Optimize PNG files

2015-05-31 19:25:34 +02:00
parent 3fbcbbe8e0
commit b52e84d1e7
3 changed files with 200 additions and 2 deletions
@@ -54,6 +54,27 @@ var ImageOptimizer = function() {
                return entry;
            });

+        } else if (isPNG(entry)) {
+
+            debug('File is a PNG');
+
+            // Starting softly with a lossless compression
+            return compressPngLosslessly(entry.weightCheck.body)
+
+            .then(function(newFile) {
+                var newFileSize = newFile.contents.length;
+
+                debug('PNG lossless compression complete for %s', entry.url);
+                
+                if (newFileSize < fileSize) {
+                    entry.weightCheck.lossless = entry.weightCheck.optimized = newFileSize;
+                    entry.weightCheck.isOptimized = false;
+                    debug('Filesize is %d bytes smaller (-%d%)', fileSize - newFileSize, Math.round((fileSize - newFileSize) * 100 / fileSize));
+                }
+
+                return entry;
+            });
+
        } else {
            debug('File type is not an optimizable image');
            deferred.resolve(entry);
@@ -92,7 +113,7 @@ var ImageOptimizer = function() {
        var deferred = Q.defer();
        var startTime = Date.now();

-        debug('Starting JPEG lossly compression');
+        debug('Starting JPEG lossy compression');

        new Imagemin()
            .src(imageBody)
@@ -110,11 +131,38 @@ var ImageOptimizer = function() {
        return deferred.promise;
    }

+    function isPNG(entry) {
+        return entry.isImage && entry.contentType === 'image/png';
+    }
+
+    function compressPngLosslessly(imageBody) {
+        var deferred = Q.defer();
+        var startTime = Date.now();
+
+        debug('Starting PNG losslessly compression');
+
+        new Imagemin()
+            .src(imageBody)
+            .use(Imagemin.optipng({optimizationLevel: 2}))
+            .run(function (err, files) {
+                if (err) {
+                    deferred.reject(err);
+                } else {
+                    deferred.resolve(files[0]);
+                    var endTime = Date.now();
+                    debug('compressPngLosslessly took %d ms', endTime - startTime);
+                }
+            });
+
+        return deferred.promise;
+    }
+
    return {
        //recompressIfImage: recompressIfImage,
        optimizeImage: optimizeImage,
        compressJpegLosslessly: compressJpegLosslessly,
-        compressJpegLossly: compressJpegLossly
+        compressJpegLossly: compressJpegLossly,
+        compressPngLosslessly: compressPngLosslessly
    };
 };