fix(types): fix types for vue < 2.7

src/index.vue2.d.ts

@@ -1,5 +1,6 @@
 /* eslint-disable @typescript-eslint/ban-types */
-import type { Ref, DefineComponent } from "vue-demi";
+import type { DefineComponent } from "@vue/runtime-core";
+import type { Ref } from "vue-demi";
 import type {
   Option,
   InitOptions,

src/index.vue2_7.d.ts

@@ -0,0 +1,63 @@
+/* eslint-disable @typescript-eslint/ban-types */
+import type { Ref, DefineComponent } from "vue-demi";
+import type {
+  Option,
+  InitOptions,
+  UpdateOptions,
+  EChartsType,
+  Emits
+} from "./types";
+
+declare const LOADING_OPTIONS_KEY = "ecLoadingOptions";
+declare const THEME_KEY = "ecTheme";
+declare const INIT_OPTIONS_KEY = "ecInitOptions";
+declare const UPDATE_OPTIONS_KEY = "ecUpdateOptions";
+
+declare type ChartProps = {
+  loading?: boolean;
+  loadingOptions?: Record<string, unknown>;
+  autoresize?: boolean;
+  option?: Option;
+  theme?: string | Record<string, unknown>;
+  initOptions?: InitOptions;
+  updateOptions?: UpdateOptions;
+  group?: string;
+  manualUpdate?: boolean;
+};
+
+type MethodNames =
+  | "getWidth"
+  | "getHeight"
+  | "getDom"
+  | "getOption"
+  | "resize"
+  | "dispatchAction"
+  | "convertToPixel"
+  | "convertFromPixel"
+  | "containPixel"
+  | "getDataURL"
+  | "getConnectedDataURL"
+  | "appendData"
+  | "clear"
+  | "isDisposed"
+  | "dispose"
+  | "setOption";
+
+declare type ChartMethods = Pick<EChartsType, MethodNames>;
+
+declare const Chart: DefineComponent<
+  ChartProps,
+  {
+    root: Ref<HTMLElement | undefined>;
+    chart: Ref<EChartsType | undefined>;
+  },
+  {},
+  {},
+  ChartMethods,
+  {},
+  {},
+  Emits
+>;
+
+export default Chart;
+export { INIT_OPTIONS_KEY, LOADING_OPTIONS_KEY, THEME_KEY, UPDATE_OPTIONS_KEY };