From d434ae71b3281ed0f90ecbcd1056bc4b93ea1a3a Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Mon, 15 Mar 2021 19:40:42 +0100
Subject: [PATCH] LibWeb: Add CanvasRenderingContext2D.clearRect()

Similar to fillRect, except this API fills with transparent black.
---
 .../LibWeb/HTML/CanvasRenderingContext2D.cpp          | 11 +++++++++++
 .../Libraries/LibWeb/HTML/CanvasRenderingContext2D.h  |  1 +
 .../LibWeb/HTML/CanvasRenderingContext2D.idl          |  1 +
 3 files changed, 13 insertions(+)

diff --git a/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.cpp b/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.cpp
index 3c08f1e73cf..ebb7640ce65 100644
--- a/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.cpp
+++ b/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.cpp
@@ -64,6 +64,17 @@ void CanvasRenderingContext2D::fill_rect(float x, float y, float width, float he
     did_draw(rect);
 }
 
+void CanvasRenderingContext2D::clear_rect(float x, float y, float width, float height)
+{
+    auto painter = this->painter();
+    if (!painter)
+        return;
+
+    auto rect = m_transform.map(Gfx::FloatRect(x, y, width, height));
+    painter->clear_rect(enclosing_int_rect(rect), Color());
+    did_draw(rect);
+}
+
 void CanvasRenderingContext2D::set_stroke_style(String style)
 {
     m_stroke_style = Gfx::Color::from_string(style).value_or(Color::Black);
diff --git a/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.h b/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.h
index 58cccfc6e6e..8a8a1f860f9 100644
--- a/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.h
+++ b/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.h
@@ -57,6 +57,7 @@ public:
 
     void fill_rect(float x, float y, float width, float height);
     void stroke_rect(float x, float y, float width, float height);
+    void clear_rect(float x, float y, float width, float height);
 
     void draw_image(const HTMLImageElement&, float x, float y);
 
diff --git a/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.idl b/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.idl
index bcfa544c674..97f0462601a 100644
--- a/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.idl
+++ b/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.idl
@@ -2,6 +2,7 @@ interface CanvasRenderingContext2D {
 
     undefined fillRect(double x, double y, double w, double h);
     undefined strokeRect(double x, double y, double w, double h);
+    undefined clearRect(double x, double y, double w, double h);
 
     undefined scale(double x, double y);
     undefined translate(double x, double y);