I'm fairly new to Android development. I'm wondering what are the different ways that are used to design XML layouts. Ive been using the eclipse drag and drop interface and I've seen http://droiddraw.org/ while doing some searching. Just wondering if there are any other possibly better ways out there to design layouts that professions use because I'm having a hard time with the eclipse interface making complex designs?
First of all check out the android developer site user interface page
http://developer.android.com/guide/topics/ui/index.html
There are basically three different ways you can make an android layout:
XML
http://developer.android.com/guide/topics/ui/declaring-layout.html
You can define a static layout using XML. Perhaps a good way to think of it is a sort of shorthand. It is very easy to declare Views and attributes, and the hierarchical format of XML makes it a bit easier to visualize.
This is a typical layout
<?xml version="1.0" encoding="utf-8"?>
<ViewGroup xmlns:android="http://schemas.android.com/apk/res/android"
android:attribute="value" >
<ViewGroup android:attribute="value" >
<View android:attribute="value" />
</ViewGroup>
<View android:attribute="value" />
</ViewGroup>
Then you use setContentView(R.layout.layout) in your activity and go about your business.
Java
You can do everything you would do in XML, plus add things like listeners, or do other dynamic things that you cannot in XML. Here is how you might declare a typical layout (ViewGroup is abstract so you would have to use a subclass. The same goes for XML)
ViewGroup parent = new ViewGroup(this);
ViewGroup vg1 = new ViewGroup(this);
View v1 = new View(this);
View v2 = new View(this);
parent.addView(vg1);
vg1.addView(v1);
parent.addView(v2);
v1.setOnAwesomeListener(new AwesomeListener() {
onAwesome(View v) {
doDynamicThings();
}
}
setContentView(parent);
Hybrid
This is the case used most often in my opinion. Declare a layout in XML with an id, like android:id="#+id/v1" then load Views from XML into Java
setContentView(R.layout.layout);
View v1 = findViewById(R.id.v1);
// dynamically change v1
How to design a layout using XML
So the lack of GUI designer tools has left you no choice but to dive into coding up your layout by hand. Good news is that once you get the hang of it you should be able to tackle any layout you wish. Let's look at the building blocks
ViewGroup
First off you need to choose a ViewGroup to define the structure of the layout, or section of the layout. Remember that these can be nested, so design top-down and try to classify sections of the layout based on the form you want them to have. There are two main options:
LinearLayout
As the name implies, useful for arranging items in a line. Choose an orientation, horizontal or vertical, and simply add items. They will be added in top to bottom or left to right ordering.
RelativeLayout
Useful for placing an item in a specific location on the screen. So if you want to put a button in the top-left, or a bar across the top, this is your ViewGroup.
Layout Parameters
Used for defining the width, height, weight, and other aspects of a view.
There are two options for width and height: fill_parent (replaced with match_parent in API level 8) and wrap_content. The view can choose to either fill the parent view's width, or take only the space it needs.
There is another useful layout parameter, unique to LinearLayout, called weight. It is useful for letting views share space in ratios, or letting one view take the space left over after other views in the LinearLayout take their share.
Example
Let's try to design the layout for Google Maps. Pretend it is a layout that I have in my head, and I want to implement it. Here is a screenshot
I will try to break this down:
Looking at it, there is a bar across the top and a map underneath it. I believe this could be implemented with either a LinearLayout or a RelativeLayout. However, the buttons in the bottom right and left scream RelativeLayout, so I will go with that.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<TODO:BAR
android:id="#+id/bar"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true">
</TODO:BAR>
<MapView
android:id="#+id/map"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_below="#+id/bar" />
<ImageButton
android:id="#+id/latitude"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_marginBottom="20dp"
android:layout_marginLeft="20dp" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_marginBottom="20dp"
android:layout_marginRight="20dp"
android:orientation="vertical" >
<ImageButton
android:id="#+id/zoom_in"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<ImageButton
android:id="#+id/zoom_out"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
</RelativeLayout>
Now some explanation. In RelativeLayout you use alignParent[direction] to specify where the view goes. I also wanted some space on the sides, so I used margin[direction] to specify in dp or density-independent pixels. As you can see, wrap_content is used most of the time, so the buttons would acquire the size of the image used on them.
