Make blit_buffer accept memoryviews and objects that implement the buffer interface in additon to bytes. Use new conversion function.

kivy/graphics/texture.pyx

@@ -42,15 +42,17 @@ Blitting custom data
 --------------------
 
 You can create your own data and blit it to the texture using
-:meth:`Texture.blit_data`::
+:meth:`Texture.blit_buffer`.
+
+For example, to blit immutable bytes data::
 
     # create a 64x64 texture, defaults to rgb / ubyte
     texture = Texture.create(size=(64, 64))
 
-    # create 64x64 rgb tab, and fill with value from 0 to 255
+    # create 64x64 rgb tab, and fill with values from 0 to 255
     # we'll have a gradient from black to white
     size = 64 * 64 * 3
-    buf = [int(x * 255 / size) for x in xrange(size)]
+    buf = [int(x * 255 / size) for x in range(size)]
 
     # then, convert the array to a ubyte string
     buf = b''.join(map(chr, buf))
@@ -63,6 +65,34 @@ You can create your own data and blit it to the texture using
     with self.canvas:
         Rectangle(texture=texture, pos=self.pos, size=(64, 64))
 
+Since 1.8.1, you can blit data stored in a instance that implements the python
+buffer interface, or a memoryview thereof, such as numpy arrays, python
+`array.array`, a `bytearray`, or a cython array. This is beneficial if you
+expect to blit similar data, with perhaps a few changes in the data.
+
+When using a bytes representation of the data, for every change you have to
+regenerate the bytes instance, from perhaps a list, which is very inefficient.
+When using a buffer object, you can simply edit parts of the original data.
+Similarly, unless starting with a bytes object, converting to bytes requires a
+full copy, however, when using a buffer instance, no memory is copied, except
+to upload it to the GPU.
+
+Continuing with the example above::
+
+    from array import array
+
+    size = 64 * 64 * 3
+    buf = [int(x * 255 / size) for x in range(size)]
+    # initialize the array with the buffer values
+    arr = array('B', buf)
+    # now blit the array
+    texture.blit_buffer(arr, colorfmt='rgb', bufferfmt='ubyte')
+
+    # now change some elements in the original array
+    arr[24] = arr[50] = 99
+    # blit again the buffer
+    texture.blit_buffer(arr, colorfmt='rgb', bufferfmt='ubyte')
+
 
 BGR/BGRA support
 ----------------
@@ -194,7 +224,6 @@ include "common.pxi"
 include "opengl_utils_def.pxi"
 include "img_tools.pxi"
 
-from array import array
 from kivy.weakmethod import WeakMethod
 from kivy.graphics.context cimport get_context
 
@@ -802,8 +831,15 @@ cdef class Texture:
             called in order to update the texture.
 
         :Parameters:
-            `pbuffer` : bytes
-                Image data.
+            `pbuffer` : bytes, or a class that implements the buffer interface\
+ (including memoryview).
+                A buffer containing the image data. It can be either a bytes
+                object or a instance of a class that implements the python
+                buffer interface, e.g. `array.array`, `bytearray`, numpy arrays
+                etc. If it's not a bytes object, the underlying buffer must
+                be contiguous, have only one dimension and must not be
+                readonly, even though the data is not modified, due to a cython
+                limitation. See module description for usage details.
             `size` : tuple, defaults to texture size
                 Size of the image (width, height)
             `colorfmt` : str, defaults to 'rgb'
@@ -820,9 +856,12 @@ cdef class Texture:
                 Indicate if we need to regenerate the mipmap from level 0.
 
         .. versionadded:: 1.0.7
-
             added `mipmap_level` and `mipmap_generation`
 
+        .. versionchanged:: 1.8.1
+            `pbuffer` can now be any class instance that implements the python
+            buffer interface and / or memoryviews thereof.
+
         '''
         cdef GLuint target = self._target
         if colorfmt is None:
@@ -839,20 +878,27 @@ cdef class Texture:
         # time.
         self.bind()
 
-        # need conversion ?
-        cdef bytes data
-        data = pbuffer
-        data, colorfmt = _convert_buffer(data, colorfmt)
+        # need conversion, do check here because it seems to be faster ?
+        if not gl_has_texture_native_format(colorfmt):
+            pbuffer, colorfmt = convert_to_gl_format(pbuffer, colorfmt)
+        cdef char [:] view
+        cdef char *cdata
+        cdef long datasize
+        if isinstance(pbuffer, bytes):  # if it's bytes, just use memory
+            cdata = <bytes>pbuffer  # explicit bytes
+            datasize = len(pbuffer)
+        else:   # if it's a memoryview or buffer type, use start of memory
+            view = pbuffer
+            cdata = &view[0]
+            datasize = view.nbytes
 
         # prepare nogil
         cdef int iglfmt = _color_fmt_to_gl(self._icolorfmt)
         cdef int glfmt = _color_fmt_to_gl(colorfmt)
-        cdef long datasize = len(pbuffer)
         cdef int x = pos[0]
         cdef int y = pos[1]
         cdef int w = size[0]
         cdef int h = size[1]
-        cdef char *cdata = <char *>data
         cdef int glbufferfmt = bufferfmt
         cdef int is_allocated = self._is_allocated
         cdef int is_compressed = _is_compressed_fmt(colorfmt)

setup.py

@@ -428,7 +428,8 @@ graphics_dependencies = {
     'texture.pxd': ['c_opengl.pxd'],
     'texture.pyx': [
         'config.pxi', 'common.pxi', 'opengl_utils_def.pxi', 'context.pxd',
-        'c_opengl.pxd', 'c_opengl_debug.pxd', 'opengl_utils.pxd'],
+        'c_opengl.pxd', 'c_opengl_debug.pxd', 'opengl_utils.pxd',
+        'img_tools.pxi'],
     'vbo.pxd': ['buffer.pxd', 'c_opengl.pxd', 'vertex.pxd'],
     'vbo.pyx': [
         'config.pxi', 'common.pxi', 'c_opengl_debug.pxd', 'context.pxd',