We ported our application from Qt3 to Qt5. It runs smoothly under Windows but not under Linux (X11). With Qt3 there is no problem with Windows or Linux.
Inside the application there is a canvas of about 1000x800 pixels. A simple vector graphic is drawn onto the canvas. The user clicks into the canvas, holding the mouse button pressed an moves the mouse. Each mouse move results in a repaint.
We registered the milliseconds in each stage:
Start of MouseMove-event handling: 10581
call of update or repaint (makes no difference which one)
Handling of resulting Paint-Event: 10583
Painting finishes: 10584
return from update/repaint: 10687 (!)
I do not find any reason for this lag of 100ms (at each mouse move event!)
I need help!
In Qt4.8 the native graphics backend was deprecated.
Remote X11 is no longer drawn with X11 calls but by painting onto a canvas and transmitting the result (a bitmap) to the client. This may result in larger bandwidth requirements and a slower when running X11 over network.
See also this
Related
Presently I'm learning the basics of real-time raytracing with the DXR API in DirectX 12 Ultimate. I'm studying the D3D12 raytracing samples on the official GitHub and am using an i9/Intel Iris Xe/RTX3070 laptop and building the programs in VS2022.
Since the samples were written for Windows 10 and I'm using a hybrid graphics PC, a Debug build will run in Windows 11 after adding D3D12_MESSAGE_ID_RESOURCE_BARRIER_MISMATCHING_COMMAND_LIST_TYPE to D3D12_INFO_QUEUE_FILTER during device creation (see DirectX 12 application is crashing in Windows 11). The only trouble is that none of the sample programs change to fullscreen (i.e. borderless windowed) mode when pressing the Alt+Enter key combination. The programs always stay in windowed mode.
This hasn't worried me so far, because I've been copying the raytracing code over to a template (based on DirectX Tool Kit for Windows desktop) where fullscreen toggling works properly. In this way, I was able to run the HelloWorld and SimpleLighting samples successfully in both windowed mode and fullscreen (2560x1440 monitor resolution).
However, this hasn't been so successful for the ProceduralGeometry sample, which introduces intersection shaders. Once again, the original sample program renders the scene properly, but only in a bordered window. But when the code is reproduced in the template where I can toggle to fullscreen, the raytraced scene does not render properly.
In the scene, the triangle geometry used for the ground plane of the scene renders ok, but a translucent bounding box around the fractal pyramid is visible, and all other procedural geometry also appears translucent. Every couple of seconds, the bounding box for the metaballs also appears briefly, then vanishes.
I was able to determine that by freezing the scene, the reason for the translucency was that the following frames were being presented in sequence:
triangle ground plane quad only
floor geometry plus opaque fractal pyramid bounding box
all of the above plus opaque metaball bounding box
completed scene with opaque geometry and no bounding boxes
At the native framerate (165Hz on my machine), this results in both the procedural geometry and bounding boxes always being visible, but 'see-through' due to all the partially complete frames being presented to the display. This happens in both windowed and fullscreen modes, but it's worse in fullscreen, because the scene gets affected by random image corruption not seen in windowed mode.
I've been grappling with this issue for a few days and can't work out the problem. The only changes I've made to the sample program are the Windows 11 fix, and using a template for proper fullscreen rendering, which the original sample ignores or doesn't implement properly.
Hopefully someone can shed light on this perplexing issue!
I found the problem. Each sample has a header file called DXSampleHelper.h. For the ProceduralGeometry sample, this header file was updated with a helper class to manage structured buffers, which is very similar to the helper class for constant buffers.
The CopyStagingToGpu() method, which consists of a one line memcpy operation in both classes, is slightly different for the structured buffer class:
memcpy(m_mappedBuffers + instanceIndex * NumElementsPerInstance(), &m_staging[0], InstanceSize());
The same method in the constant buffer class is:
memcpy(m_mappedBuffers + instanceIndex, &m_staging[0], InstanceSize());
I.e. I was missing instanceIndex * NumElementsPerInstance() and thus the procedural geometry instances within the structured buffer were not correctly aligned in GPU memory.
When screen sharing a specific window on macOS with Zoom or Skype/Teams, they draw a red or green highlight border around that window (which belongs to a different application) to indicate it is being shared. The border is following the target window in real time, with resizing, z-order changes etc.
See example:
What macOS APIs and techniques might be used to achieve this effect?
You can find the location of windows using CGWindowListCopyWindowInfo and related API, which is available to Sandboxed apps.
This is a very fast and efficient API, fast enough to be polled. The SonOfGrab sample code is great platform to try out this stuff.
You can also install a global event tap using +[NSEvent addGlobalMonitorForEventsMatchingMask:handler:] (available in sandbox) to track mouse down, drag and mouse up events and then you can respond immediately whenever the user starts or releases a drag. This way your response will be snappy.
(Drawing a border would be done by creating your own transparent window, slightly larger than, and at the same window layer as, the window you are tracking. And then simply draw a pretty green box into it. I'm not exactly sure about setting the z-order. The details of this part would be best as a separate question.)
