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[epaper_spi] Fix color mapping for weact (#14134)

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This commit is contained in:
Clyde Stubbs
2026-02-21 07:17:54 -10:00
committed by GitHub
parent 416b97311b
commit 6ff17fbf7c
2 changed files with 29 additions and 16 deletions
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2
esphome/components/epaper_spi/epaper_spi.h
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@@ -76,7 +76,7 @@ class EPaperBase : public Display,
static uint8_t color_to_bit(Color color) {
// It's always a shade of gray. Map to BLACK or WHITE.
// We split the luminance at a suitable point
if ((static_cast<int>(color.r) + color.g + color.b) > 512) {
if ((color.r + color.g + color.b) >= 382) {
return 1;
}
return 0;

43
esphome/components/epaper_spi/epaper_weact_3c.cpp
View File

@@ -5,9 +5,24 @@ namespace esphome::epaper_spi {
static constexpr const char *const TAG = "epaper_weact_3c";
enum class BwrState : uint8_t {
BWR_BLACK,
BWR_WHITE,
BWR_RED,
};
static BwrState color_to_bwr(Color color) {
if (color.r > color.g + color.b && color.r > 127) {
return BwrState::BWR_RED;
}
if (color.r + color.g + color.b >= 382) {
return BwrState::BWR_WHITE;
}
return BwrState::BWR_BLACK;
}
// SSD1680 3-color display notes:
// - Buffer uses 1 bit per pixel, 8 pixels per byte
// - Buffer first half (black_offset): Black/White plane (1=black, 0=white)
// - Buffer first half (black_offset): Black/White plane (0=black, 1=white)
// - Buffer second half (red_offset): Red plane (1=red, 0=no red)
// - Total buffer: width * height / 4 bytes = 2 * (width * height / 8)
// - For 128x296: 128*296/4 = 9472 bytes total (4736 per color)
@@ -23,20 +38,20 @@ void EPaperWeAct3C::draw_pixel_at(int x, int y, Color color) {
// Use luminance threshold for B/W mapping
// Split at halfway point (382 = (255*3)/2)
bool is_white = (static_cast<int>(color.r) + color.g + color.b) > 382;
auto bwr = color_to_bwr(color);
// Update black/white plane (first half of buffer)
if (is_white) {
// White pixel - clear bit in black plane
this->buffer_[pos] &= ~bit;
} else {
// Black pixel - set bit in black plane
if (bwr == BwrState::BWR_WHITE) {
// White pixel - set bit in black plane
this->buffer_[pos] |= bit;
} else {
// Black pixel - clear bit in black plane
this->buffer_[pos] &= ~bit;
}
// Update red plane (second half of buffer)
// Red if red component is dominant (r > g+b)
if (color.r > color.g + color.b) {
if (bwr == BwrState::BWR_RED) {
// Red pixel - set bit in red plane
this->buffer_[red_offset + pos] |= bit;
} else {
@@ -53,21 +68,20 @@ void EPaperWeAct3C::fill(Color color) {
const size_t half_buffer = this->buffer_length_ / 2u;
// Use luminance threshold for B/W mapping
bool is_white = (static_cast<int>(color.r) + color.g + color.b) > 382;
bool is_red = color.r > color.g + color.b;
auto bits = color_to_bwr(color);
// Fill both planes
if (is_white) {
// White - both planes = 0x00
if (bits == BwrState::BWR_BLACK) {
// Black - both planes = 0x00
this->buffer_.fill(0x00);
} else if (is_red) {
} else if (bits == BwrState::BWR_RED) {
// Red - black plane = 0x00, red plane = 0xFF
for (size_t i = 0; i < half_buffer; i++)
this->buffer_[i] = 0x00;
for (size_t i = 0; i < half_buffer; i++)
this->buffer_[half_buffer + i] = 0xFF;
} else {
// Black - black plane = 0xFF, red plane = 0x00
// White - black plane = 0xFF, red plane = 0x00
for (size_t i = 0; i < half_buffer; i++)
this->buffer_[i] = 0xFF;
for (size_t i = 0; i < half_buffer; i++)
@@ -112,7 +126,6 @@ bool HOT EPaperWeAct3C::transfer_data() {
ESP_LOGV(TAG, "transfer_data: buffer_length=%u, half_buffer=%u", buffer_length, half_buffer);
// Use a local buffer for SPI transfers
static constexpr size_t MAX_TRANSFER_SIZE = 128;
uint8_t bytes_to_send[MAX_TRANSFER_SIZE];
// First, send the RED buffer (0x26 = WRITE_COLOR)