#88 - image.cover

README.md

@@ -17,6 +17,7 @@
     0. [Resize](#resize)
     0. [Scale](#scale)
     0. [Rotate](#rotate)
+    0. [Cover](#cover)
     0. [Crop](#crop)
     0. [Blur](#blur)
     0. [Sharpen](#sharpen)
@@ -306,6 +307,26 @@ lwip.create(500, 500, 'yellow', function(err, image){
    - `"lanczos"`
 0. `callback {Function(err, image)}`
 
+#### Cover
+
+Cover a canvas with the image. The image will be resized to the smallest
+possible size such that both its dimensions are bigger than the canvas's
+dimensions. Margins of the image exceeding the canvas will be discarded.
+
+`image.cover(width, height, inter, callback)`
+
+0. `width {Integer}`: Canvas' width in pixels.
+0. `height {Integer}`: Canvas' height in pixels.
+0. `inter {String}`: **Optional** interpolation method. Defaults to `"lanczos"`.
+   Possible values:
+   - `"nearest-neighbor"`
+   - `"moving-average"`
+   - `"linear"`
+   - `"grid"`
+   - `"cubic"`
+   - `"lanczos"`
+0. `callback {Function(err, image)}`
+
 #### Rotate
 
 `image.rotate(degs, color, callback)`

examples/cover.js

@@ -0,0 +1,16 @@
+/**
+ * Example for using LWIP to cover a canvas with an image.
+ */
+
+var path = require('path'),
+    lwip = require('../');
+
+lwip.open('lena.jpg', function(err, image) {
+    if (err) return console.log(err);
+    image.cover(400,800,function(err, image){
+        image.writeFile('lena_cover.jpg', function(err){
+            if (err) return console.log(err);
+            console.log('done');
+        });
+    });
+});

lib/BatchPrototypeInit.js

@@ -14,6 +14,7 @@
         // batch mode.
         scale: decree(defs.args.scale.slice(0, -1)),
         resize: decree(defs.args.resize.slice(0, -1)),
+        cover: decree(defs.args.cover.slice(0, -1)),
         rotate: decree(defs.args.rotate.slice(0, -1)),
         blur: decree(defs.args.blur.slice(0, -1)),
         hslaAdjust: decree(defs.args.hslaAdjust.slice(0, -1)),
@@ -84,6 +85,14 @@
         return this;
     };
 
+    Batch.prototype.cover = function() {
+        var that = this;
+        judges.cover(arguments, function(width, height, inter) {
+            that.__addOp(that.__image.cover, [width, height, inter].filter(undefinedFilter));
+        });
+        return this;
+    };
+
     Batch.prototype.rotate = function() {
         var that = this;
         judges.rotate(arguments, function(degs, color) {

lib/ImagePrototypeInit.js

@@ -13,6 +13,7 @@
     var judges = {
         scale: decree(defs.args.scale),
         resize: decree(defs.args.resize),
+        cover: decree(defs.args.cover),
         rotate: decree(defs.args.rotate),
         blur: decree(defs.args.blur),
         hslaAdjust: decree(defs.args.hslaAdjust),
@@ -118,6 +119,21 @@
         );
     };
 
+    Image.prototype.cover = function() {
+        var that = this;
+        judges.cover(
+            arguments,
+            function(width, height, inter, callback) {
+                var s = Math.max(width / that.width(), height / that.height());
+                that.scale(s, s, inter, function(err){
+                    if (err) return callback(err);
+                    that.crop(width, height, callback);
+                });
+            }
+        );
+    };
+
+
     Image.prototype.rotate = function() {
         this.__lock();
         var that = this;

lib/defs.js

@@ -365,7 +365,23 @@
         }, {
             name: 'callback',
             type: 'function'
-        }]
+        }],
+        cover: [{
+            name: 'width',
+            type: 'p-number'
+        }, {
+            name: 'height',
+            type: 'p-number'
+        }, {
+            name: 'interpolation',
+            type: 'interpolation',
+            optional: true,
+            default: defaults.DEF_INTERPOLATION
+        }, {
+            name: 'callback',
+            type: 'function'
+        }],
+
     };
 
