Calvin Hsia's WebLog

Creating an ActiveX control is a good exercise in understanding how one works. It also helps to have full control over its source code for learning and testing purposes. A customer asked about migrating legacy ActiveX controls over to .Net. Many controls...

Here’s some C++ code to host the CLR. It’s an alternative to using COM Interop (s ee A Visual Basic COM object is simple to create, call and debug from Excel ), or using a User Control (see Create a .Net UserControl that calls a web service that acts...

I received a question from a customer: I don't know how to search for this but does ODBC, specfically Visual FoxPro support opening tables in a subdirectory? ODBC is very old.. OLEDb is much more recent. In any case, the answer is yes...

My prior post showed how to use an array of PictureBox controls to display multiple photographs on a form. Now we’ll do something similar, but instead of using the PictureBox control, which is a little bit heavyweight, we can just draw directly onto the...

Sometimes something goes wrong with your program and you want to investigate why. You can start Visual Studio, choose Debug->Attach to Process and choose the process you want to debug. (The dialog also allows remote debugging and choosing Native, Managed...

My prior 2 posts show how to display multiple photos on a VB.Net form, first using the PictureBox control, the second drawing to the form directly. Below is some code to display multiple photos on a Fox form using an array of Fox Image controls . These...

You can use an array of PictureBox controls to display multiple photographs or other images. The sample below subclasses the PictureBox control and puts an array of them on a form. You need to change the PixPath to point to a directory with your digital...

I was helping a friend fix a problem that occurred in a VB.Net application. Upon inspection, an XML file was somehow invalid. The last few bytes were wrong. We found the code that modifies the file. It takes the original file, replaces a string...

I was asked why Tooltips appear in Task Manager . I happened to be out of the country when the question was asked, so I had to wait til I got back to the office to investigate. Sure enough, tooltips show up in Task Manager, under the Applications...

Here’s an interesting bug report. The code below shows two readonly textboxes on a form, both containing floating point values. The first is left-aligned. When you hit tab from the first textbox, the value changes from 4.011 to 4.000 If you change...