I am trying to capture windows hidden behind my application. I am using windows 7 and VC++. I have tried printwindow() function which draws the both non-client and client area of hidden window, but captured window in the device context doesn't show desktop composition effects(aero effects). Instead it shows the captured window with windows 7 basic theme.
I have also tried with GetWindowDC() to retrive the DC of hidden window, and then Bitblt() it to memory DC but the captured window doesn't show non-client area (caption, close button, minimize button etc) correctly.
Anybody faced this issue?
Please help.
Click the link below. It leads to a MSDN site that lists all the existing Windows Functions ever of all history since Windows 95 up to Windows 8 (from period where Microsoft started Windows until present). It shows old windows functions of first Windows and new windows functions added for the new windows.
http://msdn.microsoft.com/en-us/library/windows/desktop/ff468919(v=vs.85).aspx
Anyway follow this site.
You will see the name of each function as a link.
Click any of them that you are interested.
Each link there leads to another MSDN site that explains all the basics knowledge that you must know about the function before using it, that you want to learn more. What that function does, its purpose, all its parameters and how to use each one, all their flags, all parameters types, return value and at last remarks section that shed more light and sometimes gives tips about the selected function.
Of course, you don't have to read all of them. Find in the list only the necessary functions to fit your needs. The functions that will solve your problem and answer your question that you posted.
By the way, I read your post, and I think that I found in the list the necessary functions that will do what you want to do, I will list them below, and say in one sentence what each does for what you need:
AnimateWindow - Enables you to produce special effects when showing or hiding windows. There are four types of animation: roll, slide, collapse or expand, and alpha-blended fade.
FlashWindow - Flashes the specified window one time. It does not change the active state of the window.
FlashWindowEx - Flashes the specified window specified number of times. It does not change the active state of the window.
Use these functions to achieve the aero effects that you want.
SetWindowPos - Changes the size, position, and Z order of a child, pop-up, or top-level window. These windows are ordered according to their appearance on the screen. The topmost window receives the highest rank and is the first window in the Z order.
Use this function to show the hidden windows on the top side (above all other windows) and on the screen front of you. The operating system will automatically draw the both non-client and client area of these windows without using any gdi, draw and paint functions yourself.
If you want these windows to return back to their previous state (where they were hidden), then save their state with GetWindowPlacement function and later call SetWindowPlacement to bring them back to their hidden state. You can try GetWindowRect and SetWindowPos instead to achieve the same goal.
I also think that you will be interested in GetWindowTheme and SetWindowTheme functions and all the draw theme functions (BackgroundEx, Edge, Icon, Text, TextEx).
There are more theme functions. Find in msdn and in other sites on the web.
Related
I'm trying to handle background color properly in a dynamically generated property sheet in dynamically generated property pages in win32 api using MFC (though I expect my question is general, and not restricted to MFC, but since my code and examples use it, it's germane to my question anyway).
So we have a:
CPropertySheet
containing multiple
CPropertyPage
I generate the contents of any given page dynamically - from file resources using a custom dialog definition language - all irrelevant other than to say - a list of controls and their coordinates is created within a given page, and the page is resized to accommodate them. This logic is working beautifully.
However, what doesn't work is that the controls and background of each page draws using the dialog default color/brush.
I've tried a number of ways to attempt to force it to draw using the white color/brush that a hard-coded property sheet / page would.
There are two important pieces to this:
Page Background
Control (on the page) background
For #1, I've tried:
acquire the background brush from parent window class (it's dialog bkgrd) (same is true if I do this and ask the tab control)
change the property page to use WS_EX_TRANSPARENT (PreCreateWindow is not called by the framework when generating a page viz PropertySheet::AddPage)
For #2, I've tried:
overriding OnWndMsg / WM_CTLCOLORSTATIC to forward that request to (A) the parent (sheet), and (B) to the tab control (which is what wants the white in the first place).
However, anytime I use any of the above "ask for the background / forward the request" up the chain to either the sheet or the tab control - I get the dialog background color, never the white I'd expect.
Using Spy64, I can see that for a fully hardcoded property sheet / page - that the only discernable differences I can see is that the dialog window created in AddPage (or its moral equivalent) has WS_CHILD instead of mine which has WS_POPUP (the rest of the styles appear to be the same, such as WS_VISIBLE|DS_3DLOOK|DS_FIXEDSYS|DS_SETFONT|DS_CONTROL and WS_EX_CONTROLPARENT.
So, other than the WS_CHILD, I see no significant differences from what I'm creating and from another property sheet that works properly from a standard resource (i.e. hard coded).
