436 lines
16 KiB
C++
436 lines
16 KiB
C++
/*#############################################################################
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## Author: Shaun Reed ##
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## Legal: All Content (c) 2025 Shaun Reed, all rights reserved ##
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## ##
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## Contact: shaunrd0@gmail.com | URL: www.shaunreed.com ##
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##############################################################################
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*/
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#ifndef PANEL_DEVICE_H
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#define PANEL_DEVICE_H
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#include <esp_lcd_panel_dev.h>
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#include <esp_lcd_panel_ops.h>
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#include <esp_lcd_panel_io.h>
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#include <esp_log.h>
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#include <display/lv_display.h>
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#include "i2c.h"
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// LVGL reserves 2x4 bytes in the buffer to be used as a palette.
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// This additional space must be added to the IPanelDevice::buf_size_.
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#define LVGL_PALETTE_SIZE 8
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#define LVGL_TICK_PERIOD_MS 5
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#define LVGL_TASK_STACK_SIZE (4 * 1024)
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#define LVGL_TASK_PRIORITY 2
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#define LCD_H_RES 128
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#define LCD_V_RES 64
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/**
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* Wraps some foundational operations performed on pixel coordinates when
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* dealing with pointer arithmetic. Most of these could be done ad-hoc as needed
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* but using this helper reduces the risk of errors.
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*/
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struct Pixel {
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/**
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* Calculate byte offset for the pixel at [x,y] within a horizontally-mapped
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* monochrome uint8 draw buffer, using the initialized horizontal resolution.
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*
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* We use `>> 3` because each pixel requires 1 bit, but each uint8 in the draw
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* buffer can hold 8 bits. To find the uint8 value in our draw buffer that
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* stores this pixel's value we must compensate for this when using pixel
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* coordinates in byte math.
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*
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* Therefore, each uint8 in the draw buffer stores the state of 8 pixels.
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* Below is an example of calculating for [x, y] pixel coordinates [20, 10].
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* The example uses a horizontal resolution of 128.
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*
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* For the horizontal case, each row (y) of the image is represented by
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* `hor_res >> 3` bytes (16). The byte-offset of the first pixel in the 10th
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* row for example is `16 * 10` = 160.
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*
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* Since the pixels are stored horizontally we must calculate the 20th pixel
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* column (x) as `160 + (20 >> 3)`, or `160 + (20 / 8)` to get a final offset
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* of 162.
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*
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* @param x X pixel coordinate to find byte offset.
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* @param y Y pixel coordinate to find byte offset.
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* @param hor_res horizontal resolution of the display.
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* @return byte offset for a single-byte monochrome pixel at [x,y].
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*/
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[[maybe_unused]] [[nodiscard]] static ptrdiff_t
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horizontal_byte_offset(const int32_t &x, const int32_t &y,
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const int32_t &hor_res = LCD_V_RES)
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{
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// Convert pixel (bit) coordinates to byte coordinates in the draw buffer.
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return (hor_res >> 3) * y + (x >> 3);
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}
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/**
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* Calculate byte offset for the pixel at [x,y] within a vertically-mapped
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* monochrome uint8 draw buffer, using the initialized horizontal resolution.
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*
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* We use `>> 3` because each pixel requires 1 bit, but each uint8 in the draw
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* buffer can hold 8 bits. To find the uint8 value in our draw buffer that
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* stores this pixel's value we must compensate for this when using pixel
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* coordinates in byte math.
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*
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* Therefore, each uint8 in the draw buffer stores the state of 8 pixels.
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* Below is an example of calculating for [x, y] pixel coordinates [20, 10].
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* The example uses a horizontal resolution of 128.
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*
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* For the vertical case, each row (y) of the image is represented by
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* `hor_res` bytes (128) - one for each column (x). Because the pixels are
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* stored vertically, the byte-offset of the first pixel in the 10th row is
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* `128 * (10 >> 3)` or * `128 * (10 / 8)` = 128.
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*
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* From this location we can simply calculate the 20th pixel column (x) as
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* `128 + 20` to get a final offset of 148, because the pixels are stored in a
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* columnar format.
