Cells and Containers

This article describes mechanism used by wxHtmlWinParser and wxHtmlWindow to parse and display HTML documents.

Cells

You can divide any text (or HTML) into small fragments. Let's call these fragments cells. Cell is for example one word, horizontal line, image or any other part of document. Each cell has width and height (except special "magic" cells with zero dimensions - e.g. colour changers or font changers).

See wxHtmlCell.

Containers

Container is kind of cell that may contain sub-cells. Its size depends on number and sizes of its sub-cells (and also depends on width of window).

See wxHtmlContainerCell, wxHtmlCell::Layout.

Using Containers in Tag Handler

wxHtmlWinParser provides a user-friendly way of managing containers. It is based on the idea of opening and closing containers.

Use OpenContainer to open new a container within an already opened container. This new container is a sub-container of the old one. (If you want to create a new container with the same depth level you can call CloseContainer(); OpenContainer();.)

Use CloseContainer to close the container. This doesn't create a new container with same depth level but it returns "control" to the parent container.

It is clear there must be same number of calls to OpenContainer as to CloseContainer...

Example

This code creates a new paragraph (container at same depth level) with "Hello, world!":

m_WParser -> CloseContainer();
c = m_WParser -> OpenContainer();

m_WParser -> AddWord("Hello, ");
m_WParser -> AddWord("world!");

m_WParser -> CloseContainer();
m_WParser -> OpenContainer();

You can see that there was opened container before running the code. We closed it, created our own container, then closed our container and opened new container. The result was that we had same depth level after executing. This is general rule that should be followed by tag handlers: leave depth level of containers unmodified (in other words, number of OpenContainer and CloseContainer calls should be same within HandleTag's body).

ymasuda 平成17年11月19日