Pie charts didn't have anti-aliasing; building them clockwise

seems to solve this problem.

git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk/program@98 a5681a0c-68f1-0310-ab6d-d61299d08faa

diff --git a/src/rrd_graph.c b/src/rrd_graph.c
index ea7ed0d2f6474a5ed389da6b6e4059efef951c3a..111aaa67bd445149e6dffc484fd3d15f28782dcb 100644 (file)
--- a/src/rrd_graph.c
+++ b/src/rrd_graph.c
@@ -1844,6 +1844,51 @@ int lazy_check(image_desc_t *im){
     return size;
 }
 
+void
+pie_part(gfx_canvas_t *canvas, gfx_color_t color,
+           double PieCenterX, double PieCenterY, double Radius,
+           double startangle, double endangle)
+{
+    gfx_node_t *node;
+    double angle;
+    double step=M_PI/50; /* Number of iterations for the circle;
+                        ** 10 is definitely too low, more than
+                        ** 50 seems to be overkill
+                        */
+
+    /* Strange but true: we have to work clockwise or else
+    ** anti aliasing nor transparency don't work.
+    **
+    ** This test is here to make sure we do it right, also
+    ** this makes the for...next loop more easy to implement.
+    ** The return will occur if the user enters a negative number
+    ** (which shouldn't be done according to the specs) or if the
+    ** programmers do something wrong (which, as we all know, never
+    ** happens anyway :)
+    */
+    if (endangle<startangle) return;
+
+    /* Hidden feature: Radius decreases each full circle */
+    angle=startangle;
+    while (angle>=2*M_PI) {
+       angle  -= 2*M_PI;
+       Radius *= 0.8;
+    }
+
+    node=gfx_new_area(canvas,
+               PieCenterX+sin(startangle)*Radius,
+               PieCenterY-cos(startangle)*Radius,
+               PieCenterX,
+               PieCenterY,
+               PieCenterX+sin(endangle)*Radius,
+               PieCenterY-cos(endangle)*Radius,
+               color);
+    for (angle=endangle;angle-startangle>=step;angle-=step) {
+       gfx_add_point(node,
+               PieCenterX+sin(angle)*Radius,
+               PieCenterY-cos(angle)*Radius );
+    }
+}
 
 /* draw that picture thing ... */
 int
@@ -1852,7 +1897,7 @@ graph_paint(image_desc_t *im, char ***calcpr)
   int i,ii;
   int lazy =     lazy_check(im);
   int piechart = 0;
-  double PieStart=0.0, PieSize, PieCenterX, PieCenterY;
+  double PieStart=0.0, PieSize=0.0, PieCenterX=0.0, PieCenterY=0.0;
   FILE  *fo;
   gfx_canvas_t *canvas;
   gfx_node_t *node;
@@ -1973,42 +2018,52 @@ graph_paint(image_desc_t *im, char ***calcpr)
                        im->graph_col[GRC_CANVAS]);
   gfx_add_point(node,0,im->ygif);
 
-  node=gfx_new_line (canvas,
-               0,              im->ygif-100,
-               im->xgif-3,     im->ygif-100,
-               1.0,
-               0xFF0000FF);
-  gfx_add_point(node,im->xgif-3,im->ygif-3);
-  gfx_add_point(node,2,im->ygif-3);
-  gfx_add_point(node,2,im->ygif-100);
-
-
-#if 0
-  node=gfx_new_area ( canvas,
-                       1,              im->ygif-99,
-                       im->xgif-1,     im->ygif-99,
-                       im->xgif-1,     im->ygif-1,
-                       im->graph_col[GRC_CANVAS]);
-  gfx_add_point(node,1,im->ygif-1);
-#endif
-
+  /* Four areas:
+  ** top left:     current way, solid color
+  ** top right:    proper way,  solid color
+  ** bottom left:  current way, alpha=0x80, partially overlapping
+  ** bottom right: proper way,  alpha=0x80, partially overlapping
+  */
+  {
+    double x,y,x1,y1,x2,y2,x3,y3,x4,y4;
+
+    x=(im->xgif-40)/6;
+    y=     (100-40)/6;
+    x1=    20;   y1=im->ygif-100+20;
+    x2=3*x+20;   y2=im->ygif-100+20;
+    x3=  x+20;   y3=im->ygif-100+20+2*y;
+    x4=4*x+20;   y4=im->ygif-100+20+2*y;
+
+    node=gfx_new_area(canvas,
+                       x1,y1,
+                       x1+3*x,y1,
+                       x1+3*x,y1+3*y,
+                       0xFF0000FF);
+    gfx_add_point(node,x1,y1+3*y);
+    node=gfx_new_area(canvas,
+                       x2,y2,
+                       x2,y2+3*y,
+                       x2+3*x,y2+3*y,
+                       0xFFFF00FF);
+    gfx_add_point(node,x2+3*x,y2);
+    node=gfx_new_area(canvas,
+                       x3,y3,
+                       x3+2*x,y3,
+                       x3+2*x,y3+3*y,
+                       0x00FF007F);
+    gfx_add_point(node,x3,y3+3*y);
+    node=gfx_new_area(canvas,
+                       x4,y4,
+                       x4,y4+3*y,
+                       x4+2*x,y4+3*y,
+                       0x0000FF7F);
+    gfx_add_point(node,x4+2*x,y4);
+  }
+                       
 #endif
 
