Update to LVGL 9.0.0 (#47)

- Updated LVGL from 8.3 to 9.0 (removed example/docs/demo folders)
- Updated esp_lvgl_port  to current status of the `lvgl9` branch on `esp-bsp`: https://github.com/espressif/esp-bsp/tree/lvgl9
- Updated all boards and drivers
- Removed `libs/lv_drivers` subproject as SDL is now supported by LVGL directly (although keyboard input seems broken)
- Updated `libs/lv_screenshot`
- Fixed the way `tt_statusbar` widget works due to behaviour change in LVGL
- Updated other lvgl code

libs/esp_lvgl_port/README.md

@@ -13,6 +13,20 @@ This component helps with using LVGL with Espressif's LCD and touch drivers. It
 * Add/remove navigation buttons input (using [`button`](https://github.com/espressif/esp-iot-solution/tree/master/components/button))
 * Add/remove encoder input (using [`knob`](https://github.com/espressif/esp-iot-solution/tree/master/components/knob))
 
+## LVGL Version
+
+This component supports **LVGL8** and **LVGL9**. By default, it selects the latest LVGL version. If you want to use a specific version (e.g. latest LVGL8), you can easily put into `idf_component.yml` in your project like this:
+
+```
+  lvgl/lvgl:
+    version: "^8"
+    public: true
+```
+
+### LVGL Version Compatibility
+
+This component is fully compatible with LVGL version 9. All types and functions are used from LVGL9. Some LVGL9 types are not supported in LVGL8 and there are retyping in [`esp_lvgl_port_compatibility.h`](include/esp_lvgl_port_compatibility.h) header file. **Please, be aware, that some draw and object functions are not compatible between LVGL8 and LVGL9.**
+
 ## Usage
 
 ### Initialization
@@ -53,6 +67,7 @@ Add an LCD screen to the LVGL. It can be called multiple times for adding multip
         },
         .flags = {
             .buff_dma = true,
+            .swap_bytes = false,
         }
     };
     disp_handle = lvgl_port_add_disp(&disp_cfg);
@@ -219,11 +234,43 @@ Every LVGL calls must be protected with these lock/unlock commands:
 ```
 
 ### Rotating screen
+
+LVGL port supports rotation of the display. You can select whether you'd like software rotation or hardware rotation.
+Software rotation requires no additional logic in your `flush_cb` callback.
+
+Rotation mode can be selected in the `lvgl_port_display_cfg_t` structure.
+``` c
+    const lvgl_port_display_cfg_t disp_cfg = {
+        ...
+        .flags = {
+            ...
+            .sw_rotate = true / false, // true: software; false: hardware
+        }
+    }
+```
+Display rotation can be changed at runtime.
+
 ``` c
     lv_disp_set_rotation(disp_handle, LV_DISP_ROT_90);
 ```
 
-**Note:** During the rotating, the component call [`esp_lcd`](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/lcd.html) API.
+**Note:** During the hardware rotating, the component call [`esp_lcd`](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/lcd.html) API. When using software rotation, you cannot use neither `direct_mode` nor `full_refresh` in the driver. See [LVGL documentation](https://docs.lvgl.io/8.3/porting/display.html?highlight=sw_rotate) for more info.
+
+### Using PSRAM canvas
+
+If the SRAM is insufficient, you can use the PSRAM as a canvas and use a small trans_buffer to carry it, this makes drawing more efficient.
+``` c
+    const lvgl_port_display_cfg_t disp_cfg = {
+        ...
+        .buffer_size = DISP_WIDTH * DISP_HEIGHT, // in PSRAM, not DMA-capable
+        .trans_size = size, // in SRAM, DMA-capable
+        .flags = {
+            .buff_spiram = true,
+            .buff_dma = false,
+            ...
+        }
+    }
+```
 
 ## Performance