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Ili9341 8bit indexed mode pt1 (#2490)

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This commit is contained in:
Dave T
2022-05-18 23:23:00 +01:00
committed by GitHub
parent 9b6b9c1fa2
commit c000e1d6dd
5 changed files with 90 additions and 3 deletions
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47
esphome/components/display/display_color_utils.h
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@@ -107,6 +107,53 @@ class ColorUtil {
uint32_t gs4 = esp_scale8(color.white, 15);
return gs4;
}
/***
* Converts a Color value to an 8bit index using a 24bit 888 palette.
* Uses euclidiean distance to calculate the linear distance between
* two points in an RGB cube, then iterates through the full palette
* returning the closest match.
* @param[in] color The target color.
* @param[in] palette The 256*3 byte RGB palette.
* @return The 8 bit index of the closest color (e.g. for display buffer).
*/
// static uint8_t color_to_index8_palette888(Color color, uint8_t *palette) {
static uint8_t color_to_index8_palette888(Color color, const uint8_t *palette) {
uint8_t closest_index = 0;
uint32_t minimum_dist2 = UINT32_MAX; // Smallest distance^2 to the target
// so far
// int8_t(*plt)[][3] = palette;
int16_t tgt_r = color.r;
int16_t tgt_g = color.g;
int16_t tgt_b = color.b;
uint16_t x, y, z;
// Loop through each row of the palette
for (uint16_t i = 0; i < 256; i++) {
// Get the pallet rgb color
int16_t plt_r = (int16_t) palette[i * 3 + 0];
int16_t plt_g = (int16_t) palette[i * 3 + 1];
int16_t plt_b = (int16_t) palette[i * 3 + 2];
// Calculate euclidian distance (linear distance in rgb cube).
x = (uint32_t) std::abs(tgt_r - plt_r);
y = (uint32_t) std::abs(tgt_g - plt_g);
z = (uint32_t) std::abs(tgt_b - plt_b);
uint32_t dist2 = x * x + y * y + z * z;
if (dist2 < minimum_dist2) {
minimum_dist2 = dist2;
closest_index = (uint8_t) i;
}
}
return closest_index;
}
/***
* Converts an 8bit palette index (e.g. from a display buffer) to a color.
* @param[in] index The index to look up.
* @param[in] palette The 256*3 byte RGB palette.
* @return The RGBW Color object looked up by the palette.
*/
static Color index8_to_color_palette888(uint8_t index, const uint8_t *palette) {
Color color = Color(palette[index * 3 + 0], palette[index * 3 + 1], palette[index * 3 + 2], 0);
return color;
}
};
} // namespace display
} // namespace esphome