I have a custom view (extends View) and I would like to add controls (buttons/text boxes etc) in the OnCreate function to add these components to the view at runtime:
public Section(Context context) {
super(context);
this.setBackgroundColor(Color.argb(255, 242, 242, 242));
this.setOnTouchListener(mSectionOnTouch);
LinearLayout l = new LinearLayout(this.getContext());
l.setOrientation(LinearLayout.VERTICAL);
Button btn = new Button(this.getContext());
btn.setId(1);
btn.setText("btn1");
l.addView(btn);
Button btn2 = new Button(this.getContext());
btn2.setId(2);
btn2.setText("btn2");
l.addView(btn2);
} // Section
but this does not seem to do anything... Could someone tell me what im doing wrong?
Many thanks
FR
You never add l to your view. It should look like this:
public Section(Context context)
{
// setup linear layout
addView(l);
}
A slightly simpler way to do this would be to have your custom view extend LinearLayout. Then you can just add the views directly to your custom view and you don't have to nest another container, which is better for performance.
Related
I am using this ExpandableView component https://github.com/nicolasjafelle/ExpandableView
which has a main class: https://github.com/nicolasjafelle/ExpandableView/blob/master/ExpandableViewProject/expandableview/src/main/java/com/expandable/view/ExpandableView.java
The component wraps other custom components specified by the user. When the custom components have fixed height, everything works fine.
However, I am creating a custom component which has a dynamic number of rows. Suppose this is the initial state:
this is row1
this is row2
this is row3
button
when I click the button, it will show
this is row1
this is row2
this is row3
this is row4
button
When I test my component in a LinearLayout, there is not problem and the new rows are shown. However, when I embed my custom component in ExpandableView, the ContentView of ExpandableView does not extend to wrap the new rows but instead, the button is hidden at the bottom.
I guess that to allow ExpandableView's ContentView to dynamically extend according to the size of the inner custom component I should implement onMeasure() method of ExpandableView. But so far, all my tests have being failed.
The hierarchy of my custom component is:
top
...
ExpandableView (extension of RelativeLayout, no onMeasure method)
LinearLayout (defined in XML)
ExpandableView (extension of RelativeLayout, no onMeasure method)
My custom component (WeekTimes, extension of LinearLayout, no onMeasure method)
Any idea?
I guess this is a bug in ExpandableView component but do not know how to fix it.
Further detail: this is the code for instantiating ExpandableView:
ExpandableView expandableContract = (ExpandableView) formsContained.findViewById(R.id.expandable_academy);
expandableContract.fillData(R.drawable.button_selected_full, getStringResource(R.string.about_academy), false);
expandableContract.addContentView(getLayoutInflater().inflate(R.layout.activity_offer_form_academy, new ExpandableView(this), true));
where R.layout.activity_offer_form_academy is just a layout with my component:
<com.dynassets.assets.util.weektimes.WeekTimes
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/weektimes"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
and the code of my custom component is
public class WeekTimes extends LinearLayout {
public WeekTimes(Context context) {
super(context);
init();
}
public WeekTimes(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.WRAP_CONTENT));
setOrientation(LinearLayout.VERTICAL);
Button button = new Button(getContext());
button.setText("click me");
addView(button);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View view) {
try {
Button button = new Button(getContext());
button.setText("click me2");
addView(button);
requestLayout();
} catch (Exception e) {
Log.e("MyApp", "exception", e);
}
}
});
}
}
So, how to tell the parent ExpandableView to extend according to the children's height? Is this a matter of creating a onMeasure() method?