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*
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* @param x X pixel coordinate to find byte offset.
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* @param y Y pixel coordinate to find byte offset.
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* @param hor_res horizontal resolution of the display.
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* @return byte offset for a single-byte monochrome pixel at [x,y].
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*/
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[[maybe_unused]] [[nodiscard]] static ptrdiff_t
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vertical_byte_offset(const int32_t &x, const int32_t &y,
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const int32_t &hor_res = LCD_V_RES)
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{
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// Convert pixel (bit) coordinates to byte coordinates in the draw buffer.
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return hor_res * (y >> 3) + x;
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}
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/**
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* Finds the Most Significant Bit location of bit `i` in a byte.
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*
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* MSB LSB
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* bits 7 6 5 4 3 2 1 0
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* data 8 7 6 5 4 3 2 1
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* Left Right
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*
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* @return bitmask for MSB location of `i`.
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*/
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[[maybe_unused]] [[nodiscard]] static uint8_t
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msb_mask(const int32_t &i) { return 1 << (7 - i % 8); }
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/**
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* Finds the Least Significant Bit location of bit `i` in a byte.
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*
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* LSB MSB
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* bits 0 1 2 3 4 5 6 7
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* data 1 2 3 4 5 6 7 8
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* Left Right
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*
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* @return bitmask for LSB location of `i`.
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*/
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[[maybe_unused]] [[nodiscard]] static uint8_t
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lsb_mask(const int32_t &i) { return 1 << (i % 8); }
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};
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/**
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* Encapsulates vendor specific ESP LCD panel initialization logic.
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* This pure virtual interface can be inherited from for using new LCD devices.
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* See SSD1306 as an example to implement IPanelDevice for NT35510 or ST7789.
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*
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* At this time only I2C is supported.
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* Classes that inherit from this interface should likely be marked final.
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*/
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class IPanelDevice {
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public:
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/**
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* Construct an IPanelDevice.
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*
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* @param i2c I2C object. Eventually this will mature to IProtocol or similar.
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* @param config I2C configuration for this device.
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* @param height Height of the device screen in pixels.
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* @param width Width of the device screen in pixels.
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*/
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explicit IPanelDevice(I2C &i2c,
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esp_lcd_panel_io_i2c_config_t config,
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int width,
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int height) :
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IPanelDevice(i2c, config, width, height,
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width * height / 8 + LVGL_PALETTE_SIZE) { }
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/**
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* Construct an IPanelDevice.
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*
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* @param i2c I2C object. Eventually this will mature to IProtocol or similar.
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* @param config I2C configuration for this device.
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* @param height Height of the device screen in pixels.
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* @param width Width of the device screen in pixels.
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* @param draw_buf_size Size of the draw buffer for this device.
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*/
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explicit IPanelDevice(I2C &i2c,
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esp_lcd_panel_io_i2c_config_t io_config,
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int width,
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int height,
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size_t draw_buf_size) :
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width_(width),
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height_(height),
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rst_num_(i2c.rst_num_),
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lv_buf_size_(draw_buf_size),
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esp_io_config_(io_config),
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lv_buf_(nullptr) { }
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virtual ~IPanelDevice() = default;
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//
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// PUBLIC METHODS
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/**
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* Create an LVGL display using the width and height of this device.
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*
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* @return Handle to the created LVGL display.
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*/
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[[nodiscard]] lv_display_t *create_display() const
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{
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auto display = lv_display_create(width_, height_);
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assert(display);
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return display;
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}
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/**
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* Create an ESP LCD panel IO handle.
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*
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* @return The created ESP LCD panel IO handle.
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*/
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[[nodiscard]] esp_lcd_panel_io_handle_t create_io_handle()
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{
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ESP_LOGI(TAG, "Creating panel IO handle");
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esp_lcd_panel_io_handle_t handle = nullptr;
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ESP_ERROR_CHECK(
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esp_lcd_new_panel_io_i2c(I2C::get(), &esp_io_config_, &handle));
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return handle;
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}
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/**
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* Create and initialize an ESP panel handle.
