Add LVGL png decoding example

examples/LVGL/ChargingAnimation/ChargingAnimation.ino

@@ -0,0 +1,115 @@
+/*
+*  In this example, the demonstration uses PNG image switching to make charging animation
+*  Need to upload the content of the data file to SPIFFS
+* Copyright 2020 Lewis he
+*/
+#include "config.h"
+
+TTGOClass *ttgo;
+AXP20X_Class *power;
+
+bool irq = false;
+lv_obj_t *label = nullptr;
+lv_obj_t *img = nullptr;
+lv_obj_t *chargelabel = nullptr;
+lv_task_t *task = nullptr;
+
+static void lv_power_monitor_task(lv_task_t *t);
+
+void setup()
+{
+    Serial.begin(115200);
+
+    ttgo = TTGOClass::getWatch();
+
+    ttgo->begin();
+
+    ttgo->openBL();
+
+    ttgo->lvgl_begin();
+
+    power = ttgo->power;
+
+    pinMode(AXP202_INT, INPUT);
+    attachInterrupt(AXP202_INT, [] {
+        irq = true;
+    }, FALLING);
+
+    // ADC monitoring must be enabled to use the AXP202 monitoring function
+    power->adc1Enable(AXP202_VBUS_VOL_ADC1
+                      | AXP202_VBUS_CUR_ADC1
+                      | AXP202_BATT_CUR_ADC1
+                      | AXP202_BATT_VOL_ADC1,
+                      true);
+
+    power->enableIRQ(AXP202_PEK_SHORTPRESS_IRQ
+                     | AXP202_VBUS_REMOVED_IRQ
+                     | AXP202_VBUS_CONNECT_IRQ
+                     | AXP202_CHARGING_IRQ, true
+                    );
+
+    power->clearIRQ();
+
+    lv_obj_set_style_local_bg_color(lv_scr_act(), LV_OBJ_PART_MAIN, LV_STATE_DEFAULT, LV_COLOR_BLACK);
+
+    label = lv_label_create(lv_scr_act(), NULL);
+    lv_obj_set_style_local_text_color(label, LV_LABEL_PART_MAIN, LV_STATE_DEFAULT, LV_COLOR_WHITE);
+    lv_label_set_long_mode(label,   LV_LABEL_LONG_BREAK);
+    lv_label_set_text(label, "Please unplug the USB plug  and plug it in again, you will be able to see a simple animation made with PNG images");
+    lv_obj_set_width(label, 239);
+    lv_obj_align(label, NULL, LV_ALIGN_CENTER, 0, 0);
+
+}
+
+#define IMG_POWER_COUNT     4
+
+static void lv_power_monitor_task(lv_task_t *t)
+{
+    static uint8_t imgIndex = 0;
+    char buf[128];
+    lv_obj_t *obj = (lv_obj_t *)t->user_data;
+    snprintf(buf, 128, "P:/%u.png", imgIndex++);
+    lv_img_set_src(obj, buf);
+    imgIndex %= IMG_POWER_COUNT;
+
+    if (!chargelabel) {
+        chargelabel  = lv_label_create(lv_scr_act(), NULL);
+    }
+    snprintf(buf, 128, "V:%.2f V C:%.2fmA", power->getVbusVoltage() / 1000.0
+             , power->getVbusCurrent());
+    lv_label_set_text(chargelabel, buf);
+    lv_obj_align(chargelabel, obj, LV_ALIGN_OUT_BOTTOM_MID, 0, 5);
+}
+
+void loop()
+{
+    if (irq) {
+        irq = false;
+        power->readIRQ();
+        // Assuming that the USB is plugged in and set to charging
+        if (power->isVbusPlugInIRQ()) {
+            if (!img) {
+                lv_obj_set_hidden(label, true);
+                ttgo->setBrightness(65);
+                img   = lv_img_create(lv_scr_act(), NULL);
+                lv_img_set_src(img, "P:/0.png");
+                lv_obj_align(img, NULL, LV_ALIGN_CENTER, 0, - 10);
+                task =   lv_task_create(lv_power_monitor_task, 1000, LV_TASK_PRIO_MID, img);
+            }
+        }
+        if (power->isVbusRemoveIRQ()) {
+            if (img) {
+                lv_task_del(task);
+                lv_obj_del(chargelabel);
+                lv_obj_del(img);
+                img = nullptr;
+                chargelabel = nullptr;
+                task = nullptr;
+                lv_obj_set_hidden(label, false);
+            }
+        }
+        power->clearIRQ();
+    }
+    lv_task_handler();
+    delay(5);
+}

examples/LVGL/ChargingAnimation/config.h

@@ -0,0 +1,17 @@
+// => Hardware select
+// #define LILYGO_WATCH_2019_WITH_TOUCH     // To use T-Watch2019 with touchscreen, please uncomment this line
+// #define LILYGO_WATCH_2019_NO_TOUCH          // To use T-Watch2019 Not touchscreen , please uncomment this line
+// #define LILYGO_WATCH_2020_V1             //To use T-Watch2020, please uncomment this line
+
+
+// NOT SUPPORT ...
+//// #define LILYGO_WATCH_BLOCK
+// NOT SUPPORT ...
+
+// => Function select
+#define LILYGO_WATCH_LVGL                                //To use LVGL, you need to enable the macro LVGL
+#define LILYGO_WATCH_LVGL_FS                        //Need to use LVGL file system need to define this macro
+#define LILYGO_WATCH_LVGL_DECODER       //Need to use PNG decoding, to define this macro
+#include <LilyGoWatch.h>
+
+