */

map.c

@@ -41,7 +41,7 @@
 
 /* compatibility wrappers (defined in _imaging.c) */
 extern int PyImaging_CheckBuffer(PyObject* buffer);
-extern int PyImaging_ReadBuffer(PyObject* buffer, const void** ptr);
+extern int PyImaging_GetBuffer(PyObject* buffer, Py_buffer *view);
 
 /* -------------------------------------------------------------------- */
 /* Standard mapper */
@@ -311,6 +311,7 @@ PyImaging_Mapper(PyObject* self, PyObject* args)
 typedef struct ImagingBufferInstance {
     struct ImagingMemoryInstance im;
     PyObject* target;
+    Py_buffer view;
 } ImagingBufferInstance;
 
 static void
@@ -318,6 +319,7 @@ mapping_destroy_buffer(Imaging im)
 {
     ImagingBufferInstance* buffer = (ImagingBufferInstance*) im;
     
+    PyBuffer_Release(&buffer->view);
     Py_XDECREF(buffer->target);
 }
 
@@ -326,10 +328,9 @@ PyImaging_MapBuffer(PyObject* self, PyObject* args)
 {
     int y, size;
     Imaging im;
-    char* ptr;
-    int bytes;
 
     PyObject* target;
+    Py_buffer view;
     char* mode;
     char* codec;
     PyObject* bbox;
@@ -359,12 +360,14 @@ PyImaging_MapBuffer(PyObject* self, PyObject* args)
     size = ysize * stride;
 
     /* check buffer size */
-    bytes = PyImaging_ReadBuffer(target, (const void**) &ptr);
-    if (bytes < 0) {
+    if (PyImaging_GetBuffer(target, &view) < 0)
+        return NULL;
+
+    if (view.len < 0) {
         PyErr_SetString(PyExc_ValueError, "buffer has negative size");
         return NULL;
     }
-    if (offset + size > bytes) {
+    if (offset + size > view.len) {
         PyErr_SetString(PyExc_ValueError, "buffer is not large enough");
         return NULL;
     }
@@ -378,15 +381,16 @@ PyImaging_MapBuffer(PyObject* self, PyObject* args)
     /* setup file pointers */
     if (ystep > 0)
         for (y = 0; y < ysize; y++)
-            im->image[y] = ptr + offset + y * stride;
+            im->image[y] = view.buf + offset + y * stride;
     else
         for (y = 0; y < ysize; y++)
-            im->image[ysize-y-1] = ptr + offset + y * stride;
+            im->image[ysize-y-1] = view.buf + offset + y * stride;
 
     im->destroy = mapping_destroy_buffer;
 
     Py_INCREF(target);
     ((ImagingBufferInstance*) im)->target = target;
+    ((ImagingBufferInstance*) im)->view = view;
 
     if (!ImagingNewEpilogue(im))
         return NULL;

path.c

@@ -46,7 +46,7 @@
 
 /* compatibility wrappers (defined in _imaging.c) */
 extern int PyImaging_CheckBuffer(PyObject* buffer);
-extern int PyImaging_ReadBuffer(PyObject* buffer, const void** ptr);
+extern int PyImaging_GetBuffer(PyObject* buffer, Py_buffer *view);
 
 /* -------------------------------------------------------------------- */
 /* Class								*/
@@ -134,16 +134,20 @@ PyPath_Flatten(PyObject* data, double **pxy)
 	
     if (PyImaging_CheckBuffer(data)) {
         /* Assume the buffer contains floats */
-        float* ptr;
-        int n = PyImaging_ReadBuffer(data, (const void**) &ptr);
-        n /= 2 * sizeof(float);
-        xy = alloc_array(n);
-        if (!xy)
-            return -1;
-        for (i = 0; i < n+n; i++)
-            xy[i] = ptr[i];
-        *pxy = xy;
-        return n;
+        Py_buffer buffer;
+        if (PyImaging_GetBuffer(data, &buffer) == 0) {
+            int n = buffer.len / (2 * sizeof(float));
+            float *ptr = (float*) buffer.buf;
+            xy = alloc_array(n);
+            if (!xy)
+                return -1;
+            for (i = 0; i < n+n; i++)
+                xy[i] = ptr[i];
+            *pxy = xy;
+            PyBuffer_Release(&buffer);
+            return n;
+        }
+        PyErr_Clear();
     }
 
     if (!PySequence_Check(data)) {