Now everything is defined but the bar at the top. I'm going to break it up into four different Views: The dropdown menu view, the search view, the layers button and the my location button. The way I would like it to work is put the menu at the far left, and the layers and my location buttons on the right, with the search box taking up the remaining space. This sounds like a job for LinearLayout and weight! Here is how I define the bar, which can be inserted into the placeholder above to get the final layout
<LinearLayout
android:id="#+id/bar"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true" >
<ImageButton
android:id="#+id/dropdown_menu"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<EditText
android:id="#+id/search"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1" />
<ImageButton
android:id="#+id/layers"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<ImageButton
android:id="#+id/my_location"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
Setting the width of the search bar to 0dp means let the other views take what they need, then the weight says take the remaining space.
And there you have it. A recreation of the basic layout for the Google Maps app (minus button images and other niceties like custom views), showing how you might use various layouts and XML fairly painlessly. Hopefully this was useful.
The tool chain is a little weak in this area. I don't really care for DroidDraw, and the Eclipse GUI editor is not very good for anything more than simple layouts. It often renders RelativeLayouts incorrectly for example.
Personally I do almost everything directly in XML. You have to understand how all the different Layout classes work to do anything complex anyway. The only real downside to XML is that all of the extra cruft from tags, attributes, etc. makes for a lot of extra stuff to type, but the editor takes care of most of that for you.
Related
After much research on both SO and google, I haven't seen any one with exactly the same problem I am experiencing, so here it is:
I recently redid the entire UI on an android app. For the most part, I made only cosmetic changes to each of the screens. They appear in the UI editor of eclipse perfectly as expected. However, directly after doing this, two of the screens stopped being laid out correctly on both all tested devices and the emulator.
Now, the big problem one these two screens was that the root level LinearLayout didn't appear to be actually honoring the fill_parent for either layout_height or layout_width. it looks like it's being measured as if it were set to wrap_content instead. It only takes up about 70% of the screen - which is just enough to wrap the individual elements inside the root LinearLayout. I would post an image, but as a new user, I am not allowed to.
The layout isn't stretching to fill the screen. Here's the code for layout, except that there are a few more in the LinearLayouts containing a TextView and an EditText.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#FF000000"
android:orientation="vertical" >
<TextView
style="#style/sans.white.16.bold"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingTop="4dp"
android:text="#string/edit_account" />
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<com.teamunify.ondeck.widget.TUTextView
style="#style/sans.white.14"
android:layout_width="100dp"
android:layout_height="wrap_content"
android:text="#string/first_name" />
<com.teamunify.ondeck.widget.TUEditText
android:id="#+id/acc_editor_first"
android:layout_width="fill_parent"
android:layout_height="40dp"
android:selectAllOnFocus="true"
android:singleLine="true" />
</LinearLayout>
I think the root LinearLayout should be filling both height and width. I've used this same layout many MANY times in our app without problems. (A quick count revealed that I used 76 LinearLayouts in our app, and all but two of them are working.)
At first, I suspected that perhaps our custom classes measure was wrecking things, so I changed the layout to use all plain EditTexts, but there was no change. I double checked the activity, but it isn't doing anything except to load this xml. So, in desperation, I redid the layout like so:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#FF000000"
android:orientation="vertical" >
<TextView
style="#style/sans.white.16.bold"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center|top"
android:paddingTop="4dp"
android:text="#string/edit_account" />
</LinearLayout>
After that, The words Edit Account appear with a black background mashed into the upper left corner. Clearly, the LinearLayout isn't filling the parent.
Long story short, I am asking how to fix this so that the LinearLayout fills the screen as expected.
I am at a complete loss as to why this is happening, and I am certainly hoping that someone on SO has an idea. This has got me pulling my hair out!
Try setting fixed width and height for the root layout.
Then only you will be able to debug who is driving length and width. It is very much possible that parent activity or background activity is setting dimensions. Once you identify the root cause you can go back to original settings.
As of now from your code snippet given here, nothing wrong here
If you use a custom activity as a container to other activities for some reason (In our case, we were recreating the look of our iOS app, and needed a custom menu to show up along the button side of the screen) the window manager seems to get a bit confused with what the actual height and width of the nested activities should be. A call to fillparent or matchparent ends up wrapping the content instead.
We ended up changing the behavior of several methods in our container activity class to make this work.
