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diff --git a/Mac/Demo/waste.html b/Mac/Demo/waste.html new file mode 100644 index 0000000..856d792 --- /dev/null +++ b/Mac/Demo/waste.html @@ -0,0 +1,69 @@ +<HTML><HEAD><TITLE>Using WASTE</TITLE></HEAD> +<BODY> +<H1>Using WASTE</H1> +<HR> + +WASTE is an almost-compatible TextEdit replacement which overcomes +some of the limitations of it (like the 32K limit) and provides some extensions +(drag and drop, images, undo support). Moreover, it has a much cleaner interface +and is therefore easier integrated in Python. <p> + +WASTE is written by Marco Piovanelli, <A HREF="mailto:piovanel@kagi.com"><piovanel@kagi.com></A>, +and copyrighted by him. You can always obtain the latest version (for use in C +or Pascal programs) and the documentation from +<A HREF="ftp://ftp.dsi.unimi.it/DSI/piovanel/WASTE"><ftp://ftp.dsi.unimi.it/DSI/piovanel/WASTE></A>. + +We explain the useage of waste here by showing how to modify the TextEdit based +<A HREF="textedit/ped.py">ped.py</A> of the +<A HREF="textedit.html">previous example</A> into the waste-based <A HREF="waste/wed.py">wed.py</A>, +so you should have both sources handy. <p> + +Functionally, <code>wed.py</code> provides three new things: resizable windows, a horizontal +scroll bar and undo. <p> + +Let us look at the code, first at the application class <code>Wed</code>. The only real change is that +we now handle <code>undo</code>. Aside from enabling it in the creation routine and the addition of +a callback routine there is a bit of new code in <code>updatemenubar</code>: Waste not only handles +the full details of implementing undo, it will also tell us what the next undo operation will undo +(or redo). We use this to our advantage by changing the undo menu label to tell the user. <p> + +The <code>WasteWindow</code> has seen a bit more change. Initialization of the waste data structure is +a bit different, in that we can specify some options at creation time. Also, waste has no <code>SetText</code> +method but a <code>UseText</code> which expects a handle as parameter. We have to be <EM>very</EM> careful +that we keep this handle around, because Python will happily free the handle if we have no more references +to it (and I doubt that Waste would like this:-). A final difference in <code>open</code> +is that we use a large number for the destination rectangle width, because we will use a horizontal scroll +bar. <p> + +The <code>idle</code> method is a bit more involved, since we also call <code>WEAdjustCursor</code> to +provide the correct cursor based on mouse-position. Users like this. <p> + +<code>Getscrollbarvalues</code> is simpler than its' TextEdit counterpart because Waste correctly +updates the destination rectangle when the document changes. Also note that waste uses accessor functions +to get at internal values, as opposed to direct struct access for TextEdit. <p> + +<code>Scrollbar_callback</code> on the other hand is more elaborate (but also provides more functionality). +It also handles horizontal scrolls (scrolling one-tenth and half a screenful with the buttons). This +function is also "multi-font-ready" in that scrolling one line will do the expected thing in case of multiple +fonts. We will implement a multi-font editor later. A minor annoyance of Waste is that is does not provide +a pinned scroll, so at the end of our callback routine we have to check that we have not scrolled past the +beginning or end of the document, and adjust when needed. <p> + +<code>do_update</code> is also changed, because Waste is completely region-based (as opposed to rect-based). +Hence, we erase regions here and we can also return immedeately if there is nothing to update. <p> + +<code>Do_postresize</code> is new: because Waste uses accessor functions we can now modify the viewRect from +Python, which is impossible in the Python TextEdit interface, and hence we can implement resize. The +<code>do_key</code> and <code>do_contentclick</code> methods have also seen minor changes, because the +corresponding waste routines need a bit more information than their TextEdit counterparts. The Cut/copy/paste +code is simplified, because Waste uses the normal desktop scrap. <p> + +Implementing undo is a wonder of simplicity: Waste handles all the details for us. Also, the new +<code>can_paste</code> method (which controls greying out of the paste menu entry) is an improvement +over what <code>ped</code> did: in ped it was possible that paste was enabled but that the data on the +scrap was incompatible with TextEdit. No more such problems here. <p> + +<hr> +That is all for now. At some point in the future I will extend this editor to incorporate multiple fonts and +pointsizes, pictures and possibly drag-and-drop editing but I will first have to write the code for it. +For now you will have to go back to the <A HREF="index.html">index</A> to pick another example. |