Hello.
Please review the fix for jdk/client.
Bug: https://bugs.openjdk.java.net/browse/JDK-8211999
Fix: http://cr.openjdk.java.net/~serb/8211999/webrev.04
(Note: the fix use API available since Windows 8.1: WM_DPICHANGED, but it
should be fine for
Windows 7, because it does not support different DPI for different mnitors)
========================================================
Short description:
In the multi-screen configurations when each screen have different DPI
we calculate the bounds of each monitor by these formulas:
userSpaceBounds = deviceX / scaleX, deviceY / scaleY, deviceW / scaleX,
deviceH / scaleY
devSpaceBounds = userX * scaleX, userY * scaleY, userW * scaleX, userH
* scaleY
This formula makes the next configuration completely broken:
- The main screen on the left and 100% DPI
- The second screen on the right and 200% DPI
When we translate the bounds of the config from the device space to the
user's space,
the bounds of both screen overlap in the user's space, because we use
bounds of
the main screen as-is, and the X/Y of the second screen are divided by the
scaleX/Y.
Since the screens are overlapped we cannot be sure how to translate the
user's space
coordinates to device space in the overlapped zone.
As a result => we use the wrong screen
=> got wrong coordinates in the device space
=> show top-level windows/popups/tooltips/menus/etc on the
wrong screen
The proposed solution for this bug is to change the formulas to these:
userSpaceBounds = deviceX, deviceY, deviceW / scaleX, deviceH / scaleY
devSpaceBounds = userX, userY, userW * scaleX, userH * scaleY
In other words, we should not transform the X and Y coordinates of the
screen. This will
complicate the way of how we transform coordinates on the screen: user's
<--> device spaces:
Before the fix:
userX = deviceX * scaleX;
deviceX = userX / scaleX;
After the fix(only the part appeared on the screen is scaled)
userX = screenX + (deviceX - screenX) * scaleX
deviceX = screenX + (userX - screenX) / scaleX
Note that this new formulas are applicable only for the coordinates on the
screen such as X and Y.
If we will need to calculate the "size" such as W and H then the old
formula should be used.
The main changes for the problem above are:
- Skip transformation of X and Y of the screen bounds:
http://cr.openjdk.java.net/~serb/8211999/webrev.04/src/java.desktop/windows/native/libawt/windows/awt_Win32GraphicsConfig.cpp.sdiff.html
- A number of utility methods in java and native:
http://cr.openjdk.java.net/~serb/8211999/webrev.04/src/java.desktop/windows/native/libawt/windows/awt_Win32GraphicsDevice.cpp.sdiff.html
http://cr.openjdk.java.net/~serb/8211999/webrev.04/src/java.desktop/share/classes/sun/java2d/SunGraphicsEnvironment.java.sdiff.html
========================================================
Long description:
Unfortunately the changes above are not enough to fix the problem when
different monitors
have different DPI, even if the bounds are *NOT* overlapped.
- Currently when we try to set the bounds of the window, we manually convert it in
"java" to the
expected device position based on the current GraphicsConfiguration of the
peer, and then
additionally tweak it in native using the device scale stored in native
code. Unfortunately
this two scale might not be in sync:(after we use the GraphicsConfiguration
scale in peer,
the config might be changed and the tweak in native will use different
screen).
As a fix I have moved all transformation from the peer to the native code,
it will be executed
on the toolkit thread:
See the change in WWindowPeer.setBounds() and awt_Window.cpp
AwtWindow::Reshape
http://cr.openjdk.java.net/~serb/8211999/webrev.04/src/java.desktop/windows/classes/sun/awt/windows/WWindowPeer.java.sdiff.html
http://cr.openjdk.java.net/~serb/8211999/webrev.04/src/java.desktop/windows/native/libawt/windows/awt_Window.cpp.sdiff.html
I think at some point we should delete all transformation in java, and
apply it in the native code only.