Well, the problem was that ExpandableView contained an animation and this animation was fixing the height preventing the android layouts work as expected. Here is described in further detail:
https://github.com/nicolasjafelle/ExpandableView/issues/5
So the fix is reassigning the height to a relative value after the animation has ended. Issue is fixed by adding these new lines on the ExpandableView extension on the animation method:
animator.addListener(new AnimatorListenerAdapter() {
#Override
public void onAnimationEnd(Animator animation) {
// release height
ViewGroup.LayoutParams layoutParams = contentLayout.getLayoutParams();
layoutParams.height = ViewGroup.LayoutParams.WRAP_CONTENT;
contentLayout.setLayoutParams(layoutParams);
}
});
I am adding views dynamically to a relative layout (let's say container) in a for loop. There is some thing strange I am noticing. When adding rows one below the other in a relative layout in a for loop, I see that the first time a few of the views are overlapping. But when I lock and unlock the screen, I can see that the views are placed correctly.
Should I be aware of something when adding views dynamically to a relative layout?
Edit
I have found a solution as to how to get rid of this (please check my answer). But I would be more than glad to accept an answer that analyses this problem and tells me why this happens.
I have simplified to code and the comments should give a good idea as to what I am doing.
int prev_id=ID_OF_THE_ELEMENT_ABOVE;
/*Empty RelativeView with width and height as MATCH_PARENT and WRAP_CONTENT respectively*/
RelativeLayout container=(RelativeLayout) findViewById(R.id.container);
while(ThereIsData){
/*GET THE DATA HERE THAT HAS TO BE ASSIGNED TO EACH TEXTVIEW*/
...
/* ADD TEXTVIEW #1 below prev_id/
...
...
/*ADD TEXTVIEW #2 (WITH BASELINE OF TEXTVIEW#
...
...
/*TEXTVIEW #3 (BELOW TEXTVIEW#1)*/
...
...
/*TEXTVIEW #4 (BELOW TEXTVIEW#2)*/
...
...
/*ASSIGN THE ID OF TEXTVIEW#3 TO prev_id SO THAT
IN THE NEXT ITERATION TEXTVIEW#1 CAN USE prev_id
*/
prev_id=ID(TEXTVIEW#2);
/*ADD TEXTVIEWS CREATED IN THIS ITERATION*/
container.addView(TEXTVIEW#1);
container.addView(TEXTVIEW#2);
container.addView(TEXTVIEW#3);
container.addView(TEXTVIEW#4);
}
It is due to the fact that you are having a RelativeLayout with height as WRAP_CONTENT, and adding a view doesn't refresh the whole container at that time.. so as you answered you can add a line to measure the dimensions explicitly or invalidate the view to recreate it completely.
In any case LinearLayout would be better to opt-for as it will automatically arrange the children in horizontal or vertical manner and you can even add the new view in any place other than last position and it will automatically be updated..
I used to struggle against common issues a year ago, when I was working on a library for dynamically creating layouts from XML files (as Android does not support this). So when you dynamically add views to a RelativeLayout you have to take in mind a few things:
Create the container View (in this case the RelativeLayout)
Create all views without assigning any layout parameters.
Add all child views to the container.
Iterate over the container's children and populate each child's layout parameters. This is needed because when the relational constraints are applied an Excpetion is thrown if the relative View is missing (was not previously added to the container).
This is an example code taken from the project I used to work on. Take in mind that it is just a single part so it contains references to classes that are not defined in the Android API. I am sure it will give you the basic idea of dynamically creating RelativeLayot:
private void setChildren(RelativeLayout layout, T widget,
InflaterContext inflaterContext, Context context,
Factory<Widget, View> factory) {
List<Widget> children = widget.getChildren();
if (Utils.isEmpty(children))) {
return;
}
// 1. create all children
for (Widget child : children) {
View view = factory.create(inflaterContext, context, child);
layout.addView(view);
}
// 2. Set layout parameters. This is done all children are created
// because there are relations between children.
for (Widget child : children) {
try {
View view = ViewIdManager.getInstance().findViewByName(layout, child.getId());
if (view != null) {
populateLayoutParmas(child, view);
}
} catch (IndexNotFoundException e) {
Log.e(LOG_TAG, "Cannot find a related view for " + child.getId(), e);
}
}
}
I have not yet found the answer to why this is happening. But I have found a solution. After adding each row in the loop, call container.measure(RelativeLayout.LayoutParams.WRAP_CONTENT,RelativeLayout.LayoutParams.WRAP_CONTENT);
This seems to solve the problem. But I really think that container.addView() should also be calling measure().
