Fix max preview, some resizing and caching issues and force preview providers to resize their previews properly

* introduces a method in OC_Image which doesn't stretch images when trying to make them fit in a box
* adds the method to all key providers so that they can do their job, as expected by the Preview class
* improves the caching mechanism of Preview in order to reduce I/O and to avoid filling the available disk space
* fixes some long standing issues
* **contains mostly tests**

1 files changed, 10 insertions, 0 deletions

diff --git a/lib/public/iimage.php b/lib/public/iimage.php
index 202adeaba54..c62bf36d2de 100644
--- a/lib/public/iimage.php
+++ b/lib/public/iimage.php
@@ -170,4 +170,14 @@ interface IImage {
 	 * @since 8.1.0
 	 */
 	public function fitIn($maxWidth, $maxHeight);
+
+	/**
+	 * Shrinks the image to fit within a boundary while preserving ratio.
+	 *
+	 * @param integer $maxWidth
+	 * @param integer $maxHeight
+	 * @return bool
+	 * @since 8.1.0
+	 */
+	public function scaleDownToFit($maxWidth, $maxHeight);
 }