Add image cropping logic

User-supplied head images will need to be square in their dimensions, so
that bootstrap displays them correctly.  This function will crop image
files after they are uploaded to the server.

1 files changed, 70 insertions, 0 deletions

diff --git a/app/class/image.php b/app/class/image.php
new file mode 100644
index 0000000..6b73cae
--- /dev/null
+++ b/app/class/image.php
@@ -0,0 +1,70 @@
+<?php
+
+/*
+ * SCROTT IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * For more information, please refer to UNLICENSE
+ */
+
+/*
+ * This file defines custom image manipulation routines for Scrott.  All
+ * are available in the global namespace.
+ */
+
+/*
+ * Mappings from image MIME types to PHP open/write functions
+ */
+$_IMG_OPEN_FUNCS['image/jpeg'] = "imagecreatefromjpeg";
+$_IMG_OPEN_FUNCS['image/jpg']  = "imagecreatefromjpeg";
+$_IMG_OPEN_FUNCS['image/png']  = "imagecreatefrompng";
+
+$_IMG_WRITE_FUNCS['image/jpeg'] = "imagejpeg";
+$_IMG_WRITE_FUNCS['image/jpg']  = "imagejpeg";
+$_IMG_WRITE_FUNCS['image/png']  = "imagepng";
+
+/*
+ * Open the given image and crop it, such that the result is a square
+ * image whose side length is equal to the smaller of the original
+ * dimensions and whose area is centered on the area of the original
+ * image.  The resulting image is written to the same path as provided,
+ * overwriting the image.
+ */
+function imageSquareCrop(string $uri) : bool
+{
+    global $_IMG_OPEN_FUNCS;
+    global $_IMG_WRITE_FUNCS;
+
+    $mime = mime_content_type($uri);
+    $img = $_IMG_OPEN_FUNCS[$mime]($uri);
+
+    if ($img === false)
+        return false;
+
+    $wid = imagesx($img);
+    $hei = imagesy($img);
+
+    $rec = array();
+    $rec['width']  = min($wid, $hei);
+    $rec['height'] = $rec['width'];
+    $rec['y'] = ($hei / 2) - ($rec['height'] / 2);
+    $rec['x'] = ($wid / 2) - ($rec['width'] / 2);
+
+    $cropped = imagecrop($img, $rec);
+    imagedestroy($img);
+
+    if ($cropped === false)
+        return false;
+
+    $ret = $_IMG_WRITE_FUNCS[$mime]($cropped, $uri);
+    imagedestroy($cropped);
+
+    return $ret;
+}
+
+?>