I'm having problems with the constraints on xamarin.ios, at the base I have a scrollingView and inside it many elements wedged into vertical and horizontal stackviews, sometimes more stack views overlap. I cannot post code because the constraints are set by the .storyboard file. When I have to set the constraints, then anchor constraints to the scrollingview by the stackviews, the problems begin, any point I insert and in any axis is not associated, but the current distance is set (constraint given by the position of the object in the viewcontroller) every now and then it becomes negative sometimes the bond remains for a few seconds then returns to mess up. I'm hoping it's a xamarin bug, so now I'm re-installing the IDE to remove any doubts, have you encountered similar problems, or scrolling view and stack layout view are not directly compatible, in case how did you solve the objects they must be necessarily grouped in a scrolling view.
Related
I'm using Draggabilly and Packery to build a optimized draggable layout as shown in this Codepen: https://codepen.io/rafaF/pen/MWjvjqO
I have some doubts about how to use Packery/Draggabily.
The first one is how to convert en element "no-draggable", i.e., avoid to be dragged. I've achieved this by no initializing its Draggabilly instance, but I would like also to not be sorted when dragging others elements.
In the other hand, I have not been able to set a fixed height on my Packery layout in order to limit how many elements fits in a column. My idea is that if you move an element to a column that has no free space, the most bottom element should be moved to the other column. I have not found any way to do this.
There is enabled and disable switch in Draggabilly instance that you create. So just disable it if you do not need it.
The second part has to be manually solved becuase the Packery and draggabily would try to adjust in the same layout giving you best possible fit. If you want to limit the height then you have to set and run the ShiftLayout() on pakery. Ideally I would leave it to packery to determine the best layout.
I disable Auto Layout and Trait Variations cause I want to fix my Objects, having lot of buttos in the storyboard. But the problem now, with XCode 8, is the layout elements are moving automatically randomly! Only few points, but never keeps the layout in the position or size I set. I'm loosing lot of time trying to keep my storyboard in order.
Please ... anyone knows how to solve it?
I am writing a Xlib app where I want the window to be centered. I have used XMoveWindow with (desktopWidth - width) / 2, (desktopHeight - height) / 2 and it is roughly in the right place.
However the problem is that width and height are the client area, not the total area. Is there any way for me to get the total area of the window?
I need to use Xlib because I am using Glx and OpenGL. I don't want to use SDL, nor have a bulky graphics library.
There are various ways to go about this, depending on why you are doing it. The first two are "officially supported" by most window managers and described in specs, and then it descends into fragile hacks.
Semantic
The specs encourage you to use _NET_WM_WINDOW_TYPE rather than setting the position, if it makes sense to do so. See http://standards.freedesktop.org/wm-spec/wm-spec-1.3.html#id2507144
For example, a DIALOG type (or a window with the WM_TRANSIENT_FOR hint set) will usually be centered on its parent window or on the screen, and the _NET_WM_WINDOW_TYPE_SPLASH (splashscreen) type will usually be centered on the screen. "Usually" here means "sensible window managers probably center it, and people using weird window managers are not your problem, let them suffer."
(Another hint along the same lines, though not what you want here, is _NET_WM_STATE_FULLSCREEN, which avoids manually sizing/positioning in order to be fullscreen.)
If semantic hints work, the window manager code to handle the positioning is hopefully smarter than anything one can easily code by hand, for example it might deal with multihead setups. Setting the proper semantic type may also allow the WM to be smart in other ways, beyond positioning.
Gravity
If there's no semantic hint in the specs that helps you, then you can center by hand. It's important to note that window managers are allowed to ignore a manual position request and some of them will. Some may only honor the request if you set the USPosition flag in WM_NORMAL_HINTS (this flag is supposed to be set only if the user explicitly requested the position, for example with a -geometry command line option). Others may ignore the request always. But, you can probably ignore WMs that do this; the user chose to use that WM.
The way you compensate for the window decorations (the titlebar, etc.) is to use the win_gravity field of WM_NORMAL_HINTS, which is originally in the ICCCM (see http://tronche.com/gui/x/icccm/sec-4.html#s-4.1.2.3) but better-specified in an implementation note in the EWMH: http://standards.freedesktop.org/wm-spec/latest/ar01s09.html#id2570420
For WM_NORMAL_HINTS see http://tronche.com/gui/x/xlib/ICC/client-to-window-manager/wm-normal-hints.html#XSizeHints (note: the type of the property is WM_SIZE_HINTS and the name of the property is WM_NORMAL_HINTS, so there are two different atom names involved).
To center, you would set the win_gravity to Center, which allows you to position the center of the window (including its decorations) instead of the top-left corner.
win_gravity is not often used and is likely to be buggy in some window managers because nobody bothered to code/test it, but it should work in the more mainstream ones.
Update, possible confusion point: There are other "gravities" in the X protocol, specifically the CreateWindow request lets you set a "bit_gravity" and "win_gravity"; these are different from the XSizeHints.win_gravity. The CreateWindow gravities describe how the contents (pixels/subwindows) of a window are handled when the window is resized.
Hacks based on guessing decoration size
It's a fragile hack, but... you can try to figure out the decoration size and then incorporate that into your positioning.
To get the size of the window decorations, one way is the _NET_FRAME_EXTENTS hint, see http://standards.freedesktop.org/wm-spec/latest/ar01s05.html#id2569862
For older-school window managers (but not the fancy new compositing ones, though those hopefully support _NET_FRAME_EXTENTS) the window decorations are an X window, so you can get your parent window and look at its size.
