Add PDF background color option

docs/api-constructor.md

@@ -40,6 +40,7 @@ where the overall height is the `pageHeight` multiplied by the number of `pages`
 | [options.page] | <code>number</code> | <code>0</code> | Page number to start extracting from for multi-page input (GIF, WebP, TIFF), zero based. |
 | [options.subifd] | <code>number</code> | <code>-1</code> | subIFD (Sub Image File Directory) to extract for OME-TIFF, defaults to main image. |
 | [options.level] | <code>number</code> | <code>0</code> | level to extract from a multi-level input (OpenSlide), zero based. |
+| [options.pdfBackground] | <code>string</code> \| <code>Object</code> |  | Background color to use when PDF is partially transparent. Parsed by the [color](https://www.npmjs.org/package/color) module to extract values for red, green, blue and alpha. Requires the use of a globally-installed libvips compiled with support for PDFium, poppler-glib, ImageMagick, or GraphicsMagick. |
 | [options.animated] | <code>boolean</code> | <code>false</code> | Set to `true` to read all frames/pages of an animated image (GIF, WebP, TIFF), equivalent of setting `pages` to `-1`. |
 | [options.raw] | <code>Object</code> |  | describes raw pixel input image data. See `raw()` for pixel ordering. |
 | [options.raw.width] | <code>number</code> |  | integral number of pixels wide. |

lib/constructor.js

@@ -139,6 +139,7 @@ const debuglog = util.debuglog('sharp');
  * @param {number} [options.page=0] - Page number to start extracting from for multi-page input (GIF, WebP, TIFF), zero based.
  * @param {number} [options.subifd=-1] - subIFD (Sub Image File Directory) to extract for OME-TIFF, defaults to main image.
  * @param {number} [options.level=0] - level to extract from a multi-level input (OpenSlide), zero based.
+ * @param {string|Object} [options.pdfBackground] - Background color to use when PDF is partially transparent. Parsed by the [color](https://www.npmjs.org/package/color) module to extract values for red, green, blue and alpha. Requires the use of a globally-installed libvips compiled with support for PDFium, poppler-glib, ImageMagick, or GraphicsMagick.
  * @param {boolean} [options.animated=false] - Set to `true` to read all frames/pages of an animated image (GIF, WebP, TIFF), equivalent of setting `pages` to `-1`.
  * @param {Object} [options.raw] - describes raw pixel input image data. See `raw()` for pixel ordering.
  * @param {number} [options.raw.width] - integral number of pixels wide.
@@ -348,6 +349,7 @@ const Sharp = function (input, options) {
     timeoutSeconds: 0,
     linearA: [],
     linearB: [],
+    pdfBackground: [255, 255, 255, 255],
     // Function to notify of libvips warnings
     debuglog: warning => {
       this.emit('warning', warning);

lib/index.d.ts

@@ -935,6 +935,8 @@ declare namespace sharp {
         subifd?: number | undefined;
         /** Level to extract from a multi-level input (OpenSlide), zero based. (optional, default 0) */
         level?: number | undefined;
+        /** Background color to use when PDF is partially transparent. Requires the use of a globally-installed libvips compiled with support for PDFium, poppler-glib, ImageMagick, or GraphicsMagick. */
+        pdfBackground?: Color | undefined;
         /** Set to `true` to read all frames/pages of an animated image (equivalent of setting `pages` to `-1`). (optional, default false) */
         animated?: boolean | undefined;
         /** Describes raw pixel input image data. See raw() for pixel ordering. */