   if (piechart) {
-       int n;
-
-       node=gfx_new_area(canvas,
-               PieCenterX,PieCenterY-PieSize*0.6,
-               PieCenterX,PieCenterY,
-               PieCenterX,PieCenterY-PieSize*0.6,
-               im->graph_col[GRC_CANVAS]);
-       for (n=1;n<500;n++) {
-               double angle;
-               angle=M_PI*2.0*n/500.0;
-               gfx_add_point(node,
-               PieCenterX+sin(angle)*PieSize*0.6,
-               PieCenterY-cos(angle)*PieSize*0.6 );
-       }
+    pie_part(canvas,im->graph_col[GRC_CANVAS],PieCenterX,PieCenterY,PieSize*0.6,0,2*M_PI);
   }
 
   if (im->minval > 0.0)
@@ -2143,25 +2198,10 @@ graph_paint(image_desc_t *im, char ***calcpr)
        im->gdes[i].yrule = im->gdes[im->gdes[i].vidx].vf.val;
      
       if (finite(im->gdes[i].yrule)) { /* even the fetched var can be NaN */
-       double angle,endangle;
-       int n;
-
-       angle=M_PI*2.0*PieStart/100.0;
-       endangle=M_PI*2.0*(PieStart+im->gdes[i].yrule)/100.0;
-       node=gfx_new_area(canvas,
-               PieCenterX+sin(endangle)*PieSize/2,
-               PieCenterY-cos(endangle)*PieSize/2,
-               PieCenterX,
-               PieCenterY,
-               PieCenterX+sin(angle)*PieSize/2,
-               PieCenterY-cos(angle)*PieSize/2,
-               im->gdes[i].col);
-       for (n=1;n<100;n++) {
-               angle=M_PI*2.0*(PieStart+n/100.0*im->gdes[i].yrule)/100.0;
-               gfx_add_point(node,
-               PieCenterX+sin(angle)*PieSize/2,
-               PieCenterY-cos(angle)*PieSize/2 );
-       }
+       pie_part(canvas,im->gdes[i].col,
+               PieCenterX,PieCenterY,PieSize/2,
+               M_PI*2.0*PieStart/100.0,
+               M_PI*2.0*(PieStart+im->gdes[i].yrule)/100.0);
        PieStart += im->gdes[i].yrule;
       }
       break;

diff --git a/src/rrd_graph.h b/src/rrd_graph.h
index e127179a4897f4e8108103a16f51f3bddb5df606..b86859c453e53c40974354ee8fce87860b6fdda1 100644 (file)
--- a/src/rrd_graph.h
+++ b/src/rrd_graph.h
@@ -192,6 +192,7 @@ void axis_paint( image_desc_t *, gfx_canvas_t *);
 void grid_paint( image_desc_t *, gfx_canvas_t *);
 int lazy_check(image_desc_t *);
 int graph_paint(image_desc_t *, char ***);
+void pie_part(gfx_canvas_t *, gfx_color_t, double, double, double, double, double);
 int gdes_alloc(image_desc_t *);
 int scan_for_col(char *, int, char *);
 int rrd_graph(int, char **, char ***, int *, int *);