Add support for flip/flop/rotate after auto-orient

docs/api-operation.md

@@ -15,8 +15,9 @@ Mirroring is supported and may infer the use of a flip operation.
 
 The use of `rotate` without an angle will remove the EXIF `Orientation` tag, if any.
 
-Only one rotation can occur per pipeline.
-Previous calls to `rotate` in the same pipeline will be ignored.
+Only one rotation can occur per pipeline (aside from an initial call without
+arguments to orient via EXIF data). Previous calls to `rotate` in the same
+pipeline will be ignored.
 
 Multi-page images can only be rotated by 180 degrees.
 
@@ -60,6 +61,22 @@ const resizeThenRotate = await sharp(input)
 ```
 
 
+## autoOrient
+> autoOrient() ⇒ <code>Sharp</code>
+
+Alias for calling `rotate()` with no arguments, which orients the image based
+on EXIF orientsion.
+
+This operation is aliased to emphasize its purpose, helping to remove any
+confusion between rotation and orientation.
+
+
+**Example**  
+```js
+const output = await sharp(input).autoOrient().toBuffer();
+```
+
+
 ## flip
 > flip([flip]) ⇒ <code>Sharp</code>
 
@@ -580,7 +597,7 @@ Recombine the image with the specified matrix.
 
 | Param | Type | Description |
 | --- | --- | --- |
-| inputMatrix | <code>Array.&lt;Array.&lt;number&gt;&gt;</code> | 3x3 or 4x4 Recombination matrix |
+| inputMatrix | <code>Array.&lt;Array.&lt;number&gt;&gt;</code> | 3x3 Recombination matrix |
 
 **Example**  
 ```js

lib/index.d.ts

@@ -364,24 +364,72 @@ declare namespace sharp {
         //#region Operation functions
 
         /**
-         * Rotate the output image by either an explicit angle or auto-orient based on the EXIF Orientation tag.
+         * Rotate the output image by either an explicit angle
+         * or auto-orient based on the EXIF `Orientation` tag.
          *
-         * If an angle is provided, it is converted to a valid positive degree rotation. For example, -450 will produce a 270deg rotation.
+         * If an angle is provided, it is converted to a valid positive degree rotation.
+         * For example, `-450` will produce a 270 degree rotation.
          *
-         * When rotating by an angle other than a multiple of 90, the background colour can be provided with the background option.
+         * When rotating by an angle other than a multiple of 90,
+         * the background colour can be provided with the `background` option.
          *
-         * If no angle is provided, it is determined from the EXIF data. Mirroring is supported and may infer the use of a flip operation.
+         * If no angle is provided, it is determined from the EXIF data.
+         * Mirroring is supported and may infer the use of a flip operation.
          *
-         * The use of rotate implies the removal of the EXIF Orientation tag, if any.
+         * The use of `rotate` without an angle will remove the EXIF `Orientation` tag, if any.
          *
-         * 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).
-         * @param angle angle of rotation. (optional, default auto)
-         * @param options if present, is an Object with optional attributes.
+         * Only one rotation can occur per pipeline (aside from an initial call without
+         * arguments to orient via EXIF data). Previous calls to `rotate` in the same
+         * pipeline will be ignored.
+         *
+         * Multi-page images can only be rotated by 180 degrees.
+         *
+         * Method order is important when rotating, resizing and/or extracting regions,
+         * for example `.rotate(x).extract(y)` will produce a different result to `.extract(y).rotate(x)`.
+         *
+         * @example
+         * const pipeline = sharp()
+         *   .rotate()
+         *   .resize(null, 200)
+         *   .toBuffer(function (err, outputBuffer, info) {
+         *     // outputBuffer contains 200px high JPEG image data,
+         *     // auto-rotated using EXIF Orientation tag
+         *     // info.width and info.height contain the dimensions of the resized image
+         *   });
+         * readableStream.pipe(pipeline);
+         *
+         * @example
+         * const rotateThenResize = await sharp(input)
+         *   .rotate(90)
+         *   .resize({ width: 16, height: 8, fit: 'fill' })
+         *   .toBuffer();
+         * const resizeThenRotate = await sharp(input)
+         *   .resize({ width: 16, height: 8, fit: 'fill' })
+         *   .rotate(90)
+         *   .toBuffer();
+         *
+         * @param {number} [angle=auto] angle of rotation.
+         * @param {Object} [options] - if present, is an Object with optional attributes.
+         * @param {string|Object} [options.background="#000000"] parsed by the [color](https://www.npmjs.org/package/color) module to extract values for red, green, blue and alpha.
+         * @returns {Sharp}
          * @throws {Error} Invalid parameters
-         * @returns A sharp instance that can be used to chain operations
          */
         rotate(angle?: number, options?: RotateOptions): Sharp;
 
+        /**
+         * Alias for calling `rotate()` with no arguments, which orients the image based
+         * on EXIF orientsion.
+         *
+         * This operation is aliased to emphasize its purpose, helping to remove any
+         * confusion between rotation and orientation.
+         *
+         * @example
+         * const output = await sharp(input).autoOrient().toBuffer();
+         *
+         * @returns {Sharp}
+         */
+        autoOrient(): Sharp
+
         /**
          * Flip the image about the vertical Y axis. This always occurs after rotation, if any.
          * The use of flip implies the removal of the EXIF Orientation tag, if any.