lib/input.js

@@ -24,8 +24,8 @@ const align = {
  * @private
  */
 function _inputOptionsFromObject (obj) {
-  const { raw, density, limitInputPixels, ignoreIcc, unlimited, sequentialRead, failOn, failOnError, animated, page, pages, subifd } = obj;
-  return [raw, density, limitInputPixels, ignoreIcc, unlimited, sequentialRead, failOn, failOnError, animated, page, pages, subifd].some(is.defined)
+  const { raw, density, limitInputPixels, ignoreIcc, unlimited, sequentialRead, failOn, failOnError, animated, page, pages, subifd, pdfBackground } = obj;
+  return [raw, density, limitInputPixels, ignoreIcc, unlimited, sequentialRead, failOn, failOnError, animated, page, pages, subifd, pdfBackground].some(is.defined)
     ? { raw, density, limitInputPixels, ignoreIcc, unlimited, sequentialRead, failOn, failOnError, animated, page, pages, subifd }
     : undefined;
 }
@@ -222,6 +222,10 @@ function _createInputDescriptor (input, inputOptions, containerOptions) {
         throw is.invalidParameterError('subifd', 'integer between -1 and 100000', inputOptions.subifd);
       }
     }
+    // PDF background color
+    if (is.defined(inputOptions.pdfBackground)) {
+      this._setBackgroundColourOption('pdfBackground', inputOptions.pdfBackground);
+    }
     // Create new image
     if (is.defined(inputOptions.create)) {
       if (

src/common.cc

@@ -109,6 +109,10 @@ namespace sharp {
     if (HasAttr(input, "subifd")) {
       descriptor->subifd = AttrAsInt32(input, "subifd");
     }
+    // // PDF background color
+    if (HasAttr(input, "pdfBackground")) {
+      descriptor->pdfBackground = AttrAsVectorOfDouble(input, "pdfBackground");
+    }
     // Create new image
     if (HasAttr(input, "createChannels")) {
       descriptor->createChannels = AttrAsUint32(input, "createChannels");
@@ -402,6 +406,9 @@ namespace sharp {
             if (imageType == ImageType::TIFF) {
               option->set("subifd", descriptor->subifd);
             }
+            if (imageType == ImageType::PDF) {
+              option->set("background", descriptor->pdfBackground);
+            }
             image = VImage::new_from_buffer(descriptor->buffer, descriptor->bufferLength, nullptr, option);
             if (imageType == ImageType::SVG || imageType == ImageType::PDF || imageType == ImageType::MAGICK) {
               image = SetDensity(image, descriptor->density);
@@ -506,6 +513,9 @@ namespace sharp {
             if (imageType == ImageType::TIFF) {
               option->set("subifd", descriptor->subifd);
             }
+            if (imageType == ImageType::PDF) {
+              option->set("background", descriptor->pdfBackground);
+            }
             image = VImage::new_from_file(descriptor->file.data(), option);
             if (imageType == ImageType::SVG || imageType == ImageType::PDF || imageType == ImageType::MAGICK) {
               image = SetDensity(image, descriptor->density);

src/common.h

@@ -74,6 +74,7 @@ namespace sharp {
     int textSpacing;
     VipsTextWrap textWrap;
     int textAutofitDpi;
+    std::vector<double> pdfBackground;
 
     InputDescriptor():
       buffer(nullptr),
@@ -108,7 +109,8 @@ namespace sharp {
       textRgba(false),
       textSpacing(0),
       textWrap(VIPS_TEXT_WRAP_WORD),
-      textAutofitDpi(0) {}
+      textAutofitDpi(0),
+      pdfBackground{ 255.0, 255.0, 255.0, 255.0 } {}
   };
 
   // Convenience methods to access the attributes of a Napi::Object

test/unit/io.js

@@ -893,6 +893,27 @@ describe('Input/output', function () {
         sharp({ subifd: 1.2 });
       }, /Expected integer between -1 and 100000 for subifd but received 1.2 of type number/);
     });
+    it('Valid pdfBackground property (string)', function () {
+      sharp({ pdfBackground: '#00ff00' });
+    });
+    it('Valid pdfBackground property (object)', function () {
+      sharp({ pdfBackground: { r: 0, g: 255, b: 0 } });
+    });
+    it('Invalid pdfBackground property (string) throws', function () {
+      assert.throws(function () {
+        sharp({ pdfBackground: '00ff00' });
+      }, /Unable to parse color from string/);
+    });
+    it('Invalid pdfBackground property (number) throws', function () {
+      assert.throws(function () {
+        sharp({ pdfBackground: 255 });
+      }, /Expected object or string for background/);
+    });
+    it('Invalid pdfBackground property (object)', function () {
+      assert.throws(function () {
+        sharp({ pdfBackground: { red: 0, green: 255, blue: 0 } });
+      }, /Unable to parse color from object/);
+    });
   });
 
   it('Fails when writing to missing directory', async () => {