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, 20 insertions, 0 deletions

diff --git a/lib/private/image.php b/lib/private/image.php
index d229ed42511..54e5ef7cad5 100644
--- a/lib/private/image.php
+++ b/lib/private/image.php
@@ -952,6 +952,8 @@ class OC_Image implements \OCP\IImage {
 	/**
 	 * Resizes the image to fit within a boundary while preserving ratio.
 	 *
+	 * Warning: Images smaller than $maxWidth x $maxHeight will end up being scaled up
+	 *
 	 * @param integer $maxWidth
 	 * @param integer $maxHeight
 	 * @return bool
@@ -973,6 +975,24 @@ class OC_Image implements \OCP\IImage {
 	}
 
 	/**
+	 * Shrinks larger images to fit within specified boundaries while preserving ratio.
+	 *
+	 * @param integer $maxWidth
+	 * @param integer $maxHeight
+	 * @return bool
+	 */
+	public function scaleDownToFit($maxWidth, $maxHeight) {
+		$widthOrig = imageSX($this->resource);
+		$heightOrig = imageSY($this->resource);
+
+		if ($widthOrig > $maxWidth || $heightOrig >$maxHeight) {
+			return $this->fitIn($maxWidth, $maxHeight);
+		}
+
+		return false;
+	}
+
+	/**
 	 * Destroys the current image and resets the object
 	 */
 	public function destroy() {