# HG changeset patch
# User Matthew Turk <matthewturk@gmail.com>
# Date 1283211810 25200
# Branch yt
# Node ID 68a3f7a4c6f107de8f84b5f2c69aab779602ef3c
# Parent  619e237aba6d3b7a7bf3de6135b592afcb388492
Adding a new function to write pngs to existing file handles, fixed the API for
the image panner

diff -r 619e237aba6d3b7a7bf3de6135b592afcb388492 -r 68a3f7a4c6f107de8f84b5f2c69aab779602ef3c yt/utilities/_amr_utils/png_writer.pyx
--- a/yt/utilities/_amr_utils/png_writer.pyx	Mon Aug 30 15:41:06 2010 -0700
+++ b/yt/utilities/_amr_utils/png_writer.pyx	Mon Aug 30 16:43:30 2010 -0700
@@ -33,6 +33,13 @@
     # NOTE that size_t might not be int
     void *alloca(int)
 
+# Idiom for accessing Python files, from Cython FAQ
+# First, declare the Python macro to access files:
+cdef extern from "Python.h":
+    ctypedef struct FILE
+    FILE* PyFile_AsFile(object)
+    void  fprintf(FILE* f, char* s, char* s)
+
 cdef extern from "png.h":
     ctypedef unsigned long png_uint_32
     ctypedef long png_int_32
@@ -99,6 +106,54 @@
     void png_destroy_write_struct(
         png_structp *png_ptr_ptr, png_infop *info_ptr_ptr)
 
+def write_png_to_file(np.ndarray[np.uint8_t, ndim=3] buffer,
+                      object py_fileobj, int dpi=100,
+                      int close = 0):
+
+    # This is something of a translation of the matplotlib _png module
+    cdef png_byte *pix_buffer = <png_byte *> buffer.data
+    cdef int width = buffer.shape[1]
+    cdef int height = buffer.shape[0]
+    cdef FILE *fileobj = PyFile_AsFile(py_fileobj)
+
+    cdef png_bytep *row_pointers
+    cdef png_structp png_ptr
+    cdef png_infop info_ptr
+
+    cdef png_color_8 sig_bit
+    cdef png_uint_32 row
+
+    row_pointers = <png_bytep *> alloca(sizeof(png_bytep) * height)
+
+    for row in range(height):
+        row_pointers[row] = pix_buffer + row * width * 4
+    png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL)
+    info_ptr = png_create_info_struct(png_ptr)
+    
+    # Um we are ignoring setjmp sorry guys
+
+    png_init_io(png_ptr, fileobj)
+
+    png_set_IHDR(png_ptr, info_ptr, width, height, 8,
+                 PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
+                 PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE)
+
+    cdef size_t dots_per_meter = <size_t> (dpi / (2.54 / 100.0))
+    png_set_pHYs(png_ptr, info_ptr, dots_per_meter, dots_per_meter,
+                 PNG_RESOLUTION_METER)
+
+    sig_bit.gray = 0
+    sig_bit.red = sig_bit.green = sig_bit.blue = sig_bit.alpha = 8
+
+    png_set_sBIT(png_ptr, info_ptr, &sig_bit)
+
+    png_write_info(png_ptr, info_ptr)
+    png_write_image(png_ptr, row_pointers)
+    png_write_end(png_ptr, info_ptr)
+
+    if close == 1: fclose(fileobj)
+    png_destroy_write_struct(&png_ptr, &info_ptr)
+
 def write_png(np.ndarray[np.uint8_t, ndim=3] buffer,
               char *filename, int dpi=100):
 
diff -r 619e237aba6d3b7a7bf3de6135b592afcb388492 -r 68a3f7a4c6f107de8f84b5f2c69aab779602ef3c yt/visualization/image_panner/__init__.py
--- a/yt/visualization/image_panner/__init__.py	Mon Aug 30 15:41:06 2010 -0700
+++ b/yt/visualization/image_panner/__init__.py	Mon Aug 30 16:43:30 2010 -0700
@@ -20,7 +20,3 @@
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 """
-
-from vm_panner import VariableMeshPanner, WindowedVariableMeshPanner, \
-                MultipleWindowVariableMeshPanner, ImageSaver, \
-                PanningCeleritasStreamer, NonLocalDataImagePanner
diff -r 619e237aba6d3b7a7bf3de6135b592afcb388492 -r 68a3f7a4c6f107de8f84b5f2c69aab779602ef3c yt/visualization/image_panner/api.py
--- a/yt/visualization/image_panner/api.py	Mon Aug 30 15:41:06 2010 -0700
+++ b/yt/visualization/image_panner/api.py	Mon Aug 30 16:43:30 2010 -0700
@@ -27,3 +27,7 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 """
+
+from vm_panner import VariableMeshPanner, WindowedVariableMeshPanner, \
+                MultipleWindowVariableMeshPanner, ImageSaver, \
+                PanningCeleritasStreamer, NonLocalDataImagePanner
diff -r 619e237aba6d3b7a7bf3de6135b592afcb388492 -r 68a3f7a4c6f107de8f84b5f2c69aab779602ef3c yt/visualization/image_panner/vm_panner.py
--- a/yt/visualization/image_panner/vm_panner.py	Mon Aug 30 15:41:06 2010 -0700
+++ b/yt/visualization/image_panner/vm_panner.py	Mon Aug 30 16:43:30 2010 -0700
@@ -23,9 +23,12 @@
 
 import numpy as na
 import types, os
-from yt.raven import FixedResolutionBuffer, ObliqueFixedResolutionBuffer
-from yt.lagos import data_object_registry, AMRProjBase, AMRSliceBase, \
-                     x_dict, y_dict
+from yt.visualization.fixed_resolution import \
+    FixedResolutionBuffer, ObliqueFixedResolutionBuffer
+from yt.data_objects.data_containers import \
+    data_object_registry, AMRProjBase, AMRSliceBase
+from yt.utilities.definitions import \
+    x_dict, y_dict
 from yt.funcs import *
 
 class VariableMeshPanner(object):