Implement ImageSurface.get_data(), using some code from Paul Colomiets.

bug #44935.

5 files changed, 137 insertions, 48 deletions

diff --git a/doc/reference/surfaces.rst b/doc/reference/surfaces.rst
index 2058a2a..bc57a6e 100644
--- a/doc/reference/surfaces.rst
+++ b/doc/reference/surfaces.rst
@@ -313,12 +313,9 @@ those defined in :ref:`FORMAT attributes <constants_FORMAT>`.
 
    .. method:: get_data()
 
-      Not yet available in Python 3
-
-   .. comment block - old docs:
-      :returns: a Python buffer object for the data of the *ImageSurface*, for direct inspection or modification.
+      :returns: a Python memoryview for the data of the *ImageSurface*, for direct inspection or modification.
 
-      .. versionadded:: 1.2
+      .. versionadded:: 1.10.0
 
    .. method:: get_format()
 
diff --git a/src/cairomodule.c b/src/cairomodule.c
index 675676d..886c6d5 100644
--- a/src/cairomodule.c
+++ b/src/cairomodule.c
@@ -255,7 +255,7 @@ PyInit__cairo(void)
 #endif
 #ifdef CAIRO_HAS_RECORDING_SURFACE
   if (PyType_Ready(&PycairoRecordingSurface_Type) < 0)
-    return;
+    return NULL;
 #endif
 #ifdef CAIRO_HAS_SVG_SURFACE
   if (PyType_Ready(&PycairoSVGSurface_Type) < 0)
diff --git a/src/surface.c b/src/surface.c
index 35ca169..7d00141 100644
--- a/src/surface.c
+++ b/src/surface.c
@@ -546,9 +546,7 @@ image_surface_format_stride_for_width (PyObject *self, PyObject *args) {
 
 static PyObject *
 image_surface_get_data (PycairoImageSurface *o) {
-  PyErr_SetString(PyExc_NotImplementedError, "Surface.get_data: Not Implemented yet.");
-  return NULL;
-  // return PyBuffer_FromReadWriteObject((PyObject *)o, 0, Py_END_OF_BUFFER);
+  return PyMemoryView_FromObject((PyObject*)o);
 }
 
 static PyObject *
@@ -573,6 +571,24 @@ image_surface_get_width (PycairoImageSurface *o) {
 
 
 /* Buffer interface functions, used by ImageSurface.get_data() */
+static int
+image_surface_buffer_getbufferproc (PycairoImageSurface *o, Py_buffer *view,
+				                    int flags) {
+  cairo_surface_t *surface = o->surface;
+  int height, stride;
+  void *data;
+
+  height = cairo_image_surface_get_height (surface);
+  stride = cairo_image_surface_get_stride (surface);
+  data   = cairo_image_surface_get_data   (surface);
+
+  if(!PyBuffer_FillInfo(view, (PyObject *)o, data,
+        height * stride, 0, PyBUF_CONTIG))
+    return 0;
+  return -1;
+}
+
+/* Buffer interface functions, used by ImageSurface.get_data() */
 /*
 static int
 image_surface_buffer_getreadbuf (PycairoImageSurface *o, int segment,
@@ -630,6 +646,11 @@ static PyBufferProcs image_surface_as_buffer = {
   (charbufferproc) NULL,
 };
 */
+static PyBufferProcs image_surface_as_buffer = {
+  (getbufferproc) image_surface_buffer_getbufferproc,
+  (releasebufferproc) NULL,
+};
+
 
 static PyMethodDef image_surface_methods[] = {
   {"create_for_data",(PyCFunction)image_surface_create_for_data,
@@ -669,8 +690,7 @@ PyTypeObject PycairoImageSurface_Type = {
   0,                                  /* tp_str */
   0,                                  /* tp_getattro */
   0,                                  /* tp_setattro */
-  //  &image_surface_as_buffer,		/* tp_as_buffer */
-  0,                    		/* tp_as_buffer */
+  &image_surface_as_buffer,           /* tp_as_buffer */
   Py_TPFLAGS_DEFAULT,                 /* tp_flags */
   0,                                  /* tp_doc */
   0,                                  /* tp_traverse */
diff --git a/test/isurface_get_data.py b/test/isurface_get_data.py
index f2662d4..6875042 100755
--- a/test/isurface_get_data.py
+++ b/test/isurface_get_data.py
@@ -5,46 +5,85 @@ Test ImageSurface.get_data()
 import tempfile
 
 import cairo
-import numpy
 
 if not (cairo.HAS_IMAGE_SURFACE and cairo.HAS_PNG_FUNCTIONS):
   raise SystemExit ('cairo was not compiled with ImageSurface and PNG support')
 
