Changeset 9149 for src/django_gheat/website

Timestamp:

May 5, 2011, 9:34:53 AM (14 years ago)

Author:

rick

Message:

Make sure that we generate a slightly bigger image, to ensure the borders are
properly set. Next chop/crop the image to match is proper size.

File:

• src/django_gheat/website/tile.py (modified) (6 diffs)

src/django_gheat/website/tile.py

@@ -11 +11 @@
 import logging
 import numpy as np
-import settings
+import pygame
 import sys
-import pygame
 import tempfile
 
@@ -23 +22 @@
   def __init__(self, method, size):
     self.surf = pygame.Surface(size,flags=pygame.SRCALPHA)
+
+  def center_crop(self,size):
+    """ Resize to make centered rectange from image """
+    new_surf = pygame.Surface(size, flags=pygame.SRCALPHA)
+    curr_size = self.surf.get_size()
+    new_surf.blit(self.surf,(0,0),
+      ((curr_size[0] - size[0]) / 2, (curr_size[1] - size[1]) / 2, size[0], size[1]))
+    self.surf = new_surf
 
   def write(self, fh,format='png'):
@@ -34 +41 @@
   def add_circle(self, center, radius, colour=(255,0,0)):
     # Quirky hack to generate lineair gradient circles and merge them with the parent.
-    new_surf = pygame.Surface((250,250),flags=pygame.SRCALPHA)
+    new_surf = pygame.Surface(self.surf.get_size(),flags=pygame.SRCALPHA)
     for r in range(radius,1,-1):
       pygame.draw.circle(new_surf,colour + (255 - (r * (float(255)/radius)),),center,r,0)
@@ -123 +130 @@
 def make_tile(x,y,z):
   """ Crude attempt to generate tiles, by placing a gradient circle on a
-  coordinate point.
+  coordinate point.  Generate a larger tile  and make sure to plot related
+  points first and then crop it to the required size (250x250).
   
   Many stuff NOT implemented yet, like:
   - Caching Images
-  - Generate a larger tile (300x300) at first and then crop it to the required
-    size (250x250).
   """
+  SIZE = 250
+  
   nw_deg,se_deg = boundbox_deg(x,y,z)
+
   
   Picture = PyGamePicture
-  resolution_deg = nw_deg.deg_per_pixel(se_deg, 250)
-  im = Picture("RGBA",(250,250))
+  resolution_deg = nw_deg.deg_per_pixel(se_deg, SIZE)
+  # Converting LatLon to Meters is discussed here:
+  #  http://stackoverflow.com/questions/3024404/transform-longitude-latitude-into-meters
+  tile_height = float(40008000) / (2 ** z)
+  meters_per_pixel = float(tile_height) / SIZE
+  
+  # Worst case scenario could a circle with 100% 'outside' our 250x250 range
+  # also add data to the picture as circles are used
+  border_pixels = 100 / meters_per_pixel / 2
+
+  im = Picture("RGBA", (SIZE + border_pixels * 2,) * 2)
+
+  nw_deg.lat += resolution_deg.lat * border_pixels
+  nw_deg.lon -= resolution_deg.lon * border_pixels
+  se_deg.lat -= resolution_deg.lat * border_pixels
+  se_deg.lon += resolution_deg.lon * border_pixels
   
   lat_min = 999
@@ -147 +170 @@
     return max(x,y) - min(x,y)
   
-  # Converting LatLon to Meters is discussed here:
-  #  http://stackoverflow.com/questions/3024404/transform-longitude-latitude-into-meters
-  tile_height = float(40008000) / (2 ** z)
-  meters_per_pixel = float(tile_height) / 250
   for meting in metingen:
     lat_min = min(lat_min, meting.latitude)
@@ -175 +194 @@
   log.info("Metingen Count: %s" % metingen.count())
 
+  im.center_crop((SIZE,SIZE))
   return im