chrisjhoughton · January 9, 2021 05:19 · Sep 12, 2014 · Sep 11, 2014 · Sep 11, 2014 · Sep 11, 2014
diff --git a/crop-resize.js b/crop-resize.js
@@ -77,6 +77,14 @@ module.exports = function (url, requiredWidth, requiredHeight) {
         cropX = 0;
         cropY = (actualSize.height - cropHeight) / 2;
       }
+
+      // we're already the correct ratio
+      else {
+        cropWidth = 0;
+        cropHeight = 0;
+        cropX = 0;
+        cropY = 0;
+      }
 
       // Crop and resize
       im(url)

diff --git a/crop-resize.js b/crop-resize.js
@@ -1,3 +1,9 @@
+/* 
+* Given an image URL or path, crop and resize it to be exactly a specific size. 
+* Crops centrally to force enforce the correct aspect ratio, and then resizes as per normal. 
+* Depends on the `when` and `gm` NPM modules. 
+* Returns a promise that resolves with an image buffer in a .PNG format.
+*/
 var when = require('when');
 var gm   = require('gm');
 var im   = gm.subClass({ imageMagick: true }); // use `im` in place of `gm` for heroku compatibility

diff --git a/crop-resize.js b/crop-resize.js
@@ -86,5 +86,5 @@ module.exports = function (url, requiredWidth, requiredHeight) {
 
     });
 
-  }.bind(this));
+  });
 };
diff --git a/crop-resize.js b/crop-resize.js
@@ -0,0 +1,90 @@
+var when = require('when');
+var gm   = require('gm');
+var im   = gm.subClass({ imageMagick: true }); // use `im` in place of `gm` for heroku compatibility
+
+/*
+* Get the size of an image
+*/
+var getImageSize = function (file) {
+  return when.promise(function (resolve, reject) {
+
+    im(file).size(function (err, size) {
+      if (err) {
+        reject(err);
+      } else {
+        resolve(size);
+      }
+    });
+
+  });
+};
+
+
+/*
+* Crop and resize an image to precisely the correct dimensions.
+* Crops first to get to the correct aspect ratio, and then resizes
+* accordingly.
+*
+* Works with either a URL, or a path.
+*/
+module.exports = function (url, requiredWidth, requiredHeight) {
+  return when.promise(function (resolve, reject) {
+
+    // We need to resize and then crop. These dimensions
+    // help us choose how to do this.
+    var requiredRatio = requiredWidth / requiredHeight;
+
+    // Get the size of the image
+    getImageSize(url)
+
+    // Crop to required dimensions and then resize
+    .then(function (actualSize) {
+
+      // If the actual width or height are too small, then reject
+      if (actualSize.width < requiredWidth || actualSize.height < requiredHeight) {
+        reject('image_too_small');
+        return;
+      }
+
+      var actualRatio = actualSize.width / actualSize.height;
+
+      // dimensions we'll crop to
+      var cropWidth;
+      var cropHeight;
+
+      // crop co-ordinates (top left)
+      var cropX;
+      var cropY;
+
+      // If actual ratio is too high, we need to crop the width
+      if (actualRatio > requiredRatio) {
+        cropWidth = actualSize.height * requiredRatio;
+        cropHeight = actualSize.height; // no change
+        cropX = (actualSize.width - cropWidth) / 2
+        cropY = 0;
+      }
+
+      // If actual ratio is too low, we need to crop the height
+      else if (actualRatio < requiredRatio) {
+        cropWidth = actualSize.width
+        cropHeight = actualSize.width / requiredRatio; // no change
+        cropX = 0;
+        cropY = (actualSize.height - cropHeight) / 2;
+      }
+
+      // Crop and resize
+      im(url)
+      .crop(cropWidth, cropHeight, cropX, cropY)
+      .resize(requiredWidth, requiredHeight)
+      .toBuffer('PNG', function (err, buffer) {
+        if (err) {
+          reject(err);
+        } else {
+          resolve(buffer);
+        }
+      });
+
+    });
+
+  }.bind(this));
+};