Simplify extent computation

locationtech · Jan 8, 2021 · c38562d · c38562d
1 parent a86048b
commit c38562d
Showing 1 changed file with 22 additions and 14 deletions.
diff --git a/gdal/src/main/scala/geotrellis/raster/gdal/GDALDataset.scala b/gdal/src/main/scala/geotrellis/raster/gdal/GDALDataset.scala
@@ -231,8 +231,6 @@ case class GDALDataset(token: Long) extends AnyVal {
   /**
     * Compute extent, takes into account a possible rotation.
     *
-    * https://github.com/mapbox/rasterio/blob/1.2b1/rasterio/_base.pyx#L865-L895
-    *
     * Note for a reader:
     * affine.Affine(a, b, c, d, e, f)
     * GDALTransform(c, a, b, f, d, e)
@@ -243,20 +241,30 @@ case class GDALDataset(token: Long) extends AnyVal {
   def extent(transform: Array[Double], cols: Int, rows: Int): Extent = {
     val Array(upx, xres, xskew, upy, yskew, yres) = transform
 
-    val ulx = upx + 0 * xres + 0 * xskew
-    val uly = upy + 0 * yskew + 0 * yres
-
-    val llx = upx + 0 * xres + rows * xskew
-    val lly = upy + 0 * yskew + rows * yres
-
-    val lrx = upx + cols * xres + rows * xskew
-    val lry = upy + cols * yskew + rows * yres
+    /**
+      * val ulx = upx + 0 * xres + 0 * xskew
+      * val uly = upy + 0 * yskew + 0 * yres
+      *
+      * val llx = upx + 0 * xres + rows * xskew
+      * val lly = upy + 0 * yskew + rows * yres
+      *
+      * val lrx = upx + cols * xres + rows * xskew
+      * val lry = upy + cols * yskew + rows * yres
+      *
+      * val urx = upx + cols * xres + 0 * xskew
+      * val ury = upy + cols * yskew + 0 * yres
+      *
+      * val xs = List(ulx, llx, lrx, urx)
+      * val ys = List(uly, lly, lry, ury)
+      */
 
-    val urx = upx + cols * xres + 0 * xskew
-    val ury = upy + cols * yskew + 0 * yres
+    val xys =
+      for {
+        px <- List(0, cols)
+        py <- List(0, rows)
+      } yield (upx + px * xres + py * xskew, upy + px * yskew + py * yres)
 
-    val xs = List(ulx, llx, lrx, urx)
-    val ys = List(uly, lly, lry, ury)
+    val (xs, ys) = xys.unzip
 
     Extent(xs.min, ys.min, xs.max, ys.max)
   }