GPU Display: Raster font at correct pixel size taking into accound fractional scaling

Author: davidrohr

GPU/GPUTracking/display/backend/GPUDisplayBackend.cxx

@@ -66,9 +66,23 @@ int32_t GPUDisplayBackend::InitBackend()
   if (retVal) {
     return retVal;
   }
-  if (mDisplay->cfg().noFreetype) {
-    return retVal;
+  if (!mDisplay->cfg().noFreetype) {
+    loadFont();
+  }
+  return retVal;
+}
+
+void GPUDisplayBackend::updateFontScale(float scale)
+{
+  if (mFreetypeInitialized && scale != mFontRasterScale) {
+    clearFontSymbols();
+    mFreetypeInitialized = false;
+    loadFont();
   }
+}
+
+void GPUDisplayBackend::loadFont()
+{
   std::string fontName = mDisplay->cfg().font;
 #ifdef GPUCA_BUILD_EVENT_DISPLAY_FONTCONFIG
   FcInit();
@@ -97,24 +111,25 @@ int32_t GPUDisplayBackend::InitBackend()
   FT_Face face;
   if (FT_Init_FreeType(&ft)) {
     GPUError("Error initializing freetype");
-    return 0;
+    return;
   }
   if (FT_New_Face(ft, fontName.c_str(), 0, &face)) {
     GPUError("Error loading freetypoe font");
-    return 0;
+    return;
   }
 
   int32_t fontSize = mDisplay->cfg().fontSize;
   mDisplay->drawTextFontSize() = fontSize;
   if (smoothFont()) {
     fontSize *= 4; // Font size scaled by 4, can be downsampled
   }
-  FT_Set_Pixel_Sizes(face, 0, fontSize);
+  mFontRasterScale = mDisplay->frontend()->getDisplayScale();
+  FT_Set_Pixel_Sizes(face, 0, (uint32_t)(fontSize * mFontRasterScale + 0.5f)); // Rasterize at physical pixel size for HiDPI
 
   for (uint32_t i = 0; i < 128; i++) {
     if (FT_Load_Char(face, i, FT_LOAD_RENDER)) {
       GPUError("Error loading freetype symbol");
-      return 0;
+      return;
     }
     const auto& glyph = face->glyph;
     addFontSymbol(i, glyph->bitmap.width, glyph->bitmap.rows, glyph->bitmap_left, glyph->bitmap_top, glyph->advance.x, glyph->bitmap.buffer);
@@ -124,7 +139,6 @@ int32_t GPUDisplayBackend::InitBackend()
   FT_Done_FreeType(ft);
   mFreetypeInitialized = true;
 #endif // GPUCA_BUILD_EVENT_DISPLAY_FREETYPE
-  return retVal;
 }
 
 void GPUDisplayBackend::ExitBackend()

GPU/GPUTracking/display/backend/GPUDisplayBackend.h

@@ -86,6 +86,7 @@ class GPUDisplayBackend
   virtual int32_t InitBackendA() = 0;
   virtual void ExitBackendA() = 0;
   int32_t InitBackend();
+  void updateFontScale(float scale); // Rasterize the font again if the display (HiDPI) scale changed
   void ExitBackend();
   virtual void loadDataToGPU(size_t totalVertizes) = 0;
   virtual void prepareDraw(const hmm_mat4& proj, const hmm_mat4& view, bool requestScreenshot = false, bool toMixBuffer = false, float includeMixImage = 0.f) = 0;
@@ -108,6 +109,8 @@ class GPUDisplayBackend
  protected:
   virtual void addFontSymbol(int32_t symbol, int32_t sizex, int32_t sizey, int32_t offsetx, int32_t offsety, int32_t advance, void* data) = 0;
   virtual void initializeTextDrawing() = 0;
+  virtual void clearFontSymbols() {} // Release glyphs / font atlas before loading the font again
+  void loadFont();
 
   float getDownsampleFactor(bool screenshot = false);
   void fillIndirectCmdBuffer();
@@ -117,6 +120,7 @@ class GPUDisplayBackend
   std::vector<int32_t> mIndirectSectorOffset;
   vecpod<DrawArraysIndirectCommand> mCmdBuffer;
   bool mFreetypeInitialized = false;
+  float mFontRasterScale = 1.f; // Display scale the font was rasterized for
   bool mFrontendCompatTextDraw = false;
   std::vector<char> mScreenshotPixels;
 

