[BUG]ILI9341 display error

[hrikken]

Describe the bug
When text is written on the first line (via the plugin)the topmost pixelrow is always set to the background color (e.g. blacked-out). This renders the characters in the first line distorted.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'ILI93xx' display plugin
2. Settings:

• the display text print mode setting is "Clear then truncate exceeding message"
• when the text print mode setting is: "Continue to next line" or "Truncate exceeding message" the problem does NOT occur!
• rotation 270
• display model ILI9341 240x320 px
• font: default scaling 2
• Forgr/Back: white / black
• Refresh: 1 sec

3. Line 1 content: %systime%
4. See error

Expected behavior
Display the time on the first line and refresh every second

Error
The topmost pixelrow is set in background color (or cleared?).

Used platform :

• ESP type: ESP32
• Build version: [ESP_Easy_mega_20250203_climate_ESP32_4M316k Feb 3 2025]
• Build set: climate

Platform Specifics (when applicable, please complete the following information):

• Flash size: 4M]

[tonhuisman]

Does this also happen if font scaling is set to 1? (Some fonts have their height setting either 0 or have an off-by-1 error)

NB: This behavior is dependent on the 'Background-fill for text' setting.

[hrikken]

Just tested it.
The behavior is exactly the same when scaling down to 1: topmost pixelrow cleared / blacked

[tonhuisman]

@hrikken
To quote myself:

NB: This behavior is dependent on the 'Background-fill for text' setting.

Have you tested with that setting enabled and disabled?

I've just tried to reproduce your report (used a very similiar ILI9342 in an M5Stack unit, with command tft,txl,1,%systime%), but can't duplicate that behavior on the top-line. I can however see the background color untouched when clearing the screen to blue, and using the above command and then command tft,txl,2,%systime%, where it leaves some blue background between the first and second line, when setting "Background-fill for text" is turned off. This is the intended behavior, and the reason this setting exists! In most situations, you would want to have that setting checked.

The fact it is or isn't changing the top-most line of the display often depends on the manufacturer of the display, it seems, as some cover (or disconnect...) the top-most line of the display, and others don't. The effect can be simulated by using line 1 and 2 with the txl sub-command, as demonstrated.

If you want to print text 'on top' of an image, with the image shining through, you should use the txtfull sub-command, and specify the background-color the same as the foreground color, resulting in a transparent background (this is by design behavior in the underlying Adafruit GFX library).