/*ADD TEXTVIEWS CREATED IN THIS ITERATION*/
container.addView(TEXTVIEW#1);
container.addView(TEXTVIEW#2);
container.addView(TEXTVIEW#3);
container.addView(TEXTVIEW#4);
//---------------------------------------------------------------------
container.measure(RelativeLayout.LayoutParams.WRAP_CONTENT,RelativeLayout.LayoutParams.WRAP_CONTENT);
//Declare globally
LinearLayout[] layout;
ImageView[] imageView1;
ImageView[] imageView2;
ImageView[] imageView3;
// Initialize your layout. It would be RelativeLayout too. Just reference to it.
LinearLayout ll = (LinearLayout) findViewById(R.id.mylinear);
// set listview row size as your demand
layout = new LinearLayout[200];
imageView1 = new ImageView[200];
imageView2 = new ImageView[200];
imageView3 = new ImageView[200];
for (int i = 0; i < 200; i++) {
layout[i] = new LinearLayout(this);
layout[i].setBackgroundResource(R.drawable.book_shelf);
// layout[i].setLayoutParams(new
// LinearLayout.LayoutParams(android.widget.LinearLayout.LayoutParams.FILL_PARENT,
// 120));
layout[i].setLayoutParams(new LinearLayout.LayoutParams(
android.widget.LinearLayout.LayoutParams.FILL_PARENT, 220));
imageView1[i] = new ImageView(this);
imageView2[i] = new ImageView(this);
imageView3[i] = new ImageView(this);
imageView1[i].setLayoutParams(new LinearLayout.LayoutParams(0, 200,
0.33f));
imageView1[i].setPadding(0, 20, 0, 0);
imageView1[i].setImageResource(R.drawable.bibid_one_bankim);
imageView2[i].setLayoutParams(new LinearLayout.LayoutParams(0, 200,
0.33f));
imageView2[i].setPadding(0, 20, 0, 0);
imageView2[i].setImageResource(R.drawable.bibid_two_bankim);
imageView3[i].setLayoutParams(new LinearLayout.LayoutParams(0, 200,
0.33f));
imageView3[i].setImageResource(R.drawable.dena_pawna);
imageView3[i].setPadding(0, 20, 0, 0);
layout[i].setId(i);
layout[i].setClickable(true);
final int j = i;
layout[i].addView(imageView1[i]);
layout[i].addView(imageView2[i]);
layout[i].addView(imageView3[i]);
ll.addView(layout[i]);
}
}
Try adding your views in vertical Linear Layout.
Following link might help you
http://www.myandroidsolutions.com/2012/06/19/android-layoutinflater-turorial/
Inflate your layout in for loop.
I want to know how to add or link with findviewID a LinearLayout with multiple buttons (programatically added) and space between them. I have tried to create a XML layout in my fragment and link it to a variable of the type LinearLayout and work from there with LayoutParams but I don't get it to work properly. I would like to know if anyone here has any suggestions. below is my code.
private GuiLoader guiloader = new GuiLoader();
private LinearLayout layout;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.media_list_fragment, container, false);
layout = (LinearLayout)v.findViewById(R.id.LinearLayout1);
LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT, 2.0f);
param.setMargins(100, 100, 100, 100);
layout.setPadding(500, 86, 50, 50);
layout.setLayoutParams(param);
and the button creation throug a class
for (final VideoDevice videoDevice : videoDevices) {
Button myButton = guiloader.createButton(getActivity());
myButton.setBackgroundColor(getResources().getColor(R.color.green));
myButton.setText(videoDevice.description);
layout.addView(myButton, guiloader.buttonWidth, guiloader.buttonHeight);
Thanks in advance!
When you call setPadding and setLayoutParams on your LinearLayout - this deals with the padding/margins around the edges of the LinearLayout - not between the buttons.