I'm also flummoxed as to how this works normally anyway - since forwarding things like the ctrlcolor message doesn't respond correctly - and asking for the windows background colors similar doesn't - then how is it in a standard case the background colors of controls and pages comes out as white, and not dialog background?
Any ideas or help would be appreciated - I'm kind of running out of ideas...
When Visual Styles were added in Windows XP they really wanted to show off this new feature so they made the tab background a gradient (really a stretched image) instead of a single color and this caused problems in old applications that did custom drawing with the dialog brush as the background.
Because of this, only applications with a comctl32 v6 manifest got the new look but there was a problem; old propertysheet shell extensions would load in new applications (including Explorer) and things would look wrong.
To work around this they also require you (or your UI framework) to call EnableThemeDialogTexture(.., ETDT_ENABLETAB) to get the correct tab page look.
As if things are not tricky enough, there is a undocumented requirement that you also need a button or a static control on the page!
If you have custom controls they have to call DrawThemeParentBackground when you draw if they are partially transparent.
Turns out my old code had defined an ON_WM_ERASEBKGND handler - and removing that (and all of my above attempts) makes it work.
So simply doing NOTHING is the correct answer. D'oh!!!
I'm leaving my shame here in case someone else trips on this! [Whoops!]
(Still interested if anyone has deeper insight into how this mechanism works under the hood)
I'm trying to write my own window manager. One issue I faced is that I don't understand how to define in which order windows should be displayed. The only means I found is to use xcb_configure_window. But it looks very limited to me: it only allows either to rise the window on top of all, or put it to the very bottom (no notion of layers or something). What a limited functionality :(.
What I really would like to do is to define the window order and tell X about it. Or to define multiple layers of windows (e.g, normal, above all, below all). So I could rise (or lower) the window with respect to its layer. So windows from lower layers will not ever cover windows from upper layers.
So, is there any other library function to define the order of windows apart from xcb_configure_window? Or I need to live with it? That would mean I have to track the order of windows in my window manager.
Link to relevant XCB documentation: https://www.x.org/releases/X11R7.6/doc/libxcb/tutorial/index.html#winstack
X11 only gives you the absolute minimum. There are no layers or always-over or always-under windows. You implement all the fancy stuff yourself, typically in the window manager, which is what you are writing.
There is no raw protocol request to change the stacking order of windows at once. Xlib has a function XRestackWindows which does that, but it uses one configure request per window. The pseudocode is just
for each window in the list except the first
change the stacking order to be under the previous window
That's it. Nothing more fancy than that.
You do need to track the stacking order in your WM in order to implement layers, so that when a program tries to restack a top level window, you intercept the request and only restack it within its layer.
Another possible way to implement layers is to have several transparent full-screen windows and reparent users' top-level windows to those, instead of to the root window. I'm not totally sure it will always work though, and you need to deal with transparency in one way or another, which requires transparency supporting hardware or the composite extension or possibly both.
It is the responsibility of the window manager to order the windows. A window gives hints about which type it is (popup dialog, menu window, splashscreen, toolbox, etc), the window manager then decides how to display this on the screen. This includes keeping track of the order and deciding which gets priority.
There is a X11 call to change the order (XRestackWindows), but I don't know the Xcb equivalent.
It is possible to use the SetWindowPos API on Windows to keep a windows always on top of other windows, and there are many questions on StackOverflow dealing with this.
It is possible to keep only part of a Window always visible? I.e. specify a clipping region inside an existing window, and keep only that part visible?
A use case would be the following (on Windows):
User clicks on icon to run app.
User highlights a portion of the screen to focus on (similar to the Snipping Tool on Windows 7)
The highlighted part of the screen remains always visible, even when other windows/programs are moved over the selected region.
I know the issues that would spring up with having other applications that are also set to being topmost. Just curious if this is even possible?
Even if you change part of your window to be transparent to what's below (with a clipping region) it's still going to take all the mouse clicks, etc. that occur over the transparent part.
Your best bet is to create a new smaller window and make it top-most while hiding the main one.
To modify a window of another program, I need to find a specific SysTreeView32 in it using EnumChildWindows API call.
When I inspect the window using Spy++, there are a number of SysTreeView32's in it but all are greyed out except one, which is the one I'm looking for.
The following picture is an example of grey items:
Why are the shown items gray and what API call does Spy++ use to know whether it should grey out an item or not?
Those are just non-visible windows - ie HWNDs that don't have the WS_VISIBLE style bit set. They are often worker windows - windows that just exist to process various messages in the background - or in some cases are UI that's yet to become visible. For example, a window that lets you hide or show a toolbar may just hide it by making it invisible rather than destroying it and recreating it later.
