Support for cropping imageB

[koola]

Would be great if blinkdiff supported image cropping so that for example a small image could be compared with a cropped region of a larger image like a screenshot.

Something like:

function BlinkDiff (options) {

    this._imageCropRegion = options.imageCropRegion || {};

}

    run: function (fn) { 
        ...
            }.bind(this)).then(function (imageB) {
                this._imageB = imageB;

                if (Object.keys(this._imageCropRegion).length > 0) {
                    this._crop(this._imageB, this._imageCropRegion);
                }

                this._clip(this._imageA, this._imageB);
      ...
    },

    /**
     * Crops the source image to the bounds of rect
     *
     * @private
     * @method _crop
     * @param {PNGImage} image Source image
     * @param {object} rect Values for rect
     * @param (int} rect.left Left value of rect
     * @param (int} rect.top Top value of rect
     * @param (int} rect.width Width value of rect
     * @param (int} rect.height Height value of rect
     */
    _crop: function (image, rect) {

        if ((rect.left + rect.width) <= image.getWidth() && (rect.top + rect.height) <= image.getHeight()) {

            this.log("Cropping from " + rect.left + "," + rect.top + " by " + rect.width + " x " + rect.height);

            image.clip(rect.left, rect.top, rect.width, rect.height);
        }
    },

[marcelerz]

I just pushed the cropping feature. Now, you can crop each of the images by supplying a crop-object. The properties of these objects are:

• x - X coordinate (Left)
• y - Y coordinate (Top)
• width - Width of image
• height - Height of image

Note that the x and y coordinates are different to your suggested left and top property names.
You can also leave some of the values off. Then, they will be calculated according to some rules.

Thank you again for these great suggestions. I really appreciate it.

I still work on two more features, and I will publish the code then to NPM. I will keep you posted.

[koola]

That's awesome! Thanks a lot for implementing this.

[marcelerz]

No problem. I thank you! 👍
Also, I just pushed it to NPM.