Is there a method in Android to get the height of the entire 'ScrollView'?
I tried 'layout.getMeasuredHeight()' but it gives the height only of the visible region.
You want the height of the ScrollView's child. Try scrollView.getChildAt(0).getMeasuredHeight().
EDIT
You could possibly try having the View measure itself and give it a measurespec that lets it use as much space as it wants. Something like this:
int width = ... // get screen width;
int height = 65536; // arbitrarily large value
final int widthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.AT_MOST);
final int heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.AT_MOST);
view.onMeasure(widthMeasureSpec, heightMeasureSpec);
// now get the height
int measuredHeight = view.getMeasuredHeight();
Full disclosure: I don't know if this will work or what effect it may have in your app. There is a side-effect of calling this method, which is that the view's measured dimensions are set. If it's possible, you might try to create a separate, duplicate view and measure that one; or, after you do this measuring hack, call requestLayout() on the view to schedule another measure & layout of the view tree.
A ScrollView always has only one child, so using:
ScrollView.getChildAt(0).getHeight();
should work.
Related
I have an Android application that extensively uses PopupWindows. I've found that when the layouts of the contents of the PopupWindow use WRAP_CONTENT the dialog will only grow to a specific width before it begins truncating the content. I've traced this down to a config.xml dimension:
<dimen name="config_prefDialogWidth">580dp</dimen>
This dimension is used to create a maximum width in the measureHierarchy method of ViewRootImpl when determining the dialog size. The following code is used to access the value:
final DisplayMetrics packageMetrics = res.getDisplayMetrics();
res.getValue(com.android.internal.R.dimen.config_prefDialogWidth, mTmpValue, true);
int baseSize = 0;
if (mTmpValue.type == TypedValue.TYPE_DIMENSION) {
baseSize = (int)mTmpValue.getDimension(packageMetrics);
}
The config_prefDialogWidth seems to have values for different device configurations, for example, the one I listed is for sw600dp. The one for default devices has 320dp as a value.
It would seem that this dimension is tuned for portrait orientation. Since my app forces landscape orientation this width is too small.
How do I override the config_prefDialogWidth dimension?
What you need is to make the width of your PopupWindow(wrap_content) larger than config_prefDialogWidth.
So here is my solution.
Choose one child View from the contentView of your PopupWindow.
A TextView, for example.
Override its onMeasure, add View.MEASURED_STATE_TOO_SMALL if necessary:
TextView textView = new TextView(context) {
#Override
protected void onMeasure(final int widthMeasureSpec, final int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
// Text breaks into at least 2 lines, maybe the width is too small
if (getLineCount() > 1) {
int measuredWidth = getMeasuredWidth();
final int desiredMaxWidth = (getResources().getDisplayMetrics().widthPixels >> 2) * 3;
// Compare with the desired max width you want, for example: 3/4 * screenWidth
if (measuredWidth < disiredMaxWidth) {
// Tell ViewRootImpl that the width used to measure is too small
measuredWidth |= View.MEASURED_STATE_TOO_SMALL;
// ViewRootImpl will remeasure contentView with screem width.
setMeasuredDimension(measuredWidth, getMeasuredHeight());
}
}
}
};
Generally speaking:
Override onMeasure of one child View
Check whether the measured width is too small
Ask for remeasurement if necessary (Using View.MEASURED_STATE_TOO_SMALL)
You cannot override nor change config_prefDialogWidth's value because this dimension is a internal resource. A workaround is you must create your own class. You can copy PopupWindows from its source code, and modify it.
One of Android samples (FixedGridLayout) extends a ViewGroup to allow for custom transitions when new items are added to a grid. The code works as expected, but doesn't implement scrolling. I thus wrapped the entire layout in a ScrollView expecting that this would solve the issue. However, it appears that the FixedGridLayout view is actually much larger than it should be, leaving a lot of scrollable space after the items.
I suspect the issue is related to the way onMeasure() is implemented. Am I right, and if so, what is wrong with this code?