It sounds like you would like to have a gap between the buttons. For that, you can:
1) add a margin to each button inside your for loop
2) consider using GridView which allows you to specify the spacing between children using android:horizontalSpacing and android:verticalSpacing
I'm developing an Android app in which I use LayoutInflator to generate new layout. What the app does basically is - Its has one imageview. When I click on a button, I change the layout to display multiple ImageViews (like 2x2 or 4x4). I am successful in displaying these layouts using the LayoutInflator. However, the previous Layout stays intact and the new Layout is displayed over the old Layout which, kind of, messes the whole layout. My question is - is there anyway to destroy the old layout before displaying the new one?
Edit:
Here is the code (on the onClick event that I'm using)
public void oneby1onClick(View view){
RelativeLayout main = (RelativeLayout)findViewById(R.id.main_layout);
view = getLayoutInflater().inflate(R.layout.activity_main, main,false);
main.removeView(main);
main.addView(view);
}
public void twoby2onClick(View view){
RelativeLayout main = (RelativeLayout)findViewById(R.id.main_layout);
view = getLayoutInflater().inflate(R.layout.twoby2, main,false);
main.removeView(main);
main.addView(view);
}
public void fourby4onClick(View view){
RelativeLayout main = (RelativeLayout)findViewById(R.id.main_layout);
view = getLayoutInflater().inflate(R.layout.fourby4, main,false);
main.removeView(main);
main.addView(view);
}
Maybe you could just make your layout invisible if that is the case.
This can be done quite easily programmaticaly:
layout.setVisibility(View.GONE);
According to #ookami.kb's suggestion I should use main.removeAllViews(); instead of main.removeView(main);, that helped me.
I have a question regarding Android Activitys:
An Activity has the Method addContentView(View) while a ViewGroup has a (similar?) addView(View) Method.
Unfortunately its undocumented where the View from addContentView is placed. Is it like a LinearLayout just adding the View to the bottom, or is it more like a FrameLayout, which adds its Views "onTop" ? Does it depend on the ViewGroup set by setContentView?
If I dive into the sources I see that addContentView will call Window's abstract Method addContentView. Unfortunately I cannot see which class is implementing this Method. So whats the behaviour of Activitys addContentView exactly?
The base layout of every activity is a FrameLayout. This means the layout you usually set via setContentView() is a child of this layout. addContentView() adds just another child, therefore it behaves like a FrameLayout (which means it adds new UI elements above existing ones).
You can check this by using a tool called hierachyviewer from your ANDROID_SDK\tools folder. Here are two screenshots:
This is the layout before calling addContentView(), my activity consists of the default FrameLayout, holding a LinearLayout with a Button (my layout here). This is reflected in the bottom row here, the other elements above are the title/statusbar.
After adding a TextView via addContentView() it looks like this. You can see that the base FrameLayout got a new child.
public void addContentView(View view,
LayoutParams params) {
mActivity.addContentView(view, params);
}
//
public static void SetActivityRoot(Activity c) {
View v = ((ViewGroup)c.findViewById(android.R.id.content)).getChildAt(0);
ScrollView sv = new ScrollView(c);
LayoutParams lp = new LayoutParams(LayoutParams.MATCH_PARENT,
LayoutParams.MATCH_PARENT);
sv.setLayoutParams(lp);
((ViewGroup) v.getParent()).removeAllViews();
sv.addView((View) v);
c.addContentView(sv, lp);
}
//
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
LinearLayout mainLayout =
(LinearLayout)findViewById(R.id.mainlayout);
//newButton added to the existing layout
Button newButton = new Button(this);
newButton.setText("Hello");
mainLayout.addView(newButton);
//anotherLayout and anotherButton added
//using addContentView()
LinearLayout anotherLayout = new LinearLayout(this);
LinearLayout.LayoutParams linearLayoutParams =
new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT);
Button anotherButton = new Button(this);
anotherButton.setText("I'm another button");
anotherLayout.addView(anotherButton);
addContentView(anotherLayout, linearLayoutParams);
}
}