在 nuxtjs中通过fabric.js实现画图功能

取名不易2026-03-31 15:13

环境要求nuxtjs^2.15.8+nuxt-property-decorator^2.9.1+fabric.js "^5.3.0"，无需在plugins下创建文件中引入

··· components/fabricCnavas.vue

js 复制代码 
<template>
  <div class="canvas-wrapper">
    <div class="canvas-container" ref="container">
      <canvas ref="canvasEl"></canvas>
    </div>
  </div>
</template>

<script lang="ts">
import { Component, Vue, Prop } from "nuxt-property-decorator";

declare const fabric: any;

@Component
export default class FabricCanvas extends Vue {
  @Prop({ default: 800 }) width!: number;
  @Prop({ default: 600 }) height!: number;

  private fabric: any = null;
  private canvas: any = null;

  mounted() {
    this.fabric = require("fabric").fabric || require("fabric");

    // 1. 初始化画布
    this.canvas = new this.fabric.Canvas(this.$refs.canvasEl, {
      width: this.width,
      height: this.height,
      backgroundColor: "#ffffff",
      preserveObjectStacking: true,
      strokeUniform: true, // 【关键修复】让边框宽度保持固定，不随图形缩放而改变
    });

    // 强制开启"统一缩放变换"，这会让图形在拖拽大小时，
    // 实际上是改变了 width/height，而不是应用 scale 缩放，从而避免边框变形
    this.canvas.uniScaleTransform = true;

    // 2. 在拖拽缩放时，强制恢复边框宽度
    this.canvas.on("object:scaling", (e: any) => {
      const target = e.target;
      // 如果有记录的原始宽度，就强制设回去
      if (target && target.originalStrokeWidth) {
        target.set("strokeWidth", target.originalStrokeWidth);
      }
    });

    // 2. 绘制网格
    this.drawGrid();

    // 3. 监听选中变化
    this.canvas.on("selection:created", () => this.emitSelection());
    this.canvas.on("selection:updated", () => this.emitSelection());
    this.canvas.on("selection:cleared", () => this.$emit("selection:cleared"));

    // 4. 监听窗口大小变化
    window.addEventListener("resize", this.handleResize);

    this.$nextTick(() => {
      this.handleResize();
    });

    this.$emit("ready", this.canvas);
  }

  beforeDestroy() {
    window.removeEventListener("resize", this.handleResize);
    if (this.canvas) {
      this.canvas.dispose();
    }
  }

  // --- 核心方法：处理全屏自适应 ---
  private handleResize() {
    if (!this.canvas) return;
    const container = this.$refs.container as HTMLElement;
    if (container) {
      const newWidth = container.clientWidth;
      const newHeight = container.clientHeight;
      this.canvas.setDimensions({ width: newWidth, height: newHeight });
      this.drawGrid(); // 重绘网格以适应新大小
      this.canvas.renderAll();
    }
  }

  // --- 绘图方法 (已加入随机位置逻辑) ---

  addRect() {
    const randomLeft = Math.random() * (this.canvas.width - 150) + 20;
    const randomTop = Math.random() * (this.canvas.height - 150) + 20;
    const colors = ["#42b983"];
    const randomColor = colors[Math.floor(Math.random() * colors.length)];

    const rect = new this.fabric.Rect({
      left: randomLeft,
      top: randomTop,
      fill: randomColor,
      width: 100,
      height: 100,
      stroke: "#000000",
      strokeWidth: 2,
      strokeUniform: true, // 【关键修复】强制边框不随缩放变化
    });
    this.canvas.add(rect);
    this.canvas.setActiveObject(rect);
  }

  addCircle() {
    const randomLeft = Math.random() * (this.canvas.width - 150) + 20;
    const randomTop = Math.random() * (this.canvas.height - 150) + 20;
    const colors = ["#ff5722", "#42b983", "#1890ff", "#faad14"];
    const randomColor = colors[Math.floor(Math.random() * colors.length)];

    const circle = new this.fabric.Circle({
      left: randomLeft,
      top: randomTop,
      fill: randomColor,
      radius: 50,
      stroke: "#000000",
      strokeWidth: 2,
      strokeUniform: true, // 【关键修复】强制边框不随缩放变化
    });
    this.canvas.add(circle);
    this.canvas.setActiveObject(circle);
  }

