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  discrete heatmap axis labels not showing negative sign
Posted by David on Jun-22-2022 19:10
Hello,

There seems an issue with axis labels in discrete heatmap in ChartDirector 7:

As an example, modifying the labels of the discreteheatmap example in mfcdemo:

void discreteheatmap(CChartViewer *viewer, int /* chartIndex */)
{
    // The x-axis and y-axis labels
    const char* xLabels[] = {"-10", "-5", "-0.0001", "0.0001", "E", "F", "G", "H", "I", "J"};
    const int xLabels_size = (int)(sizeof(xLabels)/sizeof(*xLabels));
    const char* yLabels[] = {"-10", "1000", "2", "3", "4", "5", "6", "7", "8", "9"};
    const int yLabels_size = (int)(sizeof(yLabels)/sizeof(*yLabels));

....


The negative signs were not shown in the chart.

  Re: discrete heatmap axis labels not showing negative sign
Posted by Peter Kwan on Jun-22-2022 22:36
Hi David,

Strange as it seems, it is by design.

Due to a decision we made a long long time ago when we first supported minor ticks, we chose to use the "-" character to mean that the label is associated with a minor tick. In the discrete heat map examples, they hide the ticks. But in charts that show the ticks, you can see the ticks associated with the "-" labels are shorter.

We now think using "-" for minor ticks is not a good idea, but due to our commitment to backwards compatibility, we have not changed this behaviour. See:

https://www.advsofteng.com/doc/cdcpp.htm#Axis.setLabels.htm

To add the "-0.0001", we need to escape it to "-0.0001". Now "" has a special meaning in C++ literal string, and we need to escape it too. So in C++, it becomes "\-0.0001".

Regards
Peter Kwan

  Re: discrete heatmap axis labels not showing negative sign
Posted by Peter Kwan on Jun-22-2022 22:38
Hi David,

For the last paragraph, I mean:

To add the "-0.0001", we need to escape it to "\-0.0001". Now "" has a special meaning in C++ literal string, and we need to escape it too. So in C++, it becomes "\\-0.0001".

(The forum itself will escape the \ character. So I need to type 4 backslashes in order to display 2 backslashes in the forum.)

Regards
Peter Kwan

  Re: discrete heatmap axis labels not showing negative sign
Posted by David on Jun-22-2022 22:48
Cool. I'll get it a try. Thanks!