gui-examples.ht

Title: Graphical User Interface Examples

<h1>PyQwt Graphical User Interface Examples</h1>

<p>(Py)Qt is a huge library offering many programming idioms to the user.
  You should check out Mark Summerfeld's
  "Rapid GUI Programming with Python and Qt" <a href=
  "http://www.qtrac.eu/pyqtbook.html">paper book</a> when you intend to do
  serious PyQt and PyQwt programming.
  The
  <a href="http://www.riverbankcomputing.com/Docs/PyQt4/pyqt4ref.html">
    PyQt v4 documentation</a>
  may be sufficient for experienced Qt programmers with some Python knowledge.
  A cheap and nowadays outdated start for newbies is Boudewijn Rempt's
  "GUI Programming with Python Using the Qt Toolkit"
  <a href="http://www.commandprompt.com/community/pyqt/">online book</a>.
</p>

<p> The examples below demonstrate some intermediate programming techniques
  specific to (Py)Qwt.
  The most advanced examples are based on subclassing of the
  <tt class="class">QwtPlotItem</tt>, <tt class="class">QwtPlotCurve</tt>, and
  <tt class="class">QwtData</tt> classes.
</p>


<h5><a href="examples/BarPlotDemo.py.html">BarPlotDemo.py</a> demonstrates</h5>
<ul>
  <li>
    how to enable plot cursor tracking by the <tt class="class">Spy</tt> class,
    a subclass of <tt class="class">QObject</tt> that implements event
    filtering.
  </li>
  <li>
    how to program <tt class="class">QwtBarCurve</tt> to plot bars.
    <tt class="class">QwtBarCurve</tt> is a subclass of
    <tt class="class">QwtPlotCurve</tt>.
  </li>
  <li>
    how to use a <tt class="class">QwtCounter</tt> instance to control the
    number of bars to display.
  </li>
  <li>
    how to use <tt class="class">QComboBox</tt> instances to control outline
    and fill colors of the bars.
  </li>
  <li>
    how to use <tt class="class">QwtPlotZoomer</tt>.
  </li>
  <li>
    how to configure the <tt class="class">QwtPlotZoomer</tt> by attaching
   different sets of mouse events to different zoomer actions.
  </li>
</ul>

<p><img alt="BarPlotDemo Widget" src="examples/BarPlotDemo.png"
        width=500 height=500 border=1></p>


<h5><a href="examples/BodeDemo.py.html">BodeDemo.py</a> demonstrates</h5>
<ul>
  <li>
    improved rendering of scientific formula's by a combination of rich text
    and unicode.
  </li>
  <li>
    how to customize printing by derivation from
    <tt class="class">QwtPlotPrintFilter</tt>.    
  </li>
  <li>
    how to zoom on more than two scales. 
  </li>
</ul>

<p><img alt="BodeDemo Widget" src="examples/BodeDemo.png"
        width=540 height=468 border=1>
</p>

<p>Note:
<ol>
  <li>
    this example requires a font with some unicode support such as the
    <a href="http://corefonts.sourceforge.net">MicroSoft TrueType Core Fonts</a>
  </li>
  <li>
    the Verdana font is the best MicroSoft TrueType Core Font.
  </li>
  <li>
    use as much unicode as possible (get or buy a real unicode font).
  </li>
  <li>
    fall back on rich text if a requested glyph is missing from the font
    (sub-scripts are missing from the MicroSoft TrueType Core fonts).
  </li>
</ol> 
</p>


<h5><a href="examples/CartesianDemo.py.html">CartesianDemo.py</a>
  demonstates</h5>
<ul>
  <li>
    how to subclass <tt class="class">QwtPlotItem</tt> so that it uses a
    <tt class="class">QwtScaleDraw</tt> to draw itself
  </li>
  <li>
    how to piggy-back on the <tt class="class">QwtScaleDiv</tt> of a hidden
    axis 
  </li>
  <li>
    how to place the axes as in this
    <a href="http://en.wikipedia.org/wiki/Image:Cartesian-coordinate-system.svg">
      example</a>
  </li>
</ul>

<p><img alt="CartesianDemo Widget" src="examples/CartesianDemo.png"
        width=400 height=300 border=1>
</p>


<h5><a href="examples/DataDemo.py.html">DataDemo.py</a> demonstrates</h5>
<ul>
  <li>
    how to use <tt class="class">QwtPlot</tt>.
  </li>
  <li>
    how to produce timer events.
  </li>
  <li>
    how to handle timer events by reimplementing
    <tt class="function">QObject.timerEvent()</tt>.
  </li>
</ul>

<p><img alt="DataPlotDemo Widget" src="examples/DataDemo.png"
        width=500 height=300 border=1>
</p>


<h5><a href="examples/ErrorBarDemo.py.html">ErrorBarDemo.py</a> demonstrates
</h5>

<ul>
  <li>
    how to implement a subclass of <tt class="class">QwtPlotCurve</tt> which
    has error bars in either no, or the x-, or the y-, or both directions. 
  </li>
  <li>
    how to make autoscaling take account of the error bars by reimplementing
    <tt class="function">QwtCurve.boundingRect()</tt>.
  </li>
</ul>

<p><img alt="ErrorBarDemo Widget" src="examples/ErrorBarDemo.png"
        width=400 height=300 border=1>
</p>


<h5><a href="examples/MaskedDataDemo.py.html">MaskedDataDemo.py</a> demonstrates
</h5>

<ul>
  <li>
    how to plot masked data by subclassing <tt class="class">QwtData</tt> and
    <tt class="class">QwtPlotCurve</tt>.
  </li>
  <li>
    how to plot several valid chunks of masked data by subclassing
    <tt class="class">QwtPlotCurve</tt> and reimplementing
    <tt class="function">QwtPlotCurve.draw()</tt>.
  </li>
  <li>
    how to make autoscaling take account of the mask by subclassing
    <tt class="class">QwtData</tt> and reimplementing
    <tt class="function">QwtData.boundingRect()</tt>.
  </li>
  <li>
    how to plot y = 1/sin(x) for -3 < y < 3 and -6 < x < 6.
  </li>
</ul>

<p><img alt="MaskedDataDemo Widget" src="examples/MaskedDataDemo.png"
        width=500 height=300 border=1>
</p>


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