--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tile.c	Mon Jul 07 04:36:03 2008 +0300
@@ -0,0 +1,35 @@
+
+#include "tile.h"
+#include "render_struct.h"
+
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+
+int render_set_tile (struct render *render_info, u_int32_t view_w, u_int32_t view_h, u_int32_t x, u_int32_t y, u_int16_t zoom) {
+    // figure out how many tiles will fit onto the view area
+    u_int16_t tiles = MIN(
+        MAX(view_w / TILE_WIDTH, 1),
+        MAX(view_h / TILE_HEIGHT, 1)
+    ) + 1;
+    
+    // have it be square
+    view_w = tiles * TILE_WIDTH;
+    view_h = tiles * TILE_HEIGHT;
+    
+    // the image width is fixed
+    render_info->img_w = TILE_WIDTH;
+    render_info->img_h = TILE_HEIGHT;
+    
+    // calcuate how wide each pixel is
+    double width_scale = REGION_W/(view_w << zoom);
+    double height_scale = REGION_H/(view_h << zoom);
+    
+    // calcuate the region
+    render_info->x1 = REGION_X1 + x * width_scale;
+    render_info->y1 = REGION_Y1 + y * height_scale;
+    render_info->x2 = render_info->x1 + TILE_WIDTH * width_scale;
+    render_info->y2 = render_info->y1 + TILE_HEIGHT * height_scale;
+    
+    // ok
+    return 0;
+}