Display
The display component is responsible for managing the memory associated the display buffer / video RAM (vram). It ensures that the LVGL subsystem is configured appropriately.
API Reference
Header File
Classes
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template<typename Pixel>
class Display : public espp::BaseComponent Wrapper class around LVGL display buffer and display driver.
Optionally allocates and owns the memory associated with the pixel display buffers. Initializes the LVGL subsystem.
For more information, see https://docs.lvgl.io/9.1/porting/display.html#display-interface
- Template Parameters:
Pixel – The pixel format to be used for the display. This allows the class to be used with displays of different color depths and formats.
Public Types
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typedef std::function<void(lv_display_t *disp, const lv_area_t *area, uint8_t *color_map)> flush_fn
Callback for lvgl to flush segments of pixel data from the pixel buffers to the display.
- Param disp:
The display to flush data to.
- Param area:
The area of the display to flush data to.
- Param color_map:
The color data to flush to the display.
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typedef std::function<void(const DisplayRotation &rotation)> rotation_fn
Callback for lvgl event handler to reconfigure the display hardware.
- Param rotation:
The new rotation setting for the display.
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typedef std::function<void(float brightness)> set_brightness_fn
Callback for setting the display brightness.
- Param brightness:
Brightness value between 0.0 and 1.0.
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typedef std::function<float()> get_brightness_fn
Callback for getting the display brightness.
- Return:
float Brightness value between 0.0 and 1.0.
Public Functions
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inline explicit Display(const LvglConfig &lvgl_conf, const LcdConfig &lcd_config, const StaticMemoryConfig &mem_conf, const Logger::Verbosity log_level = Logger::Verbosity::WARN)
Initialize LVGL.
- Parameters:
lvgl_conf – LVGL Configuration, including display size, flush callback and optional rotation callback.
lcd_config – LCD specific configuration.
mem_conf – Static memory configuration.
log_level – The verbosity level for the Display logger_.
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inline explicit Display(const LvglConfig &lvgl_conf, const LcdConfig &lcd_config, const DynamicMemoryConfig &mem_conf, const Logger::Verbosity log_level = Logger::Verbosity::WARN)
Allocate the display buffers and initialize LVGL.
- Parameters:
lvgl_conf – LVGL Configuration, including display size, flush callback and optional rotation callback.
lcd_config – LCD specific configuration.
mem_conf – Dynamic memory configuration.
log_level – The verbosity level for the Display logger_.
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inline explicit Display(const LvglConfig &lvgl_conf, const OledConfig &oled_config, const StaticMemoryConfig &mem_conf, const Logger::Verbosity log_level = Logger::Verbosity::WARN)
Initialize LVGL.
- Parameters:
lvgl_conf – LVGL Configuration, including display size, flush callback and optional rotation callback.
oled_config – OLED specific configuration.
mem_conf – Static memory configuration.
log_level – The verbosity level for the Display logger_.
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inline explicit Display(const LvglConfig &lvgl_conf, const OledConfig &oled_config, const DynamicMemoryConfig &mem_conf, const Logger::Verbosity log_level = Logger::Verbosity::WARN)
Allocate the display buffers then initialize LVGL.
- Parameters:
lvgl_conf – LVGL Configuration, including display size, flush callback and optional rotation callback.
oled_config – OLED specific configuration.
mem_conf – Dynamic memory configuration.
log_level – The verbosity level for the Display logger_.
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inline ~Display()
Frees the display buffer memory.
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inline size_t width() const
Return the configured width of the display in pixels.
- Returns:
size_t width of the display.
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inline size_t height() const
Return the configured height of the display in pixels.
- Returns:
size_t height of the display.
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inline void set_brightness(float brightness)
Set the brightness of the display.
- Parameters:
brightness – Brightness value between 0.0 and 1.0.
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inline float get_brightness() const
Get the brightness of the display.
- Returns:
float Brightness value between 0.0 and 1.0.
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inline void force_refresh() const
Force a redraw / refresh of the display.
Note
This is mainly useful after you have called pause() on the display (to draw to it with something other than LVGL) and want to switch back to the LVGL gui. Normally you should not call this function.
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inline Pixel *vram0()
Get pointer to main display buffer for custom writing.
- Returns:
uint16_t* Pointer to the main display buffer.
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inline Pixel *vram1()
Get pointer to secondary display buffer for custom writing.
- Returns:
uint16_t* Pointer to the secondary display buffer.
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inline size_t vram_size_px() const
Return the number of pixels that vram() can hold.
- Returns:
size_t Number of pixels that fit in the display buffer.
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inline size_t vram_size_bytes() const
Return the number of bytes that vram() can hold.
- Returns:
size_t Number of bytes that fit in the display buffer.
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inline void set_rotation(DisplayRotation rotation)
Set the rotation of the display.
Note
This function is called by the event handler when the display resolution changes, so that the display hardware can be reconfigured to match the new software rotation setting.
- Parameters:
rotation – The new rotation setting for the display.
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inline void flush(lv_display_t *disp, const lv_area_t *area, uint8_t *color_map)
Flush the data to the display.
Warning
This function is called by the LVGL flush callback, so it is recommended to not call this function directly.
- Parameters:
disp – The display to flush data to.
area – The area of the display to flush data to.
color_map – The color data to flush to the display.
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inline void notify_flush_ready()
Notify LVGL that the flush operation is complete.
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inline lv_display_t *get_lvgl_display() const
Get pointer to the LVGL display object.
- Returns:
lv_display_t* Pointer to the LVGL display object.
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inline const std::string &get_name() const
Get the name of the component
Note
This is the tag of the logger
- Returns:
A const reference to the name of the component
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inline void set_log_tag(const std::string_view &tag)
Set the tag for the logger
- Parameters:
tag – The tag to use for the logger
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inline espp::Logger::Verbosity get_log_level() const
Get the log level for the logger
See also
See also
- Returns:
The verbosity level of the logger
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inline void set_log_level(espp::Logger::Verbosity level)
Set the log level for the logger
See also
See also
- Parameters:
level – The verbosity level to use for the logger
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inline void set_log_verbosity(espp::Logger::Verbosity level)
Set the log verbosity for the logger
See also
See also
See also
Note
This is a convenience method that calls set_log_level
- Parameters:
level – The verbosity level to use for the logger
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inline espp::Logger::Verbosity get_log_verbosity() const
Get the log verbosity for the logger
See also
See also
See also
Note
This is a convenience method that calls get_log_level
- Returns:
The verbosity level of the logger
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inline void set_log_rate_limit(std::chrono::duration<float> rate_limit)
Set the rate limit for the logger
See also
Note
Only calls to the logger that have _rate_limit suffix will be rate limited
- Parameters:
rate_limit – The rate limit to use for the logger
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struct DynamicMemoryConfig
Used if you want the Display to manage the allocation / lifecycle of the display buffer memory itself.
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struct LcdConfig
LCD specific configuration.
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struct LvglConfig
Base component configuration for LVGL.
Public Members
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size_t width
Width of th display, in pixels.
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size_t height
Height of the display, in pixels.
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rotation_fn rotation_callback{nullptr}
Optional function used to configure display with new rotation setting.
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DisplayRotation rotation = {DisplayRotation::LANDSCAPE}
Default / Initial rotation of the display.
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size_t width
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struct OledConfig
OLED specific configuration.
Public Members
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set_brightness_fn set_brightness_callback{nullptr}
Callback for setting the display brightness
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get_brightness_fn get_brightness_callback = {nullptr}
Callback for getting the display brightness.
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set_brightness_fn set_brightness_callback{nullptr}