Use atlas to draw text. (#128)

src/rendering/caches/RenderCache.cpp

@@ -195,6 +195,7 @@ void RenderCache::attachToContext(tgfx::Context* current, bool forHitTest) {
     imageTasks.erase(assetID);
     clearSequenceCache(assetID);
     clearFilterCache(assetID);
+    removeTextAtlas(assetID);
   }
 }
 
@@ -288,6 +289,46 @@ void RenderCache::removeSnapshot(ID assetID) {
   snapshotCaches.erase(assetID);
 }
 
+TextAtlas* RenderCache::getTextAtlas(ID assetID) {
+  auto textAtlas = textAtlases.find(assetID);
+  if (textAtlas == textAtlases.end()) {
+    return nullptr;
+  }
+  return textAtlas->second;
+}
+
+TextAtlas* RenderCache::getTextAtlas(const TextGlyphs* textGlyphs) {
+  auto maxScaleFactor = stage->getAssetMaxScale(textGlyphs->assetID());
+  auto textAtlas = getTextAtlas(textGlyphs->assetID());
+  if (textAtlas && (textAtlas->textGlyphsID() != textGlyphs->id() ||
+                    fabsf(textAtlas->scaleFactor() - maxScaleFactor) > SCALE_FACTOR_PRECISION)) {
+    removeTextAtlas(textGlyphs->assetID());
+    textAtlas = nullptr;
+  }
+  if (textAtlas) {
+    return textAtlas;
+  }
+  if (maxScaleFactor < SCALE_FACTOR_PRECISION) {
+    return nullptr;
+  }
+  textAtlas = TextAtlas::Make(textGlyphs, this, maxScaleFactor).release();
+  if (textAtlas) {
+    graphicsMemory += textAtlas->memoryUsage();
+    textAtlases[textGlyphs->assetID()] = textAtlas;
+  }
+  return textAtlas;
+}
+
+void RenderCache::removeTextAtlas(ID assetID) {
+  auto textAtlas = textAtlases.find(assetID);
+  if (textAtlas == textAtlases.end()) {
+    return;
+  }
+  graphicsMemory -= textAtlas->second->memoryUsage();
+  delete textAtlas->second;
+  textAtlases.erase(textAtlas);
+}
+
 void RenderCache::clearAllSnapshots() {
   for (auto& item : snapshotCaches) {
     graphicsMemory -= item.second->memoryUsage();

src/rendering/caches/RenderCache.h

@@ -20,6 +20,8 @@
 
 #include <memory>
 #include <unordered_set>
+#include "TextAtlas.h"
+#include "TextGlyphs.h"
 #include "gpu/Device.h"
 #include "pag/file.h"
 #include "pag/pag.h"
@@ -99,6 +101,12 @@ class RenderCache : public Performance {
    */
   void removeSnapshot(ID assetID);
 
+  TextAtlas* getTextAtlas(ID assetID);
+
+  TextAtlas* getTextAtlas(const TextGlyphs* textGlyphs);
+
+  void removeTextAtlas(ID assetID);
+
   /**
    * Prepares a bitmap task for next getImageBuffer() call.
    */
@@ -149,6 +157,7 @@ class RenderCache : public Performance {
   std::unordered_set<ID> usedAssets = {};
   std::unordered_map<ID, Snapshot*> snapshotCaches = {};
   std::list<Snapshot*> snapshotLRU = {};
+  std::unordered_map<ID, TextAtlas*> textAtlases = {};
   std::unordered_map<ID, std::shared_ptr<Task>> imageTasks;
   std::unordered_map<ID, std::shared_ptr<SequenceReader>> sequenceCaches;
   std::unordered_map<ID, Filter*> filterCaches;