Introduce some functional programming techniques

src/file/drawing/inline/graphic/graphic-data/pic/shape-properties/form/extents/extents-attributes.ts

@@ -1,12 +1,12 @@
 import { XmlAttributeComponent } from "file/xml-components";
 
 export interface IExtentsAttributes {
-    cx?: number;
-    cy?: number;
+    readonly cx?: number;
+    readonly cy?: number;
 }
 
 export class ExtentsAttributes extends XmlAttributeComponent<IExtentsAttributes> {
-    protected xmlKeys = {
+    protected readonly xmlKeys = {
         cx: "cx",
         cy: "cy",
     };

src/file/drawing/inline/graphic/graphic-data/pic/shape-properties/form/offset/off-attributes.ts

@@ -1,12 +1,12 @@
 import { XmlAttributeComponent } from "file/xml-components";
 
 export interface IOffsetAttributes {
-    x?: number;
-    y?: number;
+    readonly x?: number;
+    readonly y?: number;
 }
 
 export class OffsetAttributes extends XmlAttributeComponent<IOffsetAttributes> {
-    protected xmlKeys = {
+    protected readonly xmlKeys = {
         x: "x",
         y: "y",
     };

src/file/drawing/inline/graphic/graphic-data/pic/shape-properties/preset-geometry/preset-geometry-attributes.ts

@@ -1,11 +1,11 @@
 import { XmlAttributeComponent } from "file/xml-components";
 
 export interface IPresetGeometryAttributes {
-    prst?: string;
+    readonly prst?: string;
 }
 
 export class PresetGeometryAttributes extends XmlAttributeComponent<IPresetGeometryAttributes> {
-    protected xmlKeys = {
+    protected readonly xmlKeys = {
         prst: "prst",
     };
 }

src/file/drawing/inline/graphic/graphic-data/pic/shape-properties/shape-properties-attributes.ts

@@ -1,11 +1,11 @@
 import { XmlAttributeComponent } from "file/xml-components";
 
 export interface IShapePropertiesAttributes {
-    bwMode?: string;
+    readonly bwMode?: string;
 }
 
 export class ShapePropertiesAttributes extends XmlAttributeComponent<IShapePropertiesAttributes> {
-    protected xmlKeys = {
+    protected readonly xmlKeys = {
         bwMode: "bwMode",
     };
 }