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<h3 class="sectionHead"><span class="titlemark">6.12 </span> <a
id="x44-790006.12"></a>Controlling the interface</h3>
<!--l. 1293--><p class="noindent" ><a name="nip_label_sec:bowser"></a>
<!--l. 1295--><p class="indent" > <span
class="pcrr7t-">nip2 </span>looks at the scraps of program you type in and
execute and tries to show them on the screen in a graphical
way. The sorts of display you get depend on where in <span
class="pcrr7t-">nip2</span>
you define the expression, and what sort of value it
has.
<!--l. 1300--><p class="noindent" >
<h4 class="subsectionHead"><span class="titlemark">6.12.1 </span> <a
id="x44-800006.12.1"></a>Tools and toolkits</h4>
<!--l. 1301--><p class="noindent" ><a name="nip_label_sec:tools"></a>
<!--l. 1303--><p class="indent" > Definitions in toolkits are turned into menus off the
<span
class="pcrr7t-">Toolkits </span>menu in the main window, and added to
the toolkit browser. Toolkits are loaded from files at
startup or can be made in the program window. Toolkit
or a definition names which start with an underscore
character are hidden and not displayed. The toolkits
are always displayed in alphabetical order, but you
can order the items within a toolkit in any way you
like.
<!--l. 1311--><p class="indent" > There are two ways to write toolkit definitions. Function
definitions and zero-argument classes simply appear as
menu items, built from static analysis of their source code.
However, if a definition evaluates to an instance of the class
<span
class="pcrr7t-">Menu</span>, a menu item is built from dynamic analysis of the
value of the definition.
<!--l. 1317--><p class="noindent" >
<h5 class="subsubsectionHead"><a
id="x44-810006.12.1"></a>Static menu items</h5>
<!--l. 1319--><p class="noindent" >Zero-argument classes within toolkits are displayed as
pull-right menus. You can nest classes to any depth.
<!--l. 1322--><p class="indent" > <span
class="pcrr7t-">nip2 </span>uses the first line of the comment before a
definition as help text for that function, so it’s a good idea to
put a simple one-line description of the function at the start
of a comment.
<!--l. 1326--><p class="indent" > For example, if the following text is placed in a file called
<span
class="pcrr7t-">Fred.def </span>on <span
class="pcrr7t-">nip2</span>’s start path, you’ll get a menu in the
tookits called <span
class="pcrr7t-">Fred </span>with a pull-right and a tooltip. See
Figure <a
href="#x44-810011">6.1<!--tex4ht:ref: fg:toolkit --></a>.
<div class="verbatim" id="verbatim-84">
Banana a = a ⋆ 3;
 <br />
 <br />Subfred = class {
 <br />  // add two things
 <br />  Jim a b = a + b;
 <br />  Apple e = e ⋆ 12;
 <br />  Harry z = 12 + z;
 <br />}
</div>
<!--l. 1339--><p class="nopar" >
<!--l. 1341--><p class="indent" > <hr class="figure"><div class="figure"
>
<a
id="x44-810011"></a>
<div class="center"
>
<!--l. 1342--><p class="noindent" >
<!--l. 1342--><p class="noindent" ><img
src="figs/toolkit.jpg" alt="PIC"
></div>
<br /> <div class="caption"
><span class="id">Figure 6.1: </span><span
class="content">How <span
class="pcrr7t-">Fred.def </span>will look</span></div><!--tex4ht:label?: x44-810011 -->
<!--l. 1344--><p class="noindent" ><a name="nip_label_fg:toolkit"></a>
<!--l. 1345--><p class="indent" > </div><hr class="endfigure">
<h5 class="subsubsectionHead"><a
id="x44-820006.12.1"></a>Dynamic menu items</h5>
<!--l. 1349--><p class="noindent" >Dynamic menus give you much more control over the way
menus are drawn and make it easy to reuse menus. A
dynamic menu item is a class instance that is a sub-class of
<span
class="pcrr7t-">Menuitem</span>. It needs to have three members: <span
class="pcrr7t-">label</span>, the
text that should appear in the menu (with an underscore
character to indicate the mnenonic); <span
class="pcrr7t-">tooltip</span>, a short hint
that appears as a tooltip or in the toolkit browser; <span
class="pcrr7t-">icon</span>, an
optional image file to be displayed in the menu next to the
text; and <span
class="pcrr7t-">action</span>, the function that is called when
the menu item is activated. <span
class="pcrr7t-">label </span>and <span
class="pcrr7t-">tooltip </span>are
constructor arguments for <span
class="pcrr7t-">Menu</span>.
