I have made class called ProgressButton that extended RelativeLayout.Now in main xml i added this class:
<com.tazik.progressbutton.ProgressButton
android:id="#+id/pb_button"
android:layout_width="200dp"
android:layout_height="wrap_content"/>
As you can see i added android:layout_width="200dp", now in ProgressButton class i want to get this size to create a button with this size:
public class ProgressButton extends RelativeLayout {
private AppCompatButton button;
public ProgressButton(Context context) {
super(context);
initView();
}
private void initView() {
initButton();
}
private void initButton() {
button = new AppCompatButton(getContext());
LayoutParams button_params = new LayoutParams(????, ViewGroup.LayoutParams.WRAP_CONTENT);
button_params.addRule(RelativeLayout.CENTER_IN_PARENT,RelativeLayout.TRUE);
button.setLayoutParams(button_params);
button.setText("click");
addView(button);
}
I want to create button exactly to size of relativeLayout, so how can i get layout_width in my custom view to set button_params width?
now in ProgressButton class i want to get this size to create a button with this size
As #MikeM. suggested in a comment. It could be as easy as giving that child view a width of MATCH_PARENT. See below...
LayoutParams button_params = new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
With that in place you don't need to worry about the actual size because MATCH_PARENT will stretch your child view to occupy the whole parent's width...obviosuly respecting margins and paddings.
However, if you do need to know the parent's width, you should query that in onMeasure. I strongly suggest you to stay away from onMeasure whenever possible because it is a bit complex and it might take a lot of your development time.
Either way, in onMeasure you can know what measurements the parent view wants to give to its child views, this is based on the space available to render inside the parent and the layout params specified...
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);
int childWidth = 0;
if(widthSpecMode == MeasureSpec.AT_MOST){
//The parent doesn't want the child to exceed "childWidth", it doesn't care if it smaller than that, just not bigger/wider
childWidth = MeasureSpec.getSize(widthMeasureSpec);
}
else if(widthSpecMode == MeasureSpec.EXACTLY){
//The parent wants the child to be exactly "childWidth"
childWidth = MeasureSpec.getSize(widthMeasureSpec);
}
else {
//The parent doesn't know yet what its children's width will be, probably
//because it's still taking measurements
}
//IMPORTANT!!! set your desired measurements (width and height) or call the base class's onMeasure method. Do one or the other, NOT BOTH
setMeasuredDimension(dimens, dimens);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
Add a few Log.d calls inside onMeasure for a better understanding of what's happening. Be aware that this method will be called multiple times.
Again, this is an unnecessary overkill for your case scenario. Setting MATCH_PARENT to the button should produce the results you want
I have an HorizontalScrollView that contain a LinearLayout that contain some custom views. For now, I fixe the size of the children by this line (in the constructor of the child) :
setLayoutParams(new LayoutParams(200, LayoutParams.FILL_PARENT));
What I would like to do, is to set the width of the component to 30% of the height of itself instead of the actual 200px. But I still need the height to "FILL_PARENT".
When I overrided the onMeasure methode, I tryed that :
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
System.out.println(widthMeasureSpec + "/" + heightMeasureSpec);
}
But I obtained the output :
1073742024/1073742586
So it look likes I can't do a lot of thing here, still I don't have a lot of information :)
Any idea how to do the trick ?
I precise that I'm testing on the simulator (don't know if that matter).
You could do something like get the dimensions of the screen
DisplayMetrics display = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics( display );
int screenW = display.widthPixels;
int screenH = display.heightPixels;
and if the height of the component you want to take 0.3 out of, is the height of the entire screen, then do something like so:
setLayoutParams(new LayoutParams((int)(screenH*0.3), LayoutParams.FILL_PARENT));
I might have misunderstood your question, I just woke up :) Let me know if it worked or if you're looking for something else
What's the correct way of overriding onMeasure()? I've seen various approaches. For example, Professional Android Development uses MeasureSpec to calculate the dimensions, then ends with a call to setMeasuredDimension(). For example:
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
this.setMeasuredDimension(parentWidth/2, parentHeight);
}
On the other hand, as per this post, the "correct" way is to use MeasureSpec, call setMeasuredDimensions(), followed by a call to setLayoutParams(), and ending with a call to super.onMeasure(). For example:
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
this.setMeasuredDimension(parentWidth/2, parentHeight);
this.setLayoutParams(new *ParentLayoutType*.LayoutParams(parentWidth/2,parentHeight));
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
So which is the right way? Neither approach has worked 100% for me.
I guess really what I'm asking is does anyone know of a tutorial that explains onMeasure(), layout, dimensions of child views etc.?
The other solutions are not comprehensive. They may work in some cases, and are a good place to start, but they may are not guaranteed to work.