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int cellWidthSpec = MeasureSpec.makeMeasureSpec(mCellWidth, MeasureSpec.AT_MOST);
int cellHeightSpec = MeasureSpec.makeMeasureSpec(mCellHeight, MeasureSpec.AT_MOST);
int count = getChildCount();
for (int index=0; index<count; index++) {
final View child = getChildAt(index);
child.measure(cellWidthSpec, cellHeightSpec);
}
// Use the size our parents gave us, but default to a minimum size to avoid
// clipping transitioning children
int minCount = count > 3 ? count : 3;
setMeasuredDimension(resolveSize(mCellWidth * minCount, widthMeasureSpec),
resolveSize(mCellHeight * minCount, heightMeasureSpec));
}
ScrollView only cares about the vertical height of the inner child view after measuring it, but it will not scroll unless the inner child sets the height to something larger than the parent.
You could call getHeight() on the inner view to see if it's computed a larger value than you expected. The method is only valid after layout is complete.
The code you posted does appear to have a mistake in it.
int minCount = count > 3 ? count : 3;
setMeasuredDimension(resolveSize(mCellWidth * minCount, widthMeasureSpec),
resolveSize(mCellHeight * minCount, heightMeasureSpec));
The code is setting the width and height based upon the total number of children. If I assume a grid layout pattern, then the width is calculated as mCellWidth * columns and height is calculated as mCellHeight * rows.
If you set the height value using the total number of children, then this would explain why your scrolling beyond the bottom of the layout.
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
I tried to do custom component. I extended View class and do some drawing in onDraw overrided method. Why I need to override onMeasure? If I didn't, everything seen to be right. May someone explain it? How should I write my onMeasure method? I've seen couple tutorials, but each one is a little bit different than the other. Sometimes they call super.onMeasure at the end, sometimes they use setMeasuredDimension and didn't call it. Where is a difference?
After all I want to use several exactly the same components. I added those components to my XML file, but I don't know how big they should be. I want to set its position and size later (why I need to set size in onMeasure if in onDraw when I draw it, is working as well) in custom component class. When exactly I need to do that?
onMeasure() is your opportunity to tell Android how big you want your custom view to be dependent the layout constraints provided by the parent; it is also your custom view's opportunity to learn what those layout constraints are (in case you want to behave differently in a match_parent situation than a wrap_content situation). These constraints are packaged up into the MeasureSpec values that are passed into the method. Here is a rough correlation of the mode values:
EXACTLY means the layout_width or layout_height value was set to a specific value. You should probably make your view this size. This can also get triggered when match_parent is used, to set the size exactly to the parent view (this is layout dependent in the framework).
AT_MOST typically means the layout_width or layout_height value was set to match_parent or wrap_content where a maximum size is needed (this is layout dependent in the framework), and the size of the parent dimension is the value. You should not be any larger than this size.
UNSPECIFIED typically means the layout_width or layout_height value was set to wrap_content with no restrictions. You can be whatever size you would like. Some layouts also use this callback to figure out your desired size before determine what specs to actually pass you again in a second measure request.
The contract that exists with onMeasure() is that setMeasuredDimension() MUST be called at the end with the size you would like the view to be. This method is called by all the framework implementations, including the default implementation found in View, which is why it is safe to call super instead if that fits your use case.
Granted, because the framework does apply a default implementation, it may not be necessary for you to override this method, but you may see clipping in cases where the view space is smaller than your content if you do not, and if you lay out your custom view with wrap_content in both directions, your view may not show up at all because the framework doesn't know how large it is!
Generally, if you are overriding View and not another existing widget, it is probably a good idea to provide an implementation, even if it is as simple as something like this:
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int desiredWidth = 100;
int desiredHeight = 100;
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
int width;
int height;
//Measure Width
if (widthMode == MeasureSpec.EXACTLY) {
//Must be this size
width = widthSize;
} else if (widthMode == MeasureSpec.AT_MOST) {
//Can't be bigger than...
width = Math.min(desiredWidth, widthSize);
} else {
//Be whatever you want
width = desiredWidth;
}
//Measure Height
if (heightMode == MeasureSpec.EXACTLY) {
//Must be this size
height = heightSize;
} else if (heightMode == MeasureSpec.AT_MOST) {
//Can't be bigger than...
height = Math.min(desiredHeight, heightSize);
} else {
//Be whatever you want
height = desiredHeight;
}
//MUST CALL THIS
setMeasuredDimension(width, height);
}
actually, your answer is not complete as the values also depend on the wrapping container. In case of relative or linear layouts, the values behave like this:
EXACTLY match_parent is EXACTLY + size of the parent
AT_MOST wrap_content results in an AT_MOST MeasureSpec
UNSPECIFIED never triggered
In case of an horizontal scroll view, your code will work.
