Fix transparency in capturePage (#12561)

* 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
2018-04-10 03:07:15 -07:00 · 2018-04-10 03:07:15 -07:00 · 6fc819dae1
commit 6fc819dae1
parent eca0436f58
2 changed files with 26 additions and 0 deletions
--- a/spec/api-browser-window-spec.js
+++ b/spec/api-browser-window-spec.js
@ -442,6 +442,29 @@ describe('BrowserWindow module', () => {
        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)', () => {