Refactor: opt memory for texture of font atlas

packages/core/src/2d/atlas/FontAtlas.ts

@@ -1,6 +1,7 @@
 import { Vector2 } from "@galacean/engine-math";
 import { Engine } from "../../Engine";
 import { ReferResource } from "../../asset/ReferResource";
+import { TextureFilterMode, TextureFormat } from "../../texture";
 import { Texture2D } from "../../texture/Texture2D";
 import { CharInfo } from "../text/CharInfo";
 
@@ -15,9 +16,17 @@ export class FontAtlas extends ReferResource {
   private _curX: number = 1;
   private _curY: number = 1;
   private _nextY: number = 1;
+  private _preSize: number = 0;
+  private _curSize: number = 128;
 
   constructor(engine: Engine) {
     super(engine);
+    this.isGCIgnored = true;
+    const size = this._curSize;
+    const texture = new Texture2D(engine, size, size, TextureFormat.R8G8B8A8, false);
+    texture.filterMode = TextureFilterMode.Bilinear;
+    texture.isGCIgnored = true;
+    this.texture = texture;
   }
 
   uploadCharTexture(charInfo: CharInfo): boolean {
@@ -26,21 +35,30 @@ export class FontAtlas extends ReferResource {
     const textureSize = texture.width;
     const offsetWidth = width + space;
     const offsetHeight = height + space;
-    if (1 + offsetWidth >= textureSize || 1 + offsetHeight >= textureSize) {
-      throw Error("The char fontSize is too large.");
-    }
+    const tempCurX = this._curX;
+    const tempNextY = this._nextY;
 
-    const endX = this._curX + offsetWidth;
+    const endX = tempCurX + offsetWidth;
     if (endX >= textureSize) {
-      this._curX = space;
-      this._curY = this._nextY + space;
+      this._curX = space + (tempNextY > this._preSize ? 0 : this._preSize);
+      this._curY = tempNextY + space;
     }
     const endY = this._curY + offsetHeight;
-    if (endY > this._nextY) {
+    if (endY > tempNextY) {
       this._nextY = endY;
     }
+    // Exceed cur texture size.
     if (endY >= textureSize) {
-      return false;
+      if (textureSize >= 1024) {
+        console.warn("Exceed max size.");
+        return false;
+      } else {
+        this._curX = textureSize + space;
+        this._curY = space;
+        this._nextY = space;
+        this._resizeTexture();
+        return this.uploadCharTexture(charInfo);
+      }
     }
 
     if (width > 0 && height > 0 && data) {
@@ -88,4 +106,33 @@ export class FontAtlas extends ReferResource {
     this.texture = null;
     this._charInfoMap = {};
   }
+
+  private _resizeTexture(): void {
+    const curSize = (this._preSize = this._curSize);
+    const newSize = (this._curSize *= 2);
+    const resizeTexture = new Texture2D(this.engine, newSize, newSize, TextureFormat.R8G8B8A8, false);
+    resizeTexture.filterMode = TextureFilterMode.Bilinear;
+    resizeTexture.isGCIgnored = true;
+    const texture = this.texture;
+    this.texture = resizeTexture;
+
+    // Write data from texture to resize texture.
+    const data = new Uint8Array(curSize * curSize * 4);
+    texture.getPixelBuffer(data);
+    resizeTexture.setPixelBuffer(data, 0, 0, 0, curSize, curSize);
+    resizeTexture.generateMipmaps();
+
+    // Reset uvs
+    const map = this._charInfoMap;
+    for (const key in map) {
+      const charInfo = map[key];
+      const uvs = charInfo.uvs;
+      uvs[0].scale(0.5);
+      uvs[1].scale(0.5);
+      uvs[2].scale(0.5);
+      uvs[3].scale(0.5);
+    }
+
+    texture.destroy();
+  }
 }

packages/core/src/2d/text/SubFont.ts

@@ -1,7 +1,7 @@
 import { AssetPromise } from "../../asset/AssetPromise";
 import { ContentRestorer } from "../../asset/ContentRestorer";
 import { Engine } from "../../Engine";
-import { Texture2D, TextureFilterMode, TextureFormat } from "../../texture";
+import { Texture2D } from "../../texture";
 import { FontAtlas } from "../atlas/FontAtlas";
 import { CharInfo } from "./CharInfo";
 import { TextUtils } from "./TextUtils";
@@ -93,10 +93,6 @@ export class SubFont {
   private _createFontAtlas(): FontAtlas {
     const { _engine: engine } = this;
     const fontAtlas = new FontAtlas(engine);
-    const texture = new Texture2D(engine, 256, 256, TextureFormat.R8G8B8A8, false);
-    texture.filterMode = TextureFilterMode.Bilinear;
-    fontAtlas.texture = texture;
-    fontAtlas.isGCIgnored = texture.isGCIgnored = true;
     this._fontAtlases.push(fontAtlas);
 
     const nativeFontString = this.nativeFontString;