fped/gui.html

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<TITLE>Fped GUI Manual</TITLE>
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<H1>Fped GUI Manual</H1>

This manual introduces the basic concepts of Fped and explains the elements
of the graphical user interface. Please refer to the file 
<A href="README">README</A> for more
technical details and a discussion of the scripting language used by fped.


<H1>Objects and instances</H1>

Footprints tend to be highly repetitive, with many pads placed in a
simple geometrical pattern. With fped, the user specifies the elements
to repeat and the way they are repeated. Fped then generates the
repetitions automatically.

<H2>Hands-on example</H2>
<P>
Here is a simple example that illustrated the basic steps of constructing
things with fled:
<UL>
  <LI> Start fped without a command-line argument.
  <LI> Right-click on the yellow field that says "(root)" and select
    "Add loop". An entry saying "_ = 0 ... 0 (0)" appears next to the
    yellow field.
    <P><IMG src="manual/intro-1.png">
  <LI> Click on the underscore, type <B>n=1,5</B> and press Enter.
    The entry should now show "n = 1 ... 5 (1 2 3 4 5)"
    <P><IMG src="manual/intro-2.png">
  <LI> Click on the dark-yellow vector icon on the right-hand side.
    A red frame shows that it is selected.
  <LI> Move the mouse pointer to the green dot in the middle of the
    black canvas. A red circle appears when the pointer is over the
    dot.
  <LI> Press the left mouse button, drag a little to the right, and
    release the mouse button. A white line appears and changes
    to dark yellow after the button is released.
  <LI> Click on the yellow line. It is now shown in bright yellow and
    a number of text entry fields appear below the canvas.
    <P><IMG src="manual/intro-3.png">
  <LI> Click into the field on the top that probably says "0.1mm",
    change it to <B>n*1mm</B> and press Enter.
  <LI> Select "Zoom all" from the "View" drop-down menu. The canvas
    should now show the green dot on the left, with a yellow arrow
    pointing to the right, and four more even darker arrows following
    that arrow.
    <P><IMG src="manual/intro-4.png">
  <LI> Click on the icon depicting a light-blue circle.
  <LI> Move the mouse pointer over the green dot, then drag to the
    circle at the end of the vector, and release the mouse button.
    A series of partial circles should appear.
    <P><IMG src="manual/intro-5.png">
  <LI> Select "Zoom all" again to show the full circles.
    <P><IMG src="manual/intro-6.png">
</UL>
The graphical items you have entered are a vector and a circle with the
radius determined by the vector. We call these items "objects". Furthermore,
you have defined a variable that gets set to the values from 1 to 5, in
increments of one. Fped had repeatedly drawn the objects for each such
value. We call the item that have been drawn "instances".
<P>
The innermost vector and circle are highlighted. You can highlight other
instances of the same objects by clicking on the numbers (1 2 3 4 5) shown
next to the loop.

<H2>Conceptual view</H2>
The following picture illustrates the concept: the model is defined in
terms of objects, in this case a vector from the origin to the circle's
center, a vector for the radius, and the circle itself.
<P>
<IMG src="manual/concept-inst.png">
<P>
The vector to the center uses a variable that gets iterated through the
values 0, 1, and 2. For each iteration, an instance is generated.
<P>
Only the instances of silk screen objects and pads are exported to KiCad.
Elements used for construction, such as vectors, only appear in fped.


<H1>Frames</H1>

Frames serve various purposes:
<UL>
  <LI> To structure the footprint drawing by grouping like elements.
    For example, one may want to place pads, outline, and the keep-out
    area in different frames, and probably subdivide some of those 
    constructs even further.
  <LI> To define an element that is used in several places. For example,
    a pad.
  <LI> To define a repetition through a loop or a table.
  <LI> To set variables for child frames. 
</UL>

At the bottom of the hierarchy, we have the root frame. To add another
frame, right-click on the root frame's label "(root)" and select "Add
frame".
<P>
To be able to put items into the new frame, it has to be attached to
the root frame (or to any other frame that's attached). This is called a
<I>frame reference</I>. First, we need a place to attach it to. This
can be the origin of its parent frame or it can be the end of a vector
in the parent frame. To create the frame reference, do this:
<P>
<UL>
  <LI> Click on the parent frame to select it.
  <LI> Press the left mouse button on the frame you wish to reference
    and drag it (move the mouse pointer while keeping the left button
    pressed) into the canvas. When dragging, the mouse cursor changes
    to show a hand.
  <LI> When the mouse pointer is above a suitable point of attachment,
    the point of attachment is highlighted with a red circle and the
    mouse cursor changes to show a hand with a plus sign.
  <LI> At the desired location, release the mouse button.
</UL>

If you wish to cancel the operation, simply release the mouse button at
any place that isn't a point of attachment.


<H1>Variables</H1>


<H1>Iconography</H1>

The right-hand side of the fped window shows the component being drawn on a
black background. We call this the canvas. It is surrounded by a toolbar on
the right side and a few buttons with visibility options at the top.


<H2>The canvas</H2>


<H2>Blue screen</H2>

When an expression uses an unknown variable or evaluates to an incorrect
value (e.g., a bare number where a dimension is expected), the
instantiation fails. Fped indicates this by changing the background color
of the canvas from black to blue. The cause of the failure is explained
in the status bar at the bottom.
<P>
In this state, the canvas is no longer updated when making changes until
the problem has been resolved. The most common causes are a misspelt
variable name in an expression, the use of a number without unit where a
dimension is expected, or the removal of a variable that's still used
somewhere.
<P>
If the location of the error is not obvious, the list of objects can be
shown by selecting "Swap var&amp;code" from the View menu. The object
in which the error occurred is shown in red. If the error occurred in a
loop variable, the variable name is shown in red.


