From 10d6aa1bbafaed50021a56cbb7de434d0cb05b19 Mon Sep 17 00:00:00 2001
From: Hermet Park <hermetpark@gmail.com>
Date: Sat, 2 Mar 2024 05:45:12 +0900
Subject: [PATCH] wasm: update the gif conversion function

re-implement the gif conversion function with the correct approach.
The input data is not reusable as it undergoes modifications during parsing.

To address this, the function now creates a backup of the original data for use in GIF conversion.

This also resolves issues where the GIF viewport was incorrectly matched.

This implementation may be revisited upon
the availability of Animation::duplicate().
---
 src/bindings/wasm/tvgWasmLottieAnimation.cpp | 43 ++++++++++++++++++--
 1 file changed, 40 insertions(+), 3 deletions(-)

diff --git a/src/bindings/wasm/tvgWasmLottieAnimation.cpp b/src/bindings/wasm/tvgWasmLottieAnimation.cpp
index d46589b8..87486b6d 100644
--- a/src/bindings/wasm/tvgWasmLottieAnimation.cpp
+++ b/src/bindings/wasm/tvgWasmLottieAnimation.cpp
@@ -85,6 +85,9 @@ public:
             return false;
         }
 
+        //back up for saving
+        this->data = data;
+
         canvas->clear(true);
 
         animation = Animation::gen();
@@ -204,7 +207,10 @@ public:
     {
         errorMsg = NoError;
 
-        if (!animation) return false;
+        if (data.empty()) {
+            errorMsg = "Invalid data";
+            return false;
+        }
 
         auto saver = Saver::gen();
         if (!saver) {
@@ -212,12 +218,42 @@ public:
             return false;
         }
 
+        //animation to save
+        auto animation = Animation::gen();
+        if (!animation) {
+            errorMsg = "Invalid animation";
+            return false;
+        }
+
+        if (animation->picture()->load(data.c_str(), data.size(), "lottie", false) != Result::Success) {
+            errorMsg = "load() fail";
+            return false;
+        }
+
+        //gif resolution (600x600)
+        constexpr float GIF_SIZE = 600;
+
+        //transform
+        float width, height;
+        animation->picture()->size(&width, &height);
+        float scale;
+        if (width > height) scale = GIF_SIZE / width;
+        else scale = GIF_SIZE / height;
+        animation->picture()->size(width * scale, height * scale);
+
         //set a white opaque background
         auto bg = tvg::Shape::gen();
+        if (!bg) {
+            errorMsg = "Invalid bg";
+            return false;
+        }
         bg->fill(255, 255, 255, 255);
-        bg->appendRect(0, 0, width, height);
+        bg->appendRect(0, 0, GIF_SIZE, GIF_SIZE);
 
-        saver->background(std::move(bg));
+        if (saver->background(std::move(bg)) != Result::Success) {
+            errorMsg = "background() fail";
+            return false;
+        }
 
         if (saver->save(std::move(animation), "output.gif", 100, 30) != tvg::Result::Success) {
             errorMsg = "save(), fail";
@@ -280,6 +316,7 @@ private:
     string                 errorMsg;
     unique_ptr<SwCanvas>   canvas = nullptr;
     unique_ptr<Animation>  animation = nullptr;
+    string                 data;
     uint8_t*               buffer = nullptr;
     uint32_t               width = 0;
     uint32_t               height = 0;