Enable rotatable text (#1589)

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - Fix precision rounding issues in LineWrapper
 - Add support for dynamic sizing
+- Add support for rotatable text
 
 ### [v0.16.0] - 2024-12-29
 

docs/text.md

@@ -86,6 +86,7 @@ below.
 * `lineBreak` - set to `false` to disable line wrapping all together
 * `width` - the width that text should be wrapped to (by default, the page width minus the left and right margin)
 * `height` - the maximum height that text should be clipped to
+* `rotation` - the rotation of the text in degrees (by default 0)
 * `ellipsis` - the character to display at the end of the text when it is too long. Set to `true` to use the default character.
 * `columns` - the number of columns to flow the text into
 * `columnGap` - the amount of space between each column (1/4 inch by default)
@@ -132,10 +133,14 @@ The output looks like this:
 ## Text measurements
 
 If you're working with documents that require precise layout, you may need to know the
-size of a piece of text. PDFKit has two methods to achieve this: `widthOfString(text, options)`
-and `heightOfString(text, options)`. Both methods use the same options described in the
+size of a piece of text. PDFKit has three methods to achieve this: `widthOfString(text, options)`
+, `heightOfString(text, options)` and `boundsOfString(text, options)/boundsOfString(text, x, y, options)`. All methods use the same options described in the
 Text styling section, and take into account the eventual line wrapping.
 
+However `boundsOfString` factors in text rotations and multi-line wrapped text,
+effectively producing the bounding box of the text, `{x: number, y: number, width: number, height: number}`.
+If `x` and `y` are not defined they will default to use `this.x` and `this.y`.
+
 ## Lists
 
 The `list` method creates a bulleted list. It accepts as arguments an array of strings,

lib/mixins/text.js

@@ -51,6 +51,12 @@ export default {
       }
     };
 
+    // We can save some bytes if there is no rotation
+    if (options.rotation !== 0) {
+      this.save();
+      this.rotate(-options.rotation, { origin: [this.x, this.y] });
+    }
+
     // word wrapping
     if (options.width) {
       let wrapper = this._wrapper;
@@ -72,6 +78,9 @@ export default {
       }
     }
 
+    // Cleanup if there was a rotation
+    if (options.rotation !== 0) this.restore();
+
     return this;
   },
 
@@ -84,6 +93,134 @@ export default {
     return ((this._font.widthOfString(string, this._fontSize, options.features) + (options.characterSpacing || 0) * (string.length - 1)) * horizontalScaling) / 100;
   },
 