GPU/GPUTracking/display/backend/GPUDisplayBackendOpenGL.cxx

@@ -709,6 +709,16 @@ void GPUDisplayBackendOpenGL::addFontSymbol(int32_t symbol, int32_t sizex, int32
   CHKERR(glPixelStorei(GL_UNPACK_ALIGNMENT, oldAlign));
 }
 
+void GPUDisplayBackendOpenGL::clearFontSymbols()
+{
+  CHKERR(glDeleteBuffers(1, &VBO_text));
+  CHKERR(glDeleteVertexArrays(1, &VAO_text));
+  for (auto& symbol : mFontSymbols) {
+    CHKERR(glDeleteTextures(1, &symbol.texId));
+  }
+  mFontSymbols.clear();
+}
+
 void GPUDisplayBackendOpenGL::initializeTextDrawing()
 {
   CHKERR(glGenVertexArrays(1, &VAO_text));
@@ -840,5 +850,6 @@ void GPUDisplayBackendOpenGL::pointSizeFactor(float factor) {}
 void GPUDisplayBackendOpenGL::lineWidthFactor(float factor) {}
 void GPUDisplayBackendOpenGL::addFontSymbol(int32_t symbol, int32_t sizex, int32_t sizey, int32_t offsetx, int32_t offsety, int32_t advance, void* data) {}
 void GPUDisplayBackendOpenGL::initializeTextDrawing() {}
+void GPUDisplayBackendOpenGL::clearFontSymbols() {}
 void GPUDisplayBackendOpenGL::OpenGLPrint(const char* s, float x, float y, float* color, float scale) {}
 #endif // GPUCA_BUILD_EVENT_DISPLAY_OPENGL

GPU/GPUTracking/display/backend/GPUDisplayBackendOpenGL.h

@@ -71,6 +71,7 @@ class GPUDisplayBackendOpenGL : public GPUDisplayBackend
 
   void addFontSymbol(int32_t symbol, int32_t sizex, int32_t sizey, int32_t offsetx, int32_t offsety, int32_t advance, void* data) override;
   void initializeTextDrawing() override;
+  void clearFontSymbols() override;
   void OpenGLPrint(const char* s, float x, float y, float* color, float scale) override;
 
   struct FontSymbolOpenGL : public FontSymbol {

GPU/GPUTracking/display/backend/GPUDisplayBackendVulkan.cxx

@@ -1854,6 +1854,16 @@ void GPUDisplayBackendVulkan::initializeTextDrawing()
   updateFontTextureDescriptor();
 }
 
+void GPUDisplayBackendVulkan::clearFontSymbols()
+{
+  mDevice.waitIdle();
+  if (mFontImage.sizex && mFontImage.sizey) {
+    clearImage(mFontImage);
+    mFontImage.sizex = mFontImage.sizey = 0;
+  }
+  mFontSymbols.clear();
+}
+
 void GPUDisplayBackendVulkan::updateFontTextureDescriptor()
 {
   vk::DescriptorImageInfo imageInfo{};

GPU/GPUTracking/display/backend/GPUDisplayBackendVulkan.h

@@ -126,6 +126,7 @@ class GPUDisplayBackendVulkan : public GPUDisplayBackend
 
   void addFontSymbol(int32_t symbol, int32_t sizex, int32_t sizey, int32_t offsetx, int32_t offsety, int32_t advance, void* data) override;
   void initializeTextDrawing() override;
+  void clearFontSymbols() override;
   void OpenGLPrint(const char* s, float x, float y, float* color, float scale) override;
 
   uint32_t mGraphicsFamily;

GPU/GPUTracking/display/helpers/GPUDisplayHelpers.cxx

@@ -99,6 +99,7 @@ void GPUDisplay::DoScreenshot(const char* filename, std::vector<char>& pixels, f
 
 void GPUDisplay::showInfo(const char* info)
 {
+  mBackend->updateFontScale(mFrontend->getDisplayScale());
   mBackend->prepareText();
   float colorValue = mCfgL.invertColors ? 0.f : 1.f;
   OpenGLPrint(info, 40.f, 20.f + std::max(20, mDrawTextFontSize + 4), colorValue, colorValue, colorValue, 1);
@@ -129,7 +130,7 @@ void GPUDisplay::OpenGLPrint(const char* s, float x, float y, float r, float g,
       y = mBackend->mScreenHeight - y;
     }
     float color[4] = {r, g, b, a};
-    mBackend->OpenGLPrint(s, x, y, color, scale);
+    mBackend->OpenGLPrint(s, x, y, color, scale / mBackend->mFontRasterScale);
   } else if (mFrontend->mCanDrawText) {
     mFrontend->OpenGLPrint(s, x, y, r, g, b, a, fromBotton);
   }