Prevent error when cumulative rounding below target #1154

docs/changelog.md

@@ -4,6 +4,12 @@
 
 Requires libvips v8.6.1.
 
+#### v0.20.1 - TBD
+
+* Prevent smartcrop error when cumulative rounding is below target size.
+  [#1154](https://github.com/lovell/sharp/issues/1154)
+  [@ralrom](https://github.com/ralrom)
+
 #### v0.20.0 - 5<sup>th</sup> March 2018
 
 * Add support for prebuilt sharp binaries on common platforms.

src/pipeline.cc

@@ -482,6 +482,12 @@ class PipelineWorker : public Nan::AsyncWorker {
             image = image.extract_area(left, top, width, height);
           } else {
             // Attention-based or Entropy-based crop
+            if (baton->width > image.width()) {
+              baton->width = image.width();
+            }
+            if (baton->height > image.height()) {
+              baton->height = image.height();
+            }
             image = image.tilecache(VImage::option()
               ->set("access", baton->accessMethod)
               ->set("threaded", TRUE));

test/unit/crop.js

@@ -159,7 +159,7 @@ describe('Crop', function () {
     });
   });
 
-  it('Skip crop when post-resize dimensions are at or below target dimensions', function () {
+  it('Skip crop when post-resize dimensions are at target', function () {
     return sharp(fixtures.inputJpg)
       .resize(1600, 1200)
       .toBuffer()
@@ -177,6 +177,25 @@ describe('Crop', function () {
       });
   });
 
+  it('Clamp before crop when one post-resize dimension is below target', function () {
+    return sharp(fixtures.inputJpg)
+      .resize(1024, 1034)
+      .toBuffer()
+      .then(function (input) {
+        return sharp(input)
+          .rotate(270)
+          .resize(256)
+          .crop(sharp.strategy.entropy)
+          .toBuffer({ resolveWithObject: true })
+          .then(function (result) {
+            assert.strictEqual(256, result.info.width);
+            assert.strictEqual(253, result.info.height);
+            assert.strictEqual(0, result.info.cropOffsetLeft);
+            assert.strictEqual(0, result.info.cropOffsetTop);
+          });
+      });
+  });
+
   describe('Entropy-based strategy', function () {
     it('JPEG', function (done) {
       sharp(fixtures.inputJpg)