ChartDirector Ver 3.0 (C++ Edition)

Enhanced Line Chart




This example extends the Simple Line Chart example by decorating the chart using a number of chart formatting features.

In this example, random data is used. They are generated using a ChartDirector utility class RanTable. RanTable simulates a database table with the cells filled with random numbers. The columns of the table can be retrieved as arrays using RanTable.getCol.

Source Code Listing

[The following project is available in "cppdemo/enhancedline".]
#include "chartdir.h" int main(int argc, char *argv[]) { // // We use a random number generator to simulate the data from 9:30 to // 4:30 with one data point every 4 minutes. The total number of points // during that period is 106. (7 hours x 15 points/hour + 1) // int noOfPoints = 106; //Assume we have not reached the end of the day yet, and only 85 points are //available. Create a random table object of 1 col x 85 rows, using 9 as //seed. RanTable *rantable = new RanTable(9, 1, 85); //Set the 1st column to start with 1800 and with random delta from -5 to 5. rantable->setCol(0, 1800, -5, 5); //Get the data as the 1st column of the random table DoubleArray data = rantable->getCol(0); //The x-axis labels for the chart const char *labels[] = {"-", "10am", "-", " ", "-", "12am", "-", " ", "-", "2pm", "-", " ", "-", "4pm", "-"}; // // Now we obtain the data into arrays, we can start to draw the chart // using ChartDirector // //Create a XYChart object of size 180 x 180 pixels with a blue background //(0x9c9cce) XYChart *c = new XYChart(180, 180, 0x9c9cce); //Add titles to the top and bottom of the chart using 7.5pt Arial font. The //text is white 0xffffff on a deep blue 0x31319C background. c->addTitle(Top, "STAR TECH INDEX 2003-01-28", "arial.ttf", 7.5, 0xffffff, 0x31319c); c->addTitle(Bottom, "LATEST STI:1809.41 (+14.51)", "arial.ttf", 7.5, 0xffffff, 0x31319c); //Set the plotarea at (31, 21) and of size 145 x 124 pixels, with a pale //yellow (0xffffc8) background. c->setPlotArea(31, 21, 145, 124, 0xffffc8); //Add custom text at (176, 21) (top right corner of plotarea) using 11pt //Times Bold Italic font/red (0xc09090) color c->addText(176, 21, "Chart Demo", "timesbi.ttf", 11, 0xc09090 )->setAlignment(TopRight); //Use 7.5 pts Arial as the y axis label font c->yAxis()->setLabelStyle("", 7.5); //Set the labels on the x axis by spreading the labels evenly between the //first point (index = 0) and the last point (index = noOfPoints - 1) c->xAxis()->setLinearScale(0, noOfPoints - 1, StringArray(labels, sizeof(labels)/sizeof(*labels))); //Use 7.5 pts Arial as the x axis label font c->xAxis()->setLabelStyle("", 7.5); //Add a deep blue (0x000080) line layer to the chart c->addLineLayer(data, 0x80); //output the chart c->makeChart("enhancedline.png"); //free up resources delete rantable; delete c; return 0; }