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* IPanelDevice implementors must initialize the panel within init_panel.
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*
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* @param config ESP LCD panel configuration.
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* @param io ESP LCD panel IO handle.
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* @param [out] panel ESP LCD panel handle output pointer location.
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*/
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void create_panel(esp_lcd_panel_dev_config_t &config,
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esp_lcd_panel_io_handle_t io,
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esp_lcd_panel_handle_t &panel)
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{
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// If the passed handle is already allocated, delete it.
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if (panel != nullptr) {
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ESP_LOGI(TAG, "Removing unused panel");
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esp_lcd_panel_del(panel);
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}
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ESP_LOGI(TAG, "Installing vendor panel driver");
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// Call pure virtual method responsible for initializing the panel handle.
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init_panel(config, io, panel);
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}
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/**
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* Retrieve the device specific vendor configuration structure.
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*
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* @return Address of vendor configuration structure.
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* @sa SSD1306::vendor_config
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*/
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virtual void *vendor_config() = 0;
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/**
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* Registers LVGL draw buffers and callbacks for this display.
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*
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* An implementation of the interface can optionally override this method to
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* provide custom LVGL callbacks and display configurations.
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*
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* @param display_handle LVGL display handle to use for rendering.
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* @param io_handle IO handle for the ESP LCD panel.
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*/
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virtual void register_rendering_data(lv_display_t *display_handle,
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esp_lcd_panel_io_handle_t io_handle);
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/**
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* Registers LVGL ticker timer callback for rendering this display.
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*
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* An implementation of the interface can optionally override this method to
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* provide custom LVGL callbacks and tick configurations.
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*/
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virtual void register_lvgl_tick_timer();
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//
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// PUBLIC MEMBERS
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/// Width of the device screen in pixels.
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int32_t width_;
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/// Height of the device screen in pixels.
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int32_t height_;
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/// RST GPIO pin number.
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int rst_num_;
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/// LVGL draw buffer size for the device.
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size_t lv_buf_size_;
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/// ESP LCD panel IO configuration.
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esp_lcd_panel_io_i2c_config_t esp_io_config_;
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protected:
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/**
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* Static accessor to a static buffer to store draw buffer data for the panel.
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*
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* This method is protected to allow an implementation to provide a custom
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* callback method similar to IPanelDevice::lvgl_flush_cb.
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*
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* The buffer is allocated statically within the scope of this function to
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* allow creating multiple panels that _each_ manage their own statically
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* allocated draw buffer data. This simplifies implementing the interface by
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* taking this responsibility off of the implementor. The buffer will only be
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* allocated if this method is called, so the memory is only used if required.
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*
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* @return Pointer to uint8 draw buffer data.
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* @sa register_rendering_data for overriding LVGL rendering callbacks.
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*/
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static uint8_t *get_additional_draw_buffer()
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{
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// Static to the scope of this function, not the compilation unit.
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// For LV_COLOR_FORMAT_I1 we need an extra buffer to hold converted data.
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static uint8_t oled_buffer[LCD_H_RES * LCD_V_RES / 8];
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return oled_buffer;
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}
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private:
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//
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// PRIVATE METHODS
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/**
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* Initializes the ESP panel using vendor specific APIs and configurations.
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* This method should implement any setup logic specific to the device.
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*
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* @param config ESP LCD panel configuration.
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* @param io ESP LCD panel IO handle.
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* @param [out] panel ESP LCD panel handle output pointer location.
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*/
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virtual void init_panel(esp_lcd_panel_dev_config_t &config,
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esp_lcd_panel_io_handle_t io,
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esp_lcd_panel_handle_t &panel) = 0;
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//
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// PRIVATE STATIC METHODS
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/**
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* The callback invoked when panel IO finishes transferring color data.
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* This signals that the panel is ready to flush image data to the display.
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*
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* @param panel LCD panel IO handles.
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* @param data Panel IO event data, fed by driver.
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* @param user_ctx User data, passed from `esp_lcd_panel_io_xxx_config_t`.