<!--l. 1359--><p class="indent" > So for example:
<div class="verbatim" id="verbatim-85">
Wombat_find_item = class Menuitem
 <br />  "_Find Wombat"
 <br />  "analyse image and locate wombat" {
 <br />  icon = "nip-slider-16.png";
 <br />  action x = im_wombat_locate x;
 <br />}
</div>
<!--l. 1368--><p class="nopar" >
<!--l. 1370--><p class="noindent" >will appear as shown in Figure <a
href="#x44-820012">6.2<!--tex4ht:ref: fg:toolkit2 --></a>.
<!--l. 1373--><p class="indent" > <hr class="figure"><div class="figure"
>
<a
id="x44-820012"></a>
<div class="center"
>
<!--l. 1374--><p class="noindent" >
<!--l. 1374--><p class="noindent" ><img
src="figs/toolkit2.jpg" alt="PIC"
></div>
<br /> <div class="caption"
><span class="id">Figure 6.2: </span><span
class="content">How <span
class="pcrr7t-">Wombat</span><span
class="pcrr7t-">_find</span><span
class="pcrr7t-">_item </span>will look</span></div><!--tex4ht:label?: x44-820012 -->
<!--l. 1376--><p class="noindent" ><a name="nip_label_fg:toolkit2"></a>
<!--l. 1377--><p class="indent" > </div><hr class="endfigure">
<!--l. 1379--><p class="indent" > A dynamic pullright menu is a subclass of <span
class="pcrr7t-">Menupullright</span>.
It’s just like <span
class="pcrr7t-">Menuitem</span>, but without the need for an
<span
class="pcrr7t-">action </span>member. Any members which are subclasses
of <span
class="pcrr7t-">Menu </span>are displayed as items in the submenu. So
again:
<div class="verbatim" id="verbatim-86">
Wombat_item = class Menupullright
 <br />  "_Wombat"
 <br />  "wombat-related operations" {
 <br />  icon = "nip-slider-16.png";
 <br />  item1 = Wombat_find_item;
 <br />  sep = Menuseparator;
 <br />  boink = Wombat_find_item;
 <br />}
</div>
<!--l. 1393--><p class="nopar" >
<!--l. 1395--><p class="noindent" >will appear as shown in Figure <a
href="#x44-820023">6.3<!--tex4ht:ref: fg:toolkit3 --></a>.
<!--l. 1398--><p class="indent" > <hr class="figure"><div class="figure"
>
<a
id="x44-820023"></a>
<div class="center"
>
<!--l. 1399--><p class="noindent" >
<!--l. 1399--><p class="noindent" ><img
src="figs/toolkit3.jpg" alt="PIC"
></div>
<br /> <div class="caption"
><span class="id">Figure 6.3: </span><span
class="content">How <span
class="pcrr7t-">Wombat</span><span
class="pcrr7t-">_item </span>will look</span></div><!--tex4ht:label?: x44-820023 -->
<!--l. 1401--><p class="noindent" ><a name="nip_label_fg:toolkit3"></a>
<!--l. 1402--><p class="indent" > </div><hr class="endfigure">
<h4 class="subsectionHead"><span class="titlemark">6.12.2 </span> <a
id="x44-830006.12.2"></a>Workspaces</h4>
<!--l. 1405--><p class="noindent" ><a name="nip_label_sec:workspaces"></a>
<!--l. 1407--><p class="indent" > Definitions in workspaces are displayed with <span
class="pcrr7t-">nip2</span>’s
class browser. Each row is displayed in four main parts: a
button for the row name, a line of text, a set of sub-rows for
the members of the row’s class, and a graphic display
representing the row’s value. See Figure <a
href="#x44-830014">6.4<!--tex4ht:ref: fg:row2 --></a>.
<!--l. 1412--><p class="indent" > <hr class="figure"><div class="figure"
>
<a
id="x44-830014"></a>
<div class="center"
>
<!--l. 1413--><p class="noindent" >
<!--l. 1413--><p class="noindent" ><img
src="figs/ir8a.jpg" alt="PIC"
></div>
<br /> <div class="caption"
><span class="id">Figure 6.4: </span><span
class="content">Components of a workspace row</span></div><!--tex4ht:label?: x44-830014 -->
<!--l. 1415--><p class="noindent" ><a name="nip_label_fg:row2"></a>
<!--l. 1416--><p class="indent" > </div><hr class="endfigure">
<!--l. 1418--><p class="indent" > The text part of the right-hand-side of each row is always
displayed, but the sub-rows are only displayed if the row
represents a class, and the graphic is only displayed if the
class is an instance of one of the classes in Table <a
href="#x44-830025">6.5<!--tex4ht:ref: tb:classes --></a>. You
can subclass these if you want to use the graphic display in
your own widgets.
