D2D1在高DPI下具有明显的混叠

Question

• 编写一个简单的演示来验证问题，DPI越高，别名越明显，文本相同，请尝试使用SetAntialiasMode和SetTextAntialiasMode没有改善，我的系统是win10专业版。

• 是否有一些方法可以在高DPI下实现抗锯齿？

  static ID2D1Factory * g_factory;
  static IDWriteFactory*  g_dwrite_factory;
  static ID2D1HwndRenderTarget * g_render_target;
  static INT32 _dpi_x = 96;
  static INT32 _dpi_y = 96;
  
  #define DIP_TEST
  
  void OnSize(LPARAM lparam)
  {    
  UINT32 width = LOWORD(lparam);
  UINT32 height = HIWORD(lparam);
  
  UINT32 pixel_width = (UINT32)(width * _dpi_x / 96.0f);
  UINT32 pixel_height = (UINT32)(height * _dpi_x / 96.0f);
  
  if (g_render_target)
  g_render_target->Resize(D2D1::SizeU(pixel_width, pixel_height));
  }
  
  bool AppInit()
  {
  #ifdef DIP_TEST
  SetProcessDPIAware();
  _dpi_x = 384;
  _dpi_y = 384; 
  #endif
  
  D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, &g_factory);
  DWriteCreateFactory(DWRITE_FACTORY_TYPE_SHARED, __uuidof(IDWriteFactory), reinterpret_cast<IUnknown**>(&g_dwrite_factory));
  
  RECT rc;
  GetClientRect(g_hwnd, &rc);
  
  UINT32 logic_width = rc.right - rc.left;
  UINT32 logic_height = rc.bottom - rc.top;
  UINT32 w = (UINT32)(logic_width * _dpi_x / 96.0f);
  UINT32 h = (UINT32)(logic_height * _dpi_x / 96.0f);
  
  D2D1_PIXEL_FORMAT pixelFormat = D2D1::PixelFormat(DXGI_FORMAT_B8G8R8A8_UNORM, D2D1_ALPHA_MODE_PREMULTIPLIED);
  D2D1_RENDER_TARGET_PROPERTIES props = D2D1::RenderTargetProperties(D2D1_RENDER_TARGET_TYPE_DEFAULT, pixelFormat);//D2D1_RENDER_TARGET_TYPE_SOFTWARE为了截图
  #ifdef DIP_TEST
  props.dpiX = (float)_dpi_x;
  props.dpiY = (float)_dpi_y;
  #endif
  
  g_factory->CreateHwndRenderTarget(props,
  D2D1::HwndRenderTargetProperties(g_hwnd, D2D1::SizeU(w, h)),
  &g_render_target);
  
  return true;
  }
  
  void OnPaint()
  {
  if (!g_render_target)
      return;
  
  ...
  g_render_target->BeginDraw();
  g_render_target->Clear(D2D1::ColorF(0.f, 0.f, 0.0f));
  //g_render_target->SetAntialiasMode(D2D1_ANTIALIAS_MODE_PER_PRIMITIVE);
  stroke_brush->SetColor(D2D1::ColorF(1.0f, 0.0f, 0.0f, 1.0f));
  D2D1_RECT_F textLayoutRect = D2D1::RectF(100.0f, 150.0f, 600.0f, 600.0f);
  g_render_target->DrawTextW(sz, text_len, dwrite_text_format, textLayoutRect, stroke_brush, D2D1_DRAW_TEXT_OPTIONS_NONE, DWRITE_MEASURING_MODE_NATURAL);     
  g_render_target->DrawEllipse(D2D1::Ellipse(D2D1::Point2F(300.5, 200.5), 250, 150), stroke_brush, 2);
  g_render_target->EndDraw(); 
  ...
  }
  

Answer 1

似乎在创建窗口后启用了DPI感知。您应该在应用程序清单中声明dpi意识。同样，也不需要像(logic_width * _dpi_x / 96.0f);那样执行手动尺寸缩放，因为窗口大小已经在物理像素中，而不是逻辑像素中。