savers: provides a background setting.

Allow users to set a custom background with a saver.

API:
- Result Saver::background(std::unique_ptr<Paint> paint);

inc/thorvg.h

@@ -1804,6 +1804,15 @@ class TVG_API Saver final
 public:
     ~Saver();
 
+    /**
+     * @brief Sets the base background content for the saved image.
+     *
+     * @param[in] paint The paint to be drawn as the background image for the saving paint.
+     *
+     * @note Experimental API
+     */
+    Result background(std::unique_ptr<Paint> paint) noexcept;
+
     /**
      * @brief Exports the given @p paint data to the given @p path
      *

src/renderer/tvgSaveModule.h

@@ -34,7 +34,7 @@ public:
     virtual ~SaveModule() {}
 
     virtual bool save(Paint* paint, const string& path, bool compress) = 0;
-    virtual bool save(Animation* animation, const string& path, uint32_t quality, uint32_t fps) = 0;
+    virtual bool save(Animation* animation, Paint* bg, const string& path, uint32_t quality, uint32_t fps) = 0;
     virtual bool close() = 0;
 };
 

src/renderer/tvgSaver.cpp

@@ -37,9 +37,12 @@
 struct Saver::Impl
 {
     SaveModule* saveModule = nullptr;
+    Paint* bg = nullptr;
+
     ~Impl()
     {
         delete(saveModule);
+        delete(bg);
     }
 };
 
@@ -139,7 +142,16 @@ Result Saver::save(std::unique_ptr<Paint> paint, const string& path, bool compre
 }
 
 
-Result Saver::save(std::unique_ptr<Animation> animation, const string& path, uint32_t quality, uint32_t fps) noexcept
+Result Saver::background(unique_ptr<Paint> paint) noexcept
+{
+    delete(pImpl->bg);
+    pImpl->bg = paint.release();
+
+    return Result::Success;
+}
+
+
+Result Saver::save(unique_ptr<Animation> animation, const string& path, uint32_t quality, uint32_t fps) noexcept
 {
     auto a = animation.release();
     if (!a) return Result::MemoryCorruption;
@@ -156,7 +168,7 @@ Result Saver::save(std::unique_ptr<Animation> animation, const string& path, uin
     }
 
     if (auto saveModule = _find(path)) {
-        if (saveModule->save(a, path, quality, fps)) {
+        if (saveModule->save(a, pImpl->bg, path, quality, fps)) {
             pImpl->saveModule = saveModule;
             return Result::Success;
         } else {

src/savers/gif/tvgGifSaver.cpp

@@ -42,13 +42,7 @@ void GifSaver::run(unsigned tid)
 
     buffer = (uint32_t*)realloc(buffer, sizeof(uint32_t) * w * h);
     canvas->target(buffer, w, w, h, tvg::SwCanvas::ABGR8888);
-
+    canvas->push(cast(bg));
-    //base white background
-    auto bg = Shape::gen();
-    bg->appendRect(0, 0, vsize[0], vsize[1]);
-    bg->fill(255, 255, 255);
-    canvas->push(std::move(bg));
-
     canvas->push(cast(animation->picture()));
 
     //use the default fps
@@ -81,6 +75,8 @@ void GifSaver::run(unsigned tid)
     }
 
     if (!GifEnd(&writer)) TVGERR("GIF_SAVER", "Failed gif encoding");
+
+    this->bg = nullptr;
 }
 
 
@@ -98,6 +94,9 @@ bool GifSaver::close()
 {
     this->done();
 
+    delete(bg);
+    bg = nullptr;
+
     delete(animation);
     animation = nullptr;
 
@@ -118,7 +117,7 @@ bool GifSaver::save(TVG_UNUSED Paint* paint, TVG_UNUSED const string& path, TVG_
 }
 
 
-bool GifSaver::save(Animation* animation, const string& path, TVG_UNUSED uint32_t quality, uint32_t fps)
+bool GifSaver::save(Animation* animation, Paint* bg, const string& path, TVG_UNUSED uint32_t quality, uint32_t fps)
 {
     close();
 
@@ -140,6 +139,7 @@ bool GifSaver::save(Animation* animation, const string& path, TVG_UNUSED uint32_
     if (!this->path) return false;
 
     this->animation = animation;
+    if (bg) this->bg = bg->duplicate();
     this->fps = static_cast<float>(fps);
 
     TaskScheduler::request(this);

src/savers/gif/tvgGifSaver.h

@@ -34,6 +34,7 @@ class GifSaver : public SaveModule, public Task
 private:
     uint32_t* buffer = nullptr;
     Animation* animation = nullptr;
+    Paint* bg = nullptr;
     char *path = nullptr;
     float vsize[2] = {0.0f, 0.0f};
     float fps = 0.0f;
@@ -44,7 +45,7 @@ public:
     ~GifSaver();
 
     bool save(Paint* paint, const string& path, bool compress) override;
-    bool save(Animation* animation, const string& path, uint32_t quality, uint32_t fps) override;
+    bool save(Animation* animation, Paint* bg, const string& path, uint32_t quality, uint32_t fps) override;
     bool close() override;
 };
 

src/savers/tvg/tvgTvgSaver.cpp

@@ -780,15 +780,14 @@ bool TvgSaver::close()
 {
     this->done();
 
-    if (paint) {
     delete(paint);
     paint = nullptr;
-    }
+
-    if (path) {
     free(path);
     path = nullptr;
-    }
+
     buffer.reset();
+
     return true;
 }
 
@@ -822,7 +821,7 @@ bool TvgSaver::save(Paint* paint, const string& path, bool compress)
 }
 
 
-bool TvgSaver::save(TVG_UNUSED Animation* animation, TVG_UNUSED const string& path, TVG_UNUSED uint32_t quality, TVG_UNUSED uint32_t fps)
+bool TvgSaver::save(TVG_UNUSED Animation* animation, TVG_UNUSED Paint* bg, TVG_UNUSED const string& path, TVG_UNUSED uint32_t quality, TVG_UNUSED uint32_t fps)
 {
     TVGLOG("TVG_SAVER", "Animation is not supported.");
     return false;

src/savers/tvg/tvgTvgSaver.h

@@ -35,6 +35,7 @@ class TvgSaver : public SaveModule, public Task
 private:
     Array<TvgBinByte> buffer;
     Paint* paint = nullptr;
+    Paint* bg = nullptr;
     char *path = nullptr;
     uint32_t headerSize;
     float vsize[2] = {0.0f, 0.0f};
@@ -71,7 +72,7 @@ public:
     ~TvgSaver();
 
     bool save(Paint* paint, const string& path, bool compress) override;
-    bool save(Animation* animation, const string& path, uint32_t quality, uint32_t fps) override;
+    bool save(Animation* animation, Paint* bg, const string& path, uint32_t quality, uint32_t fps) override;
     bool close() override;
 };