HarmonyOS ohos.graphics.text文本模块示例demo

NativeRender.ets 文件

import { NodeController, FrameNode, RenderNode, DrawContext, Size } from "@ohos.ArkUI.node"
import { UIContext } from '@ohos.ArkUI.UIContext';

const DefaultDrawFunction = (context: DrawContext) => {};
type DrawFunction = (context: DrawContext) => void;

class NativeRenderNode extends RenderNode {
  private drawFunction: DrawFunction;

  constructor(drawFunction: DrawFunction) {
    super();
    this.drawFunction = drawFunction;
  }

  draw(context: DrawContext) {
    this.drawFunction(context);
  }
}

class NativeNodeController extends NodeController {
  private rootNode: FrameNode | null = null;
  private renderNode: NativeRenderNode | null = null;
  private drawFunction: DrawFunction;

  constructor(drawFunction: DrawFunction) {
    super();
    this.drawFunction = drawFunction;
  }

  makeNode(uiContext: UIContext): FrameNode {
    this.renderNode = new NativeRenderNode(this.drawFunction);
    this.rootNode = new FrameNode(uiContext);
    const renderNode = this.rootNode?.getRenderNode();
    if (renderNode) {
      renderNode.frame = { x: 0, y: 0, width: 1000, height: 1000 };
      this.renderNode.frame = { x: 0, y: 0, width: 1000, height: 1000 };
      renderNode.appendChild(this.renderNode);
    }
    return this.rootNode;
  }

  aboutToResize(size: Size): void {
    const renderNode = this.rootNode?.getRenderNode();
    if (renderNode) {
      renderNode.frame = { x: 0, y: 0, width: size.width, height: size.height };
      if (this.renderNode) {
        this.renderNode.frame = { x: 0, y: 0, width: size.width, height: size.height };
      }
    }
    this.invalidate();
  }

  invalidate(): void {
    this.renderNode?.invalidate();
  }
}

@Component
struct NativeRenderComponent {
  drawFunction: DrawFunction = DefaultDrawFunction;
  @State controller: NativeNodeController | null = null;

  aboutToAppear(): void {
    this.controller = new NativeNodeController(this.drawFunction);
  }

  build() {
    NodeContainer(this.controller)
      .onTouch((event: TouchEvent) => {
        if (event.type === TouchType.Up) {
          this.controller?.invalidate();
        }
      })
  }
}

export default NativeRenderComponent;
 
Index.ets 文件
import { NodeController, FrameNode, RenderNode, DrawContext, Size, LengthMetrics } from "@ohos.ArkUI.node"
import NativeRenderComponent from './NativeRender';
import drawing from '@ohos.graphics.drawing';
import { common2D, text } from '@kit.ArkGraphics2D';

import { NodeController, FrameNode, RenderNode, DrawContext, Size, LengthMetrics } from "@ohos.ArkUI.node"
import NativeRenderComponent from './NativeRender';
import drawing from '@ohos.graphics.drawing';
import { common2D, text } from '@kit.ArkGraphics2D';

@Entry
@Component
struct Index {
  static fontName: string = "myFont";
  static fontCollection: text.FontCollection = LoadFont(Index.fontName, $rawfile('font/Yarndings20-Regular.ttf'));

  build() {
    Column({ space: 20 }) {
      NativeRenderComponent({drawFunction: (context: DrawContext) => {
        let style: text.TextStyle = {color: {alpha: 255, red: 255, green: 0, blue: 0}, fontFamilies: [Index.fontName], fontSize: 100};
        // DrawParagraph(context.canvas, 'ABCD', Index.fontCollection, style, 50, 50);

        const x = 50;
        const y = 200;
        DrawParagraph(context.canvas, '你好', Index.fontCollection, style, x, y);

      }})
        .backgroundColor(0x00ff00)
        .width(300)
        .height(400)
    }
    .height('100%')
  }
}

function LoadFont(name: string, fontSrc: string | Resource) {
  const fc = new text.FontCollection();
  fc.loadFontSync(name, fontSrc);
  return fc;
}

function DrawParagraph(canvas: drawing.Canvas, str: string, fontCollection: text.FontCollection, style: text.TextStyle, x: number, y: number): text.Paragraph {
  const builder = new text.ParagraphBuilder({}, fontCollection);
  builder.pushStyle(style);
  builder.addText(str);
  builder.popStyle();

  let paragraph = builder.build();
  paragraph.layoutSync(Number.POSITIVE_INFINITY);

  let width = paragraph.getLongestLine();
  let height = paragraph.getHeight();
  DrawRect(canvas, {alpha: 255, red: 255, green: 255, blue: 0}, {left: x, top: y, right: x + width, bottom: y + height});
  paragraph.paint(canvas, x, y);

  return paragraph;
}
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