I'd like to propose some revision to the API and also have a question
about the implementation.
The question about the implementation concerns this code :-
465 AffineTransform tx = GraphicsEnvironment.
466 getLocalGraphicsEnvironment().getDefaultScreenDevice().
467 getDefaultConfiguration().getDefaultTransform();
468 double uiScaleX = tx.getScaleX();
469 double uiScaleY = tx.getScaleY();
Is Robot only capable of a screen capture from the default screen ? I
hope not.
So I would expect that where there are two screens with different DPI
settings/transforms
the logic in here will be sensitive to the target screen.
And what happens if the target rectangle overlaps the edge between two
screens ?
Regarding the API, I think that it needs to explain that it is "not 'hi
dpi" per se,
rather that it is the non-default transform that matters.
Additionally the doc should properly link to the class names, not just
write them
as words.
The more significant API change is that the isHiDPI parameter is a misnomer.
It really means something else and I think what we should do is delete it
and change the method name to something else.
Here is my draft :
/**
* Creates an image containing pixels read from the screen.
* This image does not include the mouse cursor.
* This method should be used in case there is a scaling transform from
* user space to screen (device) space.
* Typically this means that the display is a high resolution screen,
* although strictly it means any case in which there is such a transform.
* Returns a {@link java.awt.image.BufferedImage} for a non-scaled
display and
* a {@link java.awt.image.MultiResolutionImage} where there is a scaling
* transform.
* <p>
* The {@code MultiResolutionImage} will have two image variants:
* <ul>
* <li> Base Image with user specified size. This is scaled from the
screen.
* <li> Native device resolution image with device size pixels.
* </ul>
* @param screenRect Rect to capture in screen coordinates
* @return The captured image
* @throws IllegalArgumentException if {@code screenRect} width and
height
* are not greater than zero
* @throws SecurityException if {@code readDisplayPixels} permission
* is not granted
* @see SecurityManager#checkPermission
* @see AWTPermission
*/
public synchronized Image multiImageeScreenCapture(Rectangle screenRect);
-phil.
On 1/20/17, 3:20 AM, Alexandr Scherbatiy wrote:
On 1/19/2017 3:57 PM, Prem Balakrishnan wrote:
Hi Alex,
Please review updated patch as per review comments.
http://cr.openjdk.java.net/~pkbalakr/8162959/webrev.06/
<http://cr.openjdk.java.net/%7Epkbalakr/8162959/webrev.06/>
Automated test validates both Robot.getPixelColor() and output of
Robot.createScreenCapture() API's.
Jtreg and JCK tests passed on build with fix across all the
platforms(Mac, Windows and Linux) without causing any regression.
src/java.desktop/share/classes/java/awt/Robot.java
> 421 * @param isHiDPI Indicates if HiDPI Display
There should be mention that this argument value is ignored when a
screenshot is taken on non-HiDPI display
Thanks,
Alexandr.
Regards,
Prem
*From:*Alexandr Scherbatiy
*Sent:* Thursday, January 12, 2017 2:39 PM
*To:* Prem Balakrishnan; Sergey Bylokhov; awt-dev@openjdk.java.net;
Philip Race
*Subject:* Re: Review Request JDK:-8162959 [HiDPI] screenshot
artifacts using AWT Robot
> 421 * @param isHiDPI Indicates if HiDPI Display
There should be mention that this argument value is ignored when a
screenshot is taken on non-HiDPI display
Please also check the the method Robot.getPixelColor(int x, int y)
also correctly works on Mac OS X, Windows and Linux after the fix.
Thanks,
Alexandr.
On 1/10/2017 11:54 AM, Prem Balakrishnan wrote:
Hi Alex,
Please review updated patch,
http://cr.openjdk.java.net/~pkbalakr/8162959/webrev.05/
<http://cr.openjdk.java.net/%7Epkbalakr/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@openjdk.java.net <mailto:awt-dev@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,
http://cr.openjdk.java.net/~pkbalakr/8162959/webrev.04/
<http://cr.openjdk.java.net/%7Epkbalakr/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;
awt-dev@openjdk.java.net <mailto:awt-dev@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.
http://cr.openjdk.java.net/~pkbalakr/8162959/webrev.03/
<http://cr.openjdk.java.net/%7Epkbalakr/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]
http://cr.openjdk.java.net/~alexsch/8162959/screenshot/RobotScreenshot.java
<http://cr.openjdk.java.net/%7Ealexsch/8162959/screenshot/RobotScreenshot.java>
[2]
http://cr.openjdk.java.net/~alexsch/8162959/screenshot/screenshot.png
<http://cr.openjdk.java.net/%7Ealexsch/8162959/screenshot/screenshot.png>
Thanks,
Alexandr.
Regards,
Prem
*From:*Alexandr Scherbatiy
*Sent:* Monday, November 21, 2016 8:10 PM
*To:* Prem Balakrishnan; Sergey Bylokhov;
awt-dev@openjdk.java.net <mailto:awt-dev@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.
http://cr.openjdk.java.net/~pkbalakr/8162959/webrev.02/
<http://cr.openjdk.java.net/%7Epkbalakr/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;
awt-dev@openjdk.java.net <mailto:awt-dev@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.
http://cr.openjdk.java.net/~pkbalakr/8162959/webrev.01/
<http://cr.openjdk.java.net/%7Epkbalakr/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;
awt-dev@openjdk.java.net <mailto:awt-dev@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:*http://cr.openjdk.java.net/~pkbalakr/8162959/webrev.00/
<http://cr.openjdk.java.net/%7Epkbalakr/8162959/webrev.00/>
I have adapted the same fix as used for JavaFX Robot
*Bug: *JDK-8162783
<https://bugs.openjdk.java.net/browse/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
