LVGL Editor: Fixing No Image Found Warning With NULL

Nov 28, 2025 by Alex Johnson 55 views

Have you ever encountered the frustrating "No image was found with name 'NULL'" warning in your LVGL (Light and Versatile Graphics Library) editor console? You're not alone! This article dives deep into this common issue, explains why it occurs, and provides a comprehensive solution to keep your console clean and your development workflow smooth. We'll explore the intricacies of LVGL's style system, how it interacts with the editor, and how to effectively manage background images. By the end of this article, you'll have a solid understanding of how to handle NULL image sources in your LVGL projects and avoid unnecessary warnings.

Understanding the Issue: The "No Image Found" Warning

When working with LVGL and its editor, you might encounter a warning message in the console that reads: [LVGL] [Warn] (x.xxx, +xxxx) lv_xml_get_image: No image was found with name "NULL" lv_xml.c:xxx. This warning typically arises when you're using a style where the bg_image_src (background image source) is set to NULL. While setting bg_image_src to NULL is a perfectly valid and often necessary practice in LVGL programming (e.g., to remove a background image or indicate no image should be displayed), the editor's console might interpret this as an actual attempt to load an image named "NULL," leading to the warning.

This warning can be particularly confusing because the generated C code often correctly handles the NULL value. For example, the editor might generate code like lv_style_set_bg_image_src(&style_checked, NULL);, which is the standard way to set the background image source to NULL in LVGL. Despite the code being correct, the warning persists in the console, potentially obscuring other important messages and creating unnecessary anxiety for developers. It's important to highlight that this is more of an editor behavior quirk than a fundamental flaw in LVGL itself. The LVGL library correctly interprets NULL as the absence of an image.

Why Does This Happen?

The root cause of this warning lies in how the LVGL editor parses and interprets the style definitions, specifically when using XML-based configurations. The editor, when encountering bg_image_src="NULL", attempts to resolve an image with the name "NULL." Since there is no such image, it throws a warning. This behavior stems from the editor's attempt to be helpful by flagging potential issues, but in this specific case, it misinterprets a deliberate action (setting bg_image_src to NULL) as an error.

Real-World Scenario

Imagine you are designing a button with different states (e.g., normal, pressed, focused). You might want the button to have a background image in its normal state but no background image when it's pressed. To achieve this, you would set the bg_image_src to a specific image for the normal state and then set it to NULL for the pressed state. This is a common and valid design pattern in LVGL. However, the editor might generate the "No image found" warning when it encounters the bg_image_src="NULL" setting for the pressed state, even though this is exactly what you intended.

The Solution: Addressing the Warning and Keeping Your Console Clean

While the warning itself doesn't break your code, it's best practice to address it to keep your console clean and ensure you don't miss any genuine warnings. There are a couple of ways to handle this situation:

Ignore the Warning (With Caution): If you understand the cause of the warning and are confident that your code is correct, you can choose to ignore it. However, this approach should be taken with caution. It's crucial to ensure that you're not ignoring other potentially important warnings. This method is not recommended for beginners or those new to LVGL, as it could lead to overlooking genuine errors.
Conditional Image Source Setting: A more robust and recommended approach is to use conditional logic when setting the bg_image_src. Instead of directly setting it to NULL in the style definition, you can use a conditional statement in your code to set the image source based on a specific condition. For instance, you might have a variable that determines whether a background image should be displayed. If the variable is true, you set the bg_image_src to the image; otherwise, you leave it as NULL or use lv_style_remove_prop to remove background image property. This will prevent the editor from encountering the direct "NULL" value in the style definition and avoid the warning.
```
lv_style_t style_checked;
lv_style_init(&style_checked);

// Assuming 'has_background_image' is a boolean variable
if (has_background_image) {
    lv_style_set_bg_image_src(&style_checked, 
```