<H2>Visibility options</H2>

When working on a complex component, the number of elements shown can be
overwhelming. The visibility options help to quickly hide irrelevant
details and get one's bearings. They are located in the menu bar at the
top.
<DL>
  <DT><IMG src="manual/all.png">&nbsp;<IMG src="manual/all_off.png"> 
  <DD>Show all frames. If disabled, only show the currently active frame.
  <DT><IMG src="manual/stuff.png">&nbsp;<IMG src="manual/stuff_off.png">
  <DD>Show vectors and frames.
  <DT><IMG src="manual/meas.png">&nbsp;<IMG src="manual/meas_off.png">
  <DD>Show measurements.
  <DT><IMG src="manual/bright.png">&nbsp;<IMG src="manual/bright_off.png">
  <DD>Highlight the elements that will be exported to KiCad, i.e.,
    the pads and the silk screen drawings. To show the component
    exactly as it will appear in KiCad, also turn off vectors,
    frames, and measurements.
</DL>
The visibility options can be combined.


<H2>Tools</H2>

Tools are used to add new elements and to manipulate existing ones.
<DL>
  <DT><IMG src="manual/point.png">
  <DD> The pointer. This is the default tool. The pointer is used to
    select items and do move points of the selected item.
    <P>
    Clicking on an item selects it. If items overlap, the one with the
    highest priority is selected. The priority is based on how difficult
    it usually is to select an item, with frame references having a low
    priority, pads, circles, arcs, rectangles, measurements, and lines
    having increasingly higher priorities. There are a few special cases:
    <UL>
      <LI> The circle at the end of a vector has the highest priority
	while its line has the lowest priority.
      <LI> To select a frame reference, click on the L-shaped upper left
        corner.
      <LI> To select a measurement, click on the line with the text, not
	the (hypothetical) line connecting the points being measured.
    </UL>
    If multiple items are under the mouse pointer, repeatedly clicking
    iterates through them.
    <P>
    To move points, select the item, then move the mouse pointer over
    the point to move. A red circle will appear under the mouse pointer.
    Then drag the point to its new location and release the mouse button.
  <DT><IMG src="manual/delete.png">&nbsp;<IMG src="manual/delete_off.png">
  <DD> Delete the currently selected item. Whenever an item is selected,
    the delete icon lights up. Clicking the icon deletes the item.
    To undelete the item, press <B>U</B>.
  <DT><IMG src="manual/vec.png">
  <DD> Add a vector. To add a new vector, move the mouse pointer to the
    new vector's starting point then drag towards the desired end point.
    Vectors are normally specified via parameters. To enter the parameters,
    click on the new vector.
    <P>
    Note that the starting point of the vector has to be in the same
    frame as the vector being drawn. This limitation also applies to
    points defining pads and silk-screen items.
  <DT><IMG src="manual/pad.png">&nbsp;<IMG src="manual/rpad.png">
  <DD> Add a pad. Pads are either rectangular or rounded. They are
    defined by two points which are opposite corners of the rectangle
    containing the pad. Move the mouse cursor to the first point, then
    drag to the second point. The pad's name can be edited after selecting
    the pad.
  <DT><IMG src="manual/line.png">&nbsp;<IMG src="manual/rect.png">
  <DD> Add a line or a rectangle. Similar to pads, lines and rectangles
    are defined by two points. The width of the line can be edited after
    selecting the line or rectangle.
  <DT><IMG src="manual/circ.png">
  <DD> Add circle or arc. Circles are defined by their center end a
    point at their radius. An arc has a third point, which defines the
    angle at which the arc ends. If this third point is not located on
    the radius, the arc ends where an imaginary line between the center
    and the end point would intersect with the radius.
    <P>
    An arc is made by first drawing a circle with the radius point at
    the location where the arc should start. Then click and hold the
    radius point to drag the end point to the desired location.
    <P>
    To change the radius point of a circle, first drag the end point,
    then drag the radius point itself to that same location.
  <DT><IMG src="manual/meas.png">&nbsp;<IMG src="manual/meas_x.png">&nbsp;
    <IMG src="manual/meas_y.png">
  <DD> Add a measurement. Measurements show the distance between points.
    They can either measure diagonally or only horizontally or only vertically.
    Unlike other items, measurements are not limited to points in the same
    frame. Instead, they operate on the minimum, maximum, and next greater
    coordinates of instances of objects.
    <P>
    A measurement is added as follows:
    <UL>
      <LI> Click on one of the three measurement icons to select the 
	measurement type. All possible endpoints are highlighted.
      <LI> Drag from the desired starting point. Now all the endpoints
	available for this starting point are highlighted.
      <LI> Drag to the endpoint and release the mouse button. The measurement
	will now appear as a double-headed arrow and text between the two
	points (if this is a diagonal measurement) or extending vertically or
	horizontally from one of the two points.
      <LI> To move the measurement arrow away from the two points, select
	the measurement and set an offset.
    </UL>
    Sometimes, the second point becomes unavailable after selecting the
    first point. This means that the two points are not a minimum or maximum,
    or a minimum and the next greater neighbour. In this case, just try
    another pair of points measuring the same distance.
</DL>


<H1>Keyboard shortcuts</H1>

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