The problem with both of these approaches is that you have to map the window before the decorations are added, so you have to map; wait to get the MapNotify event; then get the decoration size; then move the window. This will unfortunately cause user-visible flicker (the window will initially appear and then move). I don't think there's a way to get the window decoration size without mapping first.
Descending further into the realm of awful hacks, you could assume that for windows after the first one you map, the decorations will match previously-mapped windows. (Not that this is a sound assumption: different kinds of windows may have different decorations.)
Implementation note: keep in mind that the decoration window can be destroyed at any time, which would cause an X error in any outstanding Xlib requests you have that mention that window and by default exit your program. To avoid this, set the X error handler when touching windows that don't belong to your client.
Override redirect
Using override redirect is a kind of bazooka with bad side effects, and not at all a good idea if your goal is just to center a window.
If you set the override redirect flag when creating a window, then the window manager won't manage its size, position, stacking order, decorations, or map state (the window manager's redirection of ConfigureRequest and MapRequest is overridden).
This is a really bad idea for anything the user would think of as a window. It's usually used for tooltips and popup menus. If you set override redirect on a window, then all the normal window management UI will be broken, the stacking order will end up basically random (the window will tend to get stuck on top or on bottom, or worse get in an infinite-loop restack fight with another client).
But, the override-redirected window won't have decorations or be touched by the WM, so you can surefire center it with no interference.
(If you just want no decorations, use a semantic type like SPLASH or use the "MWM" hints, don't use override redirect.)
Summary
The short answer is set the semantic hint if any is applicable, and otherwise use XSizeHints.win_gravity=Center.
You can kind of see why people use toolkits and SDL ;-) lots of weird historical baggage and corner cases in the client-to-window-manager interaction generally, setting window positions is just the beginning of the excitement!
win_gravity is not often used and is likely to be buggy in some window managers because nobody bothered to code/test it, but it should work in the more mainstream ones.
Apparently Unity haven't implemented this. Testing shows that XCB_GRAVITY_STATIC is not respected and by taking a quick look at Unity source code I could not find code implementing this part of the specification.
I'm new to Macs and iOS, I got my app running on webOS, Android, and WPF/Windows. In all cases the size of, say, a 'widget' to display a bunch of text, can change depending on the dimension of the text to be displayed, as well as the position can be up against another widget. As the text size changes, the position will change so that all the widgets are crammed together nicely.
I've been searching for this capability in IOS4 in books and on-line, and it's starting to look like in iOS, you have to actually calculate the size of the text to be displayed in ViewText and then change the dimensions of ViewText, which of course then bumps other Views around to accommodate this size change. It sounds like a nightmare. Isn't there some other way to do this (like all the other GUIs can do) to size based on content, and to position relative to other Views like stacking them all together whatever size they are?
Same with ScrollView, it looks like the size of the window you actually see has to be manually specified as well, instead of, say, taking up the entire viewable window and then you can populate the ScrollView with a bunch of sub-views, some of which are below the initially viewable area? I tried this in Xcode4, but so far, haven't gotten it to work.
Similarly with creating an object with a NIB and instantiating that NIB onto an existing View, how does it determine where to position this NIB onto the existing screen?
Thanks!
Paul,
For the scrollview you need to set the bounds so it fills the screen or the area you wish it to occupy, it will then automatically generate scrollbars based on the layout within it. In the land of iOS you do have to do extensive layout work such as positioning and sizing your controls but you can also use the UIAutoResize (if I remember correctly) masks such as if they are anchored to a size, fill the area, etc. It's a little complicated to learn initially but you'll get the hang of it.
As for text you just need to use the right control, I believe what you want is a UITextView and set the options on it as needed.
When you view a XIB it's going to layout initially as you have it, again, you need to position your controls AND set their anchors (autoresize masks) so they adjust based on the screen size (phone vs. pad) and orientation: landscape vs. portrait.
HTH
I have several nested X Windows - let's say - a scrollable window within a scrollable window (see the example below). In such case the main window contains (at least) the major scroll bars and the (major) drawing area they control. This drawing area on its turn contains (at least) a scrollable window batch - a (minor) main window, containing a scroll bar and minor drawing area.
During live scrolling of an inner drawing area the redraw procedure messes up, because I am using the XCopyArea to speed the process and move the contents that are valid and invoke the actual redraw routine for just the newly appeared content. This works fine when the inner drawing batch is by itself, but when nested within another one a problem occurs - when the inner scrolling-batck is partially visible (i.e. the major drawing area is scrolled) redrawing of newly appeared contents is clipped from the major drawing area and never actually redrawn, but considered to be so. When on the next scroll XCopyArea gets this supposedly-redrawn area it is actually empty. Finally this empty area show up on the partially visible inner scrolling-batch and it is empty. On the first general redraw message they are fixed.
If I can obtain the clipping mask for what is actually visible from (my) inner drawing area I can adjust the XCopyArea() call and redraw call and overcome the problem without the plan "B" which is redrawing all contents on each scroll bar movement.
Example: Developing a plugin for Mozilla Firefox and needing to determine the region that describes the visible area of "my" window, i.e. the one that is passed from the Mozilla system as plugin viewport.
If its really an X Window you get, and not a widget from some specific toolkit (like GTK+ maybe?) then you can use the XGetWindowAttributes function call.
This fills out a provided XWindowAttributes structure, which includes integers for the x and y position of the window as well as its width and height and other useful facts.
But in reality I think you are probably using the Mozilla plugin API inherited from Netscape, aka NSAPI, and in that case what you get is a call to your function NPP_SetWindow() at least once (and again if necessary because something changed) with a structure which contains the information you're looking for. Try looking at http://www.mozilla.org/projects/plugins/ for more information about the APIs you should use.