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image: Include alpha<1 in bg color detection

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Only ignore alpha=0 pixels instead of alpha<1 pixels.
Also apply agorithm to non transparent images.

Part-of: <https://gitlab.gnome.org/Incubator/loupe/-/merge_requests/191>
This commit is contained in:
Sophie Herold 2023-04-20 20:28:29 +02:00 • committed by Marge Bot
parent 916514604c
commit dab333e510
1 changed files with 9 additions and 12 deletions
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21
src/widgets/image.rs
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@ -60,12 +60,8 @@ static BACKGROUND_COLOR_DEFAULT_LIGHT_MODE: Lazy<gdk::RGBA> =
static BACKGROUND_COLOR_ALTERNATE_LIGHT_MODE: Lazy<gdk::RGBA> =
Lazy::new(|| gdk::RGBA::new(103. / 255., 101. / 255., 110. / 255., 1.));
/// Consider pixels with less than 70% opacity as being transparent
static BACKGROUND_GUESS_TRANSPRAENT_PIXEL_THRESHOLD: u8 = (0.70 * 255.) as u8;
/// Consider 3.5:1 contrast and worse to be bad contrast for a pixel
static BACKGROUND_GUESS_LOW_CONTRAST_RATIO: f32 = 3.5;
/// Consider images with more than 10% transparent pixels as transparent
static BACKGROUND_GUESS_TRANSPRAENT_IMAGE_THRESHOLD: f64 = 0.10;
/// Consider transparent images with more than 90% pixels bad contrast as bad contrast
///
/// Bad contrast image will use the `BACKGROUND_COLOR_ALTERNATE`.
@ -1774,7 +1770,7 @@ impl LpImage {
gio::spawn_blocking(move || {
let mut bytes_iter = bytes.iter();
// Number of transparent pixels
let mut transparent = 0;
let mut completely_transparent = 0;
// Number of non-transparent pixels with bad contrast
let mut bad_contrast = 0;
'img: loop {
@ -1785,8 +1781,8 @@ impl LpImage {
let Some(a) = bytes_iter.next() else { break 'img; };
// 70% transparency
if *a < BACKGROUND_GUESS_TRANSPRAENT_PIXEL_THRESHOLD {
transparent += 1;
if *a == 0 {
completely_transparent += 1;
} else {
let fg = gdk::RGBA::new(
*r as f32 / 255.,
@ -1811,12 +1807,13 @@ impl LpImage {
let n_pixels = texture.width() * texture.height();
let part_transparent = transparent as f64 / n_pixels as f64;
let part_bad_contrast = bad_contrast as f64 / (n_pixels as f64 - transparent as f64);
let part_bad_contrast = if completely_transparent < n_pixels {
bad_contrast as f64 / (n_pixels as f64 - completely_transparent as f64)
} else {
1.
};
if part_transparent > BACKGROUND_GUESS_TRANSPRAENT_IMAGE_THRESHOLD
&& part_bad_contrast > BACKGROUND_GUESS_LOW_CONTRAST_TRHESHOLD
{
if part_bad_contrast > BACKGROUND_GUESS_LOW_CONTRAST_TRHESHOLD {
Some(alternate_color)
} else {
Some(default_color)