Add PDFPage.drawLine() method (#201)

* Added drawLine method to PDFPage (#171) * Cleanup * Refactor PDFPage.drawline API * Update doc comment
Hopding · Sep 25, 2019 · 96d03cc · 96d03cc
1 parent e883a9e
commit 96d03cc
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Showing 4 changed files with 71 additions and 5 deletions.
diff --git a/apps/node/tests/test3.ts b/apps/node/tests/test3.ts
@@ -61,12 +61,11 @@ export default async (assets: Assets) => {
     font: helveticaFont,
     color: hotPink,
   });
-  page2.drawRectangle({
-    x: 30,
-    y: 50,
-    width: lastPageTextWidth,
-    height: 5,
+  page2.drawLine({
+    start: { x: 30, y: 50 },
+    end: { x: 30 + lastPageTextWidth, y: 50 },
     color: hotPink,
+    thickness: 5,
   });
 
   const base64Pdf = await pdfDoc.saveAsBase64();

diff --git a/src/api/PDFPage.ts b/src/api/PDFPage.ts
@@ -2,6 +2,7 @@ import { Color, rgb } from 'src/api/colors';
 import {
   drawEllipse,
   drawImage,
+  drawLine,
   drawLinesOfText,
   drawRectangle,
 } from 'src/api/operations';
@@ -17,6 +18,7 @@ import {
   PDFPageDrawCircleOptions,
   PDFPageDrawEllipseOptions,
   PDFPageDrawImageOptions,
+  PDFPageDrawLineOptions,
   PDFPageDrawRectangleOptions,
   PDFPageDrawSquareOptions,
   PDFPageDrawTextOptions,
@@ -673,6 +675,48 @@ export default class PDFPage {
     );
   }
 
+  /**
+   * Draw a line on this page. For example:
+   * ```js
+   * import { rgb } from 'pdf-lib'
+   *
+   * page.drawLine({
+   *   start: { x: 25, y: 75 },
+   *   end: { x: 125, y: 175 },
+   *   thickness: 2,
+   *   color: rgb(0.75, 0.2, 0.2)
+   * })
+   * ```
+   * @param options The options to be used when drawing the line.
+   */
+  drawLine(options: PDFPageDrawLineOptions): void {
+    assertIs(options.start, 'options.start', [
+      [Object, '{ x: number, y: number }'],
+    ]);
+    assertIs(options.end, 'options.end', [
+      [Object, '{ x: number, y: number }'],
+    ]);
+    assertIs(options.start.x, 'options.start.x', ['number']);
+    assertIs(options.start.y, 'options.start.y', ['number']);
+    assertIs(options.end.x, 'options.end.x', ['number']);
+    assertIs(options.end.y, 'options.end.y', ['number']);
+    assertOrUndefined(options.thickness, 'options.thickness', ['number']);
+    assertOrUndefined(options.color, 'options.color', [[Object, 'Color']]);
+
+    const contentStream = this.getContentStream();
+    if (!('color' in options)) {
+      options.color = rgb(0, 0, 0);
+    }
+    contentStream.push(
+      ...drawLine({
+        start: options.start,
+        end: options.end,
+        thickness: options.thickness || 1,
+        color: options.color || undefined,
+      }),
+    );
+  }
+
   /**
    * Draw a rectangle on this page. For example:
    * ```js

diff --git a/src/api/PDFPageOptions.ts b/src/api/PDFPageOptions.ts
@@ -39,6 +39,13 @@ export interface PDFPageDrawRectangleOptions {
   borderColor?: Color;
 }
 
+export interface PDFPageDrawLineOptions {
+  start: { x: number; y: number };
+  end: { x: number; y: number };
+  thickness?: number;
+  color?: Color;
+}
+
 export interface PDFPageDrawSquareOptions {
   x?: number;
   y?: number;

diff --git a/src/api/operations.ts b/src/api/operations.ts
@@ -107,6 +107,22 @@ export const drawImage = (
   popGraphicsState(),
 ];
 
+export const drawLine = (options: {
+  start: { x: number | PDFNumber; y: number | PDFNumber };
+  end: { x: number | PDFNumber; y: number | PDFNumber };
+  thickness: number | PDFNumber;
+  color: Color | undefined;
+}) =>
+  [
+    pushGraphicsState(),
+    options.color && setStrokingColor(options.color),
+    setLineWidth(options.thickness),
+    moveTo(options.start.x, options.start.y),
+    lineTo(options.end.x, options.end.y),
+    stroke(),
+    popGraphicsState(),
+  ].filter(Boolean) as PDFOperator[];
+
 export const drawRectangle = (options: {
   x: number | PDFNumber;
   y: number | PDFNumber;