I've got the following xml file:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/linearLayout1"
android:background="#android:color/transparent"
android:layout_marginTop="0px"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:weightSum="1"
android:orientation="horizontal">
<Button android:id="#+id/info" android:text="Info" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="bottom"></Button>
<Button android:id="#+id/town" android:text="Town" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="bottom"></Button>
<Button android:id="#+id/unit" android:text="Unit" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="bottom"></Button>
<Button android:layout_height="wrap_content" android:text="EndTurn" android:id="#+id/endturn" android:layout_width="wrap_content" android:layout_gravity="bottom"></Button>
</LinearLayout>
which provides the following result: http://i42.tinypic.com/otdkb4.png
Now I've got some questions about this:
The top and bottom padding, how to get rid of it?
I tried RelativeLayout, multiple layouts within each other, padding, margin, changing height nothing seem to affect it in any way.
Is there a way to get the layout transparent? android:background seems to be the wrong one.
Between the third and the fifth button is a bit more space (where the fourth button should be). I catch it the in the program and set it to invisible.
unitButton.setVisibility(INVISIBLE);
unitButton.setWidth(0);
Now the space between the two buttons is more than double of the normal range (between 1 and 2) Any idea on this? - Altough this is a minor problem
Thanks in advance.
1: Is the layout presented in a Dialog? If so, that'll give you some headaches. To get more control you should either create your own custom Dialog extension (as some dialog layout values are hardcoded), or display your layout in another way (a new activity on top, or using a framelayout perhaps)?
2: To get a layout transparent, simply don't give it a background-attribute. (Though, if you really are using a dialog, the dialog box is not transparent, and it is that which you see. You can also set it to be transparent by setting background to "#00000000" (which is what you do).
3: A View with visibility as "invisible" is still measured, that means both its width/height as well as its margins and padding is displayed as empty space in your layout. Setting the visibility to "gone" instead will not measure it, and you won't need the setWidth(0) either. (You can still display it later by setting it back to "visible")
Edit: removing the unused "weightSum" attribute might also be a good idea, as the view is now expecting its children to have a total weight of something other than 0.
I recently asked a question about how to add a view on top of a view, after asking that I realized I needed to added a better layout to my app before proceeding further.
I was reading Android Layout Tricks but noticed it was specifically for text views and image views. I'm looking to do it with two custom views. So I decided to whip up a quick image in paint to hopefully show more clearly of what I'm wanting to do.
This is how I want my layout to split the views. :
This is how it would look with the views drawn. Obviously the purple and blue boundaries would be the background color (greyish). The data above simply displays the y-intercept of the graph drawn with respective color. (So there would be multiple graph views drawn on top of each other)
So my question is, what would my main content view look like? I assume it would have a Linear layout but I'm rather new to these layouts.
EDIT
Using TextViews I'm able to come up with something similar using the following XML:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView
android:text="Data Placeholder"
android:background="#733674"
android:textSize="15pt"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="20"/>
<TextView
android:text="Graph Placeholder"
android:background="#374F82"
android:textSize="15pt"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="80"/>
</LinearLayout>
</LinearLayout>
So The only question that really remains is, am I supposed to use TextViews? Meaning in my Activity am I able to add my custom views where these TextViews are? Or am I supposed to add my custom view to the XML?
Ie.
<DataView
android:text="Data Placeholder"
android:background="#733674"
android:textSize="15pt"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="20"/>
<GraphView
android:text="Graph Placeholder"
android:background="#374F82"
android:textSize="15pt"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="80"/>
My custom views are written in Java and I'm not sure how I would let the layout know where the views are located if I was to do it this way.
Try this: http://developer.android.com/resources/tutorials/views/hello-linearlayout.html
It has some very useful information which might help you out in regards to layout_weight as Michell Bak mentioned in the comment.
And here's the page for the Hello Views:
http://developer.android.com/resources/tutorials/views/index.html
Not to be rude, but it would be much better for you to peruse these and learn the xml on your own. That way you can actually understand it and be better able to re-create it later.
I was quite overwhelmed at first with all the code I didn't understand (including xml files), but with a little practice it becomes very easy - just time consuming.
The main thing I'm confused about is what kind of View to put in the
layout. In the examples they use TextView or ImageView, but mine is a
custom view
Well, for your "Custom Data View", you would use a LinearLayout with android:layout_width="fill_parent" and android:layout_height="fill_parent" and android:layout_weight="1" and android:background="#BA4AAB" (See http://www.colorpicker.com/)
Then for your Custom Graph View, I would use:
android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_weight="4" android:background="#7D4ABA"
Note the layout_weight and background values I put are kind of guesses, you might have to tweak them some to match what you want.
