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70 lines
2.3 KiB
C
70 lines
2.3 KiB
C
// SPDX-License-Identifier: Apache-2.0
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#pragma once
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#include <stdbool.h>
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#include <stdint.h>
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#include <string.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* Rotates a full 1bpp frame (row-major, MSB-first) from the display's rotated
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* space into the panel's native space. The display is the panel's native
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* width x height turned counter-clockwise by `rotation` (0 = 0, 1 = 90, 2 = 180,
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* 3 = 270 degrees), so its own dimensions are the swapped native ones for
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* 90/270. Each mapping is the inverse of LVGL's lv_display_rotate_area()
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* (Libraries/lvgl/src/display/lv_display.c), i.e. the exact transform LVGL
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* applies when displaying on the panel.
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*
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* src points to the display frame (stride = ceil(display_width / 8) bytes,
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* MSB-first bits), dst to the native frame (stride = ceil(width / 8) bytes).
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* dst is overwritten; it may not alias src.
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*/
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static inline bool esp_epaper_rotation_swaps_axes(uint8_t rotation) {
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return rotation == 1 || rotation == 3;
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}
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static inline void esp_epaper_rotate_frame(const uint8_t* src, uint8_t* dst, uint16_t width, uint16_t height, uint8_t rotation) {
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const uint16_t display_width = esp_epaper_rotation_swaps_axes(rotation) ? height : width;
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const uint32_t src_stride = (display_width + 7) / 8;
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const uint32_t dst_stride = (width + 7) / 8;
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memset(dst, 0, dst_stride * height);
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for (uint16_t y = 0; y < height; y++) {
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for (uint16_t x = 0; x < width; x++) {
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// Display pixel (u, v) that lands on native pixel (x, y).
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uint16_t u;
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uint16_t v;
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switch (rotation) {
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case 0:
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u = x;
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v = y;
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break;
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case 1:
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u = height - 1 - y;
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v = x;
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break;
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case 2:
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u = width - 1 - x;
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v = height - 1 - y;
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break;
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case 3:
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default:
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u = y;
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v = width - 1 - x;
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break;
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}
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if (src[(uint32_t)v * src_stride + u / 8] & (0x80 >> (u % 8))) {
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dst[(uint32_t)y * dst_stride + x / 8] |= (0x80 >> (x % 8));
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}
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}
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}
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}
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#ifdef __cplusplus
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}
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#endif
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