terom@27: 
terom@27: #include "tile.h"
terom@27: #include "render_struct.h"
terom@27: 
terom@27: #define MIN(a, b) ((a) < (b) ? (a) : (b))
terom@27: #define MAX(a, b) ((a) > (b) ? (a) : (b))
terom@27: 
terom@27: 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) {
terom@27:     // figure out how many tiles will fit onto the view area
terom@27:     u_int16_t tiles = MIN(
terom@27:         MAX(view_w / TILE_WIDTH, 1),
terom@27:         MAX(view_h / TILE_HEIGHT, 1)
terom@27:     ) + 1;
terom@27:     
terom@27:     // have it be square
terom@27:     view_w = tiles * TILE_WIDTH;
terom@27:     view_h = tiles * TILE_HEIGHT;
terom@27:     
terom@27:     // the image width is fixed
terom@27:     render_info->img_w = TILE_WIDTH;
terom@27:     render_info->img_h = TILE_HEIGHT;
terom@27:     
terom@27:     // calcuate how wide each pixel is
terom@27:     double width_scale = REGION_W/(view_w << zoom);
terom@27:     double height_scale = REGION_H/(view_h << zoom);
terom@27:     
terom@27:     // calcuate the region
terom@27:     render_info->x1 = REGION_X1 + x * width_scale;
terom@27:     render_info->y1 = REGION_Y1 + y * height_scale;
terom@27:     render_info->x2 = render_info->x1 + TILE_WIDTH * width_scale;
terom@27:     render_info->y2 = render_info->y1 + TILE_HEIGHT * height_scale;
terom@27:     
terom@27:     // ok
terom@27:     return 0;
terom@27: }