在运行时获取图属性，需要强制图对象转换到特定类型，如下例所示。

At runtime, to access a diagram's properties, it's required to cast your instance of a diagram object to a specific type, as the following example demonstrates.

youdao

地质符号一般均有其特定的图形特征和表示意义，用以表达地质制图中所涉及的具体或抽象的地质对象。

Geological symbols generally have the specific graphical features and geological significances and can be used to present some concrete or abstract objects in geological drawing.

youdao

即使当为集合视图提取的对象在内存中时，图像对象（连同其二进制图像数据）也可以保持故障，从而不在内存中。

The image object (along with its binary image data) can then be kept a fault, and thus not in memory, even when the object you fetch for the collection view is in memory.

youdao