Control density/DPI when loading vectors via libmagick #110

docs/api.md

@@ -6,22 +6,26 @@ var sharp = require('sharp');
 
 ### Input
 
-#### sharp([input])
+#### sharp([input], [options])
 
-Constructor to which further methods are chained. `input`, if present, can be one of:
+Constructor to which further methods are chained.
 
-* Buffer containing JPEG, PNG, WebP, GIF* or TIFF image data, or
+`input`, if present, can be one of:
+
+* Buffer containing JPEG, PNG, WebP, GIF, SVG or TIFF image data, or
 * String containing the path to an image file, with most major formats supported.
 
-The object returned implements the
-[stream.Duplex](http://nodejs.org/api/stream.html#stream_class_stream_duplex) class.
+JPEG, PNG, WebP, GIF, SVG or TIFF format image data
+can be streamed into the object when `input` is `null` or `undefined`.
 
-JPEG, PNG, WebP, GIF* or TIFF format image data
-can be streamed into the object when `input` is not provided.
+`options`, if present, is an Object with the following optional attributes:
 
-JPEG, PNG or WebP format image data can be streamed out from this object.
+* `density` an integral number representing the DPI for vector images, defaulting to 72.
 
-\* libvips 8.0.0+ is required for Buffer/Stream input of GIF and other `magick` formats.
+The object returned by the constructor implements the
+[stream.Duplex](http://nodejs.org/api/stream.html#stream_class_stream_duplex) class.
+
+JPEG, PNG or WebP format image data can be streamed out from this object.
 
 ```javascript
 sharp('input.jpg')

docs/changelog.md

@@ -2,11 +2,16 @@
 
 ### v0.13 - "*mind*"
 
+* Control density/DPI when loading vector images via libmagick.
+  [#110](https://github.com/lovell/sharp/issues/110)
+  [@bradisbell](https://github.com/bradisbell)
+
 * Switch from libvips' C to C++ bindings, requires upgrade to v8.2.2.
   [#299](https://github.com/lovell/sharp/issues/299)
 
 * Control number of open files in libvips' cache; breaks existing `cache` behaviour.
   [#315](https://github.com/lovell/sharp/issues/315)
+  [@impomezia](https://github.com/impomezia)
 
 * Ensure 16-bit input images can be embedded onto a transparent background.
   [#340](https://github.com/lovell/sharp/issues/340)

index.js

@@ -35,9 +35,9 @@ var maximum = {
 };
 
 // Constructor-factory
-var Sharp = function(input) {
+var Sharp = function(input, options) {
   if (!(this instanceof Sharp)) {
-    return new Sharp(input);
+    return new Sharp(input, options);
   }
   stream.Duplex.call(this);
   this.options = {
@@ -46,6 +46,7 @@ var Sharp = function(input) {
     streamIn: false,
     sequentialRead: false,
     limitInputPixels: maximum.pixels,
+    density: '72',
     // ICC profiles
     iccProfilePath: path.join(__dirname, 'icc') + path.sep,
     // resize options
@@ -107,12 +108,13 @@ var Sharp = function(input) {
   } else if (typeof input === 'object' && input instanceof Buffer) {
     // input=buffer
     this.options.bufferIn = input;
-  } else if (typeof input === 'undefined') {
+  } else if (typeof input === 'undefined' || input === null) {
     // input=stream
     this.options.streamIn = true;
   } else {
     throw new Error('Unsupported input ' + typeof input);
   }
+  this._inputOptions(options);
   return this;
 };
 module.exports = Sharp;
@@ -133,6 +135,27 @@ module.exports.format = sharp.format();
 */
 module.exports.versions = versions;
 
+/*
+  Set input-related options
+    density: DPI at which to load vector images via libmagick
+*/
+Sharp.prototype._inputOptions = function(options) {
+  if (typeof options === 'object') {
+    if (typeof options.density !== 'undefined') {
+      if (
+        typeof options.density === 'number' && !Number.isNaN(options.density) &&
+        options.density % 1 === 0 && options.density > 0 && options.density <= 2400
+      ) {
+        this.options.density = options.density.toString();
+      } else {
+        throw new Error('Invalid density (1 to 2400)' + options.density);
+      }
+    }
+  } else if (typeof options !== 'undefined' && options !== null) {
+    throw new Error('Invalid input options ' + options);
+  }
+};
+
 /*
   Handle incoming chunk on Writable Stream
 */

src/pipeline.cc

@@ -77,6 +77,7 @@ struct PipelineBaton {
   size_t bufferInLength;
   std::string iccProfilePath;
   int limitInputPixels;
+  std::string density;
   std::string output;
   std::string outputFormat;
   void *bufferOut;
@@ -129,6 +130,7 @@ struct PipelineBaton {
   PipelineBaton():
     bufferInLength(0),
     limitInputPixels(0),
+    density(""),
     outputFormat(""),
     bufferOutLength(0),
     topOffsetPre(-1),
@@ -201,8 +203,9 @@ class PipelineWorker : public AsyncWorker {
       if (inputImageType != ImageType::UNKNOWN) {
         try {
           image = VImage::new_from_buffer(
-            baton->bufferIn, baton->bufferInLength, nullptr,
-            VImage::option()->set("access", baton->accessMethod)
