attempt to show differences by ctx.lang

Author: mapmeld

index.d.ts

@@ -291,6 +291,7 @@ export class CanvasRenderingContext2D {
 	textAlign: CanvasTextAlign;
 	canvas: Canvas;
 	direction: 'ltr' | 'rtl';
+	lang: string;
 }
 
 export class CanvasGradient {

src/CanvasRenderingContext2d.cc

@@ -162,7 +162,8 @@ Context2d::Initialize(Napi::Env& env, Napi::Object& exports) {
     InstanceAccessor<&Context2d::GetFont, &Context2d::SetFont>("font", napi_default_jsproperty),
     InstanceAccessor<&Context2d::GetTextBaseline, &Context2d::SetTextBaseline>("textBaseline", napi_default_jsproperty),
     InstanceAccessor<&Context2d::GetTextAlign, &Context2d::SetTextAlign>("textAlign", napi_default_jsproperty),
-    InstanceAccessor<&Context2d::GetDirection, &Context2d::SetDirection>("direction", napi_default_jsproperty)
+    InstanceAccessor<&Context2d::GetDirection, &Context2d::SetDirection>("direction", napi_default_jsproperty),
+    InstanceAccessor<&Context2d::GetLanguage, &Context2d::SetLanguage>("lang", napi_default_jsproperty)
   });
 
   exports.Set("CanvasRenderingContext2d", ctor);
@@ -786,6 +787,28 @@ Context2d::SetDirection(const Napi::CallbackInfo& info, const Napi::Value& value
   state->direction = dir;
 }
 
+/*
+ * Get language.
+ */
+Napi::Value
+Context2d::GetLanguage(const Napi::CallbackInfo& info) {
+  return Napi::String::New(env, state->lang);
+}
+
+/*
+ * Set language.
+ */
+void
+Context2d::SetLanguage(const Napi::CallbackInfo& info, const Napi::Value& value) {
+  if (!value.IsString()) return;
+
+  std::string lang = value.As<Napi::String>();
+  state->lang = lang;
+
+  pango_context_set_language(pango_layout_get_context(_layout), pango_language_from_string(lang.c_str()));
+  pango_cairo_update_layout(context(), _layout);
+}
+
 /*
  * Put image data.
  *

src/CanvasRenderingContext2d.h

@@ -36,6 +36,7 @@ struct canvas_state_t {
   canvas_draw_mode_t textDrawingMode = TEXT_DRAW_PATHS;
   bool imageSmoothingEnabled = true;
   std::string direction = "ltr";
+  std::string lang = "";
 
   canvas_state_t() {
     fontDescription = pango_font_description_from_string("sans");
@@ -157,6 +158,7 @@ class Context2d : public Napi::ObjectWrap<Context2d> {
     Napi::Value GetFont(const Napi::CallbackInfo& info);
     Napi::Value GetTextBaseline(const Napi::CallbackInfo& info);
     Napi::Value GetTextAlign(const Napi::CallbackInfo& info);
+    Napi::Value GetLanguage(const Napi::CallbackInfo& info);
     void SetPatternQuality(const Napi::CallbackInfo& info, const Napi::Value& value);
     void SetImageSmoothingEnabled(const Napi::CallbackInfo& info, const Napi::Value& value);
     void SetGlobalCompositeOperation(const Napi::CallbackInfo& info, const Napi::Value& value);
@@ -179,6 +181,7 @@ class Context2d : public Napi::ObjectWrap<Context2d> {
     void SetFont(const Napi::CallbackInfo& info, const Napi::Value& value);
     void SetTextBaseline(const Napi::CallbackInfo& info, const Napi::Value& value);
     void SetTextAlign(const Napi::CallbackInfo& info, const Napi::Value& value);
+    void SetLanguage(const Napi::CallbackInfo& info, const Napi::Value& value);
     #if CAIRO_VERSION >= CAIRO_VERSION_ENCODE(1, 16, 0)
     void BeginTag(const Napi::CallbackInfo& info);
     void EndTag(const Napi::CallbackInfo& info);

test/canvas.test.js

@@ -486,6 +486,24 @@ describe('Canvas', function () {
     assert.equal(ctx.font, '15px Arial, sans-serif')
   })
 
+  it('Context2d#lang=', function () {
+    const canvas1 = createCanvas(200, 200)
+    const ctx1 = canvas1.getContext('2d')
+    assert.equal(ctx1.lang, '')
+    ctx1.font = '20px sans-serif';
+    ctx1.lang = 'ja'
+    assert.equal(ctx1.lang, 'ja')
+    ctx1.fillText('门', 10, 10)
+
+    const canvas2 = createCanvas(200, 200)
+    const ctx2 = canvas2.getContext('2d')
+    ctx2.font = '20px sans-serif';
+    ctx2.lang = 'zh'
+    ctx2.fillText('门', 10, 10)
+
+    assert.notDeepEqual(ctx1.getImageData(10, 10, 40, 40), ctx2.getImageData(10, 10, 40, 40))
+  })
+
   it('Context2d#lineWidth=', function () {
     const canvas = createCanvas(200, 200)
     const ctx = canvas.getContext('2d')