The two linearlayouts that I mentioned would be inside one larger LinearLayout with android:orientation="vertical"
Then for the data in the top, you would use 4 text Views, and in code, you'd use setText(...) on those text views to put your data in.
In the xml for textview1, you would add android:id="#+id/textview1" then in code add TextView textview1 = (TextView)findviewbyId(R.id.textview1); then textview1.setText(myString);
For the graph in the bottom part, you would use 2 views for the base of the graph, and set there android:layout_width and android:layout_height to whatever suits you using dip, dp, or px units.
For the lines that you draw, I believe you would have to use the canvas class with a bitmap and call canvas.drawLine(...) (see http://developer.android.com/reference/android/graphics/Canvas.html)
I'm trying to layout views in a relative layout on a tablet, much like a bookshelf. There will be so many across, then a new row is created.
My initial state looks like this:
<ScrollView
android:layout_marginTop="150sp"
android:layout_marginLeft="50sp"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<RelativeLayout
android:id="#+id/user_list"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<!-- Add User Avatar -->
<RelativeLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<ImageView
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:src="#drawable/user_frame" />
<ImageView
android:id="#+id/demo_image"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:src="#drawable/add_user"
android:layout_marginLeft="10px" />
<ImageView
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:src="#drawable/user_name_background"
android:layout_marginLeft="10px" />
<TextView
android:id="#+id/user_name"
android:layout_width="180px"
android:layout_height="wrap_content"
android:textSize="20sp"
android:textStyle="bold"
android:gravity="center_horizontal"
android:text="Add New User" />
</RelativeLayout>
</RelativeLayout>
</ScrollView>
I'm fetching records from a database, and for each record I need to place a version of the "add user avatar" section as seen above. I'd like to do 5, then wrap to a new row.
My initial idea was to use a layout inflater and add the views programmatically, using RelativeLayout.LayoutParams to set the layout_toRightOf values.
There must be an easier way though. I've seen lots of applications using the "bookshelf" metaphor.
There are a few options I can think of.
Instead of using a relative layout, why not use LinearLayouts with the horizontal attribute?
Using a TableLayout, much like the LinearLayout
Use a ListView with a custom adapter to fill five 'Add User Avatar's' per ListRow
Laying out views programmatically is fairly simple. I do this for all of my activities / views. I love Android's XML layout concept but find that as soon as the views become at all dynamic based on external data (such as your database) then it gets too complex.
I choose what my outermost layout will be and then only instantiate that layout in the XML. Then in my activity I find the outer layout using the normal find by id call and then use a sequence of add(View) method calls to add my dynamically created views or layouts as needed.
You will need to take into account different screen orientations, pixel densities and sizes. Device Independent Pixels will become your friend. For example, to create an image view, you would load the bitmap, figure out how much to resize it (if needed) and then set it as the drawable for a new ImageView instance, that you then add to the layout.
Sounds like your outer layout will be a scroll view with a vertical linear layout inside, that then has a horizontal layout for each "shelf" that then have up to five image views for each "book"
I have 4 buttons in a horizontal linear layout. I'd like the right edge of the 4th button to align with the right edge of the linear layout (equal to screen width) I've tried using android:layout_gravity="right" but it doesn't work - the right button is to the right of the 3rd one but not right aligned . Am I missing something obvious?
main.xml with only the relevant layout params only is:
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<LinearLayout
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<Button
android:layout_height="fill_parent"
android:layout_width="wrap_content">
<Button SAME LAYOUT AS BUTTON 1>
<Button SAME LAYOUT AS BUTTON 1>
<Button
android:layout_height="fill_parent"
android:layout_width="wrap_content"
android:layout_gravity="right" />
</LinearLayout>
</LinearLayout>
This doesn't seem to match the stated behaviour for layout_gravity in the SDK reference :"Defines how to place the view, both its x- and y-axis, within its parent view group."
I know this isn't really the proper answer to your question, but you should really consider using RelativeLayout instead of LinearLayout. It scales better to different phone screen resolutions, and you can place the buttons in the correct order by using the layout_toRightOf and layout_alignParentRight attributes in your XML (or layout_above, layout_alignParentTop, etc.). Using gravity in a linear layout won't really behave as you expect because Android is still attempting to place the widgets in a fixed position.
RelativeLayout is a bit more of a pain to get working than LinearLayout, but it's worth the trouble and is also the one which Google recommends using. Once you get the hang of it, they are very convenient to work with.