Allow rotate before pre-resize extraction #145

README.md

@@ -315,6 +315,8 @@ Rotate the output image by either an explicit angle or auto-orient based on the
 
 Use this method without `angle` to determine the angle from EXIF data. Mirroring is supported and may infer the use of a `flip` operation.
 
+Method order is important when both rotating and extracting regions, for example `rotate(x).extract(y)` will produce a different result to `extract(y).rotate(x)`.
+
 #### flip()
 
 Flip the image about the vertical Y axis. This always occurs after rotation, if any.

index.js

@@ -37,6 +37,7 @@ var Sharp = function(input) {
     canvas: 'c',
     gravity: 0,
     angle: 0,
+    rotateBeforePreExtract: false,
     flip: false,
     flop: false,
     withoutEnlargement: false,
@@ -136,6 +137,10 @@ Sharp.prototype.extract = function(topOffset, leftOffset, width, height) {
   ['topOffset', 'leftOffset', 'width', 'height'].forEach(function(name, index) {
     this.options[name + suffix] = values[index];
   }.bind(this));
+  // Ensure existing rotation occurs before pre-resize extraction
+  if (suffix === 'Pre' && this.options.angle !== 0) {
+    this.options.rotateBeforePreExtract = true;
+  }
   return this;
 };
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "sharp",
-  "version": "0.8.4",
+  "version": "0.9.0",
   "author": "Lovell Fuller <npm@lovell.info>",
   "contributors": [
     "Pierre Inglebert <pierre.inglebert@gmail.com>",
@@ -37,10 +37,10 @@
     "bluebird": "^2.6.4",
     "color": "^0.7.3",
     "nan": "^1.5.1",
-    "semver": "^4.1.0"
+    "semver": "^4.2.0"
   },
   "devDependencies": {
-    "mocha": "^2.0.1",
+    "mocha": "^2.1.0",
     "mocha-jshint": "^0.0.9",
     "istanbul": "^0.3.5",
     "coveralls": "^2.11.2"

src/resize.cc

@@ -58,6 +58,7 @@ struct ResizeBaton {
   double gamma;
   bool greyscale;
   int angle;
+  bool rotateBeforePreExtract;
   bool flip;
   bool flop;
   bool progressive;
@@ -146,6 +147,25 @@ class ResizeWorker : public NanAsyncWorker {
     }
     vips_object_local(hook, image);
 
+    // Calculate angle of rotation
+    Angle rotation;
+    bool flip;
+    std::tie(rotation, flip) = CalculateRotationAndFlip(baton->angle, image);
+    if (flip && !baton->flip) {
+      // Add flip operation due to EXIF mirroring
+      baton->flip = TRUE;
+    }
+
+    // Rotate pre-extract
+    if (baton->rotateBeforePreExtract && rotation != Angle::D0) {
+      VipsImage *rotated;
+      if (vips_rot(image, &rotated, static_cast<VipsAngle>(rotation), NULL)) {
+        return Error(baton, hook);
+      }
+      vips_object_local(hook, rotated);
+      image = rotated;
+    }
+
     // Pre extraction
     if (baton->topOffsetPre != -1) {
       VipsImage *extractedPre;
@@ -156,24 +176,15 @@ class ResizeWorker : public NanAsyncWorker {
       image = extractedPre;
     }
 
-    // Get input image width and height
+    // Get pre-resize image width and height
     int inputWidth = image->Xsize;
     int inputHeight = image->Ysize;
-
-    // Calculate angle of rotation, to be carried out later
-    Angle rotation;
-    bool flip;
-    std::tie(rotation, flip) = CalculateRotationAndFlip(baton->angle, image);
     if (rotation == Angle::D90 || rotation == Angle::D270) {
       // Swap input output width and height when rotating by 90 or 270 degrees
       int swap = inputWidth;
       inputWidth = inputHeight;
       inputHeight = swap;
     }
-    if (flip && !baton->flip) {
-      // Add flip operation due to EXIF mirroring
-      baton->flip = TRUE;
-    }
 
     // Get window size of interpolator, used for determining shrink vs affine
     int interpolatorWindowSize = InterpolatorWindowSize(baton->interpolator.c_str());
@@ -392,7 +403,7 @@ class ResizeWorker : public NanAsyncWorker {
     }
 
     // Rotate
-    if (rotation != Angle::D0) {
+    if (!baton->rotateBeforePreExtract && rotation != Angle::D0) {
       VipsImage *rotated;
       if (vips_rot(image, &rotated, static_cast<VipsAngle>(rotation), NULL)) {
         return Error(baton, hook);
@@ -918,6 +929,7 @@ NAN_METHOD(resize) {
   baton->gamma = options->Get(NanNew<String>("gamma"))->NumberValue();
   baton->greyscale = options->Get(NanNew<String>("greyscale"))->BooleanValue();
   baton->angle = options->Get(NanNew<String>("angle"))->Int32Value();
+  baton->rotateBeforePreExtract = options->Get(NanNew<String>("rotateBeforePreExtract"))->BooleanValue();
   baton->flip = options->Get(NanNew<String>("flip"))->BooleanValue();
   baton->flop = options->Get(NanNew<String>("flop"))->BooleanValue();
   // Output options

test/unit/extract.js

@@ -92,4 +92,28 @@ describe('Partial image extraction', function() {
       });
   });
 
+  it('Extract then rotate', function(done) {
+    sharp(fixtures.inputJpg)
+      .extract(10, 10, 100, 100)
+      .rotate(90)
+      .toFile(fixtures.path('output.extract.extract-then-rotate.jpg'), function(err, info) {
+        if (err) throw err;
+        assert.strictEqual(100, info.width);
+        assert.strictEqual(100, info.height);
+        done();
+      });
+  });
+
+  it('Rotate then extract', function(done) {
+    sharp(fixtures.inputJpg)
+      .rotate(90)
+      .extract(10, 10, 100, 100)
+      .toFile(fixtures.path('output.extract.rotate-then-extract.jpg'), function(err, info) {
+        if (err) throw err;
+        assert.strictEqual(100, info.width);
+        assert.strictEqual(100, info.height);
+        done();
+      });
+  });
+
 });