Bug 95020

Summary: invisible curves when width != 0 or type != solid
Product: [Applications] kst Reporter: Nicolas Brisset <nicolas.brisset>
Component: generalAssignee: kst
Status: RESOLVED FIXED    
Severity: normal    
Priority: NOR    
Version: 1.x   
Target Milestone: ---   
Platform: unspecified   
OS: Linux   
Latest Commit: Version Fixed In:
Attachments: testcase for a non-steady curve

Description Nicolas Brisset 2004-12-12 22:16:42 UTC 
Version:           1.1.0_devel (using KDE 3.2 BRANCH >= 20040204, Mandrake Linux Cooker i586 - Cooker)
Compiler:          gcc version 3.3.2 (Mandrake Linux 10.0 3.3.2-6mdk)
OS:                Linux (i686) release 2.6.3-7mdk

When you draw curves with a width > 0 or a type different from the default solid line they are not always visible !

To reproduce:
1. Create a text file containing 50 lines with a '0' in each
2. Plot the 1st column against INDEX with the data wizard: it works
3. Edit curve attributes (contextual menu) and set width to 1
4. Notice the curve has disappeared. If you zoom in with the mouse, chances are you'll see it, but not with key accelerators (Shift+Down). Intriguing, isn't it ? 

Notes:
- it is apparently not linked with grid lines
- in some cases where values are not steady, parts of the curve are also missing. It is hopefully all the same bug. To check, use the data file I'll append to the bug report (width set to 1 gives a strange curve).
Comment 1 Nicolas Brisset 2004-12-12 22:18:00 UTC 
Created attachment 8642 [details]
testcase for a non-steady curve
Comment 2 Andrew Walker 2004-12-13 02:30:54 UTC 
It seems that after changing the curve properties the curve is not updated. 
If you resize the window the plot is in then the curve correctly updates and
all appears well.
Comment 3 Nicolas Brisset 2004-12-14 00:04:29 UTC 
Resizing does not change anything here on those curves where the problem happens. By the way, it seems to always happen when variations are small or null (i.e. in those parts corresponding to more or less steady values). I hope that's a hint ?
Comment 4 Netterfield 2004-12-14 06:16:41 UTC 
CVS commit by netterfield: 

BUG: 95020
when more than one data point lies in a pixel, a vertical line is drawn
in that pixel, from the min to max point in the pixel.  If ymin==ymax,
then the line is of zero length.  With linewidth!=0, a 0 length line draws
nothing.  Hence, no line.

This adds linewidth to the length of the vertical line - so something always
gets drawn.


  M +8 -3      kst2dplot.cpp   1.319


--- kdeextragear-2/kst/kst/kst2dplot.cpp  #1.318:1.319
@@ -5093,7 +5093,10 @@ void Kst2DPlot::plotCurves(QPainter& p,
         int index = 0;
         int i0Start = i0;
+        double lw;
+
+        lw = (c->lineWidth() < penWidth ? penWidth : c->lineWidth());
 
         p.setPen(QPen(c->color(),
-                    (c->lineWidth() < penWidth ? penWidth : c->lineWidth()),
+                      int(lw),
                     style));
 
@@ -5183,4 +5186,6 @@ void Kst2DPlot::plotCurves(QPainter& p,
                     if (maxY <= Hy && minY >= Ly) {
                       if (style == Qt::SolidLine) {
+                        minY-=lw/1.99999;
+                        maxY+=lw/1.99999;
                         p.drawLine(d2i(X2), d2i(minY), d2i(X2), d2i(maxY));
                       } else {