  addText() {
    const randomLeft = Math.random() * (this.canvas.width - 200) + 20;
    const randomTop = Math.random() * (this.canvas.height - 100) + 20;

    const text = new this.fabric.IText("双击编辑", {
      left: randomLeft,
      top: randomTop,
      fill: "#333333",
      fontSize: 24,
      fontFamily: "Arial",
      stroke: "#000000",
      strokeWidth: 0,
    });
    this.canvas.add(text);
    this.canvas.setActiveObject(text);
  }

  deleteActive() {
    const activeObjects = this.canvas.getActiveObjects();
    if (activeObjects.length) {
      this.canvas.discardActiveObject();
      activeObjects.forEach((obj: any) => this.canvas.remove(obj));
    }
  }

  downloadImage() {
    const dataURL = this.canvas.toDataURL({
      format: "png",
      quality: 1,
      multiplier: 2,
    });
    const link = document.createElement("a");
    link.download = `design-${Date.now()}.png`;
    link.href = dataURL;
    link.click();
  }

  // --- 属性修改方法 ---

  changeColor(color: string | null) {
    const active = this.canvas.getActiveObject();
    if (active) {
      active.set("fill", color);
      this.canvas.requestRenderAll();
    }
  }

  changeOpacity(val: number) {
    const active = this.canvas.getActiveObject();
    if (active) {
      active.set("opacity", val);
      this.canvas.requestRenderAll();
    }
  }

  changeStrokeColor(color: string | null) {
    const active = this.canvas.getActiveObject();
    if (active) {
      active.set("stroke", color);
      this.canvas.requestRenderAll();
    }
  }

  changeStrokeWidth(width: number) {
    const active = this.canvas.getActiveObject();
    if (active) {
      active.set("strokeWidth", width);
      this.canvas.requestRenderAll();
    }
  }

  changeStrokeDashArray(val: string) {
    const active = this.canvas.getActiveObject();
    if (active) {
      let dashArray = null;
      if (val === "dashed") dashArray = [10, 5];
      if (val === "dotted") dashArray = [2, 2];
      active.set("strokeDashArray", dashArray);
      this.canvas.requestRenderAll();
    }
  }

  bringForward() {
    const active = this.canvas.getActiveObject();
    if (active) this.canvas.bringForward(active);
  }

  sendBackwards() {
    const active = this.canvas.getActiveObject();
    if (active) this.canvas.sendBackwards(active);
  }

  // --- 内部逻辑 ---

  private emitSelection() {
    const active = this.canvas.getActiveObject();
    if (active) {
      this.$emit("selection:updated", {
        fill: active.fill,
        opacity: active.opacity,
        type: active.type,
        stroke: active.stroke,
        strokeWidth: active.strokeWidth,
        strokeDashArray: active.strokeDashArray,
      });
    }
  }

  private drawGrid() {
    const existingGrid = this.canvas
      .getObjects()
      .filter((obj: any) => obj.isGrid);
    existingGrid.forEach((obj: any) => this.canvas.remove(obj));

    const gridSize = 20;
    const width = this.canvas.width;
    const height = this.canvas.height;

    for (let i = 0; i <= width; i += gridSize) {
      const line = new this.fabric.Line([i, 0, i, height], {
        stroke: "#e0e0e0",
        strokeWidth: 1,
        selectable: false,
        evented: false,
        isGrid: true,
      });
      this.canvas.add(line);
    }
    for (let j = 0; j <= height; j += gridSize) {
      const line = new this.fabric.Line([0, j, width, j], {
        stroke: "#e0e0e0",
        strokeWidth: 1,
        selectable: false,
        evented: false,
        isGrid: true,
      });
      this.canvas.add(line);
    }
    this.canvas.sendToBack(this.canvas.getObjects()[0]);
  }
}
</script>

<style scoped>
.canvas-wrapper {
  width: 100%;
  height: 100%;
  display: flex;
  justify-content: center;
  background: #333;
  overflow: hidden;
}

.canvas-container {
  width: 100%;
  height: 100%;
}
</style>
js 复制代码 
<template>
  <div class="editor-page">
    <!-- 顶部工具栏 -->
    <div class="toolbar">
      <div class="group">
        <button @click="canvasRef.addRect()">矩形</button>
        <button @click="canvasRef.addCircle()">圆形</button>
        <button @click="canvasRef.addText()">文字</button>
      </div>
      <div class="group">
        <button @click="canvasRef.deleteActive()">删除</button>
        <button @click="canvasRef.downloadImage()">导出图片</button>
      </div>
    </div>

