From fbe6d59c043873287c0fdec079a45ba81398f720 Mon Sep 17 00:00:00 2001
From: Jinny You <jinny@lottiefiles.com>
Date: Thu, 12 Sep 2024 17:43:41 +0900
Subject: [PATCH] wg_engine: Enable premultiplied canvas on browser

Emscripten 3.1.66 includes support for WebGPU's premultiplied canvas.

Surface configurations have been updated with premultiplied alpha mode to support this feature.

see: https://github.com/emscripten-core/emscripten/commit/c82a307c612d430028a3d06ddf8b3fdd2852b2fb
---
 src/renderer/wg_engine/tvgWgRenderer.cpp | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/renderer/wg_engine/tvgWgRenderer.cpp b/src/renderer/wg_engine/tvgWgRenderer.cpp
index b8e92553..211ef194 100755
--- a/src/renderer/wg_engine/tvgWgRenderer.cpp
+++ b/src/renderer/wg_engine/tvgWgRenderer.cpp
@@ -322,12 +322,15 @@ bool WgRenderer::target(WGPUSurface surface, uint32_t w, uint32_t h) {
         .device = mContext.device,
         .format = mContext.preferredFormat,
         .usage = WGPUTextureUsage_RenderAttachment,
+    #ifdef __EMSCRIPTEN__
+        .alphaMode = WGPUCompositeAlphaMode_Premultiplied,
+    #endif
         .width = w, .height = h,
-        #ifdef __EMSCRIPTEN__
+    #ifdef __EMSCRIPTEN__
         .presentMode = WGPUPresentMode_Fifo,
-        #else
+    #else
         .presentMode = WGPUPresentMode_Immediate
-        #endif
+    #endif
     };
     wgpuSurfaceConfigure(surface, &surfaceConfiguration);