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Fix transparency in capturePage (#12561)

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* Fix transparent window capture. Transparency is preserved and not converted to black pixels anymore

* Add test to make sure aplha channel exists in captured image
This commit is contained in:
Nitish Sakhawalkar 2018-04-10 03:07:15 -07:00 • committed by Cheng Zhao
parent eca0436f58
commit 6fc819dae1
2 changed files with 26 additions and 0 deletions
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3
atom/browser/api/atom_api_web_contents.cc
View file

@ -276,6 +276,9 @@ content::ServiceWorkerContext* GetServiceWorkerContext(
void OnCapturePageDone(const base::Callback<void(const gfx::Image&)>& callback, void OnCapturePageDone(const base::Callback<void(const gfx::Image&)>& callback,
const SkBitmap& bitmap, const SkBitmap& bitmap,
content::ReadbackResponse response) { content::ReadbackResponse response) {
// Hack to enable transparency in captured image
// TODO(nitsakh) Remove hack once fixed in chromium
const_cast<SkBitmap&>(bitmap).setAlphaType(kPremul_SkAlphaType);
callback.Run(gfx::Image::CreateFrom1xBitmap(bitmap)); callback.Run(gfx::Image::CreateFrom1xBitmap(bitmap));
} }

23
spec/api-browser-window-spec.js
View file

@ -442,6 +442,29 @@ describe('BrowserWindow module', () => {
done() done()
}) })
}) })
it('preserves transparency', (done) => {
w.close()
const width = 400
const height = 400
w = new BrowserWindow({
show: false,
width: width,
height: height,
transparent: true
})
w.loadURL('data:text/html,<html><body background-color: rgba(255,255,255,0)></body></html>')
w.once('ready-to-show', () => {
w.show()
w.capturePage((image) => {
let imgBuffer = image.toPNG()
// Check 25th byte in the PNG
// Values can be 0,2,3,4, or 6. We want 6, which is RGB + Alpha
assert.equal(imgBuffer[25], 6)
done()
})
})
})
}) })
describe('BrowserWindow.setSize(width, height)', () => { describe('BrowserWindow.setSize(width, height)', () => {