    <div class="main-body">
      <!-- 左侧属性面板 -->
      <div class="sidebar" v-if="selectedObj">
        <h3>属性设置</h3>

        <!-- 1. 填充设置 -->
        <div class="prop-section">
          <h4>填充</h4>
          <div class="prop-header">
            <label>启用填充</label>
            <label class="switch-label">
              <input type="checkbox" :checked="hasFill" @change="toggleFill" />
              开启
            </label>
          </div>
          <div v-if="hasFill" class="color-picker-wrapper">
            <input
              type="color"
              :value="selectedObj.fill"
              @change="updateColor($event.target.value)"
            />
          </div>
          <div v-else class="no-fill-tip">当前为透明/无填充</div>
        </div>

        <!-- 2. 边框设置 -->
        <div class="prop-section">
          <h4>边框</h4>
          <div class="prop-header">
            <label>启用边框</label>
            <label class="switch-label">
              <input
                type="checkbox"
                :checked="hasStroke"
                @change="toggleStroke"
              />
              开启
            </label>
          </div>

          <div v-if="hasStroke" class="stroke-controls">
            <div class="prop-item">
              <label>颜色:</label>
              <input
                type="color"
                :value="selectedObj.stroke"
                @change="updateStrokeColor($event.target.value)"
              />
            </div>
            <div class="prop-item">
              <label>粗细: {{ selectedObj.strokeWidth }}px</label>
              <input
                type="range"
                min="0"
                max="20"
                step="1"
                :value="selectedObj.strokeWidth"
                @change="updateStrokeWidth($event.target.value)"
              />
            </div>
            <div class="prop-item">
              <label>样式:</label>
              <select
                :value="strokeStyleType"
                @change="updateStrokeStyle($event.target.value)"
              >
                <option value="solid">实线</option>
                <option value="dashed">虚线</option>
                <option value="dotted">点线</option>
              </select>
            </div>
          </div>
        </div>

        <!-- 3. 图层控制 -->
        <div class="prop-section">
          <h4>图层</h4>
          <div class="btn-row">
            <button @click="canvasRef.bringForward()">上移一层</button>
            <button @click="canvasRef.sendBackwards()">下移一层</button>
          </div>
        </div>
      </div>

      <div class="sidebar empty" v-else>
        <p>未选中任何对象</p>
      </div>

      <!-- 画布区域 -->
      <div class="canvas-area">
        <client-only>
          <FabricCanvas
            ref="canvasRef"
            @selection:updated="onSelectionUpdated"
            @selection:cleared="onSelectionCleared"
          />
        </client-only>
      </div>
    </div>
  </div>
</template>

<script lang="ts">
import { Component, Vue } from "nuxt-property-decorator";
import FabricCanvas from "~/components/FabricCanvas.vue";

interface SelectionInfo {
  fill: string | null;
  opacity: number;
  type: string;
  stroke: string | null;
  strokeWidth: number;
  strokeDashArray: any;
}

@Component({
  components: { FabricCanvas },
})
export default class EditorPage extends Vue {
  selectedObj: SelectionInfo | null = null;

  get canvasRef() {
    return this.$refs.canvasRef as FabricCanvas;
  }

  get hasFill() {
    return this.selectedObj !== null && this.selectedObj.fill !== null;
  }

  get hasStroke() {
    return (
      this.selectedObj !== null &&
      this.selectedObj.strokeWidth > 0 &&
      this.selectedObj.stroke !== null
    );
  }

  get strokeStyleType() {
    if (!this.selectedObj) return "solid";
    const arr = this.selectedObj.strokeDashArray;
    if (!arr) return "solid";
    if (arr[0] === 10) return "dashed";
    if (arr[0] === 2) return "dotted";
    return "solid";
  }

  onSelectionUpdated(info: SelectionInfo) {
    this.selectedObj = { ...info };
  }

  onSelectionCleared() {
    this.selectedObj = null;
  }

  toggleFill(e: any) {
    const isChecked = e.target.checked;
    if (isChecked) {
      this.selectedObj!.fill = "#42b983";
    } else {
      this.selectedObj!.fill = null;
    }
    this.canvasRef.changeColor(this.selectedObj!.fill);
  }