<!--l. 1424--><p class="indent" > There are three separate ways to set the value for a row.
You can edit the line of program text, you can edit one
of the members, or you can manipulate the graphic
representation (dragging a slider, or moving a region).
These can be contradictory, so <span
class="pcrr7t-">nip2 </span>resolves conflicts by
always applying changes in the order text, then graphic,
then member.
<!--l. 1430--><p class="indent" > When it applies a graphic change, <span
class="pcrr7t-">nip2 </span>rebuilds the
class using a class member called <span
class="ptmri7t-">class-name</span><span
class="pcrr7t-">_edit</span>, or if
that is not defined, the class’s constructor member. For
example, the <span
class="pcrr7t-">Colour </span>class can be defined as:
<div class="verbatim" id="verbatim-87">
Colour colour_space value = class {}
 <br />A1 = Colour "sRGB" [255,0,0];
</div>
<!--l. 1438--><p class="nopar" >
<!--l. 1440--><p class="noindent" >There are two ways to change <span
class="pcrr7t-">A1</span>. You can open <span
class="pcrr7t-">A1</span>
and change <span
class="pcrr7t-">colour</span><span
class="pcrr7t-">_space </span>to <span
class="pcrr7t-">"Lab"</span>, or you can
double-click on the swatch and drag the disc. When you
click <span
class="pcrr7t-">OK </span>on the colour edit dialog, <span
class="pcrr7t-">nip2 </span>searches for a
member called <span
class="pcrr7t-">Colour</span><span
class="pcrr7t-">_edit</span>, fails to find it, and so picks
the <span
class="pcrr7t-">Colour </span>member instead (the default constructor
generated by <span
class="pcrr7t-">nip2</span>). It then replaces the value of A1
with
<!--l. 1448--><p class="indent" > [needs finishing]
<!--l. 1451--><p class="indent" > <a
id="x44-830025"></a><hr class="float"><div class="float"
>
<div class="center"
>
<!--l. 1451--><p class="noindent" >
<div class="tabular"> <table id="TBL-7" class="tabular"
cellspacing="0" cellpadding="0" rules="groups"
><colgroup id="TBL-7-1g"><col
id="TBL-7-1"></colgroup><colgroup id="TBL-7-2g"><col
id="TBL-7-2"></colgroup><tr
class="hline"><td><hr></td><td><hr></td></tr><tr
style="vertical-align:baseline;" id="TBL-7-1-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-1-1"
class="td11">Class </td><td style="white-space:nowrap; text-align:left;" id="TBL-7-1-2"
class="td11">Description </td>
</tr><tr
class="hline"><td><hr></td><td><hr></td></tr><tr
style="vertical-align:baseline;" id="TBL-7-2-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-2-1"
class="td11"><span
class="pcrr7t-">Clock </span><span
class="pcrro7t-">interval value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-2-2"
class="td11">A clock widget, handy for animations </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-3-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-3-1"
class="td11"><span
class="pcrr7t-">Expression </span><span
class="pcrro7t-">caption expr </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-3-2"
class="td11">Displays an editable expression </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-4-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-4-1"
class="td11"><span
class="pcrr7t-">Group </span><span
class="pcrro7t-">value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-4-2"
class="td11">A group of objects for iteration </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-5-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-5-1"
class="td11"><span
class="pcrr7t-">List </span><span
class="pcrro7t-">value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-5-2"
class="td11">A list of related objects </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-6-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-6-1"
class="td11"><span
class="pcrr7t-">Pathname </span><span
class="pcrro7t-">caption value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-6-2"
class="td11">Displays a file browser </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-7-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-7-1"
class="td11"><span
class="pcrr7t-">Fontname </span><span
class="pcrro7t-">caption value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-7-2"
class="td11">Displays a font browser </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-8-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-8-1"
class="td11"><span
class="pcrr7t-">Toggle </span><span
class="pcrro7t-">caption value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-8-2"
class="td11">A toggle switch </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-9-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-9-1"
class="td11"><span
class="pcrr7t-">Scale </span><span
class="pcrro7t-">caption from to value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-9-2"
class="td11">A slider </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-10-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-10-1"
class="td11"><span
class="pcrr7t-">Option </span><span
class="pcrro7t-">caption labels value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-10-2"
class="td11">Select one item from a list </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-11-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-11-1"
class="td11"><span
class="pcrr7t-">Colour </span><span
class="pcrro7t-">colour</span><span
class="pcrro7t-">_space value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-11-2"
