How to Make a TSpeedButton Stay Pressed in Delphi

Описание: Learn how to make a Delphi `TSpeedButton` act like it's always pressed when it's the only button in the group, with step-by-step guidance.
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This video is based on the question https://stackoverflow.com/q/202702/ asked by the user 'Peter Turner' ( https://stackoverflow.com/u/1765/ ) and on the answer https://stackoverflow.com/a/202733/ provided by the user 'Roman Ganz' ( https://stackoverflow.com/u/17981/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Make a TSpeedButton Stay Pressed in Delphi

If you're developing an application in Delphi and you find yourself puzzled by the behavior of the TSpeedButton, you’re not alone. Many developers encounter a situation where the TSpeedButton does not stay pressed when it is the only button in a designated group. This issue can be frustrating, especially when you're trying to create an intuitive user interface that visually indicates an active selection. In this guide, we will explore this problem and provide a clear solution to ensure that your button remains in the pressed state when it's the only button in its group.

Understanding the Problem

In Delphi, buttons, including TSpeedButton, can be grouped together using the GroupIndex property. The expectation is that when a button is clicked, it remains visually pressed (or down) to indicate selection. However, developers often notice that if a TSpeedButton is the only button in its group, it does not exhibit this behavior, regardless of the "AllowAllUp" property setting.

This is particularly notable in Delphi 7, but the solution extends beyond just this version. So, how do we ensure that our TSpeedButton stays pressed under these circumstances? Let’s dive into the solution.

Solution Overview

The solution is straightforward: you can manually control the Down property of the TSpeedButton using its OnClick event. Here’s how to do it step-by-step:

Step 1: Understand the Properties

Before implementing the solution, it's vital to understand the relevant properties:

GroupIndex: This property determines the group in which the button belongs. All buttons with the same GroupIndex can interact with each other in terms of selection and highlighting.

Down: This property indicates whether the button is pressed down (true) or not (false).

Step 2: Configure the Button

Make sure that your TSpeedButton is set up correctly in the Object Inspector:

Set the GroupIndex to 0: If you're intending for this button to be the sole option you can click, its GroupIndex must be set to 0.

Configure the AllowAllUp property: Be aware that this property influences button behavior when multiple buttons are part of a group.

Step 3: Implement the OnClick Event Handler

Next, you need to implement an event handler for the OnClick event of the TSpeedButton. Here’s how to do that:

In the Delphi IDE, select your TSpeedButton and locate the Events tab in the Object Inspector.

Double-click the OnClick event to generate an event handler procedure in your code.

Inside this procedure, set the Down property to True. Here’s an example code snippet:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By explicitly setting the Down property of your TSpeedButton in the OnClick event, you can ensure that it visually stays pressed even when it's the only button in the group. This method eliminates the frustrating behavior and enhances the overall user experience by providing a clear indication of active selection.

Final Thoughts

Using Delphi can sometimes yield unexpected behavior with UI components like the TSpeedButton. However, as shown above, a little manual control can go a long way. Make sure to implement this tip in your applications, especially if you're working with an older version like Delphi 7. Happy coding!