added example code.

README.md

@@ -25,7 +25,45 @@ sudo gwbuild -i
 ```
 
 
-## Code Examples
+## Code Example
+
+
+```
+  AQDG_GRAPH *g;
+  AQDG_GRAPH_DATAPAIR_LIST *dpList;
+  AQDG_DRAW_CONTEXT *dc;
+  AQDG_OBJECT *graphObject;
+
+  g=AQDG_TimeGraph_new("Title", "Subtitle", "Value", "mm", 0);
+
+  dpList=CREATE_DATA_FOR_GRAPH();
+
+  /* add first curve as bar graph */
+  AQDG_TimeGraph_AddCurve(g, "Testdata", AQDG_GRAPH_TYPE_BARS, dpList);
+
+  /* use a data modification function on initial data (hee: accumulate) */
+  derivedDpList=AQDG_Data_Accumulate(dpList);
+
+  /* add 2nd curve with accumulated data as line graph */
+  AQDG_TimeGraph_AddCurve(g, "Accumulated", AQDG_GRAPH_TYPE_LINE, derivedDpList);
+
+  /* setup ticks for X and Y axis (use auto-calculated upper and lower limit) */
+  AQDG_TimeGraph_SetupTicks(g, 0, 0.0, 0.0);
+
+  /* draw graph as PNG file (here with 800x600 pixels) */
+  dc=AQDG_Draw_ContextCairo_Png_new("/tmp/testgraph.png", 800, 600);
+  graphObject=AQDG_GraphWidget_new(NULL, AQDG_OBJECT_OPTIONS_STRETCHX | AQDG_OBJECT_OPTIONS_STRETCHY, dc);
+  AQDG_Object_SetWidth(graphObject, 800);
+  AQDG_Object_SetHeight(graphObject, 600);
+
+  /* use default pens and graphs */
+  AQDG_GraphWidget_SetupDefaultPens(graphObject);
+  AQDG_GraphWidget_SetupDefaultFonts(graphObject);
+
+  /* finish creating the PNG file */
+  AQDG_GraphWidget_FinishWithGraph(graphObject, g);
+
+  return 0;
+```
 
-https://gitea.aqbanking.de/martin/aqdiagram/src/branch/master/src/lib/aqdiagram/libtest.c