added a fast resize function

Added resize_half() and resize_half_wrap() functions to composite.c and
overviewer.h, to replace the call to PIL's resize function made by
tileset.py. Also added "resize_half" to COverviewerMethods in main.c, so
it can be called from Python. Should increase performance by 10 to 20%
for the entire program.

overviewer_core/src/composite.c

@@ -22,7 +22,8 @@
  * PIL paste if this extension is not found.
  */
 
-#include "overviewer.h"
+#include "overviewer.h"
+#include <stdio.h>
 
 typedef struct {
     PyObject_HEAD
@@ -489,3 +490,154 @@ draw_triangle(PyObject *dest, int inclusive,
     
     return dest;
 }
+
+/* scales the image to half size
+ */
+inline PyObject *
+resize_half(PyObject *dest, PyObject *src) {
+    /* libImaging handles */
+    Imaging imDest, imSrc;
+    /* alpha properties */
+    int src_has_alpha, dest_has_alpha;
+    /* iteration variables */
+    unsigned int x, y;
+    /* temp color variables */
+    unsigned int r, g, b, a;	
+    /* size values for source and destination */
+	int src_width, src_height, dest_width, dest_height;
+
+    imDest = imaging_python_to_c(dest);
+    imSrc = imaging_python_to_c(src);
+
+    if (!imDest || !imSrc)
+        return NULL;
+
+    /* check the various image modes, make sure they make sense */
+    if (strcmp(imDest->mode, "RGBA") != 0) {
+        PyErr_SetString(PyExc_ValueError,
+                        "given destination image does not have mode \"RGBA\"");
+        return NULL;
+    }
+
+    if (strcmp(imSrc->mode, "RGBA") != 0 && strcmp(imSrc->mode, "RGB") != 0) {
+        PyErr_SetString(PyExc_ValueError,
+                        "given source image does not have mode \"RGBA\" or \"RGB\"");
+        return NULL;
+    }
+	
+	src_width = imSrc->xsize;
+	src_height = imSrc->ysize;
+	dest_width = imDest->xsize;
+	dest_height = imDest->ysize;
+
+    /* make sure destination size is 1/2 src size */
+    if (src_width / 2 != dest_width || src_height / 2 != dest_height) {
+        PyErr_SetString(PyExc_ValueError,
+                        "destination image size is not one-half source image size");
+        return NULL;
+    }
+
+    /* set up flags for the src/mask type */
+    src_has_alpha = (imSrc->pixelsize == 4 ? 1 : 0);
+    dest_has_alpha = (imDest->pixelsize == 4 ? 1 : 0);
+
+    /* check that there remains anything to resize */
+    if (dest_width <= 0 || dest_height <= 0) {
+        /* nothing to do, return */
+        return dest;
+    }
+	
+    /* set to fully opaque if source has no alpha channel */
+	if(!src_has_alpha)
+		a = 0xFF << 2;
+	
+    for (y = 0; y < dest_height; y++) {
+		
+        UINT8 *out = (UINT8 *)imDest->image[y];
+        UINT8 *in_row1 = (UINT8 *)imSrc->image[y * 2];
+        UINT8 *in_row2 = (UINT8 *)imSrc->image[y * 2 + 1];
+		
+        for (x = 0; x < dest_width; x++) {
+            
+			// read first column
+			r = *in_row1;	
+			r += *in_row2;
+			in_row1++;
+			in_row2++;
+			g = *in_row1;		
+			g += *in_row2;
+			in_row1++;
+			in_row2++;
+			b = *in_row1;		
+			b += *in_row2;
+			in_row1++;
+			in_row2++;			
+
+            if (src_has_alpha)
+			{
+				a = *in_row1;		
+				a += *in_row2;
+				in_row1++;
+				in_row2++;
+			}
+			
+			// read second column 
+			r += *in_row1;		
+			r += *in_row2;
+			in_row1++;
+			in_row2++;
+			g += *in_row1;		
+			g += *in_row2;
+			in_row1++;
+			in_row2++;
+			b += *in_row1;		
+			b += *in_row2;
+			in_row1++;
+			in_row2++;
+			
+            if (src_has_alpha)
+			{
+				a += *in_row1;		
+				a += *in_row2;
+				in_row1++;
+				in_row2++;
+			}
+			
+			// write blended color			
+            *out = (UINT8)(r >> 2);
+            out++;
+            *out = (UINT8)(g >> 2);
+            out++;
+            *out = (UINT8)(b >> 2);
+            out++;
+			
+            if (dest_has_alpha)
+            {
+				*out = (UINT8)(a >> 2);
+				out++;
+			}
+        }
+    }
+
+    return dest;
+}
+
+/* wraps resize_half so it can be called directly from python */
+PyObject *
+resize_half_wrap(PyObject *self, PyObject *args)
+{
+    /* raw input python variables */
+    PyObject *dest, *src;
+    /* return value: dest image on success */
+    PyObject *ret;
+
+    if (!PyArg_ParseTuple(args, "OO", &dest, &src))
+        return NULL;
+    
+    ret = resize_half(dest, src);
+    if (ret == dest) {
+        /* Python needs us to own our return value */
+        Py_INCREF(dest);
+    }
+    return ret;
+}

overviewer_core/src/main.c

@@ -26,6 +26,9 @@ static PyMethodDef COverviewerMethods[] = {
     {"alpha_over", alpha_over_wrap, METH_VARARGS,
      "alpha over composite function"},
     
+    {"resize_half", resize_half_wrap, METH_VARARGS,
+     "downscale image to half size"},
+    
     {"render_loop", chunk_render, METH_VARARGS,
      "Renders stuffs"},
     

overviewer_core/src/overviewer.h

@@ -69,6 +69,8 @@ PyObject *draw_triangle(PyObject *dest, int inclusive,
                         int x2, int y2,
                         unsigned char r2, unsigned char g2, unsigned char b2,
                         int tux, int tuy, int *touchups, unsigned int num_touchups);
+PyObject *resize_half(PyObject *dest, PyObject *src);
+PyObject *resize_half_wrap(PyObject *self, PyObject *args);
 
 /* forward declaration of RenderMode object */
 typedef struct _RenderMode RenderMode;

overviewer_core/tileset.py

@@ -35,6 +35,7 @@ from .files import FileReplacer
 from .optimizeimages import optimize_image
 import rendermodes
 import c_overviewer
+from c_overviewer import resize_half
 
 """
 
@@ -858,13 +859,17 @@ class TileSet(object):
 
         # Create the actual image now
         img = Image.new("RGBA", (384, 384), self.options['bgcolor'])
-
+		
         # we'll use paste (NOT alpha_over) for quadtree generation because
         # this is just straight image stitching, not alpha blending
 
         for path in quadPath_filtered:
             try:
-                quad = Image.open(path[1]).resize((192,192), Image.ANTIALIAS)
+                #quad = Image.open(path[1]).resize((192,192), Image.ANTIALIAS)
+                src = Image.open(path[1])
+                src.load()
+                quad = Image.new("RGBA", (192, 192), self.options['bgcolor'])
+                resize_half(quad, src)
                 img.paste(quad, path[0])
             except Exception, e:
                 logging.warning("Couldn't open %s. It may be corrupt. Error was '%s'", path[1], e)