In your specific case, the WorkerW could be a placeholder for some other piece of UI that's not needed right now, while the msctl_statusbar32 looks like it's a hidden status bar.
I have been all over the web looking for an answer to this, and my question is this:
How does a GUI framework work? for instance how does Qt work, is there any books or wibsites on the topic of writing a GUI framework from scratch? and also does the framework have to call methods from the operating systems GUI framework?
-- Thank you to any one who takes the time to try to answer this question, and forgive me if i misspelled anything.
In the old days we did a lot of GUI programming from scratch. It is not as hard as it seems, but it requires a few weeks to come with results.
First you need a good drawing library. Minimal functionality for this library is drawing clipped rectangles (using patterns), lines, bitmaps, and fonts. You can cheat by creating fonts as bitmaps, and clipped rectangle is just a bunch of horizontal lines.
Now you need at least drivers for mouse, keyboard, and timer (if not already provided by the operating system). In general, you will need to detect keys, symbol keys (such as shift, etc.), mouse moves and mouse clicks. Basic timer functions will allow you to detect double clicks.
Then you need to create a window data structure. This data structure needs to have coordinates i.e. a rectangle, link to parent window (if not top window), and window function i.e. the function that will be called when this window should handle some events.
Once you can draw on screen you need some rectangle algebra functions. You need at least good function to calculate intersection of rectangles, and a quick resolution of relative to absolute coordinates. For example - if your child window has parent then its' x and y should recursively be added to parent x and y until you reach top window.
At this point you have your:
- primitive graphical functions,
- window structure,
- mouse driver, keyboard driver, and timer,
- rectangle arithmetic.
Now you can write your main event harvesting function. This function will run all the time. It's purpose will be to detect events and send messages to correct windows. What is an event? Well, when you start your program, store mouse x and y coordinates. Then in a loop check if they have changed. If they have changed, find the window at that position ... and send WM_MOUSEMOVE event to it. Your harvesting function should handle:
- mouse moves
- mouse clicks
- mouse double clicks (remember last click and position, measure time and decide if it is a double click or not)
- timer events
- keyboard buffer changes
...
Now you should be able to send events to windows. But you really need a mechanism for it. It is a combination of message queue, and window procedure. It usually works like this: each window has a window procedure which commonly accepts four arguments: message id (i.e. is it mouse move, is it paint message), window handle, parameter 1 and parameter 2. You can call this window procedure directly using something like a send_message functions. Or you can send this window a message via post_message function. This will put message to the queue and window will process messages one by one, eventually receiving this one. So why should you call one messages directly and put others to the queue? Because of priority. You see, a keyboard click can wait some time before being processed. But a window redraw must complete immediately to prevent flicker and wrong data on screen.
So your harvest_events function sends messages to windows using post_message, and send_message. And your window message pump gets them using typical message pump like this:
while (pmsg = get_message() != NULL) send_message(pmsg->id, pmsg->hwnd, pmsg->p1, pmsg->p2);
get_message simply obtains message from the queue, and calls send message. Simple, huh? Well, not quite so. This way you would only receive driver messages to windows, but you also need some functions to redraw windows, move them, etc.. When you create move_window function, resize_window, show_window, and hide_window function, your window coordinates will change. Parts of other windows will be uncovered (if top window is moved or closed).You need to calculate which windows are affected by coordinate changes and send paint message to those windows (to repaint only the parts that were uncovered - remember, you have clipping drawing functions so this will work).
These functions introduces messages msg_paint, msg_move, msg_resize, msg_hide...
Last, you need to maintain hierarchy of windows. Your top window should be the desktop. It should have child windows (application top windows). These windows may have further child windows (buttons, edit boxes, etc.) The obvious structure for holding these is the window tree. When you detect mouse click you have to traverse window tree and do it in a smart way (finding out who has focus, who is modal, etc.) to send message to the right window. And when you draw you also must traverse all children to see who is uncovered and who is not. Last but not least, you need to handle mouse rectangle as top window to prevent flickering the mouse as windows are re-drawn or (using timers and msg_paint events) animated.
That's roughly it.
A GUI framework like Qt generally works by taking the existing OS's primitive objects (windows, fonts, bitmaps, etc), wrapping them in more platform-neutral and less clunky classes/structures/handles, and giving you the functionality you'll need to manipulate them. Yes, that almost always involves using the OS's own functions, but it doesn't HAVE to -- if you're designing an API to draw an OpenGL UI, for example, most of the underlying OS's GUI stuff won't even work, and you'll be doing just about everything on your own.
Either way, it's not for the faint of heart. If you have to ask how a GUI framework works, you're not even close to ready to design one. You're better off sticking with an existing framework and extending it to do the spiffy stuff it doesn't do already.