Adding extraction primitives

modules/files/src/main/scala/docspell/files/Dimension.scala

@@ -0,0 +1,7 @@
+package docspell.files
+
+case class Dimension(width: Int, height: Int) {
+
+  def toAwtDimension: java.awt.Dimension =
+    new java.awt.Dimension(width, height)
+}

modules/files/src/main/scala/docspell/files/ImageSize.scala

@@ -0,0 +1,61 @@
+package docspell.files
+
+import java.io.{ByteArrayInputStream, InputStream}
+import java.nio.file.Path
+
+import cats.implicits._
+import cats.effect._
+import fs2.Stream
+import javax.imageio.stream.{FileImageInputStream, ImageInputStream}
+import javax.imageio.{ImageIO, ImageReader}
+
+import scala.jdk.CollectionConverters._
+import scala.util.{Try, Using}
+
+object ImageSize {
+
+  /** Return the image size from its header without reading
+    * the whole image into memory.
+    */
+  def get(file: Path): Option[Dimension] =
+    Using(new FileImageInputStream(file.toFile))(getDimension).toOption.flatten
+
+  /** Return the image size from its header without reading
+    * the whole image into memory.
+    */
+  def get(in: InputStream): Option[Dimension] =
+    Option(ImageIO.createImageInputStream(in)).flatMap(getDimension)
+
+  /** Return the image size from its header without reading
+    * the whole image into memory.
+    */
+  def get[F[_]: Sync](data: Stream[F, Byte]): F[Option[Dimension]] = {
+    data.take(768).compile.to(Array).map(ar => {
+      val iis = ImageIO.createImageInputStream(new ByteArrayInputStream(ar))
+      if (iis == null) sys.error("no reader given for the array")
+      else getDimension(iis)
+    })
+  }
+
+  private def getDimension(in: ImageInputStream): Option[Dimension] =
+    ImageIO
+      .getImageReaders(in)
+      .asScala
+      .to(LazyList)
+      .collectFirst(Function.unlift { reader =>
+        val dim = getDimension(in, reader).toOption
+        reader.dispose()
+        dim
+      })
+
+  private def getDimension(
+      in: ImageInputStream,
+      reader: ImageReader
+  ): Either[Throwable, Dimension] =
+    Try {
+      reader.setInput(in)
+      val width  = reader.getWidth(reader.getMinIndex)
+      val height = reader.getHeight(reader.getMinIndex)
+      Dimension(width, height)
+    }.toEither
+}