+            baton->bufferIn, baton->bufferInLength, nullptr, VImage::option()
+            ->set("access", baton->accessMethod)
+            ->set("density", baton->density.data())
           );
         } catch (...) {
           (baton->err).append("Input buffer has corrupt header");
@@ -217,8 +220,9 @@ class PipelineWorker : public AsyncWorker {
       if (inputImageType != ImageType::UNKNOWN) {
         try {
           image = VImage::new_from_file(
-            baton->fileIn.data(),
-            VImage::option()->set("access", baton->accessMethod)
+            baton->fileIn.data(), VImage::option()
+            ->set("access", baton->accessMethod)
+            ->set("density", baton->density.data())
           );
         } catch (...) {
           (baton->err).append("Input file has corrupt header");
@@ -997,6 +1001,8 @@ NAN_METHOD(pipeline) {
   baton->iccProfilePath = attrAsStr(options, "iccProfilePath");
   // Limit input images to a given number of pixels, where pixels = width * height
   baton->limitInputPixels = attrAs<int32_t>(options, "limitInputPixels");
+  // Density/DPI at which to load vector images via libmagick
+  baton->density = attrAsStr(options, "density");
   // Extract image options
   baton->topOffsetPre = attrAs<int32_t>(options, "topOffsetPre");
   baton->leftOffsetPre = attrAs<int32_t>(options, "leftOffsetPre");

test/fixtures/index.js

@@ -84,7 +84,7 @@ module.exports = {
   inputWebPWithTransparency: getPath('5_webp_a.webp'), // http://www.gstatic.com/webp/gallery3/5_webp_a.webp
   inputTiff: getPath('G31D.TIF'), // http://www.fileformat.info/format/tiff/sample/e6c9a6e5253348f4aef6d17b534360ab/index.htm
   inputGif: getPath('Crash_test.gif'), // http://upload.wikimedia.org/wikipedia/commons/e/e3/Crash_test.gif
-  inputSvg: getPath('Wikimedia-logo.svg'), // http://commons.wikimedia.org/wiki/File:Wikimedia-logo.svg
+  inputSvg: getPath('check.svg'), // http://dev.w3.org/SVG/tools/svgweb/samples/svg-files/check.svg
   inputPsd: getPath('free-gearhead-pack.psd'), // https://dribbble.com/shots/1624241-Free-Gearhead-Vector-Pack
 
   inputSvs: getPath('CMU-1-Small-Region.svs'), // http://openslide.cs.cmu.edu/download/openslide-testdata/Aperio/CMU-1-Small-Region.svs

test/unit/io.js

@@ -634,20 +634,37 @@ describe('Input/output', function() {
   });
 
   if (sharp.format.magick.input.file) {
-    it('Convert SVG, if supported, to PNG', function(done) {
+    it('Convert SVG to PNG at default 72DPI', function(done) {
       sharp(fixtures.inputSvg)
-        .resize(100, 100)
+        .resize(1024)
+        .extract({left: 290, top: 760, width: 40, height: 40})
         .toFormat('png')
         .toBuffer(function(err, data, info) {
           if (err) {
             assert.strictEqual(0, err.message.indexOf('Input file is missing or of an unsupported image format'));
             done();
           } else {
-            assert.strictEqual(true, info.size > 0);
             assert.strictEqual('png', info.format);
-            assert.strictEqual(100, info.width);
-            assert.strictEqual(100, info.height);
-            fixtures.assertSimilar(fixtures.expected('svg.png'), data, done);
+            assert.strictEqual(40, info.width);
+            assert.strictEqual(40, info.height);
+            fixtures.assertSimilar(fixtures.expected('svg72.png'), data, done);
+          }
+        });
+    });
+    it('Convert SVG to PNG at 300DPI', function(done) {
+      sharp(fixtures.inputSvg, { density: 1200 })
+        .resize(1024)
+        .extract({left: 290, top: 760, width: 40, height: 40})
+        .toFormat('png')
+        .toBuffer(function(err, data, info) {
+          if (err) {
+            assert.strictEqual(0, err.message.indexOf('Input file is missing or of an unsupported image format'));
+            done();
+          } else {
+            assert.strictEqual('png', info.format);
+            assert.strictEqual(40, info.width);
+            assert.strictEqual(40, info.height);
+            fixtures.assertSimilar(fixtures.expected('svg1200.png'), data, done);
           }
         });
     });
@@ -824,6 +841,27 @@ describe('Input/output', function() {
 
   });
 
+  describe('Input options', function() {
+    it('Non-Object options fails', function() {
+      assert.throws(function() {
+        sharp(null, 'zoinks');
+      });
+    });
+    it('Invalid density: string', function() {
+      assert.throws(function() {
+        sharp(null, { density: 'zoinks' } );
+      });
+    });
+    it('Invalid density: float', function() {
+      assert.throws(function() {
+        sharp(null, { density: 0.5 } );
+      });
+    });
+    it('Ignore unknown attribute', function() {
+      sharp(null, { unknown: true } );
+    });
+  });
+
   it('Queue length change events', function(done) {
     var eventCounter = 0;
     var queueListener = function(queueLength) {