Implement pasting image from clipboard for browsers that supports that (#5317)

Author: lafriks

public/js/index.js

@@ -171,13 +171,95 @@ function initReactionSelector(parent) {
     });
 }
 
+function insertAtCursor(field, value) {
+    if (field.selectionStart || field.selectionStart === 0) {
+        var startPos = field.selectionStart;
+        var endPos = field.selectionEnd;
+        field.value = field.value.substring(0, startPos)
+            + value
+            + field.value.substring(endPos, field.value.length);
+        field.selectionStart = startPos + value.length;
+        field.selectionEnd = startPos + value.length;
+    } else {
+        field.value += value;
+    }
+}
+
+function replaceAndKeepCursor(field, oldval, newval) {
+    if (field.selectionStart || field.selectionStart === 0) {
+        var startPos = field.selectionStart;
+        var endPos = field.selectionEnd;
+        field.value = field.value.replace(oldval, newval);
+        field.selectionStart = startPos + newval.length - oldval.length;
+        field.selectionEnd = endPos + newval.length - oldval.length;
+    } else {
+        field.value = field.value.replace(oldval, newval);
+    }
+}
+
+function retrieveImageFromClipboardAsBlob(pasteEvent, callback){
+    if (!pasteEvent.clipboardData) {
+        return;
+    }
+
+    var items = pasteEvent.clipboardData.items;
+    if (typeof(items) === "undefined") {
+        return;
+    }
+
+    for (var i = 0; i < items.length; i++) {
+        if (items[i].type.indexOf("image") === -1) continue;
+        var blob = items[i].getAsFile();
+
+        if (typeof(callback) === "function") {
+            pasteEvent.preventDefault();
+            pasteEvent.stopPropagation();
+            callback(blob);
+        }
+    }
+}
+
+function uploadFile(file, callback) {
+    var xhr = new XMLHttpRequest();
+
+    xhr.onload = function() {
+        if (xhr.status == 200) {
+            callback(xhr.responseText);
+        }
+    };
+
+    xhr.open("post", suburl + "/attachments", true);
+    xhr.setRequestHeader("X-Csrf-Token", csrf);
+    var formData = new FormData();
+    formData.append('file', file, file.name);
+    xhr.send(formData);
+}
+
+function initImagePaste(target) {
+    target.each(function(i, field) {
+        field.addEventListener('paste', function(event){
+            retrieveImageFromClipboardAsBlob(event, function(img) {
+                var name = img.name.substr(0, img.name.lastIndexOf('.'));
+                insertAtCursor(field, '![' + name + ']()');
+                uploadFile(img, function(res) {
+                    var data = JSON.parse(res);
+                    replaceAndKeepCursor(field, '![' + name + ']()', '![' + name + '](' + suburl + '/attachments/' + data.uuid + ')');
+                    var input = $('<input id="' + data.uuid + '" name="files" type="hidden">').val(data.uuid);
+                    $('.files').append(input);
+                });
+            });
+        }, false);
+    });
+}
+
 function initCommentForm() {
     if ($('.comment.form').length == 0) {
         return
     }
 
     initBranchSelector();
     initCommentPreviewTab($('.comment.form'));
+    initImagePaste($('.comment.form textarea'));
 
     // Listsubmit
     function initListSubmits(selector, outerSelector) {