add boundsOfString method

- Allow users to compute the actual rendered bounds of a string (which includes multi-line support)

lib/mixins/text.js

@@ -84,6 +84,59 @@ export default {
     return ((this._font.widthOfString(string, this._fontSize, options.features) + (options.characterSpacing || 0) * (string.length - 1)) * horizontalScaling) / 100;
   },
 
+  /**
+   * Compute the height and width of a string
+   * based on what will actually be rendered by `doc.text()`
+   *
+   * @param string - The string to measure
+   * @param options - Any text options (The same you would apply to `doc.text()`)
+   * @returns {{width: number, height: number}}
+   */
+  boundsOfString(string, options = {}) {
+    const { x, y } = this;
+
+    options = this._initOptions(options);
+
+    const lineGap = options.lineGap || this._lineGap || 0;
+    const lineHeight = this.currentLineHeight(true) + lineGap;
+    let contentWidth = 0;
+    this._text(string, this.x, this.y, options, (text, options) => {
+      text = `${text}`.replace(/\n/g, "");
+      if (text.length > 0) {
+        // handle options
+        let wordSpacing = options.wordSpacing || 0;
+        const characterSpacing = options.characterSpacing || 0;
+
+        // text alignments
+        if (options.width && options.align === "justify") {
+          // calculate the word spacing value
+          wordSpacing = Math.max(
+            0,
+            (options.lineWidth -
+              this.widthOfString(text.replace(/\s+/g, ""), options)) /
+            Math.max(1, text.trim().split(/\s+/).length - 1) -
+            (this.widthOfString(" ") + characterSpacing),
+          );
+        }
+
+        // calculate the actual rendered width of the string after word and character spacing
+        const renderedWidth =
+          options.textWidth +
+          wordSpacing * (options.wordCount - 1) +
+          characterSpacing * (text.length - 1);
+        contentWidth = Math.max(contentWidth, renderedWidth);
+      }
+
+      return (this.y += lineHeight);
+    });
+
+    const contentHeight = this.y - y;
+    this.x = x;
+    this.y = y;
+
+    return { width: contentWidth, height: contentHeight };
+  },
+
   heightOfString(text, options) {
     const { x, y } = this;