Add bandbool feature for channel-wise boolean operations (#496)

test/fixtures/index.js

@@ -79,6 +79,7 @@ module.exports = {
   inputPngOverlayLayer2LowAlpha: getPath('alpha-layer-2-ink-low-alpha.png'),
   inputPngAlphaPremultiplicationSmall: getPath('alpha-premultiply-1024x768-paper.png'),
   inputPngAlphaPremultiplicationLarge: getPath('alpha-premultiply-2048x1536-paper.png'),
+  inputPngBooleanNoAlpha: getPath('bandbool.png'),
 
   inputWebP: getPath('4.webp'), // http://www.gstatic.com/webp/gallery/4.webp
   inputWebPWithTransparency: getPath('5_webp_a.webp'), // http://www.gstatic.com/webp/gallery3/5_webp_a.webp

test/unit/bandbool.js

@@ -0,0 +1,51 @@
+'use strict';
+
+var assert = require('assert');
+var fixtures = require('../fixtures');
+var sharp = require('../../index');
+
+describe('Bandbool per-channel boolean operations', function() {
+
+  it('\'and\' Operation', function(done) {
+    sharp(fixtures.inputPngBooleanNoAlpha)
+      .bandbool('and')
+      .toBuffer(function(err, data, info) {
+        if (err) throw err;
+        assert.strictEqual(200, info.width);
+        assert.strictEqual(200, info.height);
+        assert.strictEqual(1, info.channels);
+        fixtures.assertSimilar(fixtures.expected('bandbool_and_result.png'), data, done);
+      });
+  });
+
+  it('\'or\' Operation', function(done) {
+    sharp(fixtures.inputPngBooleanNoAlpha)
+      .bandbool(sharp.bool.or)
+      .toBuffer(function(err, data, info) {
+        if (err) throw err;
+        assert.strictEqual(200, info.width);
+        assert.strictEqual(200, info.height);
+        assert.strictEqual(1, info.channels);
+        fixtures.assertSimilar(fixtures.expected('bandbool_or_result.png'), data, done);
+      });
+  });
+
+  it('\'eor\' Operation', function(done) {
+    sharp(fixtures.inputPngBooleanNoAlpha)
+      .bandbool('eor')
+      .toBuffer(function(err, data, info) {
+        if (err) throw err;
+        assert.strictEqual(200, info.width);
+        assert.strictEqual(200, info.height);
+        assert.strictEqual(1, info.channels);
+        fixtures.assertSimilar(fixtures.expected('bandbool_eor_result.png'), data, done);
+      });
+  });
+
+  it('Invalid operation', function() {
+    assert.throws(function() {
+      sharp(fixtures.inputPngBooleanNoAlpha)
+        .bandbool('fail');
+    });
+  });
+});