From 794911bc29c5ddf7a1629b4872a4bd8c663c0005 Mon Sep 17 00:00:00 2001
From: Joogab Yun <joogab.yun@samsung.com>
Date: Tue, 29 Jun 2021 15:55:23 +0900
Subject: [PATCH] Add GetBrightness()

Get the brightness value of the buffer.

Change-Id: I3b95ff0d786cfb3a60a10aeca994079504edfea8
---
 dali/devel-api/adaptor-framework/pixel-buffer.cpp  |  7 ++++-
 dali/devel-api/adaptor-framework/pixel-buffer.h    |  9 ++++++-
 dali/internal/imaging/common/pixel-buffer-impl.cpp | 31 ++++++++++++++++++++++
 dali/internal/imaging/common/pixel-buffer-impl.h   |  5 ++++
 4 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/dali/devel-api/adaptor-framework/pixel-buffer.cpp b/dali/devel-api/adaptor-framework/pixel-buffer.cpp
index 06d61d2..e5856c3 100644
--- a/dali/devel-api/adaptor-framework/pixel-buffer.cpp
+++ b/dali/devel-api/adaptor-framework/pixel-buffer.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020 Samsung Electronics Co., Ltd.
+ * Copyright (c) 2021 Samsung Electronics Co., Ltd.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -139,6 +139,11 @@ bool PixelBuffer::IsAlphaPreMultiplied() const
   return GetImplementation(*this).IsAlphaPreMultiplied();
 }
 
+uint32_t PixelBuffer::GetBrightness() const
+{
+  return GetImplementation(*this).GetBrightness();
+}
+
 } // namespace Devel
 
 } // namespace Dali
diff --git a/dali/devel-api/adaptor-framework/pixel-buffer.h b/dali/devel-api/adaptor-framework/pixel-buffer.h
index 18b5a5f..9e6f58a 100644
--- a/dali/devel-api/adaptor-framework/pixel-buffer.h
+++ b/dali/devel-api/adaptor-framework/pixel-buffer.h
@@ -2,7 +2,7 @@
 #define DALI_PIXEL_BUFFER_H
 
 /*
- * Copyright (c) 2020 Samsung Electronics Co., Ltd.
+ * Copyright (c) 2021 Samsung Electronics Co., Ltd.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -244,6 +244,13 @@ public:
    */
   bool IsAlphaPreMultiplied() const;
 
+  /**
+   * @brief Get the brightness of the pixel buffer.
+   * @note The range is 255 to 0. The closer to 255, the brighter. 0 is not bright.
+   * @return brightness of the pixel buffer.
+   */
+  uint32_t GetBrightness() const;
+
 public:
   /**
    * @brief The constructor.
diff --git a/dali/internal/imaging/common/pixel-buffer-impl.cpp b/dali/internal/imaging/common/pixel-buffer-impl.cpp
index 1b74988..e69f2c8 100644
--- a/dali/internal/imaging/common/pixel-buffer-impl.cpp
+++ b/dali/internal/imaging/common/pixel-buffer-impl.cpp
@@ -37,6 +37,10 @@ namespace Adaptor
 namespace
 {
 const float TWO_PI = 2.f * Math::PI; ///< 360 degrees in radians
+// based on W3C Recommendations (https://www.w3.org/TR/AERT/#color-contrast)
+constexpr uint32_t BRIGHTNESS_CONSTANT_R = 299;
+constexpr uint32_t BRIGHTNESS_CONSTANT_G = 587;
+constexpr uint32_t BRIGHTNESS_CONSTANT_B = 114;
 } // namespace
 
 PixelBuffer::PixelBuffer(unsigned char*      buffer,
@@ -466,6 +470,33 @@ bool PixelBuffer::IsAlphaPreMultiplied() const
   return mPreMultiplied;
 }
 
+uint32_t PixelBuffer::GetBrightness() const
+{
+  uint32_t brightness = 0;
+
+  uint32_t bytesPerPixel = Pixel::GetBytesPerPixel(mPixelFormat);
+  if(bytesPerPixel)
+  {
+    unsigned char* pixel      = mBuffer;
+    const uint32_t bufferSize = mWidth * mHeight;
+    uint64_t       red        = 0;
+    uint64_t       green      = 0;
+    uint64_t       blue       = 0;
+
+    for(uint32_t i = 0; i < bufferSize; ++i)
+    {
+      red += ReadChannel(pixel, mPixelFormat, Adaptor::RED);
+      green += ReadChannel(pixel, mPixelFormat, Adaptor::GREEN);
+      blue += ReadChannel(pixel, mPixelFormat, Adaptor::BLUE);
+      pixel += bytesPerPixel;
+    }
+    // http://www.w3.org/TR/AERT#color-contrast
+    brightness = (red * BRIGHTNESS_CONSTANT_R + green * BRIGHTNESS_CONSTANT_G + blue * BRIGHTNESS_CONSTANT_B) / (1000uLL * bufferSize);
+  }
+
+  return brightness;
+}
+
 } // namespace Adaptor
 } // namespace Internal
 } // namespace Dali
diff --git a/dali/internal/imaging/common/pixel-buffer-impl.h b/dali/internal/imaging/common/pixel-buffer-impl.h
index 47c478c..da25097 100644
--- a/dali/internal/imaging/common/pixel-buffer-impl.h
+++ b/dali/internal/imaging/common/pixel-buffer-impl.h
@@ -221,6 +221,11 @@ public:
    */
   bool IsAlphaPreMultiplied() const;
 
+  /**
+   * @copydoc Devel::PixelBuffer::GetBrightness()
+   */
+  uint32_t GetBrightness() const;
+
 private:
   /*
    * Undefined copy constructor.
-- 
2.7.4