When onMeasure gets called you may or may not have the rights to change the size. The values that are passed to your onMeasure (widthMeasureSpec, heightMeasureSpec) contain information about what your child view is allowed to do. Currently there are three values:
MeasureSpec.UNSPECIFIED - You can be as big as you'd like
MeasureSpec.AT_MOST - As big as you want (up to the spec size), This is parentWidth in your example.
MeasureSpec.EXACTLY - No choice. Parent has chosen.
This is done so that Android can make multiple passes to find the right size for each item, see here for more details.
If you do not follow these rules, your approach is not guaranteed to work.
For example if you want to check if you're allowed to change the size at all you can do the following:
final int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);
final int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);
boolean resizeWidth = widthSpecMode != MeasureSpec.EXACTLY;
boolean resizeHeight = heightSpecMode != MeasureSpec.EXACTLY;
Using this information you will know whether you can modify the values as in your code. Or if you are required to do something different. A quick and easy way to resolve your desired size is to use one of the following methods:
int resolveSizeAndState (int size, int measureSpec, int childMeasuredState)
int resolveSize (int size, int measureSpec)
While the first is only available on Honeycomb, the second is available on all versions.
Note: You may find that resizeWidth or resizeHeight are always false. I found this to be the case if I was requesting MATCH_PARENT. I was able to fix this by requesting WRAP_CONTENT on my parent layout and then during the UNSPECIFIED phase requesting a size of Integer.MAX_VALUE. Doing so gives you the max size your parent allows on the next pass through onMeasure.
The documentation is the authority on this matter: http://developer.android.com/guide/topics/ui/how-android-draws.html and http://developer.android.com/guide/topics/ui/custom-components.html
To summarize: at the end of your overridden onMeasure method you should call setMeasuredDimension.
You should not call super.onMeasure after calling setMeasuredDimension, that will just erase whatever you set. In some situations you might want to call the super.onMeasure first and then modify the results by calling setMeasuredDimension.
Don't call setLayoutParams in onMeasure. Layout happens in a second pass after measuring.
I think it depends on the parent which you are overriding.
For example, if you are extending a ViewGroup (like FrameLayout), when you have measured the size, you should call like below
super.onMeasure(MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY),
MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY));
because you may want to ViewGroup to do rest work (do some stuffs on child view)
If you are extending a View (like ImageView), you can just call this.setMeasuredDimension(width, height);, because the parent class will just do something like you have done usually.
In a word, if you want some features your parent class offers free you should call super.onMeasure() (pass MeasureSpec.EXACTLY mode measure spec usually), otherwise call this.setMeasuredDimension(width, height); is enough.
If changing the views size inside of onMeasure all you need is the setMeasuredDimension call. If you are changing the size outside of onMeasure you need to call setLayoutParams. For instance changing the size of a text view when the text is changed.
Depends on the control you are using. The instructions in the documentation work for some controls (TextView, Button, ...), but not for others (LinearLayout, ...). The way that worked very well for me was to call the super once I am done. Based on the article in the below link.
http://humptydevelopers.blogspot.in/2013/05/android-view-overriding-onmeasure.html
here is how I solved the problem:
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
....
setMeasuredDimension( measuredWidth, measuredHeight );
widthMeasureSpec = MeasureSpec.makeMeasureSpec( measuredWidth, MeasureSpec.EXACTLY );
heightMeasureSpec = MeasureSpec.makeMeasureSpec( measuredHeight, MeasureSpec.EXACTLY);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
Moreover it was necessary for the ViewPager component
I guess, setLayoutParams and recalculating the measurements is a workaround to resize the child views correctly, as this is usually done in the derived class's onMeasure.
However, this rarely works correct (for whatever reason...), better invoke measureChildren (when deriving a ViewGroup) or try something similar when necessary.
