The Android Toast class provides methods to get and set margins. I'm pretty sure they refer to the outside margins for the whole toast message. Since Toast messages float over the UI, why exactly are these Margins necessary?
I tried looking over the SDK reference as well as searching the Internet. The closest thing to a solution I found was a one line suggestion that both margins and offsets allowed control over the positioning of a Toast. Why would I need two methods (albeit conceptually different, since margins allow specification in terms of percentage container width), to control the positioning of the Toast?
Just to be sure, these margins don't work like padding for other layouts does it? That would not make sense, but I'd like to be clear.
In sum, I want to know why margins are needed, what margins do, and the use-cases for margins versus offsets, that is, when should I use margins, when should I use offsets, and why?
Update:
I haven't managed to find any answers yet. I've tried using margins versus using offsets in code and found that they seem to offer two different paradigms of positioning the Toast. The design intent (why two methods), when I should use one method versus the other (or at least examples of when one was found more useful than the other by other programmers/UI designers), and even the exact operation (do margins "center" the toast inside them? are margins applied against the closest container edges?) of these methods remain unclear.
Update 2:
I looked at the docs closely, and also at some code for Toast.java that Google pointed me to. What became apparent is that the Toast is contained within a Window (Activity window?) and that it might be an overlay. The WindowManager.LayoutParams class has also provided further clues. I've decided to play a bit more with using Toasts, offsets and margins, as well as look at the code from the AOSP to get a clearer understanding.
I'll update here as I discover more.
I believe the margins determine how far the toast appears from the screen edge. You can also call setGravity() to change which side of the screen it appears on, and then use the margins to control how far away it is from the side of the screen. So for example:
myToast.setMargin(10, 20);
Will create a toast that has 10% of the containers width between the edge and the container, and 20% of the containers height between the toast and the containers edge
To create a toast that is in the top left corner of the container, with a 10 pixel margin on the left and 20 pixel margin from the top:
myToast.setGravity(Gravity.LEFT| Gravity.TOP, 10, 20)
Related
I am trying to replicate the below layout (Boxes with Text and a line going outwards on a dedicated section) on Android
As evident, these boxes can be implemented as individual views (or drawable) to have the shape as
.
It is apparent that these boxes need to have some flexibility for the "wires" going out of them, most importantly deciding the "turning" point of the line. I have thought of a few approaches to achieve this:
Achieve the entire layout just by using image drawable and positioning the text boxes at exact places
Implement this with a dedicated view to have full flexibility of positioning the text boxes at any position and be compatible with all screen sizes.
I am inclined towards trying #2, but can't get my head around where to start. At first, I am not able to decide on whether I should be using a ViewGroup as the base class and add a TextView and a plain view as a child or should I be using a single View to implement this? The second thing I am concerned about, is whether I am overthinking it and there is an easy way to achieve the same thing (Just to save time, nothing else)?
Any help/guiding material is deeply appreciated. Thanks in advance.
I think that approach #2 will be better longer term. Because of the nature of the image, you will have to maintain the aspect ratio; otherwise, the person is stretched. Because you are maintaining the aspect ratio (at least the person-part), the placement of each text box and end point can be expressed as a percentage distance from an edge or the center lines.
Assuming the image you show is the entire image, the belly end point can be set at, say, 45% of of distance from the left edge and, also let's say, 42% of the distance from the top. The text boxes can be placed likewise. Once the text boxes and end point are place, the lines simply connect them. Now the image can stretch to any size to support multiple screen sizes and, as long as the aspect ratio is respected, and look good.
Take a look at ConstraintLayout and its percentage guidelines and barriers. There is also some radial placement which may help. You may still have to support the layout with a little code, but ConstraintLayout should be able to get you 95% of the way to a solution.
Edit: I meant to mention biases as well which may be the most helpful to you. Here is an example of using biases for a checkerboard solution that may be useful.
In an app I'm developing, I need to layout 2 to 5 buttons as if on the edge of a circle. The app starts with 5 buttons, but buttons gradually disappear (based on user input) until there are 2 of them.
I thought I would use an AbsoluteLayout control, and set the position of each button in code (taking into account the screen size). However, it says more or less everywhere that AbsoluteLayout should not be used. Since I'm targeting this app to Android 2.2 and up, I can't use the fancier layouts introduced with ICS.
I know I can use a RelativeLayout and play with the margins, but this seems less intuitive, and just as error prone, as using AbsoluteLayout.
Do I have any reasonable alternative?
I think, you dont have many alternatives. Except relative layout you mentioned, you could of course use FrameLayout and set left and bottom margin to position your buttons correctly.
