Basic concepts of VML_VML related

VML is equivalent to the brush in IE, which can realize the graphics you want, and combined with scripts, it can produce dynamic effects on graphics. VML was released by Microsoft in September 1999 with IE5.0. In my opinion, VML is actually the product of the combination of Word and HTML. You can save Word documents as HTML, and the text and pictures in it can be easily converted. However, hand-drawn graphics cannot be interpreted in IE in the past, and it is not practical to convert them into graphics files. So Microsoft integrated the graphics controls in Word into IE, so that IE also has drawing functions.
The full name of VML is Vector Markup Language (Vector Markup Language). Vector graphics mean that graphics can be enlarged or reduced without losing the quality of the graphics. This is of great use in making maps. In order to show its power and increase your confidence in learning VML, let me first show you a VML example:

Hello world!
Hello VML!

In VML, tags use XML expansion and require a namespace. You can use the customary "v" as the namespace. The common definitions used from IE5.0 to IE6.0 are as follows:

xmlns:v="urn:schemas-microsoft-com:vml">

v:* { Behavior: url(#default#VML) }


The full name of xmlns is XML NameSpace, which is the namespace. Behavior is also a new thing introduced in IE5.0. Its function is very powerful. Combined with style sheets, it can add behaviors (new attributes, methods, events) to any HTML object. Here, its use is to name The space "v" is connected to the system's predefined behavioral VML. After this definition, you can use the following tags, which are different from ordinary HTML tags. Each tag adds a namespace:



Like other HTML elements, most of the DHTML attributes and events can be defined in VML tags, such as id, name, title, onmouseover, etc. VML is more flexible in terms of writing. Many attributes can be written in tags or represented by a new tag independently:
StrokeColor=red Path="m 0,0 l 10,10 x e"
>
is equivalent to the following writing:




Of course not all attributes can be written as independent tags. Commonly used ones include the above Stroke (can be translated into linear according to my understanding), Path, Shadow, Fill (fill), etc. VML can be understood in this way. Classify the attributes of the shape to make the attributes more intuitive. Some objects derived from the Shape object, more direct images, such as Rect (rectangle), RoundRect (rectangle with rounded edges), Oval (circle), Line (line), PolyLine (irregular polyline), Image (Graphic files) and so on, these objects will be described in detail later.