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* @return Whether a high priority task has been waken up by this function.
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* @sa SSD1306::SSD1306 for setting user_ctx data passed to the callback.
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* @sa register_rendering_data for overriding this callback.
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*/
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static bool lvgl_flush_ready_cb(esp_lcd_panel_io_handle_t panel,
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esp_lcd_panel_io_event_data_t *data,
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void *user_ctx);
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/**
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* The callback invoked for flushing the rendered image to the display.
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*
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* `px_map` contains the rendered image as raw pixel map and it should be
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* copied to `area` on the display.
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*
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* The following details are crucial for understanding the logic surrounding
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* flushing to the display in this example.
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*
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* The order of bits within the px_map from _LVGL_ is MSB first.
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* MSB LSB
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* bits 7 6 5 4 3 2 1 0
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* pixels 0 1 2 3 4 5 6 7
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* Left Right
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*
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* The bytes from _LVGL_ are mapped to pixel rows of the display
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* 8 bits (pixels) per byte -
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* [0, 0, 0, 0, 0, 0, 0, 0]
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* [0, 0, 0, 0, 0, 0, 0, 0]
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* [0, 0, 0, 0, 0, 0, 0, 0]
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*
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* The order of bits expected by the _display driver_ is LSB first.
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* We must preserve pairing of each bit and pixel when writing to the display.
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* LSB MSB
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* bits 0 1 2 3 4 5 6 7
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* pixels 7 6 5 4 3 2 1 0
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* Left Right
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*
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* Bytes expected by the _display driver_ map to pixel columns of the display.
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* 8 bits (pixels) per byte -
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* [0, [0, [0, [0,
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* 0, 0, 0, 0,
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* 0, 0, 0, 0,
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* 0, 0, 0, 0,
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* 0, 0, 0, 0,
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* 0, 0, 0, 0,
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* 0, 0, 0, 0,
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* 0] 0] 0] 0]
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*
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* These layouts in memory have no opinion on the shape of the image. The
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* beginning and end of a row or a column for example is entirely dependent
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* on how the data is accessed. The vertical and horitzontal resolution may
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* vary between displays.
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*
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* For the LV_COLOR_FORMAT_I1 color format we are using, an additional buffer
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* is needed for transposing the bits to the vertical arrangement required by
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* the display driver that is outlined above.
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*
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* This callback implementation is an example of handling this transposition
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* and flushing the data to the display in the expected format.
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*
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* @param display LVGL display handle to use for rendering.
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* @param area Area of the display being flushed.
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* @param px_map Rendered image data for writing to the display area.
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* @sa register_rendering_data for overriding this callback.
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* @sa get_additional_draw_buffer
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*/
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static void lvgl_flush_cb(lv_display_t *display,
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const lv_area_t *area,
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uint8_t *px_map);
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/**
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* Callback invoked for every period of the timer.
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*
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* This callback _must_ call lv_tick_inc to inform LVGL how much time has
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* elapsed since the last period of the timer.
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*
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* @param data User data passed to the callback.
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* @sa register_lvgl_tick_timer for setting user data and the tick period of
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* the timer, or overriding this callback entirely.
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*/
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static void lvgl_increase_tick_cb(void *data);
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/**
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* FreeRTOS task callback invoked for handling LVGL events or updating the UI.
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*
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* This function is intentionally an endless loop and should never return.
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* LVGL initialization logic can optionally be added before entering the loop.
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* Input logic can optionally be handled within the loop.
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*
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* This callback _must_ call lv_timer_handler to handle LVGL periodic timers.
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*
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* @param data User data passed to the callback.
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* @sa register_lvgl_tick_timer for overriding this callback.
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*/
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[[noreturn]] static void lvgl_port_task(void *data);
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//
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// PRIVATE MEMBERS
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/// LVGL draw buffer associated with this Display's lv_display_t.
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void *lv_buf_;
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/// Tag used for ESP logging.
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constexpr static const char *TAG = "IPanelDevice";
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};
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#endif // PANEL_DEVICE_H
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