BLF: fade out shadow when text color itself is dark #121222

Aras Pranckevicius · 2024-04-29T20:17:55+02:00

2024-04-29 20:17:55 +02:00

Spawned by discussion in chat: https://blender.chat/channel/sequencer-module?msg=PuiLkG3KfrGAhCeHa

BLF_draw_default_shadowed and one place in view2d_draw were using black text shadow color, even if the text itself might be dark enough already (since the color is coming from a theme). So e.g. a black text would result in additional black shadow, which only makes everything more muddy:

Make these places fade out the shadow: when color luminance is below 0.5 the shadow starts to fade out, and is completely got when luminance drops below 0.25. This is done by the new helper function
BLF_shadow_auto_color.

Python API (blf.shadow) and other existing cases of BLF_shadow remain unchanged.

Spawned by discussion in chat: https://blender.chat/channel/sequencer-module?msg=PuiLkG3KfrGAhCeHa `BLF_draw_default_shadowed` and one place in `view2d_draw` were using black text shadow color, even if the text itself might be dark enough already (since the color is coming from a theme). So e.g. a black text would result in additional black shadow, which only makes everything more muddy: ![shadow_black_current.png](/attachments/8bb0b238-ee09-413f-b3be-6625be85f7e4) Make these places fade out the shadow: when color luminance is below 0.5 the shadow starts to fade out, and is completely got when luminance drops below 0.25. This is done by the new helper function `BLF_shadow_auto_color`. ![blender_0429_211457.gif](/attachments/314e174e-e512-49ae-8d12-b6b60dff7f1c) Python API (`blf.shadow`) and other existing cases of `BLF_shadow` remain unchanged.

blender_0429_211457.gif

3.4 MiB

shadow_black_current.png

17 KiB

❤️ 1

Aras Pranckevicius added 1 commit 2024-04-29 20:17:59 +02:00

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30b04aa73d BLF: fade out shadow when text color itself is dark

BLF_draw_default_shadowed and one place in view2d_draw were using
black text shadow color, even if the text itself might be dark
enough already (since the color is coming from a theme).

Make these places fade out the shadow: when color luminance is below
0.5 the shadow starts to fade out, and is completely got when luminance
drops below 0.25. This is done by the new helper function
BLF_shadow_auto_color.

Python API (blf.shadow) and other existing cases of BLF_shadow remain
unchanged.

Aras Pranckevicius requested review from Pablo Vazquez 2024-04-29 20:18:11 +02:00

Aras Pranckevicius requested review from Harley Acheson 2024-04-29 20:18:55 +02:00

Aras Pranckevicius commented

2024-04-29 20:19:08 +02:00

@blender-bot build

Harley Acheson commented

2024-04-30 02:48:19 +02:00

I should start by saying that yes, the overlay text drawing is a problem. And I have struggled with it forever.

That said, I'm not certain this gets us very far. It does make the dark text look better on a light background for sure. But the auto shadow color here does so with very little context, in that it can only do so based on the text color.

For example, this PR changes draw_vertical_scale_indicators to use this. I think this is for drawing the numbers on the vertical axis in Graph Editor. The text shadow there now is set to a (dumb) black. And this PR just makes it use something better if the text color is made brighter. But that removes contrast in that case. So that could be fixed by replacing that black with the background color:

  float shadow_color[4];
  UI_GetThemeColor4fv(TH_BACK, shadow_color);
  BLF_shadow(font_id, 5, shadow_color);

This way the text color and its shadow have the same contrast as TH_TEXT and TH_BACK. And using the background color you wouldn't get that "glow" effect when using a white shadow color. You wouldn't notice the shadow at all unless something is placed under it that is far off the background color.

The 3DView overlay text is an entirely different problem though. We could make that BLF_draw_default_shadowed smarter, and give it a default parameter of shadow color. So it just uses black unless you supply a specific color.

But 3DView can have a background color that is very dark or completely white, yet we only have a single theme setting for text color. So if you set a color that looks good for Grease Pencil it will be bad for regular views.

We do have a ED_view3d_background_color_get that does an okay job of getting a background color. So we use that to manufacture both the text and shadow colors. So when the background is dark we use a black shadow and light text, and if a light background use black text and shadow of background color. Basically allow the shadow to get as dark as black, but not allow it to get lighter than the background - which avoid glowing.

I'll make a different PR so we can stare at it.

I should start by saying that yes, the overlay text drawing is a problem. And I have struggled with it forever. That said, I'm not certain this gets us very far. It does make the dark text look better on a light background for sure. But the auto shadow color here does so with very little context, in that it can only do so based on the text color. For example, this PR changes `draw_vertical_scale_indicators` to use this. I think this is for drawing the numbers on the vertical axis in Graph Editor. The text shadow there now is set to a (dumb) black. And this PR just makes it use something better if the text color is made brighter. But that removes contrast in that case. So that could be fixed by replacing that black with the background color: ``` float shadow_color[4]; UI_GetThemeColor4fv(TH_BACK, shadow_color); BLF_shadow(font_id, 5, shadow_color); ``` This way the text color and its shadow have the same contrast as TH_TEXT and TH_BACK. And using the background color you wouldn't get that "glow" effect when using a white shadow color. You wouldn't notice the shadow at all unless something is placed under it that is far off the background color. The 3DView overlay text is an entirely different problem though. We could make that `BLF_draw_default_shadowed` smarter, and give it a default parameter of shadow color. So it just uses black unless you supply a specific color. But 3DView can have a background color that is very dark or completely white, yet we only have a single theme setting for text color. So if you set a color that looks good for Grease Pencil it will be bad for regular views. We do have a `ED_view3d_background_color_get` that does an _okay_ job of getting a background color. So we use that to manufacture both the text and shadow colors. So when the background is dark we use a black shadow and light text, and if a light background use black text and shadow of background color. Basically allow the shadow to get as dark as black, but not allow it to get lighter than the background - which avoid glowing. I'll make a different PR so we can stare at it.

Harley Acheson referenced this pull request

2024-04-30 03:10:04 +02:00

WIP: UI: Automatic Text Contrast for Overlays #121239

Aras Pranckevicius commented

2024-05-03 08:37:20 +02:00

Closing this in favor of #121239

Aras Pranckevicius closed this pull request

2024-05-03 08:37:22 +02:00

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BLF: fade out shadow when text color itself is dark #121222

Pull request closed