| FreePCB User Guide | Version 1.2

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5. PCB Layout (continued)

5.6 Function Key and Context Menus

Most Windows drawing programs make heavy use of "click-dragging" with the mouse for editing. This means holding the left mouse button down while moving the mouse. For example, the user may move an item by click-dragging it to a new position. An item may be resized by clicking on it, which brings up a selection box with "handles", which may then be click-dragged to stretch or shrink the item. The endpoints of lines may be click-dragged to new positions, etc., etc.

However, click-dragging doesn't work very well for routing traces, which is the most time-consuming part of PCB layout. Traces are basically polylines, consisting of multiple connected line segments. Placing each segment requires a separate mouse-click, which implies that the segments must be dragged without holding the mouse button down.

Also, while routing traces or placing parts, it is useful to be able to pan and zoom, which I like to do with the scroll wheel on the mouse. It is very difficult to use the scroll wheel while simultaneously holding down a mouse button.

Therefore, FreePCB uses a slightly different approach. Generally, an item will be selected by clicking on it. This will highlight the item, to indicate that it has been selected, and a description of the item will appear on the status bar. An editing operation can then be performed by pressing a function-key on the keyboard. The operations assigned to each function-key are always listed across the bottom of the FreePCB window. This list is context-sensitive, and will change depending on which item has been selected. For example, the menu when a part is selected is shown below.

If the operation requires dragging, this will commence as soon as the function-key is pressed. The operation is usually completed by left-clicking the mouse, or it can be cancelled by right-clicking. While dragging, the function-keys remain active, so that additional operations can be performed. For example, while dragging a part, pressing F3 will rotate it, while pressing F2 will flip it to the opposite side of the board.

This style of user interface requires that you keep your left hand on the keyboard and your right hand on the mouse while editing (assuming that you are right-handed). In the days of DOS, many CAD programs used this style, and some still do. If you have any doubt about the speed and efficiency of the "left hand on keyboard, right hand on mouse" approach, just spend a few minutes watching someone play one of the popular first-person shooter games for the PC, such as Doom, Quake, Unreal Tournament, Half-life, Tribes, etc. They ALL use this style of user interface. And routing a PCB is usually easier than circle-strafing a horde of rampaging Nazi mutants while dodging flying chainsaws in zero-G!

The assignment of editing operations to the function keys is not completely random, as it might first appear. Since the fingers of the left hand will normally rest on keys F1-F4, these are used for the primary editing operations. F4 (under the index finger) is used for the most common operation on the selected item (such as moving a part), while F2-F3 are used for less common operations. F1 is often used to pop up some sort of dialog to edit the properties of the selected item. The keys F5-F7 are usually used for deleting or unrouting, since they require moving the hand and are less likely to be hit accidentally. F8 is reserved for recalculating ratlines. This arrangement is obviously optimized for users who are right-handed (like me). I expect to add a "left-handed" option in the future.

If you prefer not to use the function keys, right-clicking the mouse will pop up a more traditional Windows menu, as shown below. This is called the "context menu".

The context menu is not available while you are dragging an item with the mouse, so function keys must be used to perform operations while dragging.

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