From b12068e1c8c716382e9dbfdc6bec412a19fa95a9 Mon Sep 17 00:00:00 2001
From: halx99 <halx99@live.com>
Date: Mon, 31 Aug 2020 15:32:59 +0800
Subject: [PATCH] Use etc2_decode_image decode etc1 to RGBA8888 [skip appveyor]
 [skip travis] This can avoid further texture data convert

---
 cocos/platform/CCImage.cpp | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/cocos/platform/CCImage.cpp b/cocos/platform/CCImage.cpp
index 360572afa3..a46f1e3b84 100644
--- a/cocos/platform/CCImage.cpp
+++ b/cocos/platform/CCImage.cpp
@@ -1532,7 +1532,7 @@ bool Image::initWithETCData(const unsigned char* data, ssize_t dataLen, bool own
     else
         compressedFormat = backend::PixelFormat::NONE;
 
-    if (compressedFormat != backend::PixelFormat::NONE)
+    if (compressedFormat != backend::PixelFormat::NONE && false)
     {
         //old opengl version has no define for GL_ETC1_RGB8_OES, add macro to make compiler happy. 
 #if defined(GL_ETC1_RGB8_OES) || defined(CC_USE_METAL)
@@ -1552,15 +1552,13 @@ bool Image::initWithETCData(const unsigned char* data, ssize_t dataLen, bool own
         CCLOG("cocos2d: Hardware ETC1 decoder not present. Using software decoder");
 
         bool ret = true;
-         //if it is not gles or device do not support ETC, decode texture by software
-        int bytePerPixel = 3;
-        unsigned int stride = _width * bytePerPixel;
-        _pixelFormat = backend::PixelFormat::RGB888;
-        
-        _dataLen =  _width * _height * bytePerPixel;
+        // if it is not gles or device do not support ETC1, decode texture by software
+        // directly decode ETC1_RGB to RGBA8888
+        _pixelFormat = backend::PixelFormat::RGBA8888;
+
+        _dataLen = _width * _height * 4;
         _data = static_cast<unsigned char*>(malloc(_dataLen * sizeof(unsigned char)));
-        
-        if (etc1_decode_image(static_cast<const unsigned char*>(data) + ETC_PKM_HEADER_SIZE, static_cast<etc1_byte*>(_data), _width, _height, bytePerPixel, stride) != 0)
+        if (etc2_decode_image(ETC2_RGB_NO_MIPMAPS, static_cast<const unsigned char*>(data) + ETC2_PKM_HEADER_SIZE, static_cast<etc2_byte*>(_data), _width, _height) != 0)
         {
             _dataLen = 0;
             if (_data != nullptr)
@@ -1572,6 +1570,7 @@ bool Image::initWithETCData(const unsigned char* data, ssize_t dataLen, bool own
         }
 
         if (ownData) free((void*)data);
+
         return ret;
     }