GDS II Viewer Documentation

Joacim Haglund

Contents

• Introduction
• Usage
• Commands
• Bugs

Introduction

This is a simple viewer for the ``Stream Format'' for CALMA GDSII CAD libraries (``GDS II'', ``.gds'' or ``.sf'') with a couple of limitations (see the Bugs section). The main functionality is viewing the library layers with different colors and to export the view to different image formats.

Usage

You start the program by executing 'simplegdsview'.

Some settings can be changed by editing ~/simplegdsview.cfg, which is self-explanatory ;-). The first time you start the program, you can choose to create it from the default settings. You can also change the settings by saving the changes you make during use of the program with the Save Settings button.

Commands

These are the things you can do with the program:

• Menu Bar:
  • File is a pull-down menu with the commands:
    • Open (Alt+o) lets you load a new GDSII library.

    • Save Image lets you choose a graphics file format and a file to store the currently viewed image in.

    • Print (Alt+p) is a (not so flexible) way to send the image directly to a printer. You should almost certainly save your image in your favourite format and use a graphics image tool for this instead. Or, even better, use the ``Postscript Export''

    • Postscript Export lets you export the library to postscript for printing in vector format with controlled scale. The polygons are filled/ outlined with the colour from the layer settings. Only the layers currently ``On'' are exported. (These things are good to know in advance if you plan to make a cheap-ass photo-mask with your printer on OH-foil.) In other words, you can manipulate which layers are exported (through the ``Layers'' dialogue) and the ``filling'' of polygons but not the ``filling'' of paths.

    • Quit (Alt+q) ends the program.

  • Control Pad (Alt+c) shows the ``Control Pad'' window (below).

  • Settings (Alt+s) starts the ``Viewer Settings'' dialogue with the current settings (below). If the dialogue is open (visible) the settings in the dialogue are discarded and the current viewer settings are loaded instead.

  • Layers (Alt+l) shows the ``Layers'' dialogue (below).

  • Help sends a command to start up a browser to view this file. You can change the command with ``Help Browser'' in the ``Settings'' dialogue.

• The Control Pad window:
  • In the Current Structure ``list-box'' you can select the current structure to view from the library.

  • Direction buttons move the window 1/4 of the currently viewed area in their respective direction (over the CAD -- think of it as a camera over a map).

  • The Home button moves the window to the center of the current structure and re-scales to fit it within the window.

  • The Magnification slider shows/ changes the magnification. In addition to using the ``pointing device'', the magnification can also be changed in tiny steps with the arrow keys. PgUp/ PgDn changes it in larger steps. (You might need to press ``tab'' to ``focus'' the slider before using the keys, though.)

  • Instant Redraws toggles whether a change in the settings should cause a redraw (see (Redraw).

  • Draw Layers Ordered toggles whether drawing should be done in the order specified in ``Layers'' Dialogue (below) or structure-by-structure (which is at least 20-30% faster). Initiates a redraw (see Redraw above).

  • Redraw causes the image to be updated using the current settings. Executing this is a complete waste of time if ``Instant Redraws'' is on.

• The Settings dialogue:
  • The Save Settings button saves the current state to ~/simplegdsview.cfg.

  • The Load Settings button loads settings from ~/simplegdsview.cfg. This can be handy if you want to change settings by editing that text-file instead of using the GUI. It might be that some settings can only be changed there too...

  • The Background button lets you change the color of the background.

  • The Help Browser button is for changing the command to start a browser to view this file (by pressing ``Help'' (above). Usually it's enough to just state the name of the executable (e.g. 'netscape'), but some browsers might work (better) if some switches are specified.

  • The OK button applies the settings from the dialogue and hides it.

  • The Apply button applies the settings from the dialogue but leaves it visible.

  • The Cancel button discards the setings in the dialogue and hides it.

• The Layers dialogue:
  • The All Layers On button turns on drawing for all layers that have ``elements'' in the currently viewed ``structure'' (or possibly the whole library -- not entirely sure).

  • The All Layers Off button turns off drawing for all layers.

  • The GDS II Layer list-box shoes the current settings for each layer. The order in the list is used when ``Draw Layers Ordered'' drawing layers from bottom to top of the list.

  • The Layer On button turns drawing of the current layer on.

  • The Layer Off button turns drawing of the current layer off.

  • The Fill/ Outline-toggle decides whether polygons (BOUNDARY-elements) in the current layer should be filled or outlined when drawing. (Wires (PATH-elements) are always ``filled''.)

  • The Colour button lets you change the color of the current layer.

• ``Keys'' in the main window (These do the same as the buttons in the ``Controls'' window):
  • ``Arrow keys'' move the window 1/4 of the currently viewed area in their respective direction (over the CAD -- think of it as a camera over a map).

  • Home moves the window to the center of the current structure and re-scales to fit it within the window.

• ``Mouse'' or other ``pointing devices'':
  • ``Left-Click'' moves the center of the window to the clicked position.

  • ``Left-Drag'' zooms the window to the region defined by the rectangle ``Drag-Start'' .. ``Drag-Stop''.

  • ``Right-Click'' measures the distance defined by the first click and the next. When the second ``right-click'' has been received a message box is displayed with the distance.

Bugs

• Too slow! But this is (afaik) the penalty for using Qt's windowing widgets for X rather naively. I believe they are intended for GUI-graphics and not this type of demanding graphics applications. There may be some stupid things in the code too. ;-) The use of virtual methods...

• Paths are always filled (even when ``Fill Polygons'' is off for the layer). The penalty for using Qt::QPainter::drawPolyline() instead of converting it to a polygon (which can be a bit of a hassle)...

• There is a lot of stuff in the GDS II-format that isn't implemented. Some examples are:
  • Drawing of TEXT elements and all that comes with it.
  • Absolute magnification, absolute rotation and absolute reflection (i.e. everything in STRANS except reflection). Negative value of WIDTH as absolute width. I really don't see the point of these anyway - Don't use them!
  • Rounded PATH-ends will not influence PATH-corners. I don't know if this is according to the standard or not. I have seen both implementations in other software and can't find any decisive answer in the spec. I have.

  • REFLIBS.

• Structures with coordinates far apart compared to the viewing window may be misrepresented due to coarse rounding for X's 16bit coordinates.

• Zooming and measuring lacks those nice help-lines other programs have. It is especially a drawback for the ``measure'' functionality, because a click is not registered if the mouse moves (ever so slightly) when clicking and there is no feedback of this (not happening) to the user until the next click, when the user expects the second measurement point but is actually only registering the first.

About this document ...

GDS II Viewer Documentation

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