<AWT Dev> Review Request JDK:-8162959 [HiDPI] screenshot artifacts using AWT Robot

Tue Jan 10 08:54:33 UTC 2017

Hi Alex,

Please review updated patch,

http://cr.openjdk.java.net/~pkbalakr/8162959/webrev.05/

updated imageOption to kCGWindowImageBestResolution  which returns Best Resolution Image while capturing screen using CGWindowListCreateImage() method.

Regards,

Prem

From: Alexandr Scherbatiy 
Sent: Tuesday, January 10, 2017 1:08 AM
To: Prem Balakrishnan; Sergey Bylokhov; awt-dev at openjdk.java.net; Philip Race
Subject: Re: Review Request JDK:-8162959 [HiDPI] screenshot artifacts using AWT Robot

  CGWindowListCreateImage() method which is used to capture a screenshot on Mac OS X by Robot has imageOption argument which can have value: kCGWindowImageBestResolution
    https://developer.apple.com/reference/coregraphics/1666230-quartz_window_services/window_image_types?language=objc
   "When capturing the window, return the best image resolution. The returned image size may be different than the screen size."

  Could this option help to get a high-resolution CGImageRef on HiDPI display?

  Thanks,
  Alexandr.

On 12/27/2016 12:14 PM, Prem Balakrishnan wrote:

Hi Alexander,

Please review updated patch,

HYPERLINK "http://cr.openjdk.java.net/%7Epkbalakr/8162959/webrev.04/"http://cr.openjdk.java.net/~pkbalakr/8162959/webrev.04/ 

I used  wrong bounds while creating images, correct it in this patch.

Regards,

Prem

From: Alexander Scherbatiy 
Sent: Wednesday, December 14, 2016 5:18 PM
To: Prem Balakrishnan; Sergey Bylokhov; HYPERLINK "mailto:awt-dev at openjdk.java.net"awt-dev at openjdk.java.net; Philip Race
Subject: Re: Review Request JDK:-8162959 [HiDPI] screenshot artifacts using AWT Robot

On 07/12/16 10:24, Prem Balakrishnan wrote:

Hi Alexander,

Please review updated patch as per review comments.

HYPERLINK "http://cr.openjdk.java.net/%7Epkbalakr/8162959/webrev.03/"http://cr.openjdk.java.net/~pkbalakr/8162959/webrev.03/

  I used a simple app [1] to create a screenshot of a frame on Mac OS X:
        Rectangle rect = frame.getBounds();
        rect.setLocation(frame.getLocationOnScreen());
        BufferedImage img = robot.createScreenCapture(rect);

  It takes only bottom right quarter of the frame [2].

  Is it possible to use some API that makes a screenshot and returns an NSImage on Mac OS X?
  In this case it would be possible to get a high resolution representation from the NSImage and return it in the same way as it is updated on Windows and Linux.

  [1] HYPERLINK "http://cr.openjdk.java.net/%7Ealexsch/8162959/screenshot/RobotScreenshot.java"http://cr.openjdk.java.net/~alexsch/8162959/screenshot/RobotScreenshot.java
  [2] HYPERLINK "http://cr.openjdk.java.net/%7Ealexsch/8162959/screenshot/screenshot.png"http://cr.openjdk.java.net/~alexsch/8162959/screenshot/screenshot.png

  Thanks,
  Alexandr.

Regards,

Prem

From: Alexandr Scherbatiy 
Sent: Monday, November 21, 2016 8:10 PM
To: Prem Balakrishnan; Sergey Bylokhov; HYPERLINK "mailto:awt-dev at openjdk.java.net"awt-dev at openjdk.java.net; Phil Race
Subject: Re: Review Request JDK:-8162959 [HiDPI] screenshot artifacts using AWT Robot

On 11/16/2016 8:46 AM, Prem Balakrishnan wrote:

Hi Alexander, 

Please review update patch as per review comments.

HYPERLINK "http://cr.openjdk.java.net/%7Epkbalakr/8162959/webrev.02/"http://cr.openjdk.java.net/~pkbalakr/8162959/webrev.02/

With this patch, Robot.createScreenCapture(Rectangle) method returns a scaled down image on the HiDPI display.

- The native part on Mac OS X and Linux should be updated as well.

- 416      * Returns BufferedImage for Non-HiDPI display and MultiResolutionImage 
  417      * for HiDPI display with two resolution variants.

There should be added an explanation what is the content of the first and the second resolution variant.

Thanks,
Alexandr.

Regards,

Prem

From: Alexandr Scherbatiy 
Sent: Thursday, November 03, 2016 4:05 PM
To: Prem Balakrishnan; Sergey Bylokhov; HYPERLINK "mailto:awt-dev at openjdk.java.net"awt-dev at openjdk.java.net
Subject: Re: Review Request JDK:-8162959 [HiDPI] screenshot artifacts using AWT Robot

On 11/2/2016 1:57 PM, Prem Balakrishnan wrote:

Hi Alexander,

Please review updated patch.

HYPERLINK "http://cr.openjdk.java.net/%7Epkbalakr/8162959/webrev.01/"http://cr.openjdk.java.net/~pkbalakr/8162959/webrev.01/

Added a new public API "Image createHiDPIScreenCapture(Rectangle screenRect)".

Returns an ordinary screenshot(BufferedImage) if the UI scale is 1.

Returns MultiResolutionImage for HiDPI display with two resolution variants,

1.       Low Resolution/base image with user input width and height,  I have used interpolation algorithm for scaling , adapted from JavaFX Robot (http://hg.openjdk.java.net/openjfx/9-dev/rt/rev/89a5de54b7dc),

2.       High Resolution image with scaled width and height .

  - Please, check that the Robot.createScreenCapture(Rectangle) method returns a scaled down image on the HiDPI display
  - Probably existing Java methods can be used for an image scaling.
  For example, there is the Image.getScaledInstance(int width, int height, int hints) method.
  Or may be it is better just to create an image with required size and draw the high-resolution image into it using a specific scale and rendering hints.

  Thanks,
  Alexandr.

Regards,

Prem

From: Alexander Scherbatiy 
Sent: Thursday, October 13, 2016 3:21 PM
To: Prem Balakrishnan; Sergey Bylokhov; HYPERLINK "mailto:awt-dev at openjdk.java.net"awt-dev at openjdk.java.net
Subject: Re: Review Request JDK:-8162959 [HiDPI] screenshot artifacts using AWT Robot

On 06/10/16 15:28, Prem Balakrishnan wrote:

Hi,

Please review fix for JDK 9, 

Bug: https://bugs.openjdk.java.net/browse/JDK-8162959 

Webrev: HYPERLINK "http://cr.openjdk.java.net/%7Epkbalakr/8162959/webrev.00/"http://cr.openjdk.java.net/~pkbalakr/8162959/webrev.00/ 

I have adapted the same fix as used for JavaFX Robot 

Bug: HYPERLINK "https://bugs.openjdk.java.net/browse/JDK-8162783"JDK-8162783.

Patch: http://hg.openjdk.java.net/openjfx/9-dev/rt/rev/89a5de54b7dc

New Public API " BufferedImage createScreenCapture(Rectangle screenRect, boolean isHiDPI)" is added,
Which will have a parameter to specify if HiDPI.

  It is better to a add public method which returns MultiResolution image on HiDPI display and  consists of two resoltion variants
   - base image which has size requested by a user
   - high-resolution image which creates an original screen capture

  The proposed by your algorithm can be applied to the base image. 
  For more details see JDK-8020618 [macosx] java.awt.Robot makes blurry screen captures on Retina 

  Thanks,
  Alexandr.

Regards,
Prem

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