 })();

tests/02.operations/119.cover.js

@@ -0,0 +1,61 @@
+var join = require('path').join,
+    should = require('should'),
+    assert = require('assert'),
+    mkdirp = require('mkdirp'),
+    lwip = require('../../'),
+    imgs = require('../imgs');
+
+var tmpDir = join(__dirname, '../results'),
+    basename = 'cover',
+    current;
+
+describe('lwip.cover', function() {
+
+    var image;
+
+    before(function(done) {
+        mkdirp(tmpDir, done);
+    });
+
+    beforeEach(function(done) {
+        lwip.open(imgs.png.rgb, function(err, img) {
+            image = img;
+            done(err);
+        });
+    });
+
+    afterEach(function(done) {
+        image.writeFile(join(tmpDir, current.join('_') + '.jpg'), 'jpg', {
+            quality: 90
+        }, done);
+    });
+
+    beforeEach(function(){
+        current = [ basename ];
+    });
+
+    describe('800X300, unspecified interpolation', function() {
+        it('image should have the correct size', function(done) {
+            current.push('800X300','unspecified_inter');
+            image.cover(800, 300, function(err, im) {
+                if (err) return done(err);
+                assert(im.width() === 800);
+                assert(im.height() === 300);
+                done();
+            });
+        });
+    });
+
+    describe('300X800, lanczos interpolation', function() {
+        it('image should have the correct size', function(done) {
+            current.push('300X800','lanczos');
+            image.cover(300, 800, 'lanczos', function(err, im) {
+                if (err) return done(err);
+                assert(im.width() === 300);
+                assert(im.height() === 800);
+                done();
+            });
+        });
+    });
+
+});

tests/03.safety/00.locks.js

@@ -143,6 +143,13 @@ describe('simultaneous operations locks', function() {
     describe('image.paste lock', function() {
         it('should lock image', function() {
             image.paste.bind(image, 0, 0, tmpImage, function() {}).should.not.throwError();
+            image.cover.bind(image, 100, 100, function() {}).should.throwError();
+        });
+    });
+
+    describe('image.cover lock', function() {
+        it('should lock image', function() {
+            image.cover.bind(image, 200, 300, function() {}).should.not.throwError();
             image.resize.bind(image, 100, 100, function() {}).should.throwError();
         });
     });

tests/03.safety/01.releases.js

@@ -143,6 +143,13 @@ describe('failed ops lock release', function() {
     describe('image.paste release', function() {
         it('should release image lock', function() {
             image.paste.bind(image, 'foo', 'foo', 'foo', function() {}).should.throwError();
+            image.cover.bind(image, 100, 100, function() {}).should.not.throwError();
+        });
+    });
+
+    describe('image.cover release', function() {
+        it('should release image lock', function() {
+            image.cover.bind(image, 'foo', 'foo', function() {}).should.throwError();
             image.resize.bind(image, 100, 100, function() {}).should.not.throwError();
         });
     });

tests/utils.js

@@ -6,7 +6,7 @@ module.exports = {
 function generateRandomBatch(batch, n) {
     var ops = [];
     for (var i = 0; i < n; i++) {
-        var r = Math.floor(Math.random() * 14);
+        var r = Math.floor(Math.random() * 15);
         switch (r) {
             case 0:
                 var sd = Math.floor(Math.random() * 20);
@@ -81,6 +81,12 @@ function generateRandomBatch(batch, n) {
                 batch = batch.opacify();
                 ops.push('opc');
                 break;
+            case 14:
+                var w = Math.floor(Math.random() * 1000) + 10;
+                var h = Math.floor(Math.random() * 1000) + 10;
+                batch = batch.cover(w, h);
+                ops.push('cvr' + w + 'X' + h);
+                break;
         }
     }
     return ops;