 w, h = 128, 128
 
-surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, w, h)
-ctx = cairo.Context(surface)
-
-ctx.set_source_rgb(1, 1, 1)  # white
-ctx.set_operator(cairo.OPERATOR_SOURCE)
-ctx.paint()
-
-# Draw out the triangle using absolute coordinates
-ctx.move_to(w/2, h/3)
-ctx.line_to(2*w/3, 2*h/3)
-ctx.rel_line_to(-1*w/3, 0)
-ctx.close_path()
-
-ctx.set_source_rgb(0, 0, 0)  # black
-ctx.set_line_width(15)
-ctx.stroke()
-_, outFileName = tempfile.mkstemp(prefix='pycairo_', suffix='.png')
-surface.write_to_png(outFileName)
-print "see %s output file" % outFileName
-
-# modify surface using numpy
-buf = surface.get_data()
-# alternative which should work (?) but reports
-# TypeError: buffer is read-only
-# - is a Python bug?
-#buf = buffer (surface1)
-
-a = numpy.ndarray(shape=(w,h,4), dtype=numpy.uint8, buffer=buf)
-
-# draw a vertical line
-a[:,40,0] = 255  # byte 0 is blue on little-endian systems
-a[:,40,1] = 0
-a[:,40,2] = 0
-_, outFileName = tempfile.mkstemp(prefix='pycairo_', suffix='.png')
-surface.write_to_png(outFileName)
-print "see %s output file" % outFileName
+def create_surface():
+  "create black triangle on white background"
+  surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, w, h)
+  ctx = cairo.Context(surface)
+
+  ctx.set_source_rgb(1, 1, 1)  # white
+  ctx.set_operator(cairo.OPERATOR_SOURCE)
+  ctx.paint()
+
+  # Draw out the triangle using absolute coordinates
+  ctx.move_to(w/2, h/3)
+  ctx.line_to(2*w/3, 2*h/3)
+  ctx.rel_line_to(-1*w/3, 0)
+  ctx.close_path()
+
+  ctx.set_source_rgb(0, 0, 0)  # black
+  ctx.set_line_width(15)
+  ctx.stroke()
+  return surface
+
+
+def test_python_buffer():
+  "get_data() and modify data using Python"
+  surface = create_surface()
+  _, f1 = tempfile.mkstemp(prefix='pycairo_', suffix='.png')
+  surface.write_to_png(f1)
+
+  buf = surface.get_data()
+  stride = surface.get_stride()
+  for i in range(h):
+      offset = i * stride + 120
+      buf[offset]     = b'\xFF'
+      buf[offset + 1] = b'\x00'
+      buf[offset + 2] = b'\x00'
+
+  _, f2 = tempfile.mkstemp(prefix='pycairo_', suffix='.png')
+  surface.write_to_png(f2)
+  print("""\
+test_python_buffer:
+  original data: %s
+  modified data: %s
+""" % (f1, f2))
+
+
+def test_numpy_and_python_buffer():
+  "get_data() and modify data using numpy"
+  try:
+    import numpy
+  except:
+    print("numpy not installed")
+    return
+
+  surface = create_surface()
+  _, f1 = tempfile.mkstemp(prefix='pycairo_', suffix='.png')
+  surface.write_to_png(f1)
+
+  buf = surface.get_data()
+
+  a = numpy.ndarray(shape=(w,h,4), dtype=numpy.uint8, buffer=buf)
+
+  # draw a vertical line
+  a[:,40,0] = 255  # byte 0 is blue on little-endian systems
+  a[:,40,1] = 0
+  a[:,40,2] = 0
+
+  _, f2 = tempfile.mkstemp(prefix='pycairo_', suffix='.png')
+  surface.write_to_png(f2)
+  print("""\
+test_numpy_and_python_buffer:
+  original data: %s
+  modified data: %s
+""" % (f1, f2))
+
+
+test_python_buffer()
+test_numpy_and_python_buffer()
diff --git a/test/isurface_get_data_memleak.py b/test/isurface_get_data_memleak.py
new file mode 100755
index 0000000..5a30c1e
--- /dev/null
+++ b/test/isurface_get_data_memleak.py
@@ -0,0 +1,33 @@
+#!/usr/bin/env python
+"""test cairo.ImageSurface.get_data() for a memory leak
+"""
+
+import array
+import resource
+import tempfile
+
+import cairo
+
+
+pagesize = resource.getpagesize()
+
+if not (cairo.HAS_IMAGE_SURFACE and cairo.HAS_PNG_FUNCTIONS):
+  raise SystemExit ('cairo was not compiled with ImageSurface and PNG support')
+
+width, height = 32, 32
+
+while True:
+  for i in range(100000):
+    surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
+    ctx = cairo.Context(surface)
+    data = surface.get_data()
+    b = memoryview(memoryview(data))
+    del surface
+    del ctx
+    b = bytes(data)
+
+    surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
+    #ctx = cairo.Context(surface)
+    b = bytes(surface.get_data())
+
+  print(resource.getrusage(resource.RUSAGE_SELF).ru_maxrss * pagesize)