I have a custom layout defined in XML file which has a RelativeLayout root with a bunch of child view.
Now, I defined the following class:
public class MyCustomView extends RelativeLayout {
public MyCustomView(Context context) {
super(context);
init();
}
public MyCustomView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public MyCustomView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
private void init() {
LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
inflater.inflate(R.layout.my_custom_view, this, true);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
Log.d("Widget", "Width spec: " + MeasureSpec.toString(widthMeasureSpec));
Log.d("Widget", "Height spec: " + MeasureSpec.toString(heightMeasureSpec));
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
int chosenWidth = chooseDimension(widthMode, widthSize);
int chosenHeight = chooseDimension(heightMode, heightSize);
int chosenDimension = Math.min(chosenWidth, chosenHeight);
setMeasuredDimension(chosenDimension, chosenDimension);
}
private int chooseDimension(int mode, int size) {
if (mode == MeasureSpec.AT_MOST || mode == MeasureSpec.EXACTLY) {
return size;
} else {
return getPreferredSize();
}
}
private int getPreferredSize() {
return 400;
}
}
As you can see I'm setting the root to MyCustomView instance and the attach flag to true.
What I want to achieve is that when I will add this custom view in another layout's xml, it will instantiate the MyCustomView class which will have the layout defined in the XML.
I already tries to use <merge> tag, but that way I lose the ability to arrange my child views in the XML as I want.
I also tried to inflate the XML and add it as a view to MyCustomView, but that way I get redundant RelativeLayout.
Last thing, I added the onMeasure() just for completeness.
the inflation occurs but the child view are not shown
The RelativeLayout does a bit more(a lot) than what you've done in the onMeasure layout(basically the children aren't measured at all with your code so they don't have something to show). If you extend a ViewGroup like RelativeLayout you need to let that class to do its callbacks(onMeasure, onLayout) or at least, very carefully replicate the methods and modify it like you want (if you want to see something).
So, remove the onMeasure method to see the children or explain better why did you override it.
Related
I am trying to create a textview that will always be squared so I have implemented this custom class.
public class SquareTextView extends TextView {
public SquareTextView(Context context) {
super(context);
}
public SquareTextView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public SquareTextView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int max = Math.max(getMeasuredWidth(), getMeasuredHeight());
setMeasuredDimension(max, max);
}
}
Here is an example layout that illustrates the problem:
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="8dp"
android:paddingLeft="16dp"
android:paddingRight="16dp"
android:paddingTop="8dp">
<com.mypackage.SquareTextView
android:layout_width="wrap_content"
android:layout_height="50dp"
android:layout_gravity="right|top"
android:background="#000"
android:gravity="center"
android:padding="4dp"
android:text="1"
android:textColor="#FFF"/>
</LinearLayout>
Here is an image of this
This works great in getting the view squared, however, it seems like the gravity gets messed up. With this, the text seems to always be in the top left corner. How can I have a TextView that will always be squared but still keep the gravity or at least be able to center the text?
EDIT: After some testing I have noticed that if you set the width or height to a specific dp size the gravity seems to be working again. So it probably has to do with the WRAP_CONTENT attribute. Will that be handled in another way in the onmeasure method that could cause my own method to not work as expected?
Hope you have already got the answer by now. If not, you can use this:
public class TextAlphaSquareTextView extends AppCompatTextView {
private int mTextAlpha = 0;
private boolean isSquare = false;
public TextAlphaSquareTextView(Context context) {
super(context);
init(null);
}
public TextAlphaSquareTextView(Context context, AttributeSet attrs) {
super(context, attrs);
init(attrs);
}
public TextAlphaSquareTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(attrs);
}
private void init(AttributeSet attrs) {
if (attrs == null) {
} else {
TypedArray a = getContext().obtainStyledAttributes(attrs, R.styleable.TextAlphaSquareTextView);
mTextAlpha = a.getInteger(R.styleable.TextAlphaSquareTextView_textAlpha, 100);
isSquare = a.getBoolean(R.styleable.TextAlphaSquareTextView_squareMode, false);
a.recycle();
if(mTextAlpha < 0 || mTextAlpha > 100)
throw new IllegalArgumentException("Alpha range should be b/w 0 to 100 (in percentage)");
else {
setAlphaOnTextColor();
}
}
setText(getText());
}
void setAlphaOnTextColor() {
int alpha = ((255 * mTextAlpha) / 100);
setTextColor(getTextColors().withAlpha(alpha));
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (isSquare) {
int width = this.getMeasuredWidth();
int height = this.getMeasuredHeight();
int size = Math.max(width, height);
int widthSpec = MeasureSpec.makeMeasureSpec(size, MeasureSpec.EXACTLY);
int heightSpec = MeasureSpec.makeMeasureSpec(size, MeasureSpec.EXACTLY);
super.onMeasure(widthSpec, heightSpec);
}
}
}
you need to call super.onMeasure() again with EXACT spec and the calculated size, since setMeasureDimension() seems to be ignoring the gravity.
