<AWT Dev> Review Request JDK:-8162959 [HiDPI] screenshot artifacts using AWT Robot
Philip Race
philip.race at oracle.com
Wed Jan 25 18:13:40 UTC 2017
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 at 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 at openjdk.java.net <mailto: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,
>>
>> 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 at openjdk.java.net <mailto: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.
>>
>> 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 at openjdk.java.net <mailto: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.
>>
>> 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 at openjdk.java.net <mailto: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.
>>
>> 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 at openjdk.java.net <mailto: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:*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
>>
>>
>>
>
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