lib/operation.js

@@ -21,8 +21,9 @@ const is = require('./is');
  *
  * The use of `rotate` without an angle will remove the EXIF `Orientation` tag, if any.
  *
- * Only one rotation can occur per pipeline.
- * Previous calls to `rotate` in the same pipeline will be ignored.
+ * Only one rotation can occur per pipeline (aside from an initial call without
+ * arguments to orient via EXIF data). Previous calls to `rotate` in the same
+ * pipeline will be ignored.
  *
  * Multi-page images can only be rotated by 180 degrees.
  *
@@ -81,6 +82,22 @@ function rotate (angle, options) {
   return this;
 }
 
+/**
+ * Alias for calling `rotate()` with no arguments, which orients the image based
+ * on EXIF orientsion.
+ *
+ * This operation is aliased to emphasize its purpose, helping to remove any
+ * confusion between rotation and orientation.
+ *
+ * @example
+ * const output = await sharp(input).autoOrient().toBuffer();
+ *
+ * @returns {Sharp}
+ */
+function autoOrient () {
+  return this.rotate();
+}
+
 /**
  * Mirror the image vertically (up-down) about the x-axis.
  * This always occurs before rotation, if any.
@@ -787,22 +804,24 @@ function linear (a, b) {
  *     // With this example input, a sepia filter has been applied
  *   });
  *
- * @param {Array<Array<number>>} inputMatrix - 3x3 or 4x4 Recombination matrix
+ * @param {Array<Array<number>>} inputMatrix - 3x3 Recombination matrix
  * @returns {Sharp}
  * @throws {Error} Invalid parameters
  */
 function recomb (inputMatrix) {
-  if (!Array.isArray(inputMatrix)) {
-    throw is.invalidParameterError('inputMatrix', 'array', inputMatrix);
-  }
-  if (inputMatrix.length !== 3 && inputMatrix.length !== 4) {
-    throw is.invalidParameterError('inputMatrix', '3x3 or 4x4 array', inputMatrix.length);
-  }
-  const recombMatrix = inputMatrix.flat().map(Number);
-  if (recombMatrix.length !== 9 && recombMatrix.length !== 16) {
-    throw is.invalidParameterError('inputMatrix', 'cardinality of 9 or 16', recombMatrix.length);
+  if (!Array.isArray(inputMatrix) || inputMatrix.length !== 3 ||
+      inputMatrix[0].length !== 3 ||
+      inputMatrix[1].length !== 3 ||
+      inputMatrix[2].length !== 3
+  ) {
+    // must pass in a kernel
+    throw new Error('Invalid recombination matrix');
   }
-  this.options.recombMatrix = recombMatrix;
+  this.options.recombMatrix = [
+    inputMatrix[0][0], inputMatrix[0][1], inputMatrix[0][2],
+    inputMatrix[1][0], inputMatrix[1][1], inputMatrix[1][2],
+    inputMatrix[2][0], inputMatrix[2][1], inputMatrix[2][2]
+  ].map(Number);
   return this;
 }
 
@@ -895,6 +914,7 @@ function modulate (options) {
  */
 module.exports = function (Sharp) {
   Object.assign(Sharp.prototype, {
+    autoOrient,
     rotate,
     flip,
     flop,

src/pipeline.cc

@@ -77,10 +77,10 @@ class PipelineWorker : public Napi::AsyncWorker {
         // Rotate and flip image according to Exif orientation
         std::tie(autoRotation, autoFlip, autoFlop) = CalculateExifRotationAndFlip(sharp::ExifOrientation(image));
         image = sharp::RemoveExifOrientation(image);
-      } else {
-        rotation = CalculateAngleRotation(baton->angle);
       }
 
+      rotation = CalculateAngleRotation(baton->angle);
+
       // Rotate pre-extract
       bool const shouldRotateBefore = baton->rotateBeforePreExtract &&
         (rotation != VIPS_ANGLE_D0 || autoRotation != VIPS_ANGLE_D0 ||
@@ -102,18 +102,14 @@ class PipelineWorker : public Napi::AsyncWorker {
           image = image.rot(autoRotation);
           autoRotation = VIPS_ANGLE_D0;
         }
-        if (autoFlip) {
+        if (autoFlip != baton->flip) {
           image = image.flip(VIPS_DIRECTION_VERTICAL);
           autoFlip = false;
-        } else if (baton->flip) {
-          image = image.flip(VIPS_DIRECTION_VERTICAL);
           baton->flip = false;
         }
-        if (autoFlop) {
+        if (autoFlop != baton->flop) {
           image = image.flip(VIPS_DIRECTION_HORIZONTAL);
           autoFlop = false;
-        } else if (baton->flop) {
-          image = image.flip(VIPS_DIRECTION_HORIZONTAL);
           baton->flop = false;
         }
         if (rotation != VIPS_ANGLE_D0) {
@@ -405,11 +401,11 @@ class PipelineWorker : public Napi::AsyncWorker {
         image = image.rot(autoRotation);
       }
       // Mirror vertically (up-down) about the x-axis
-      if (baton->flip || autoFlip) {
+      if (baton->flip != autoFlip) {
         image = image.flip(VIPS_DIRECTION_VERTICAL);
       }
       // Mirror horizontally (left-right) about the y-axis
-      if (baton->flop || autoFlop) {
+      if (baton->flop != autoFlop) {
         image = image.flip(VIPS_DIRECTION_HORIZONTAL);
       }
       // Rotate post-extract 90-angle