sane-project-website/old-archive/1998-04/0278.html

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<title>sane-devel: Two *other* problems with xscanimage</title>
<h1>Two *other* problems with xscanimage</h1>
<b>Matto Marjanovic</b> (<a href="mailto:maddog@mir.com"><i>maddog@mir.com</i></a>)<br>
<i>Sun, 26 Apr 1998 11:59:42 -0400 (EDT)</i>
<p>
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Here are two bugs that have cropped up with xscanimage, something new to<br>
 chew on.  Someone else with more (i.e. any) experience with GTK+ may see<br>
 the solutions quicker than me, otherwise I'll keep plugging away.<br>
<p>
(Environment:  SANE-0.72, GTK 1.0.0 from Debian(2.0) package, glibc, and<br>
                last-but-not-least, GNU make)<br>
<p>
<p>
a)  ___Closing the Preview Window (by any means) causes a segfault.___<br>
    The segfault is correlated with the call to "gtk_widget_destroy (p-&gt;top)"<br>
     in preview_destroy() in frontend/preview.c.<br>
<p>
b)  ___Gamma Curve data is corrupted.___<br>
    When turning on table-based gamma correction (and thus instantiating the<br>
    gamma curve widget), the following happen:<br>
      o correct values are read from the (microtek) backend, so far so good.<br>
      o immediately after the call to gtk_curve_set_gamma in curve_new(),<br>
         a call to gtk_curve_get_gamma reveals the correct values were <br>
	 written to the widget.<br>
      o sometime later (when the event loop updates/displays the widget, I<br>
         imagine), xscanimage declares<br>
<p>
** WARNING **: file gdkdraw.c: line 375 (gdk_draw_points): "(points != NULL) &amp;&amp; (npoints &gt; 0)"<br>
<p>
         and the curve is drawn (very) incorrectly.<br>
      o the values read out from the widget when it is time to send to the<br>
         backend are very *wrong* -- always a couple of continuous sequences<br>
	 of the same number (i.e. many 8501's, followed by many 85's, etc --<br>
	 note that some are simply out of range).<br>
<p>
      o AND, this problem only appears for the grayscale or red plane gamma<br>
         curves, not the green or blue (when unbound gamma is selected).<br>
<p>
    It looks like some kind of memory allocation problem to me; perhaps a bug<br>
    crept into the 1.0.0 release of the gamma curve widget?<br>
<p>
c) Bonus Bug:  The preview selection box doesn't move around any more in <br>
   reponse to moving the geometry sliders.  I believe it used to, and there<br>
   is also a ChangeLog entry (1998-04-02) saying this behavior was fixed.<br>
<p>
d) Bonus Bug Fix:  The error message for the "-g" option when there is no<br>
   GIMP support does not get printed.  Here is a small patch to fix this:<br>
<p>
<p>
--- xscanimage.c-dist	Sun Apr 26 11:46:31 1998<br>
+++ xscanimage.c	Sun Apr 26 11:50:29 1998<br>
@@ -1623,12 +1623,12 @@<br>
       static const SANE_Device *device_list[] = { &amp;dev, 0 };<br>
       int ch;<br>
 <br>
-      while ((ch = getopt_long (argc, argv, "hV", long_options, 0)) != EOF)<br>
+      while ((ch = getopt_long (argc, argv, "ghV", long_options, 0)) != EOF)<br>
 	{<br>
 	  switch (ch)<br>
 	    {<br>
 	    case 'g':<br>
-	      printf ("%s: GIMP support missing.", argv[0]);<br>
+	      printf ("%s: GIMP support missing.\n", argv[0]);<br>
 	      exit (0);<br>
 <br>
 	    case 'V':<br>
<p>
<p>
<p>
That's it for now; time to get some sun!<br>
-matt m.<br>
<p>
<pre>
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</pre>
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<ul>
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<li> <b>Next message:</b> <a href="0279.html">Oliver.Rauch@Wolfsburg.DE: "Re: gtk_tooltips"</a>
<li> <b>Previous message:</b> <a href="0277.html">hopp@darkstar.fact.rhein-ruhr.de: "Re[2]: gtk_tooltips"</a>
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<li> <b>Next in thread:</b> <a href="0281.html">Oliver.Rauch@Wolfsburg.DE: "Re: Two *other* problems with xscanimage"</a>
<li> <b>Reply:</b> <a href="0281.html">Oliver.Rauch@Wolfsburg.DE: "Re: Two *other* problems with xscanimage"</a>
<li> <b>Reply:</b> <a href="0304.html">Matto Marjanovic: "Re: Two *other* problems with xscanimage"</a>
<li> <b>Reply:</b> <a href="0306.html">Matto Marjanovic: "Re: Two *other* problems with xscanimage"</a>
<li> <b>Reply:</b> <a href="0308.html">Matto Marjanovic: "Re: Two *other* problems with xscanimage"</a>
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