I'm creating a Dialog, setting a content view with two Buttons, and displaying it. Oddly enough, even though I properly centered it vertically and horizontally, on the Droid X extra blank space appears at the top and on the right side.
I discovered the top is reserved for the Dialog title; even when that title is blank, the space is kept empty. The workaround there is easy enough--I set a title.
The right side, however, baffles me. When I test the same app on other devices it works beautifully; the Droid X, however, keeps the right side of the screen empty. When the root layout of my Dialog's layout has a width of match_parent or fill_parent, it does not extend to that empty area. However, if I manually set a fixed large width, it does extend as far as it needs to--no more empty space on the right side. That's hardly an ideal solution though.
Does anyone know how to get around this Droid X layout quirk so Dialogs do not have that empty space on the right side?
After some experimenting, I found that if I change the margin and/or padding sizes, suddenly the Dialog becomes centered! For example: margins of 4dp creates an offset. But making the top, bottom, left, and right margins all larger and different makes the problem go away.
This sort of behavior generally means one of two things: There's a bug in how the layout is drawn, or I have a gross misunderstanding of how these things work. Both seem equally likely.
So my answer is: play with the margin (and padding) numbers. It's possible that you can find something that both works and is aesthetically pleasing.
Sorry, I know this answer sucks. So it goes.
I am trying to write a calendar app and I plan to have a grid (week view) which will probably be a TableLayout and directly on top of that I will have to absolutely position events on the grid.
But AbsoluteLayout is deprecated. What should I use instead?
Events may overlap and I think it would be really silly to try and use a non absolute layout to achieve what I want.
Maybe I should use RelativeLayout with a margin left and margin top on each of the child nodes. Seems odd to do it that way and might not be as efficient. Is this the best way or is there an alternative?
But AbsoluteLayout is deprecated. What should I use instead?
Write your own layout manager that implements the rules you want.
CommonsWare suggested writing my own layout manager and Christian pointed out it sounds easier than it is.
Yahel suggested SurfaceView/OpenGl and draw whatever I want.
I found out you can recreate absolute positioning by adding your child views to a RelativeLayout and set the RelativeLayout.LayoutParams to have only default values except width, height, marginTop and marginLeft. The top and left margin will be similar to top and left in AbsoluteLayout. Also, negative margins are supported.
Make sure you account for screen density and width and orientation changes and all the other caveats of absolute positioning that used to apply to AbsoluteLayout
If you have problems with getting your content to overflow past the right edge of the screen, try supplementing your positive left margin with an equally negative right margin. (original question)
I would suggest either going the easy way :
Setting your calendar for 15(or 30) minutes intervals, this way you don't need absolute positionning. A table view filled with linear view each representing 15 minutes interval and fill these with events.
Or going the hard but a lot more stable/speedy/customisable way :
SurfaceView/OpenGl draw your own however you want.
The problem with number 1 is the fact that the more you add elements in your view hierachy the more your app will take a performance hit. Say a conventional month you have 3 appointments a day, your hierarchy will be filled with a hundred views wich will be very long to render and heavy memory-wise too.
The problem with number 2 : Well it's a lot harder to code at first. If you have to write your own layoutmanager, don't, go surfaceview or openGL.
I'm trying to understand Android's View structure and I'm a little confused on how to position child views
Let's say I have a FrameLayout that will contain my custom view. My custom view only draws a rectangle 50x50 px.
So I set my View.setMeasureDimension(50, 50);
Now how should I move this view? I found a couple of ways of doing it.
1: I could do something like canvas.drawRect(new Rect(offsetX, offsetY, right, bottom)); but this will make my View larger and thereby my measureWidth / height are not valid any longer?
2: Set padding on the parent element, and thereby affect the left / top View.getLeft() / View.getTop(). But this will affect all child elements.
3: Use View.offsetLeftAndRight( number of pixels to move ). I do not quite understand what this actually does. Does it cause some kind of canvas.translate() ? But this way I need to keep the state on how many times I called offsetLeftANdRight() because calling offsetLeftANdRight(10) and then offsetLeftANdRight(10) will move it 20px.
I'm a bit confused on what way is the "correct" way of doing it. Is there a better way?
Android apps run on devices of different sizes, with often completely different screens. Because of that you shouldn't be using any absolute positioning or sizing. Wherever possible create views and position them relative to each other.
You need to become familiar with the various views Android provides to create layouts:
http://developer.android.com/guide/topics/ui/layout-objects.html
It sometimes takes a lot of thought as items will be positioned differently on different devices (and orientations) so the view relationships are more important than absolute positions.
LinearLayout is a good all-purpose container for placing controls, though RelativeLayout is often more efficient (if a bit harder to use sometimes)
Once items are positioned relative to each other you can use padding and margins to tweak their positions.