Added option - no-upscale, nu - as resizing strategy to decline upscaling of smaller images. Fix #61.

CImage.php

@@ -231,6 +231,14 @@ class CImage
     private $dpr = 1;
 
 
+    /**
+     * Always upscale images, even if they are smaller than target image.
+     */
+    const UPSCALE_DEFAULT = true;    
+    private $upscale = self::UPSCALE_DEFAULT;
+
+
+
     /**
      * Array with details on how to crop, incoming as argument and calculated.
      */
@@ -443,6 +451,7 @@ class CImage
             'fillToFit'   => null,
             'crop'        => null, //array('width'=>null, 'height'=>null, 'start_x'=>0, 'start_y'=>0),
             'area'        => null, //'0,0,0,0',
+            'upscale'     => self::UPSCALE_DEFAULT,
 
             // Options for caching or using original
             'useCache'    => true,
@@ -949,6 +958,7 @@ class CImage
             && !$this->rotateAfter
             && !$this->autoRotate
             && !$this->bgColor
+            && ($this->upscale === self::UPSCALE_DEFAULT)
         ) {
             $this->log("Using original image.");
             $this->output($this->pathToImage);
@@ -1027,11 +1037,16 @@ class CImage
             $convolve = 'convolve' . preg_replace('/[^a-zA-Z0-9]/', '', $this->convolve);
         }
 
+        $upscale = null;
+        if ($this->upscale !== self::UPSCALE_DEFAULT) {
+            $upscale = 'nu';
+        }
+
         $subdir = str_replace('/', '-', dirname($this->imageSrc));
         $subdir = ($subdir == '.') ? '_.' : $subdir;
         $file = $subdir . '_' . $parts['filename'] . '_' . $width . '_'
             . $height . $offset . $crop . $cropToFit . $fillToFit
-            . $crop_x . $crop_y
+            . $crop_x . $crop_y . $upscale
             . $quality . $filters . $sharpen . $emboss . $blur . $palette . $optimize
             . $scale . $rotateBefore . $rotateAfter . $autoRotate . $bgColor . $convolve
             . '.' . $this->extension;
@@ -1285,6 +1300,7 @@ class CImage
     {
 
         $this->log("Starting to Resize()");
+        $this->log("Upscale = '$this->upscale'");
 
         // Only use a specified area of the image, $this->offset is defining the area to use
         if (isset($this->offset)) {
@@ -1302,7 +1318,6 @@ class CImage
             // Do as crop, take only part of image
             $this->log("Cropping area width={$this->crop['width']}, height={$this->crop['height']}, start_x={$this->crop['start_x']}, start_y={$this->crop['start_y']}");
             $img = $this->CreateImageKeepTransparency($this->crop['width'], $this->crop['height']);
-            //imagecopyresampled($img, $this->image, 0, 0, $this->crop['start_x'], $this->crop['start_y'], $this->crop['width'], $this->crop['height'], $this->crop['width'], $this->crop['height']);
             imagecopy($img, $this->image, 0, 0, $this->crop['start_x'], $this->crop['start_y'], $this->crop['width'], $this->crop['height']);
             $this->image = $img;
             $this->width = $this->crop['width'];
@@ -1312,22 +1327,26 @@ class CImage
         if ($this->cropToFit) {
             