+  /**
+   * Compute the bounding box of a string
+   * based on what will actually be rendered by `doc.text()`
+   *
+   * @param string - The string
+   * @param x - X position of text (defaults to this.x)
+   * @param y - Y position of text (defaults to this.y)
+   * @param options - Any text options (The same you would apply to `doc.text()`)
+   * @returns {{x: number, y: number, width: number, height: number}}
+   */
+  boundsOfString(string, x, y, options) {
+    options = this._initOptions(x, y, options);
+    ({ x, y } = this);
+    const lineGap = options.lineGap ?? this._lineGap ?? 0;
+    const lineHeight = this.currentLineHeight(true) + lineGap;
+    let contentWidth = 0,
+      contentHeight = 0;
+
+    // Convert text to a string
+    string = String(string ?? '');
+
+    // if the wordSpacing option is specified, remove multiple consecutive spaces
+    if (options.wordSpacing) {
+      string = string.replace(/\s{2,}/g, ' ');
+    }
+
+    // word wrapping
+    if (options.width) {
+      let wrapper = new LineWrapper(this, options);
+      wrapper.on('line', (text, options) => {
+        contentHeight += lineHeight;
+        text = text.replace(/\n/g, '');
+
+        if (text.length) {
+          // handle options
+          let wordSpacing = options.wordSpacing ?? 0;
+          const characterSpacing = options.characterSpacing ?? 0;
+
+          // justify alignments
+          if (options.width && options.align === 'justify') {
+            // calculate the word spacing value
+            const words = text.trim().split(/\s+/);
+            const textWidth = this.widthOfString(
+              text.replace(/\s+/g, ''),
+              options,
+            );
+            const spaceWidth = this.widthOfString(' ') + characterSpacing;
+            wordSpacing = Math.max(
+              0,
+              (options.lineWidth - textWidth) / Math.max(1, words.length - 1) -
+                spaceWidth,
+            );
+          }
+
+          // calculate the actual rendered width of the string after word and character spacing
+          contentWidth = Math.max(
+            contentWidth,
+            options.textWidth +
+              wordSpacing * (options.wordCount - 1) +
+              characterSpacing * (text.length - 1),
+          );
+        }
+      });
+      wrapper.wrap(string, options);
+    } else {
+      // render paragraphs as single lines
+      for (let line of string.split('\n')) {
+        const lineWidth = this.widthOfString(line, options);
+        contentHeight += lineHeight;
+        contentWidth = Math.max(contentWidth, lineWidth);
+      }
+    }
+
+    /**
+     * Rotates around top left corner
+     * [x1,y1]  >  [x2,y2]
+     *    ⌃           ⌄
+     * [x4,y4]  <  [x3,y3]
+     */
+    if (options.rotation === 0) {
+      // No rotation so we can use the existing values
+      return { x, y, width: contentWidth, height: contentHeight };
+      // Use fast computation without explicit trig
+    } else if (options.rotation === 90) {
+      return {
+        x: x,
+        y: y - contentWidth,
+        width: contentHeight,
+        height: contentWidth,
+      };
+    } else if (options.rotation === 180) {
+      return {
+        x: x - contentWidth,
+        y: y - contentHeight,
+        width: contentWidth,
+        height: contentHeight,
+      };
+    } else if (options.rotation === 270) {
+      return {
+        x: x - contentHeight,
+        y: y,
+        width: contentHeight,
+        height: contentWidth,
+      };
+    }
+
+    // Non-trivial values so time for trig
+    const angleRad = (options.rotation * Math.PI) / 180;
+    const cos = Math.cos(angleRad);
+    const sin = Math.sin(angleRad);
+
+    const x1 = x;
+    const y1 = y;
+    const x2 = x + contentWidth * cos;
+    const y2 = y - contentWidth * sin;
+    const x3 = x + contentWidth * cos + contentHeight * sin;
+    const y3 = y - contentWidth * sin + contentHeight * cos;
+    const x4 = x + contentHeight * sin;
+    const y4 = y + contentHeight * cos;
+
+    const xMin = Math.min(x1, x2, x3, x4);
+    const xMax = Math.max(x1, x2, x3, x4);
+    const yMin = Math.min(y1, y2, y3, y4);
+    const yMax = Math.max(y1, y2, y3, y4);
+
+    return { x: xMin, y: yMin, width: xMax - xMin, height: yMax - yMin };
+  },
+
   heightOfString(text, options) {
     const { x, y } = this;
 
@@ -272,6 +409,10 @@ export default {
       result.columnGap = 18;
     } // 1/4 inch
 
+    // Normalize rotation to between 0 - 360
+    result.rotation = Number(options.rotation ?? 0) % 360;
+    if (result.rotation < 0) result.rotation += 360;
+
     return result;
   },
 

tests/visual/text.spec.js

@@ -101,4 +101,45 @@ describe('text', function() {
     });
   });
 
+  test('rotated text', function () {
+    let i = 0;
+    const cols = [
+      '#292f56',
+      '#492d73',
+      '#8c2f94',
+      '#b62d78',
+      '#d82d31',
+      '#e69541',
+      '#ecf157',
+      '#acfa70',
+    ];
+    function randColor() {
+      return cols[i++ % cols.length];
+    }
+
+    return runDocTest(function (doc) {
+      doc.font('tests/fonts/Roboto-Regular.ttf');
+      for (let i = -360; i < 360; i += 5) {
+        const withLabel = i % 45 === 0;
+        const margin = i < 0 ? '            ' : ' ';
+        let text = `—————————> ${withLabel ? `${margin}${i}` : ''}`;
+
+        if (withLabel) {
+          const bounds = doc.boundsOfString(text, 200, 200, { rotation: i });
+          doc
+            .save()
+            .rect(bounds.x, bounds.y, bounds.width, bounds.height)
+            .stroke(randColor())
+            .restore();
+        }
+
+        doc
+          .save()
+          .fill(withLabel ? 'red' : 'black')
+          .text(text, 200, 200, { rotation: i })
+          .restore();
+      }
+      doc.save().circle(200, 200, 1).fill('blue').restore();
+    });
+  });
 });