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Add hasAlpha attribute to metadata API

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Provides internal sharp_image_has_alpha method

Hopefully this helps with #91
This commit is contained in:
Lovell Fuller 2014-09-25 10:07:26 +01:00
parent 150971fa92
commit 513b07ddcf
3 changed files with 38 additions and 0 deletions
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16
src/sharp.cc
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@ -161,6 +161,19 @@ sharp_calc_crop(int const inWidth, int const inHeight, int const outWidth, int c
return std::make_tuple(left, top);
}
/*
Does this image have an alpha channel?
Uses colourspace interpretation with number of channels to guess this.
*/
static bool
sharp_image_has_alpha(VipsImage *image) {
return (
(image->Bands == 2 && image->Type == VIPS_INTERPRETATION_B_W) ||
(image->Bands == 4 && image->Type != VIPS_INTERPRETATION_CMYK) ||
(image->Bands == 5 && image->Type == VIPS_INTERPRETATION_CMYK)
);
}
/*
Initialise a VipsImage from a buffer. Supports JPEG, PNG and WebP.
Returns the ImageType detected, if any.
@ -228,6 +241,7 @@ struct metadata_baton {
int height;
std::string space;
int channels;
bool has_alpha;
int orientation;
std::string err;
@ -276,6 +290,7 @@ class MetadataWorker : public NanAsyncWorker {
baton->height = image->Ysize;
baton->space = vips_enum_nick(VIPS_TYPE_INTERPRETATION, image->Type);
baton->channels = image->Bands;
baton->has_alpha = sharp_image_has_alpha(image);
// EXIF Orientation
const char *exif;
if (!vips_image_get_string(image, "exif-ifd0-Orientation", &exif)) {
@ -303,6 +318,7 @@ class MetadataWorker : public NanAsyncWorker {
info->Set(NanNew<String>("height"), NanNew<Number>(baton->height));
info->Set(NanNew<String>("space"), NanNew<String>(baton->space));
info->Set(NanNew<String>("channels"), NanNew<Number>(baton->channels));
info->Set(NanNew<String>("hasAlpha"), NanNew<Boolean>(baton->has_alpha));
if (baton->orientation > 0) {
info->Set(NanNew<String>("orientation"), NanNew<Number>(baton->orientation));
}

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tests/fixtures/blackbug.png vendored Normal file
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22
tests/unit.js
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@ -21,6 +21,7 @@ var inputJpgWithExif = path.join(fixturesPath, "Landscape_8.jpg"); // https://gi
var inputJpgWithGammaHoliness = path.join(fixturesPath, "gamma_dalai_lama_gray.jpg"); // http://www.4p8.com/eric.brasseur/gamma.html
var inputPng = path.join(fixturesPath, "50020484-00001.png"); // http://c.searspartsdirect.com/lis_png/PLDM/50020484-00001.png
var inputPngWithTransparency = path.join(fixturesPath, "blackbug.png"); // public domain
var inputWebP = path.join(fixturesPath, "4.webp"); // http://www.gstatic.com/webp/gallery/4.webp
var inputGif = path.join(fixturesPath, "Crash_test.gif"); // http://upload.wikimedia.org/wikipedia/commons/e/e3/Crash_test.gif
@ -593,6 +594,7 @@ async.series([
assert.strictEqual(600, metadata.height);
assert.strictEqual('srgb', metadata.space);
assert.strictEqual(3, metadata.channels);
assert.strictEqual(false, metadata.hasAlpha);
assert.strictEqual(8, metadata.orientation);
done();
});
@ -606,6 +608,7 @@ async.series([
assert.strictEqual(3248, metadata.height);
assert.strictEqual('b-w', metadata.space);
assert.strictEqual(1, metadata.channels);
assert.strictEqual(false, metadata.hasAlpha);
done();
});
},
@ -618,6 +621,20 @@ async.series([
assert.strictEqual(2074, metadata.height);
assert.strictEqual('b-w', metadata.space);
assert.strictEqual(1, metadata.channels);
assert.strictEqual(false, metadata.hasAlpha);
done();
});
},
// Metadata - Transparent PNG
function(done) {
sharp(inputPngWithTransparency).metadata(function(err, metadata) {
if (err) throw err;
assert.strictEqual('png', metadata.format);
assert.strictEqual(2048, metadata.width);
assert.strictEqual(1536, metadata.height);
assert.strictEqual('srgb', metadata.space);
assert.strictEqual(4, metadata.channels);
assert.strictEqual(true, metadata.hasAlpha);
done();
});
},
@ -630,6 +647,7 @@ async.series([
assert.strictEqual(772, metadata.height);
assert.strictEqual('srgb', metadata.space);
assert.strictEqual(3, metadata.channels);
assert.strictEqual(false, metadata.hasAlpha);
done();
});
},
@ -641,6 +659,7 @@ async.series([
assert.strictEqual(800, metadata.width);
assert.strictEqual(533, metadata.height);
assert.strictEqual(3, metadata.channels);
assert.strictEqual(false, metadata.hasAlpha);
done();
});
},
@ -652,6 +671,7 @@ async.series([
assert.strictEqual(2225, metadata.height);
assert.strictEqual('srgb', metadata.space);
assert.strictEqual(3, metadata.channels);
assert.strictEqual(false, metadata.hasAlpha);
done();
});
},
@ -665,6 +685,7 @@ async.series([
assert.strictEqual(2225, metadata.height);
assert.strictEqual('srgb', metadata.space);
assert.strictEqual(3, metadata.channels);
assert.strictEqual(false, metadata.hasAlpha);
done();
});
readable.pipe(pipeline);
@ -679,6 +700,7 @@ async.series([
assert.strictEqual(2225, metadata.height);
assert.strictEqual('srgb', metadata.space);
assert.strictEqual(3, metadata.channels);
assert.strictEqual(false, metadata.hasAlpha);
image.resize(metadata.width / 2).toBuffer(function(err, data, info) {
if (err) throw err;
assert.strictEqual(true, data.length > 0);