feat: Add basic support for RTL text direction.

src/Context.ts

@@ -77,11 +77,13 @@ var CONTEXT_PROPERTIES = [
   'shadowBlur',
   'shadowOffsetX',
   'shadowOffsetY',
+  'letterSpacing',
   'lineCap',
   'lineDashOffset',
   'lineJoin',
   'lineWidth',
   'miterLimit',
+  'direction',
   'font',
   'textAlign',
   'textBaseline',
@@ -91,6 +93,11 @@ var CONTEXT_PROPERTIES = [
 ] as const;
 
 const traceArrMax = 100;
+
+interface ExtendedCanvasRenderingContext2D extends CanvasRenderingContext2D {
+  letterSpacing: string;
+}
+
 /**
  * Konva wrapper around native 2d canvas context. It has almost the same API of 2d context with some additional functions.
  * With core Konva shapes you don't need to use this object. But you will use it if you want to create
@@ -763,7 +770,7 @@ export class Context {
 
 // supported context properties
 type CanvasContextProps = Pick<
-  CanvasRenderingContext2D,
+  ExtendedCanvasRenderingContext2D,
   (typeof CONTEXT_PROPERTIES)[number]
 >;
 

src/shapes/Text.ts

@@ -22,6 +22,7 @@ export function stringToArray(string: string) {
 }
 
 export interface TextConfig extends ShapeConfig {
+  direction?: string;
   text?: string;
   fontFamily?: string;
   fontSize?: number;
@@ -41,11 +42,13 @@ export interface TextConfig extends ShapeConfig {
 var AUTO = 'auto',
   //CANVAS = 'canvas',
   CENTER = 'center',
+  INHERIT = 'inherit',
   JUSTIFY = 'justify',
   CHANGE_KONVA = 'Change.konva',
   CONTEXT_2D = '2d',
   DASH = '-',
   LEFT = 'left',
+  LTR = 'ltr',
   TEXT = 'text',
   TEXT_UPPER = 'Text',
   TOP = 'top',
@@ -55,11 +58,13 @@ var AUTO = 'auto',
   PX_SPACE = 'px ',
   SPACE = ' ',
   RIGHT = 'right',
+  RTL = 'rtl',
   WORD = 'word',
   CHAR = 'char',
   NONE = 'none',
   ELLIPSIS = '…',
   ATTR_CHANGE_LIST = [
+    'direction',
     'fontFamily',
     'fontSize',
     'fontStyle',
@@ -132,6 +137,7 @@ function checkDefaultFill(config?: TextConfig) {
  * @memberof Konva
  * @augments Konva.Shape
  * @param {Object} config
+ * @param {String} [config.direction] default is inherit
  * @param {String} [config.fontFamily] default is Arial
  * @param {Number} [config.fontSize] in pixels.  Default is 12
  * @param {String} [config.fontStyle] can be 'normal', 'italic', or 'bold', '500' or even 'italic bold'.  'normal' is the default.
@@ -185,6 +191,7 @@ export class Text extends Shape<TextConfig> {
       fontSize = this.fontSize(),
       lineHeightPx = this.lineHeight() * fontSize,
       verticalAlign = this.verticalAlign(),
+      direction = this.direction(),
       alignY = 0,
       align = this.align(),
       totalWidth = this.getWidth(),
@@ -194,19 +201,26 @@ export class Text extends Shape<TextConfig> {
       shouldUnderline = textDecoration.indexOf('underline') !== -1,
       shouldLineThrough = textDecoration.indexOf('line-through') !== -1,
       n;
+
+    direction = direction === INHERIT ? context.direction : direction;
 
     var translateY = 0;
     var translateY = lineHeightPx / 2;
 
     var lineTranslateX = 0;
     var lineTranslateY = 0;
 
+    if (direction === RTL) {
+      context.setAttr('direction', direction);
+    }
+
     context.setAttr('font', this._getContextFont());
 
     context.setAttr('textBaseline', MIDDLE);
 
     context.setAttr('textAlign', LEFT);
 