             // Resize by crop to fit
-            $this->log("Crop to fit");
+            $this->log("Resizing using strategy - Crop to fit");
-            $cropX = round(($this->cropWidth/2) - ($this->newWidth/2));
+
-            $cropY = round(($this->cropHeight/2) - ($this->newHeight/2));
+            if (!$this->upscale && ($this->width < $this->newWidth || $this->height < $this->newHeight)) {
-            $imgPreCrop   = $this->CreateImageKeepTransparency($this->cropWidth, $this->cropHeight);
+                $this->log("Resizing - smaller image, do not upscale.");
-            $imageResized = $this->CreateImageKeepTransparency($this->newWidth, $this->newHeight);
+            } else {
-            imagecopyresampled($imgPreCrop, $this->image, 0, 0, 0, 0, $this->cropWidth, $this->cropHeight, $this->width, $this->height);
+                $cropX = round(($this->cropWidth/2) - ($this->newWidth/2));
-            //imagecopyresampled($imageResized, $imgPreCrop, 0, 0, $cropX, $cropY, $this->newWidth, $this->newHeight, $this->newWidth, $this->newHeight);
+                $cropY = round(($this->cropHeight/2) - ($this->newHeight/2));
-            imagecopy($imageResized, $imgPreCrop, 0, 0, $cropX, $cropY, $this->newWidth, $this->newHeight);
+                $imgPreCrop   = $this->CreateImageKeepTransparency($this->cropWidth, $this->cropHeight);
-            $this->image = $imageResized;
+                $imageResized = $this->CreateImageKeepTransparency($this->newWidth, $this->newHeight);
-            $this->width = $this->newWidth;
+                imagecopyresampled($imgPreCrop, $this->image, 0, 0, 0, 0, $this->cropWidth, $this->cropHeight, $this->width, $this->height);
-            $this->height = $this->newHeight;
+                imagecopy($imageResized, $imgPreCrop, 0, 0, $cropX, $cropY, $this->newWidth, $this->newHeight);
+                $this->image = $imageResized;
+                $this->width = $this->newWidth;
+                $this->height = $this->newHeight;
+            }
         
         } else if ($this->fillToFit) {
             
             // Resize by fill to fit
-            $this->log("Fill to fit");
+            $this->log("Resizing using strategy - Fill to fit");
 
             $posX = 0;
             $posY = 0;
@@ -1342,23 +1361,41 @@ class CImage
                 $posY = round(($this->newHeight - $this->fillHeight) / 2);
             }
 
-            $imgPreFill   = $this->CreateImageKeepTransparency($this->fillWidth, $this->fillHeight);
+            if (!$this->upscale && ($this->width < $this->newWidth || $this->height < $this->newHeight)) {
-            $imageResized = $this->CreateImageKeepTransparency($this->newWidth, $this->newHeight);
+                
-            imagecopyresampled($imgPreFill, $this->image, 0, 0, 0, 0, $this->fillWidth, $this->fillHeight, $this->width, $this->height);
+                $this->log("Resizing - smaller image, do not upscale.");
-            imagecopy($imageResized, $imgPreFill, $posX, $posY, 0, 0, $this->fillWidth, $this->fillHeight);
+                $posX = round(($this->fillWidth - $this->width) / 2);
-            $this->image = $imageResized;
+                $posY = round(($this->fillHeight - $this->height) / 2);
-            $this->width = $this->newWidth;
+                $imageResized = $this->CreateImageKeepTransparency($this->newWidth, $this->newHeight);
-            $this->height = $this->newHeight;
+                imagecopy($imageResized, $this->image, $posX, $posY, 0, 0, $this->fillWidth, $this->fillHeight);
+                $this->image = $imageResized;
+                $this->width = $this->newWidth;
+                $this->height = $this->newHeight;
+            
+            } else {
+                $imgPreFill   = $this->CreateImageKeepTransparency($this->fillWidth, $this->fillHeight);
+                $imageResized = $this->CreateImageKeepTransparency($this->newWidth, $this->newHeight);
+                imagecopyresampled($imgPreFill, $this->image, 0, 0, 0, 0, $this->fillWidth, $this->fillHeight, $this->width, $this->height);
+                imagecopy($imageResized, $imgPreFill, $posX, $posY, 0, 0, $this->fillWidth, $this->fillHeight);
+                $this->image = $imageResized;
+                $this->width = $this->newWidth;
+                $this->height = $this->newHeight;
+            }
         
         } else if (!($this->newWidth == $this->width && $this->newHeight == $this->height)) {
             