  updateColor(color: string) {
    if (this.selectedObj) {
      this.selectedObj.fill = color;
      this.canvasRef.changeColor(color);
    }
  }

  toggleStroke(e: any) {
    const isChecked = e.target.checked;
    if (isChecked) {
      this.selectedObj!.stroke = "#000000";
      this.selectedObj!.strokeWidth = 2;
    } else {
      this.selectedObj!.strokeWidth = 0;
    }
    this.updateStrokeWidth(this.selectedObj!.strokeWidth);
  }

  updateStrokeColor(color: string) {
    if (this.selectedObj) {
      this.selectedObj.stroke = color;
      this.canvasRef.changeStrokeColor(color);
    }
  }

  updateStrokeWidth(val: string) {
    if (this.selectedObj) {
      const width = parseInt(val);
      this.selectedObj.strokeWidth = width;
      this.canvasRef.changeStrokeWidth(width);
    }
  }

  updateStrokeStyle(val: string) {
    this.canvasRef.changeStrokeDashArray(val);
  }
}
</script>

<style scoped>
.editor-page {
  display: flex;
  flex-direction: column;
  height: 100vh;
  background: #f0f2f5;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  overflow: hidden;
}

.toolbar {
  height: 60px;
  background: #fff;
  border-bottom: 1px solid #e8e8e8;
  display: flex;
  align-items: center;
  padding: 0 20px;
  flex-shrink: 0;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
  z-index: 10;
}

.group {
  display: flex;
  gap: 10px;
  padding-right: 20px;
  border-right: 1px solid #eee;
}
.group:last-child {
  border-right: none;
}

button {
  padding: 8px 16px;
  border: 1px solid #d9d9d9;
  background: #fff;
  border-radius: 4px;
  cursor: pointer;
  font-size: 14px;
  transition: all 0.2s;
  color: rgba(0, 0, 0, 0.85);
}
button:hover {
  color: #1890ff;
  border-color: #1890ff;
}

.main-body {
  display: flex;
  flex: 1;
  overflow: hidden;
  position: relative;
}

.sidebar {
  width: 260px;
  background: #fff;
  border-right: 1px solid #e8e8e8;
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 24px;
  flex-shrink: 0;
  overflow-y: auto;
}

.sidebar h3 {
  margin: 0 0 10px 0;
  font-size: 16px;
  color: #333;
  border-bottom: 1px solid #eee;
  padding-bottom: 10px;
}

.sidebar.empty {
  justify-content: center;
  align-items: center;
  color: #999;
  text-align: center;
}

.prop-section h4 {
  margin: 0 0 10px 0;
  font-size: 14px;
  color: #333;
  border-bottom: 1px solid #eee;
  padding-bottom: 5px;
  font-weight: 600;
}

.prop-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.switch-label {
  font-size: 12px !important;
  color: #1890ff !important;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 4px;
  font-weight: normal !important;
}
.switch-label input {
  margin: 0;
}

.color-picker-wrapper input {
  width: 100%;
  height: 40px;
  border: 1px solid #d9d9d9;
  border-radius: 4px;
  padding: 2px;
  background: #fff;
  cursor: pointer;
}

.no-fill-tip {
  padding: 12px;
  background: #fafafa;
  border: 1px dashed #d9d9d9;
  color: #999;
  text-align: center;
  font-size: 12px;
  border-radius: 4px;
}

.stroke-controls {
  background: #fafafa;
  padding: 10px;
  border-radius: 4px;
  border: 1px solid #eee;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.prop-item {
  display: flex;
  flex-direction: column;
  gap: 5px;
}

.prop-item label {
  font-size: 13px;
  color: #555;
}

input[type="range"] {
  width: 100%;
  cursor: pointer;
}

select {
  width: 100%;
  height: 30px;
  border: 1px solid #d9d9d9;
  border-radius: 4px;
  padding: 0 5px;
  outline: none;
}
select:focus {
  border-color: #1890ff;
}

.btn-row {
  display: flex;
  gap: 10px;
}
.btn-row button {
  flex: 1;
  font-size: 12px;
  padding: 6px;
}

.canvas-area {
  flex: 1;
  height: 100%;
  background: #333;
  position: relative;
  overflow: hidden;
}
</style>
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