If you don't need to change something onMeasure - there's absolutely no need for you to override it.
Devunwired code (the selected and most voted answer here) is almost identical to what the SDK implementation already does for you (and I checked - it had done that since 2009).
You can check the onMeasure method here :
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec),
getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec));
}
public static int getDefaultSize(int size, int measureSpec) {
int result = size;
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);
switch (specMode) {
case MeasureSpec.UNSPECIFIED:
result = size;
break;
case MeasureSpec.AT_MOST:
case MeasureSpec.EXACTLY:
result = specSize;
break;
}
return result;
}
Overriding SDK code to be replaced with the exact same code makes no sense.
This official doc's piece that claims "the default onMeasure() will always set a size of 100x100" - is wrong.
I wanted to create a custom LinearLayout (and later a custom ImageButton) that could take percentage values for both dimensions of size based on its parent's size regardless of the parent type (Relative or Linear). I was following this post: How to size an Android view based on its parent's dimensions, and it was very helpful, but I have a problem that those answers don't address.
When I place my Custom LinearLayout inside another LinearLayout, everything works as expected. My Custom LinearLayout covers the expected space (80% of the parent's width in the example below).
However if I place it inside a RelativeLayout, my screen always shows empty, I am not sure why this happens.
Here is my class:
public class ButtonPanel extends LinearLayout {
public ButtonPanel(Context context, AttributeSet attrs) {
super(context, attrs);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int newWidth = (int) Math.ceil(parentWidth * 0.8);
this.setMeasuredDimension(newWidth, parentHeight);
this.setLayoutParams(new RelativeLayout.LayoutParams(newWidth,parentHeight));
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}
And here is my testing layout for the activity.
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<com.android.tests.views.ButtonPanel
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#drawable/inner_panel"
android:gravity="center_horizontal"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true">
</com.android.tests.views.ButtonPanel>
</RelativeLayout>
In my activity all I do is set the Content View to the above layout.
(Incidentally, does anybody now how I could get the type of the parent dynamically for setting the new LayoutParameters? Above you'll see the parent type (RelativeLayout) hard-coded into the Custom View onMeasure function)
Thanks in advance for any help!
Is this exposed to be a problem?
this.setLayoutParams(new RelativeLayout.LayoutParams(newWidth,parentHeight)); // <-- a RelativeLayout params?
In the onMeasure function you could use something like this to know what class is the parent of the view.
this.getParent().getClass().getName()
This should also work
a instanceof B
or
B.class.isAssignableFrom(a.getClass())
When using "instanceof", you need to know the class of "B" at compile time. When using "isAssignableFrom" it can be dynamic and change during runtime.
If you are not compfortable with string comparison, you could also use enums.
Turns out my two inquiries in this post were more related than expected.
I realized that by setting my view's LayoutParams to a completely new instance, I was overwriting the layout positioning information needed by the Relative Layout to position my view.
By 'zeroing out' that information, my view has the right dimensions, but the layout doesn't know where to place it, so it simply doesn't.
The following code for the new onMeasure shows how just directly modifying the height and width of the LayoutParams already attached to my view I avoid both overwriting the layout position information and having to create new LayoutParams based on the parent's type.
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int specWidth = MeasureSpec.getSize(widthMeasureSpec);
int specHeight = MeasureSpec.getSize(heightMeasureSpec);
int newWidth = (int) Math.ceil(parentWidth * 0.8);
int newHeight = (int) Math.ceil(parentHeight * 0.8);
this.setMeasuredDimension(newWidth, newHeight);
this.getLayoutParams().height = newHeight;
this.getLayoutParams().width = newWidth;
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
Now, I'll be honest and say that this code is still not bug-free. Bringing the activity to the foreground and background multiple times constantly reduces the size of this custom view. The 0.8 reduction factor gets applied over and over each time the activity is brought up (I suspect the setting of the LayoutParams has to do with it, it might actually be unnecessary, but I haven't has time to test).
BUT, this still answered the question concerning this post, namely, why was my view not appearing at all despite having the right dimensions.