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Allow arbitrary gravity shifts when cropping #205

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Allow arbitrary gravity shifts when cropping #205

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15 changes: 12 additions & 3 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ var Sharp = function(input) {
width: -1,
height: -1,
canvas: 'crop',
gravity: 0,
gravity: { left: 0.5, top: 0.5 },
angle: 0,
rotateBeforePreExtract: false,
flip: false,
Expand Down Expand Up @@ -132,11 +132,20 @@ Sharp.prototype._write = function(chunk, encoding, callback) {
};

// Crop this part of the resized image (Center/Centre, North, East, South, West)
module.exports.gravity = {'center': 0, 'centre': 0, 'north': 1, 'east': 2, 'south': 3, 'west': 4};
module.exports.gravity = {
'center': { left: 0.5, top: 0.5 },
'centre': { left: 0.5, top: 0.5 },
'north': { left: 0.5, top: 0.0 },
'east': { left: 1.0, top: 0.5 },
'south': { left: 0.5, top: 1.0 },
'west': { left: 0.0, top: 0.5 }
};

Sharp.prototype.crop = function(gravity) {
this.options.canvas = 'crop';
if (typeof gravity === 'number' && !Number.isNaN(gravity) && gravity >= 0 && gravity <= 4) {
if (typeof gravity === 'object' &&
typeof gravity.left === 'number' && !Number.isNaN(gravity.left) && gravity.left >= 0 && gravity.left <= 1 &&
typeof gravity.top === 'number' && !Number.isNaN(gravity.top) && gravity.top >= 0 && gravity.top <= 1) {
this.options.gravity = gravity;
} else {
throw new Error('Unsupported crop gravity ' + gravity);
Expand Down
38 changes: 12 additions & 26 deletions src/resize.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -73,7 +73,8 @@ struct ResizeBaton {
int width;
int height;
Canvas canvas;
int gravity;
double gravityLeft;
double gravityTop;
std::string interpolator;
double background[4];
bool flatten;
Expand Down Expand Up @@ -111,7 +112,8 @@ struct ResizeBaton {
topOffsetPre(-1),
topOffsetPost(-1),
canvas(Canvas::CROP),
gravity(0),
gravityLeft(0.5),
gravityTop(0.5),
flatten(false),
blurSigma(0.0),
sharpenRadius(0),
Expand Down Expand Up @@ -619,7 +621,7 @@ class ResizeWorker : public NanAsyncWorker {
// Crop/max/min
int left;
int top;
std::tie(left, top) = CalculateCrop(image->Xsize, image->Ysize, baton->width, baton->height, baton->gravity);
std::tie(left, top) = CalculateCrop(image->Xsize, image->Ysize, baton->width, baton->height, baton->gravityLeft, baton->gravityTop);
int width = std::min(image->Xsize, baton->width);
int height = std::min(image->Ysize, baton->height);
VipsImage *extracted;
Expand Down Expand Up @@ -1054,28 +1056,10 @@ class ResizeWorker : public NanAsyncWorker {
within the input image, applying the given gravity.
*/
std::tuple<int, int>
CalculateCrop(int const inWidth, int const inHeight, int const outWidth, int const outHeight, int const gravity) {
int left = 0;
int top = 0;
switch (gravity) {
case 1: // North
left = (inWidth - outWidth + 1) / 2;
break;
case 2: // East
left = inWidth - outWidth;
top = (inHeight - outHeight + 1) / 2;
break;
case 3: // South
left = (inWidth - outWidth + 1) / 2;
top = inHeight - outHeight;
break;
case 4: // West
top = (inHeight - outHeight + 1) / 2;
break;
default: // Centre
left = (inWidth - outWidth + 1) / 2;
top = (inHeight - outHeight + 1) / 2;
}
CalculateCrop(int const inWidth, int const inHeight, int const outWidth, int const outHeight,
double const gravityLeft, double const gravityTop) {
int left = (inWidth - outWidth) * gravityLeft;
int top = (inHeight - outHeight) * gravityTop;
return std::make_tuple(left, top);
}

Expand Down Expand Up @@ -1177,7 +1161,9 @@ NAN_METHOD(resize) {
}
// Resize options
baton->withoutEnlargement = options->Get(NanNew<String>("withoutEnlargement"))->BooleanValue();
baton->gravity = options->Get(NanNew<String>("gravity"))->Int32Value();
Local<Object> gravity = options->Get(NanNew<String>("gravity"))->ToObject();
baton->gravityLeft = gravity->Get(NanNew<String>("left"))->NumberValue();
baton->gravityTop = gravity->Get(NanNew<String>("top"))->NumberValue();
baton->interpolator = *String::Utf8Value(options->Get(NanNew<String>("interpolator"))->ToString());
// Operators
baton->flatten = options->Get(NanNew<String>("flatten"))->BooleanValue();
Expand Down