you can take this piece of code as an example of onMeasure()::
public class MyLayerLayout extends RelativeLayout {
public MyLayerLayout(Context context) {
super(context);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
int currentChildCount = getChildCount();
for (int i = 0; i < currentChildCount; i++) {
View currentChild = getChildAt(i);
//code to find information
int widthPercent = currentChildInfo.getWidth();
int heightPercent = currentChildInfo.getHeight();
//considering we will pass height & width as percentage
int myWidth = (int) Math.round(parentWidth * (widthPercent / 100.0));
int myHeight = (int) Math.round(parentHeight * (heightPercent / 100.0));
//Considering we need to set horizontal & vertical position of the view in parent
AlignmentTraitValue vAlign = currentChildInfo.getVerticalLocation() != null ? currentChildlayerInfo.getVerticalLocation() : currentChildAlignmentTraitValue.TOP;
AlignmentTraitValue hAlign = currentChildInfo.getHorizontalLocation() != null ? currentChildlayerInfo.getHorizontalLocation() : currentChildAlignmentTraitValue.LEFT;
int topPadding = 0;
int leftPadding = 0;
if (vAlign.equals(currentChildAlignmentTraitValue.CENTER)) {
topPadding = (parentHeight - myHeight) / 2;
} else if (vAlign.equals(currentChildAlignmentTraitValue.BOTTOM)) {
topPadding = parentHeight - myHeight;
}
if (hAlign.equals(currentChildAlignmentTraitValue.CENTER)) {
leftPadding = (parentWidth - myWidth) / 2;
} else if (hAlign.equals(currentChildAlignmentTraitValue.RIGHT)) {
leftPadding = parentWidth - myWidth;
}
LayoutParams myLayoutParams = new LayoutParams(myWidth, myHeight);
currentChildLayoutParams.setMargins(leftPadding, topPadding, 0, 0);
currentChild.setLayoutParams(myLayoutParams);
}
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}
I have an array of Buttons (different sizes etc) which are configured from and xml file (written by me). I want to add those buttons on the bottom of the screen and when the row of buttons ends, just start a new row and add buttons until the array ends. I want to mention that I do not set the size of the buttons in the xml file so I don't know the size from the beginning. Another problem is that after or before I add the button to the layout programatically with layout.addView(button) the method button.getWidth() returns 0 because the UI elements are not drawn in the UI yet. I also overrided the onLayout() method but still wasn't able to redraw the buttons.
If you have any ideas, please help.
Thanks
Well you could make the button take the same size using weight property. In that case, decide how many buttons you need in a row and use a for loop to do it accordingly. If you need the width you could use something like
Add this to your onCreate
ViewTreeObserver vto = layout.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
You should be able to get the width and height
over here.
layout.getViewTreeObserver().removeGlobalOnLayoutListener(this);
}
});
This is how I did it. I overrided the onMeasure() method of the layout containing the buttons.
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int specSize = MeasureSpec.getSize(widthMeasureSpec);
this.width = specSize;
specSize = MeasureSpec.getSize(heightMeasureSpec);
this.height = specSize;
//now you can use the sizes before the layout is drawn
this.webview.setLayoutParams(new FrameLayout.LayoutParams(LayoutParams.FILL_PARENT,this.height - this.menuBarHeight) );
//don't forget for the parent method!
//but at the end, after the measures are done
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
I am creating a custom view which will have a bitmap so that user can draw in it and some normal Android buttons in the bottom for user interaction.
To size my bitmap (height of drawing areas should be 50% ) I am overriding
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
this.setMeasuredDimension(widthMeasureSpec, (int)(parentHeight * 0.50));
super.onMeasure(widthMeasureSpec, (int)(parentHeight * 0.50));
}
This gives me exception that
"java.lang.IllegalArgumentException: width and height must be > 0"
If I set super.onMeasure(widthMeasureSpec, heightMeasureSpec);
I cannot see my buttons places in the bottom.
If I dont write super.onMeasure() anything I draw is not seen once I release the mouse.
I am using a xml file for layout :
<view class="com.my.CustomView" android:id="#+id/myView"
android:layout_width="fill_parent" android:layout_height="wrap_content"/>
<LinearLayout android:layout_width="fill_parent"
android:layout_height="wrap_content" android:orientation="horizontal">
<Button android:layout_height="wrap_content"
android:text="B1" android:layout_width="wrap_content"/>
<Button android:layout_height="wrap_content"
android:layout_width="wrap_content" android:text="B2"/>
</LinearLayout>
What else should I do ?
Wouldn't be easier to give your custom view a size in dp. You then can see your layout in design mode. Then use onSizeChanged to find out the size of your canvas.
onMeasure is usually used when the size of the canvas depends on runtime values, like the result of a game or number of loaded items etc.
Here is an example that works:
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
int newH = (int) (parentHeight / 1.5f);
this.setMeasuredDimension(parentWidth, newH );
}
Also the constructor for your custom vuew must include attribute set:
public CustomView(Context context, AttributeSet attrs) {
super(context, attrs);
}
Your onMeasure() is incomplete, it should take into account also the mode (UNSPECIFIED, EXACTLY, AT_MOST). Docs say that onMeasure() might get called several times, even with UNSPECIFIED 0-0 sizes, to see what size the view would like to be. See View, section Layout. There's no need to call super.onMeasure().
I don't get if your custom view includes only the drawing area or you're inflating the buttons too in it (my guess is the first case), but try Hierarchy Viewer, it will help you to understand how views are being laid out (and hence why in some cases you see drawings and sometimes not).