Add rotate-left button to bitmap editor toolbar

core/modules/editor/operations/bitmap/rotate-left.js

@@ -0,0 +1,24 @@
+/*\
+title: $:/core/modules/editor/operations/bitmap/rotate-left.js
+type: application/javascript
+module-type: bitmapeditoroperation
+
+Bitmap editor operation to rotate the image left by 90 degrees
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+exports["rotate-left"] = function(event) {
+	// Rotate the canvas left by 90 degrees
+	this.rotateCanvasLeft();
+	// Update the input controls
+	this.refreshToolbar();
+	// Save the image into the tiddler
+	this.saveChanges();
+};
+
+})();

core/modules/widgets/edit-bitmap.js

@@ -189,6 +189,33 @@ EditBitmapWidget.prototype.changeCanvasSize = function(newWidth,newHeight) {
 	ctx.drawImage(this.currCanvas,0,0);
 };
 
+/*
+** Rotate the canvas left by 90 degrees
+*/
+EditBitmapWidget.prototype.rotateCanvasLeft = function() {
+	// Get the current size of the image
+	var origWidth = this.canvasDomNode.width,
+		origHeight = this.canvasDomNode.height;
+	// Create and size a new canvas
+	var newCanvas = this.document.createElement("canvas"),
+		newWidth = origHeight,
+		newHeight = origWidth;
+	this.initCanvas(newCanvas,newWidth,newHeight);
+	// Copy the old image
+	var ctx = newCanvas.getContext("2d");
+	ctx.translate(newWidth / 2,newHeight / 2);
+	ctx.rotate(-Math.PI / 2);
+	ctx.drawImage(this.currCanvas,-origWidth / 2,-origHeight / 2);
+	// Set the new canvas as the current one
+	this.currCanvas = newCanvas;
+	// Set the size of the onscreen canvas
+	this.canvasDomNode.width = newWidth;
+	this.canvasDomNode.height = newHeight;
+	// Paint the onscreen canvas with the offscreen canvas
+	ctx = this.canvasDomNode.getContext("2d");
+	ctx.drawImage(this.currCanvas,0,0);
+};
+
 EditBitmapWidget.prototype.handleTouchStartEvent = function(event) {
 	this.brushDown = true;
 	this.strokeStart(event.touches[0].clientX,event.touches[0].clientY);