I'm using a tiling window manager i3 to run selenium tests. Sometimes I run tests using Chrome & Firefox besides PhantomJS. I realize that one cannot resize an i3 window that's tiled, so I wonder what, if any, workarounds are there to resize window, or detecting if the window is currently tiled and setting it floating?
I realize that one option would be setting chrome and firefox to always run floating in i3 config, but that would impede my regular workflow.
You actually can resize tiled windows, either with the mouse or with the resize command:
resize <grow|shrink> <up|down|left|right|height|width> [<px> px [or <ppt> ppt]]
This grows or shrinks the window in the given direction. With the optional parameters you can specify by what amount the window should be resized. The first argument - <px> px - is used for floating windows and defaults to 10 px. The second argument - <ppt> ppt is for tiled windows and gives the amount in percentage points of the parent container, it defaults to 10 ppt.
In the default configuration there is a resize mode that can be reach with Mod+r (with Mod being either Alt or Super, depending on the choice when first starting i3). While in this mode, windows - floating and tiled - can be grown with Down or Right and shrunken with Up and Left.
For example: Say, you have a container with 3 equally wide windows side-by-side - each taking 33.33 % of the containers width. If you run resize grow width on the middle one, it will be resized to take 43.33 % of the parent container, while the windows to either side will be shrunken to 28.33 %.
As for setting a window to floating, you can always do that with the command floating enable, so there is actually no need to query the current floating state.
If you really want to, you could query this information from i3's IPC interface.
Proof of concept:
Use i3-msg -t get_tree to retrieve the JSON-encoded layout tree (this gets you the whole JSON in one line, so maybe you want to put it through json_xs, json_pp or some similar program for more human-friendliness).
Get the ID of the current window with xdotool getactivewindow
Look in the tree for a node with attribute "window": <WINDOWID>
Check whether the attribute "floating" is set to "user_on" (or possibly "<ANYTHING>_on", I am not sure about that)
I like to make an overlay with the following properties:
should work at least on Windows 8.1
should be on top on everything, like a mouse cursor
should incorporate the pixels which are already on the background, like a blur filter
no flickering
Details to each of this points:
1) I assume that WDM is activated and DirectX 11.2 is used. Sure it would be nice to have it working on other Windows versions but this has no priority.
2) The problem is that with simply using the WS_EX_TOPMOST, menus from applications are over my overlay. In my case this really hurts as I like to display something with the same properties as a cursor. Imagine that a cursor suddenly is hidden if you open a menu -> unacceptable.
3) I like to read the pixels from the Windows desktop, including any effect Windows applies (like blur), and use this information for my filter. If I add my overlay, as described in 2, I should be able to get a fresh unobstructed copy of the background in the next frame and not read out my own overlay.
4) If I just write something into the Windows desktop directly, it gets overwritten immediately on the next frame by Windows itself. This is not acceptable.
One example of such an application is a magnifying glass, which exactly has all the properties I need. But for this case Windows 8.1 has an API. In contrast I like to write a program which displays a hand on the desktop (which is controlled by Leap Motion) which influences the Windows desktop, so you almost "feel" how you move your hand over the desktop.
If I write a tiny DirectX and/or OpenGL application for myself this is all very easy:
render all the regular stuff to a texture
use this texture for a post processing filter and add all my stuff on top of it
render just a quad to the back buffer
But I like to do that for the whole Windows desktop.
I found many different application, but they are to no use for me:
application which claim to be on top, are still behind menus. This normally doesn't really hurt, but is unacceptable for a cursor-alike thing
screen capturing programs which hook them self in all running programs are nice, but I want to hook myself into WDM
normally screen capturing programs do not draw anything into the back buffer, so they get every frame a new unobstructed back buffer
My questions can be boiled down to: How can I write my own magnifying glass for Windows 8.1.
I fear that my only serious option is to hook myself into WDM, what I try to avoid.
I'm happy to hear any idea how to achieve this, or hints to application which are doing what I describe.
I have a situation in which I ask and get a double-buffering OpenGL context, but when I draw in it, both the front and back buffer are affected. The draw buffer is set to the back buffer (And only the back buffer). If I look in OpenGL Profiler, I do see all that: the value for GL_DRAW_BUFFER (GL_BACK) and the actual back and front buffer being drawn to.
Since I'm working with an NSWindow that has a backing store, We do not see any of this happening on the screen. The problem is that I'm getting screenshots of this window with CGWindowListCreateImage. This function seems to be fetching the image from the front buffer, and not from the screen buffer (Wherever that is...). So the image returned is incomplete: it only contains the elements that are drawn at the moment it is grabbed, even if no flush has been called.
There is a utility in the mac developer package called Pixie. It basically grab the screen at the mouse position, and display it zoomed in so you can analyze it. This program has the same behavior than calling CGWindowListCreateImage: you can see incomplete images. So I guess the problem is not with the way I use CGWindowListCreateImage, but rather with my window or my display...
Also, It does not seems to happen all the time. Not every windows show this behavior, and even for a given window, it seems to come and go, especially if I move the window to a different screen (In a dual display).
Anyone faced this before?