Support Image creation from byte buffer (edits stacked from #32)

CHANGELOG.md

@@ -1,3 +1,11 @@
+# Next
+
+* Add support to reading images from a `bytes` buffer, e.g.
+  ```python 
+  with open("chicago.jpg", "rb") as f:
+      img = accimage.Image(f.read())
+  ```
+
 # v0.1.1
 
 * Bug fix: Horizontal crops prior to v0.1.1 didn't work.

accimage.h

@@ -16,6 +16,7 @@ typedef struct {
 
 void image_copy_deinterleave(ImageObject* self, unsigned char* output_buffer);
 void image_copy_deinterleave_float(ImageObject* self, float* output_buffer);
+void image_from_buffer(ImageObject* self, void* buf, size_t size);
 void image_from_jpeg(ImageObject* self, const char* path);
 void image_resize(ImageObject* self, int new_height, int new_width, int antialiasing);
 void image_flip_left_right(ImageObject* self);

accimagemodule.c

@@ -242,13 +242,22 @@ static PyTypeObject Image_Type = {
 };
 
 static int Image_init(ImageObject *self, PyObject *args, PyObject *kwds) {
-    static char* argnames[] = { "path", NULL };
     const char *path;
 
-    if (!PyArg_ParseTupleAndKeywords(args, kwds, "s", argnames, &path))
-        return -1;
-
-    image_from_jpeg(self, path);
+    if (PyArg_ParseTuple(args, "s", &path)) {
+        image_from_jpeg(self, path);
+    }
+    else {
+        Py_buffer buffer;
+
+        PyErr_Clear();
+        if (PyArg_ParseTuple(args, "y*", &buffer)) {
+            void* buf = buffer.buf;
+            Py_ssize_t size = buffer.len;
+            image_from_buffer(self, buf, size);
+            PyBuffer_Release(&buffer);
+        }
+    }
 
     return PyErr_Occurred() ? -1 : 0;
 }

jpegloader.c

@@ -20,26 +20,17 @@ static void accimage_jpeg_error_exit(j_common_ptr cinfo) {
 }
 
 
-void image_from_jpeg(ImageObject* self, const char* path) {
+void image_from_file(ImageObject* self, FILE* file) {
     struct jpeg_decompress_struct state = { 0 };
     struct accimage_jpeg_error_mgr jpeg_error;
-    FILE* file = NULL;
     unsigned char* buffer = NULL;
 
-    file = fopen(path, "rb");
-    if (file == NULL) {
-        PyErr_Format(PyExc_IOError, "failed to open file %s", path);
-        goto cleanup;
-    }
-
     state.err = jpeg_std_error(&jpeg_error.pub);
     jpeg_error.pub.error_exit = accimage_jpeg_error_exit;
     if (setjmp(jpeg_error.setjmp_buffer)) {
         char error_message[JMSG_LENGTH_MAX];
         (*state.err->format_message)((j_common_ptr) &state, error_message);
-        PyErr_Format(PyExc_IOError, "JPEG decoding failed: %s in file %s",
-            error_message, path);
-
+        PyErr_Format(PyExc_IOError, "JPEG decoding failed: %s", error_message);
         goto cleanup;
     }
 
@@ -87,3 +78,23 @@ void image_from_jpeg(ImageObject* self, const char* path) {
         fclose(file);
     }
 }
+
+void image_from_buffer(ImageObject* self, void* buf, size_t size) {
+    FILE* source = fmemopen(buf, size, "rb");
+    if (source == NULL) {
+        PyErr_Format(PyExc_IOError, "failed to call fmemopen on buffer");
+        return;
+    }
+
+    image_from_file(self, source);
+}
+
+void image_from_jpeg(ImageObject* self, const char* path) {
+    FILE* file = file = fopen(path, "rb");
+    if (file == NULL) {
+        PyErr_Format(PyExc_IOError, "failed to open file %s", path);
+        return;
+    }
+
+    image_from_file(self, file);
+}

test.py

@@ -32,6 +32,17 @@ def test_reading_image():
     assert image.height == 931
 
 
+def test_reading_image_from_memory():
+    from_file = accimage.Image("chicago.jpg")
+    bytes = open("chicago.jpg", "rb").read()
+    from_bytes = accimage.Image(bytes)
+    if SAVE_IMAGES:
+        save_image('test_reading_image_from_memory.jpg', from_bytes)
+    assert from_bytes.width == 1920
+    assert from_bytes.height == 931
+    np.testing.assert_array_equal(image_to_np(from_file), image_to_np(from_bytes))
+
+
 def test_resizing():
     image = accimage.Image("chicago.jpg")