When working with LittlevGL (LVGL) for graphical user interfaces, developers may encounter an issue when using the lv_obj_clean(lv_scr_act()) function to clean the whole screen. This action can sometimes result in a blank screen being inserted, causing an unwanted flash effect. In this article, we will delve into the root of this problem and provide solutions to effectively address it.
Display in LVGL
The display in LVGL serves as the canvas where all graphical elements are rendered. When cleaning the screen using lv_obj_clean(lv_scr_act()), the intention is to clear the display of any existing content before rendering new elements. However, the insertion of a blank screen during this process leads to a flashing effect that disrupts the user experience.
Understanding the Issue
The flashing effect occurs because the clean operation is not instantaneous and results in a brief moment where the screen is empty before new content is drawn. This transition creates the perception of a flash, which can be distracting and unappealing to users.
Solution: Double Buffering
One effective solution to mitigate the flashing issue is to implement double buffering in LVGL. Double buffering involves using two buffers – one for rendering content off-screen and another for displaying the final output on the screen. By rendering new content in the off-screen buffer and then seamlessly swapping it with the on-screen buffer, the transition becomes smooth and eliminates the flashing effect.
Implementing Double Buffering
To implement double buffering in LVGL, developers can follow these steps:
1. Create two buffers: one for rendering (off-screen buffer) and one for displaying (on-screen buffer).
2. Render all graphical elements in the off-screen buffer.
3. Swap the off-screen buffer with the on-screen buffer to display the updated content without any flashing effects.
By utilizing double buffering, developers can maintain a seamless user experience when cleaning the screen in LVGL.
Conclusion
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