             // Resize it
             $this->log("Resizing, new height and/or width");
-            $imageResized = $this->CreateImageKeepTransparency($this->newWidth, $this->newHeight);
+
-            imagecopyresampled($imageResized, $this->image, 0, 0, 0, 0, $this->newWidth, $this->newHeight, $this->width, $this->height);
+            if (!$this->upscale && ($this->width < $this->newWidth || $this->height < $this->newHeight)) {
-            $this->image = $imageResized;
+                $this->log("Resizing - smaller image, do not upscale.");
-            $this->width = $this->newWidth;
+            } else {
-            $this->height = $this->newHeight;
+                $imageResized = $this->CreateImageKeepTransparency($this->newWidth, $this->newHeight);
+                imagecopyresampled($imageResized, $this->image, 0, 0, 0, 0, $this->newWidth, $this->newHeight, $this->width, $this->height);
+                $this->image = $imageResized;
+                $this->width = $this->newWidth;
+                $this->height = $this->newHeight;
+            }
         }
 
         return $this;

README.md

@@ -212,6 +212,7 @@ These options affect strategy to use when resizing an image into a target image
 | `nr, no-ratio, stretch` | Do *not* keep aspect ratio when resizing and using both width & height constraints. Results in stretching the image, if needed, to fit in the resulting box. |
 | `cf, crop-to-fit`  | Set together with both `h` and `w` to make the image fit into dimensions, and crop out the rest of the image. |
 | `ff, fill-to-fit` | Set together with both `h` and `w` to make the image fit into dimensions, and fill the rest using a background color. You can optionally supply a background color as this `ff=00ff00`, or `ff=00ff007f` when using the alpha channel. |
+| `nu, no-upscale` | Avoid smaller images from being upscaled to larger ones. Combine with `fill-to-fit` to get the smaller image centered on a larger canvas. |
 
 
 
@@ -280,6 +281,7 @@ Revision history
 
 v0.6.x (latest)
 
+* Added option `no-upscale, nu` as resizing strategy to decline upscaling of smaller images. Fix #61.
 * Minor change in `CImage::resize()`, crop now does imagecopy without resamling.
 * Correcting internal details for save-as and response json which indicated wrong colors. Fix #62.
 * Fixed fill-to-fit that failed when using aspect-ratio. Fix #52.

webroot/img.php

@@ -529,6 +529,15 @@ verbose("convolve = " . print_r($convolve, 1));
 
 
 
+/**
+ * no-upscale, nu - Do not upscale smaller image to larger dimension.
+ */
+$upscale = getDefined(array('no-upscale', 'nu'), false, true);
+
+verbose("upscale = $upscale");
+
+
+
 /**
  * Display image if verbose mode
  */
@@ -565,6 +574,7 @@ $img->log("Incoming arguments: " . print_r(verbose(), 1))
             'fillToFit' => $fillToFit,
             'crop'      => $crop,
             'area'      => $area,
+            'upscale'   => $upscale,
 
             // Pre-processing, before resizing is done
             'scale'        => $scale,

webroot/test/test_option-no-upscale.php

@@ -0,0 +1,50 @@
+<?php
+// Include config for all testcases
+include __DIR__ . "/config.php";
+
+
+
+// The title of the test case
+$title = "Testing option no-upscale";
+
+
+
+// Provide a short description of the testcase.
+$description = "Do not upscale image when original image (slice) is smaller than target image.";
+
+
+
+// Use these images in the test
+$images = array(
+    'car.png',
+);
+
+
+
+// For each image, apply these testcases
+$nc = null; //"&nc"; //null; //&nc'; 
+$testcase = array(
+    $nc . '&w=600',
+    $nc . '&w=600&no-upscale',
+    $nc . '&h=400',
+    $nc . '&h=400&no-upscale',
+    $nc . '&w=600&h=400',
+    $nc . '&w=600&h=400&no-upscale',
+    $nc . '&w=600&h=400&stretch',
+    $nc . '&w=600&h=400&no-upscale&stretch',
+    $nc . '&w=600&h=400&crop-to-fit',
+    $nc . '&w=600&h=400&no-upscale&crop-to-fit',
+    $nc . '&w=600&h=400&fill-to-fit',
+    $nc . '&w=600&h=400&no-upscale&fill-to-fit',
+/*
+    $nc . '&w=600&ar=1.6',
+    $nc . '&w=600&ar=1.6&no-upscale',
+    $nc . '&h=400&ar=1.6',
+    $nc . '&h=400&ar=1.6&no-upscale',
+*/
+);
+
+
+
+// Apply testcases and present results
+include __DIR__ . "/template.php";