- We had a special code that tracked the dragging of the window by the user
from one screen to another,
and change the size of the window only when the user stop the drag
operation. I've propose to use standard Windows
machinery for that via WM_DPICHANGED:
https://docs.microsoft.com/en-us/windows/win32/hidpi/wm-dpichanged
As a result the Windows will provide a "best" windows bounds on the new
screen. Note that the code have a
workaround for https://bugs.openjdk.java.net/browse/JDK-8249164
- I've also fix variation of the bug previously fixed on macOS https://hg.openjdk.java.net/jdk/jdk/rev/b5cdba232fca
If we try to change the position of the window, and Windows ignores this
request then we need to
call all "callbacks" manually, otherwise the shared code will uses the
bounds ignored by the Windows.
See the end of void AwtWindow::Reshape():
http://cr.openjdk.java.net/~serb/8211999/webrev.04/src/java.desktop/windows/native/libawt/windows/awt_Window.cpp.sdiff.html
- Currently the HW componets such as Canvas scales everything based on such
code:
770 int AwtComponent::ScaleUpX(int x) {
4771 int screen =
AwtWin32GraphicsDevice::DeviceIndexForWindow(GetHWnd());
4772 Devices::InstanceAccess devices;
4773 AwtWin32GraphicsDevice* device = devices->GetDevice(screen);
4774 return device == NULL ? x : device->ScaleUpX(x);
4775 }
But it does not work well if the smaller part of the top-level window is
located on one screen1(DPI=100) but
the biggest part is located on the screen2(DPI=200). If the Canvas is located on the
"smaller" part of the
window, then the canvas will use DPI=100 for scale, but the whole window
will use DPI=200
As a fix, all HW components will try to use the scale factor of the
top-level window, see AwtComponent::GetScreenImOn:
http://cr.openjdk.java.net/~serb/8211999/webrev.04/src/java.desktop/windows/native/libawt/windows/awt_Component.cpp.sdiff.html
- Our current implementation does not take care about the case when the HW
component bounds are updated when the top-level
window is moved to other screen. For example if the window does not use
LayoutManager and the user set some specific bounds
for the Canvas. It is expected that the size of the Canvas will be updated
when the window will be moved to other screen, but
only HW top-level window and Swing components will update its size.
As a fix I suggest to resync the bounds of the HW components if the
GraphicsCOnfiguration is changed, see WComponentPeer.syncBounds():
http://cr.openjdk.java.net/~serb/8211999/webrev.04/src/java.desktop/windows/classes/sun/awt/windows/WComponentPeer.java.sdiff.html
- Note that the current fix is for Windows only, but the bug exists on Linux as well,
so I have to create a kind of "ifdef" in the
Robot class, on windows we will use the new logic, on other platforms the
old logic will be used.
========================================================
Some other bugs which are not fixed.
- We have a lot of places where we mix(unintentionally) the coordinate in
user's space and device space.
For example when we create the component we read x/y/width/height by the
JNI(of course in a user's space)
but pass this coordinates as-is to the ::CreateWindowEx() which is
incorrect. It works currently
because later we reshape the component to the correct bounds. Will fix it
later.
- When the frame is iconized and we try to save a new bounds for the future
use, we store the
coordinates in the user's space to the field which use device space:
https://github.com/openjdk/jdk/blob/master/src/java.desktop/windows/native/libawt/windows/awt_Frame.cpp#L664
Probably there are some other bugs and possibility to cleanups, but I would
like to do that in a separate issues.
========================================================
The tests
- I have updated a couple of the tests to check multiple screen if possible,
it helps to found some bugs
in my initial implementation
- Three new tests were added: SetComponentsBounds, SlowMotion,
WindowSizeDifferentScreens
- One test is moved from the closed repo(I made a small cleanup of it):
ListMultipleSelectTest
========================================================
I have run jck, regression tests in a different configurations, when the main
screen is on the left, up, down,
right, and have different DPI such as 100, 125, 150 and 200. No new issues were
found so far.
The mach5 is also green, but I still investigate some common intermittent
failures.
PS: hope I did not forget some important information, will send it later if any.
--
Best regards, Sergey.
