Creating tree view check boxes manually: Responding to clicks

Raymond ChenNovember 30, 2017Nov 30, 201711/30/17

Last time, we added state images to the tree view, but we didn't provide any way for the user to click on them. Let's add the code so that the user can click on the check box to change the value. For simplicity, we will just cycle through the state images. In real life, you would probably have more complex logic for deciding what to do when ...

Creating tree view check boxes manually: A simple state image list

Raymond ChenNovember 29, 2017Nov 29, 201711/29/17

Before the introduction of the TVS_CHECK­BOXES style, you had to create your own state images which consisted of a checked and unchecked check box. To draw check boxes manually, you used the Draw­Frame­Control function. So let's do that: Build check boxes with the Draw­Frame­Control function. As a bonus, we will add an "...

Beware of the leaked image list when using the TVS_CHECKBOXES style

Raymond ChenNovember 28, 2017Nov 28, 201711/28/17

The TVS_CHECK­BOXES tree view style is quirky, which is a nice way of saying that it's crazy. As we noted last time, the support for check boxes was migrated in from external code, and it followed the pattern for external code. In particular, the state image list for the check boxes needs to be manually destroyed, because when you created...

The TVS_CHECKBOXES style is quirky, which is a polite way of saying that it is crazy

Raymond ChenNovember 27, 2017Nov 27, 201711/27/17

A customer was having trouble with tree view checkboxes. We have a tree view control in a dialog box. It is defined like this: As you can see, the TVS_CHECK­BOXES style is set in the dialog template. When the dialog is created, but before it is shown, we have code that populates the tree. At that time, we want to set the checked state of...

Getting a parent and child window to have the same UI states

Raymond ChenNovember 24, 2017Nov 24, 201711/24/17

Last time, we created a program that moved a child window between two parents in such a way that the child and parent ended up with different UI states. We saw the weird things that result from this mismatch, which is why the documentation told us, "you should synchronize the UISTATE of both windows." So let's try it. Take the program we had ...

Demonstrating what happens when a parent and child window have different UI states

Raymond ChenNovember 23, 2017Nov 23, 201711/23/17

Last time, we dug into the statement in the documentation that says, "When you change the parent of a window, you should synchronize the UISTATE of both windows." Today we'll set up a situation where the states are out of sync so we can play with it. Start with the new scratch program and make these changes: We define a global variable to ...

What is the documentation for SetParent trying to tell me about synchronizing the UI state?

Raymond ChenNovember 22, 2017Nov 22, 201711/22/17

The documentation for the Set­Parent function says When you change the parent of a window, you should synchronize the UISTATE of both windows. For more information, see WM_CHANGE­UI­STATE and WM_UPDATE­UI­STATE. What does that mean? Recall how the WM_UPDATE­UI­STATE and WM_CHANGE­UI­STATE messages work. ...

How can I find the installation directory for my UWP application?

Raymond ChenNovember 20, 2017Nov 20, 201711/20/17

After you've installed a UWP application, you may want to know where it got installed to. Maybe there's a deployment bug that you're trying to resolve. Maybe it's just because you're curious. Programmatically, your application can ask for the Windows.Application­Model.Package.Current.Installed­Location.Path. From PowerShell, you can ...

The wrong way of benchmarking the most efficient integer comparison function

Raymond ChenNovember 17, 2017Nov 17, 201711/17/17

On StackOverflow, there's a question about the most efficient way to compare two integers and produce a result suitable for a comparison function, where a negative value means that the first value is smaller than the second, a positive value means that the first value is greater than the second, and zero means that they are equal. There was ...