I have an imageview. I want its width to be fill_parent. I want its height to be whatever the width ends up being. For example:
<ImageView
android:layout_width="fill_parent"
android:layout_height="whatever the width ends up being" />
Is something like that possible in a layout file without having to create my own view class?
Thanks
Updated July 28 2021 to use AndroidX instead of the support library
First, make sure your project has AndroidX imported, by following the directions here.
Then wrap your image inside a ConstraintLayout, and its fields as such:
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:layout_width="wrap_content"
android:layout_height="0dp"
app:layout_constraintDimensionRatio="1:1" />
</androidx.constraintlayout.widget.ConstraintLayout>
See here
This can be done using LayoutParams to dynamically set the Views height once your know the Views width at runtime. You need to use a Runnable thread in order to get the Views width at runtime or else you'll be trying to set the Height before you know the View's width because the layout hasn't been drawn yet.
Example of how I solved my problem:
final FrameLayout mFrame = (FrameLayout) findViewById(R.id.frame_id);
mFrame.post(new Runnable() {
@Override
public void run() {
RelativeLayout.LayoutParams mParams;
mParams = (RelativeLayout.LayoutParams) mFrame.getLayoutParams();
mParams.height = mFrame.getWidth();
mFrame.setLayoutParams(mParams);
mFrame.postInvalidate();
}
});
The LayoutParams must be of the type of the Parent View that your view is in. My FrameLayout is inside of a RelativeLayout in the xml file.
mFrame.postInvalidate();
is called to force the view to redraw while on a separate thread than the UI thread
I couldn't get David Chu's answer to work for a RecyclerView item and figured out I needed to constrain the ImageView to the parent. Set the ImageView width to 0dp and constrain its start and end to the parent. I'm not sure if setting the width to wrap_content or match_parent works in some cases, but I think this is a better way to get the child of a ConstraintLayout to fill its parent.
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintDimensionRatio="1:1"/>
</android.support.constraint.ConstraintLayout>
Here I what I did to have an ImageButton which always have a width equals to its height (and avoid stupid empty margins in one direction...which I consider a as a bug of the SDK...):
I defined a SquareImageButton class which extends from ImageButton:
package com.myproject;
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.ImageButton;
public class SquareImageButton extends ImageButton {
public SquareImageButton(Context context) {
super(context);
// TODO Auto-generated constructor stub
}
public SquareImageButton(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
}
public SquareImageButton(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
}
int squareDim = 1000000000;
@Override
public void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int h = this.getMeasuredHeight();
int w = this.getMeasuredWidth();
int curSquareDim = Math.min(w, h);
// Inside a viewholder or other grid element,
// with dynamically added content that is not in the XML,
// height may be 0.
// In that case, use the other dimension.
if (curSquareDim == 0)
curSquareDim = Math.max(w, h);
if(curSquareDim < squareDim)
{
squareDim = curSquareDim;
}
Log.d("MyApp", "h "+h+"w "+w+"squareDim "+squareDim);
setMeasuredDimension(squareDim, squareDim);
}
}
Here is my xml:
<com.myproject.SquareImageButton
android:id="@+id/speakButton"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:scaleType="centerInside"
android:src="@drawable/icon_rounded_no_shadow_144px"
android:background="#00ff00"
android:layout_alignTop="@+id/searchEditText"
android:layout_alignBottom="@+id/searchEditText"
android:layout_alignParentLeft="true"
/>
Works like a charm !
If your image view is inside a constraint layout, you can use following constraints to create a square image view make sure to use 1:1 to make square
<ImageView
android:layout_width="0dp"
android:layout_height="0dp"
android:id="@+id/ivImageView"
app:layout_constraintDimensionRatio="1:1"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"/>
You can't do it with the layout alone, I've tried. I ended up writing a very simple class to handle it, you can check it out on github. SquareImage.java Its part of a larger project but nothing a little copy and paste can't fix (licensed under Apache 2.0)
Essentially you just need to set the height/width equal to the other dimension (depending on which way you want to scale it)
Note: You can make it square without a custom class using the scaleType attribute but the view's bounds extend beyond the visible image, which makes it an issue if you are placing other views near it.
In Android 26.0.0 PercentRelativeLayout has been deprecated.
The best way to solve it is now with ConstraintLayout like this:
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView android:layout_width="match_parent"
android:layout_height="0dp"
android:scaleType="centerCrop"
android:src="@drawable/you_image"
app:layout_constraintDimensionRatio="1:1"/>
</android.support.constraint.ConstraintLayout>
Here is a tutorial on how to add ConstraintLayout to your project.
To set your ImageView equal to half the screen, you need to add the following to your XML for the ImageView:
<ImageView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true"
android:scaleType="fitXY"
android:adjustViewBounds="true"/>
To then set the height equal to this width, you need to do it in code. In the getView method of your GridView adapter, set the ImageView height equal to its measured width:
mImageView.getLayoutParams().height = mImageView.getMeasuredWidth();
For people passing by now, in 2017, the new best way to achieve what you want is by using ConstraintLayout like this:
<ImageView
android:layout_width="0dp"
android:layout_height="0dp"
android:scaleType="centerCrop"
app:layout_constraintDimensionRatio="1:1" />
And don't forget to add constraints to all of the four directions as needed by your layout.
Build a Responsive UI with ConstraintLayout
Furthermore, by now, PercentRelativeLayout has been deprecated (see Android documentation).
Here's how I solved that problem:
int pHeight = picture.getHeight();
int pWidth = picture.getWidth();
int vWidth = preview.getWidth();
preview.getLayoutParams().height = (int)(vWidth*((double)pHeight/pWidth));
preview - imageView with width setted to "match_parent" and scaleType to "cropCenter"
picture - Bitmap object to set in imageView src.
That's works pretty well for me.
I don't think there's any way you can do it in XML layout file, and I don't think android:scaleType attribute will work like you want it to be.
The only way would be to do it programmatically. You can set the width to fill_parent and can either take screen width as the height of the View or can use View.getWidth() method.
The ImageView "scaleType" function may help you here.
This code will keep the aspect ratio and position the image at the top:
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:scaleType="fitStart"
Here is a great post showing the possibilities and appearances from using scaleType.