I am creating a custom imageview and I am trying to find the height of the parent. The only detail I know about the parent is that it would potentially scroll. The reason I need the parent's height is because I am trying to figure out the imageview's position on the screen. I have made an equation that works for accurately calculating its position, but it only works when I manually enter in the parents height. Is there any way to retrieve this information or is there another way to get my imageview's position on the screen every time it changes?
Try this way
public class MyImageView extends ImageView {
int parentHeight;
int parentWidth;
public MyImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public MyImageView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public MyImageView(Context context) {
super(context);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
if(((View)this.getParent()).getMeasuredWidth()!=0){
parentHeight = ((View)this.getParent()).getMeasuredHeight();
parentWidth = ((View)this.getParent()).getMeasuredWidth();
}
}
}
I have a class MyLayout extending RelativeLayout which includes View type field. MyLayout object is created in xml layout file, so all properties are set there. I need to programatically set size of View field which depends on size of it's parent (MyLayout).
I was trying to set it in constructor, but when I try to use getWidth() method, it returns 0, so I assume that the size is not yet set inside a constructor. I was also trying to set it in onDraw() method, but when I run an application, this internal View is displayed for like second with it's default size and after that time it's scaled to the right size. Then I tried putting it inside onMeasure() method, but this one is called a few times, so again it doesn't seem to be efficient at all.
So what could be the best place to set it?
This is my class:
public class MyLayout extends RelativeLayout {
private View pointer;
public MyLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}
public MyLayout(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public MyLayout(Context context) {
super(context);
init(context);
}
private void init(Context c) {
pointer = new View(c);
pointer.setBackgroundResource(R.drawable.pointer);
addView(pointer);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams)pointer.getLayoutParams();
lp.height = (int)(getHeight() * 0.198);
lp.width = (int)(getWidth() * 0.198);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}
in your MyLayout class, override onSizeChanged():
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams)pointer.getLayoutParams();
lp.height = (int)(getHeight() * 0.198);
lp.width = (int)(getWidth() * 0.198);
};
I inflate Views on ScrollView.
And I need to get event, when on scrolling one of this Views (last, for example, or special type) becomes visible (in screen zone).
If a view changes visibility, the onlayout method is called, you could try overwriting that method and check it's state.
You need to override the view's onVisibilityChanged(). This is also called when one of the view's ancestors changes visibility.
This I inflated my GridView and get what you want
public class MyGrideView extends GridView {
boolean expanded = false;
public MyGrideView(Context context) {
super(context);
}
public MyGrideView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public MyGrideView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public boolean isExpanded() {
return expanded;
}
#Override
public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// HACK! TAKE THAT ANDROID!
if (isExpanded()) {
// Calculate entire height by providing a very large height hint.
// But do not use the highest 2 bits of this integer; those are
// reserved for the MeasureSpec mode.
int expandSpec = MeasureSpec.makeMeasureSpec(
Integer.MAX_VALUE >> 2, MeasureSpec.AT_MOST);
super.onMeasure(widthMeasureSpec, expandSpec);
ViewGroup.LayoutParams params = getLayoutParams();
params.height = getMeasuredHeight();
} else {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}
public void setExpanded(boolean expanded) {
this.expanded = expanded;
}
}
I am trying to make a custom view that is square, using the width as the height. I am also using a pre-defined layout which I inflate as it's UI. As soon as I overrode onMeasure, the custom view no longer appears. Here is my code:
public class MyView extends RelativeLayout{
public MyView(Context context) {
super(context);
addView(setupLayout(context));
}
public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
addView(setupLayout(context));
}
public MyView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
addView(setupLayout(context));
}
private View setupLayout(Context context) {
LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View myView = inflater.inflate(R.layout.view_layout, null);
return myView;
}
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(MeasureSpec.getSize(widthMeasureSpec), MeasureSpec.getSize(widthMeasureSpec));
}
}
I have 2 questions:
How do I override onMeasure so that it draws my view the way I am expecting it to?
Is there any way I can make this more efficient in terms of the view hierarchy (i.e. not be putting a RelativeLayout inside a RelativeLayout)
You can use this code from Jan Němec's answer to a similar question :
import android.content.Context;
import android.util.AttributeSet;
import android.widget.LinearLayout;
public class SquareLayout extends LinearLayout {
public SquareLayout(Context context) {
super(context);
}
public SquareLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int width = MeasureSpec.getSize(widthMeasureSpec);
int height = MeasureSpec.getSize(heightMeasureSpec);
if (width > (int)(mScale * height + 0.5)) {
width = (int)(mScale * height + 0.5);
} else {
height = (int)(width / mScale + 0.5);
}
super.onMeasure(
MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY),
MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY)
);
}
}
Or try to use this library project.