Automatically compress and scale large images

Do nothing to other file types. Continue to block files that are too
large even after scaling and compression.

conversation.html

@@ -35,7 +35,7 @@
                 <form class='send'>
                     <div class='attachments'>
                         <div class='paperclip'></div>
-                        <input type='file' name='files[]' multiple class='file-input'>
+                        <input type='file' class='file-input'>
                     </div>
                     <input class="send-btn" type='submit' value='' />
                     <input class='send-message' type='textarea' placeholder="Send a message">

js/views/file_input_view.js

@@ -46,37 +46,75 @@ var Whisper = Whisper || {};
             this.$el.find('.paperclip').append(this.thumb.render().el);
         },
 
+        autoScale: function(file) {
+            if (file.type.split('/')[0] !== 'image' || file.size/1024 < 420) {
+                // nothing to do
+                return Promise.resolve(file);
+            }
+
+            return new Promise(function(resolve, reject) {
+                // components/blueimp-load-image
+                window.loadImage(file, resolve, {
+                    maxWidth: 1920,
+                    maxHeight: 1920,
+                    canvas: true,
+                    contain: true
+                });
+            }).then(this.autoCompress.bind(this));
+        },
+
+        autoCompress: function(canvas, numRetries, quality) {
+            if (numRetries === undefined) { numRetries = 3; }
+            if (quality === undefined) { quality = 0.95; }
+
+            var autoCompress = this.autoCompress.bind(this);
+
+            return new Promise(function(resolve, reject) {
+                canvas.toBlob(function(blob) {
+                    var kb = blob.size/1024;
+                    if (kb < 420 || numRetries === 0) {
+                        resolve(blob);
+                    } else {
+                        quality = quality * 420 / kb;
+                        if (quality < 50) {
+                            quality = 50;
+                            numRetries = 1;
+                        }
+                        resolve(autoCompress(canvas, numRetries - 1, quality));
+                    }
+                }, 'image/jpeg', quality);
+            });
+        },
+
         previewImages: function() {
             this.clearForm();
-            var files = this.$input.prop('files');
-            for (var i = 0; i < files.length; i++) {
-                var type = files[i].type.split('/')[0];
+            var file = this.$input.prop('files')[0];
+            if (!file) { return; }
+
+            var type = file.type.split('/')[0];
+            switch (type) {
+                case 'audio': this.addThumb('/images/audio.png'); break;
+                case 'video': this.addThumb('/images/video.png'); break;
+                case 'image':
+                    this.oUrl = URL.createObjectURL(file);
+                    this.addThumb(this.oUrl);
+                    break;
+            }
+
+            this.autoScale(file).then(function(blob) {
                 var limitKb = 1000000;
                 switch (type) {
                     case 'image': limitKb = 420; break;
                     case 'audio': limitKb = 32000; break;
                     case 'video': limitKb = 8000; break;
                 }
-                if ((files[i].size/1024).toFixed(4) >= limitKb) {
+                if ((blob.size/1024).toFixed(4) >= limitKb) {
                     new Whisper.FileSizeToast({
                         model: {limit: limitKb}
                     }).render();
                     this.deleteFiles();
                 }
-                else {
-                    switch (type) {
-                        case 'audio': this.addThumb('/images/audio.png'); break;
-                        case 'video': this.addThumb('/images/video.png'); break;
-                        case 'image':
-                            var FR = new FileReader();
-                            FR.onload = function(e) {
-                                this.addThumb(e.target.result);
-                            }.bind(this);
-                            FR.readAsDataURL(files[i]);
-                            break;
-                    }
-                }
-            }
+            }.bind(this));
         },
 
         hasFiles: function() {
@@ -88,12 +126,18 @@ var Whisper = Whisper || {};
             var promises = [];
             var files = this.$input.prop('files');
             for (var i = 0; i < files.length; i++) {
-                promises.push(this.readFile(files[i]));
+                promises.push(this.getFile(files[i]));
             }
             this.clearForm();
             return Promise.all(promises);
         },
 
+        getFile: function(file) {
+            file = file || this.$input.prop('files')[0];
+            if (file === undefined) { throw 'No file'; }
+            return this.autoScale(file).then(this.readFile);
+        },
+
         readFile: function(file) {
             var contentType = file.type;
             return new Promise(function(resolve, reject) {
@@ -106,6 +150,10 @@ var Whisper = Whisper || {};
         },
 
         clearForm: function() {
+            if (this.oUrl) {
+                URL.revokeObjectURL(this.oUrl);
+                this.oUrl = null;
+            }
             this.thumb.remove();
         },