class="td11">A patch of colour </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-12-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-12-1"
class="td11"><span
class="pcrr7t-">Matrix</span><span
class="pcrr7t-">_vips </span><span
class="pcrro7t-">value scale offset filename display</span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-12-2"
class="td11">A matrix </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-13-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-13-1"
class="td11"><span
class="pcrr7t-">Arrow </span><span
class="pcrro7t-">image left top width height </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-13-2"
class="td11">Two points joined by a line on an image</td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-14-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-14-1"
class="td11"><span
class="pcrr7t-">Region </span><span
class="pcrro7t-">image left top width height </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-14-2"
class="td11">A sub-area of an image </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-15-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-15-1"
class="td11"><span
class="pcrr7t-">Plot </span><span
class="pcrro7t-">options value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-15-2"
class="td11">Displays a plot widget </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-16-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-16-1"
class="td11"><span
class="pcrr7t-">Image </span><span
class="pcrro7t-">value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-16-2"
class="td11">An image </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-17-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-17-1"
class="td11"><span
class="pcrr7t-">Number </span><span
class="pcrro7t-">caption value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-17-2"
class="td11">Displays an editable number </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-18-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-18-1"
class="td11"><span
class="pcrr7t-">Real </span><span
class="pcrro7t-">value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-18-2"
class="td11">Displays a real number </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-19-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-19-1"
class="td11"><span
class="pcrr7t-">Vector </span><span
class="pcrro7t-">value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-19-2"
class="td11">Displays a list of reals </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-20-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-20-1"
class="td11"><span
class="pcrr7t-">String </span><span
class="pcrro7t-">caption value </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-20-2"
class="td11">Displays an editable string </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-21-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-21-1"
class="td11"><span
class="pcrr7t-">Mark </span><span
class="pcrro7t-">image left top </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-21-2"
class="td11">A point on an image </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-22-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-22-1"
class="td11"><span
class="pcrr7t-">HGuide </span><span
class="pcrro7t-">image top </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-22-2"
class="td11">A horizontal line on an image </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-23-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-23-1"
class="td11"><span
class="pcrr7t-">VGuide </span><span
class="pcrro7t-">image left </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-23-2"
class="td11">A vertical line on an image </td>
</tr><tr
style="vertical-align:baseline;" id="TBL-7-24-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-24-1"
class="td11"><span
class="pcrr7t-">Area </span><span
class="pcrro7t-">image left top width height </span></td><td style="white-space:nowrap; text-align:left;" id="TBL-7-24-2"
class="td11">A sub-area of an image, fixed in size </td>
</tr><tr
class="hline"><td><hr></td><td><hr></td></tr><tr
style="vertical-align:baseline;" id="TBL-7-25-"><td style="white-space:nowrap; text-align:left;" id="TBL-7-25-1"
class="td11"> </td></tr></table></div></div>
<br /><div class="caption"
><span class="id">Table 6.5: </span><span
class="content"><span
class="pcrr7t-">nip2 </span>built in graphic classes</span></div><!--tex4ht:label?: x44-830025 -->
<!--l. 1507--><p class="noindent" ><a name="nip_label_tb:classes"></a>
</div><hr class="endfloat" />
<h4 class="subsectionHead"><span class="titlemark">6.12.3 </span> <a
id="x44-840006.12.3"></a>The <span
class="pcrr7t-">Image </span>class</h4>
<!--l. 1511--><p class="noindent" ><a name="nip_label_sec:Image"></a> .
<!--l. 1513--><p class="indent" > say supports mioxed ops with real, vector and complex
constants
<!--l. 1515--><p class="noindent" >
<h4 class="subsectionHead"><span class="titlemark">6.12.4 </span> <a
id="x44-850006.12.4"></a>The <span
class="pcrr7t-">Colour </span>class</h4>
<!--l. 1516--><p class="noindent" ><a name="nip_label_sec:colour"></a>
<!--l. 1518--><p class="indent" > This class displays a swatch of colour. If you double-click
on the
<div class="verbatim" id="verbatim-88">
Pathname caption value = class {}
</div>
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