+
     // handle vertical alignment
     if (verticalAlign === MIDDLE) {
       alignY = (this.getHeight() - textArrLen * lineHeightPx - padding * 2) / 2;
@@ -282,7 +296,10 @@ export class Text extends Shape<TextConfig> {
         context.stroke();
         context.restore();
       }
-      if (letterSpacing !== 0 || align === JUSTIFY) {
+      // As `letterSpacing` isn't supported on Safari, we use this polyfill.
+      // The exception is for RTL text, which we rely on native as it cannot
+      // be supported otherwise.
+      if (direction !== RTL && (letterSpacing !== 0 || align === JUSTIFY)) {
         //   var words = text.split(' ');
         spacesNumber = text.split(' ').length - 1;
         var array = stringToArray(text);
@@ -303,6 +320,9 @@ export class Text extends Shape<TextConfig> {
           lineTranslateX += this.measureSize(letter).width + letterSpacing;
         }
       } else {
+        if (letterSpacing !== 0) {
+          context.setAttr('letterSpacing', `${letterSpacing}px`);
+        }
         this._partialTextX = lineTranslateX;
         this._partialTextY = translateY + lineTranslateY;
         this._partialText = text;
@@ -615,6 +635,7 @@ export class Text extends Shape<TextConfig> {
     return super._useBufferCanvas();
   }
 
+  direction: GetSet<string, this>;
   fontFamily: GetSet<string, this>;
   fontSize: GetSet<number, this>;
   fontStyle: GetSet<string, this>;
@@ -682,6 +703,22 @@ Factory.overWriteSetter(Text, 'width', getNumberOrAutoValidator());
 
 Factory.overWriteSetter(Text, 'height', getNumberOrAutoValidator());
 
+
+/**
+ * get/set direction
+ * @name Konva.Text#direction
+ * @method
+ * @param {String} direction
+ * @returns {String}
+ * @example
+ * // get direction
+ * var direction = text.direction();
+ *
+ * // set direction
+ * text.direction('rtl');
+ */
+Factory.addGetterSetter(Text, 'direction', INHERIT);
+
 /**
  * get/set font family
  * @name Konva.Text#fontFamily

test/unit/Text-test.ts

@@ -1654,4 +1654,63 @@ describe('Text', function () {
 
     assert.equal(layer.getContext().getTrace(), trace);
   });
+
+  it('sets ltr text direction', function () {
+    var stage = addStage();
+    var layer = new Konva.Layer();
+
+    stage.add(layer);
+    var text = new Konva.Text({
+      text: 'ltr text',
+      direction: 'ltr',
+    });
+
+    layer.add(text);
+    layer.draw();
+
+    var trace =
+      'clearRect(0,0,578,200);clearRect(0,0,578,200);save();transform(1,0,0,1,0,0);font=normal normal 12px Arial;textBaseline=middle;textAlign=left;translate(0,0);save();fillStyle=black;fillText(ltr text,0,6);restore();restore();';
+
+    assert.equal(layer.getContext().getTrace(), trace);
+  });
+
+
+ it('sets rtl text direction', function () {
+    var stage = addStage();
+    var layer = new Konva.Layer();
+
+    stage.add(layer);
+    var text = new Konva.Text({
+      text: 'rtl text',
+      direction: 'rtl',
+    });
+
+    layer.add(text);
+    layer.draw();
+
+    var trace =
+      'clearRect(0,0,578,200);clearRect(0,0,578,200);save();transform(1,0,0,1,0,0);direction=rtl;font=normal normal 12px Arial;textBaseline=middle;textAlign=left;translate(0,0);save();fillStyle=black;fillText(rtl text,0,6);restore();restore();';
+
+    assert.equal(layer.getContext().getTrace(), trace);
+  });
+
+  it('sets rtl text direction with letterSpacing', function () {
+    var stage = addStage();
+    var layer = new Konva.Layer();
+
+    stage.add(layer);
+    var text = new Konva.Text({
+      text: 'rtl text',
+      direction: 'rtl',
+      letterSpacing: 2,
+    });
+
+    layer.add(text);
+    layer.draw();
+
+    var trace =
+      'clearRect(0,0,578,200);clearRect(0,0,578,200);save();transform(1,0,0,1,0,0);direction=rtl;font=normal normal 12px Arial;textBaseline=middle;textAlign=left;translate(0,0);save();letterSpacing=2px;fillStyle=black;fillText(rtl text,0,6);restore();restore();';
+
+    assert.equal(layer.getContext().getTrace(), trace);
+  });
 });