add user manual in app instead of pdf

src/node_image.cpp

@@ -40,6 +40,8 @@ void NodeImage::create()
         auto tex_sz = TextureManager::get(m_tex_id).size();
         m_off = xy(m_region) / tex_sz;
         m_sz = (zw(m_region) - xy(m_region)) / tex_sz;
+        if (m_autosize)
+            SetAspectRatio(tex_sz.x / tex_sz.y);
     }
 }
 
@@ -72,6 +74,9 @@ void NodeImage::parse_attributes(kAttribute ka, const tinyxml2::XMLAttribute* at
         }
         break;
     }
+    case kAttribute::AutoSize:
+        m_autosize = attr->BoolValue();
+        break;
     default:
         break;
     }