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Custom ImageButton, which method to override for simplest RadioButton interface?

I am in the process of making a custom view that is essentially an ImageButton with added logic so it also have the behavior of a RadioButton. All I want to do is have it built into the view that when the user clicks the button the image is changed, an internal boolean is marked true to note it is selected, and an interface method is called to let the RadioGroup it is a part of to unselect all the other views within it. I don't want to impact the existing behavior of the base ImageButton whatsoever.
I've only made one other custom view before and that was by following a tutorial almost exactly to the letter and since there are so many different methods inhereted from View that deal with clicks/touches (i.e. onTouch, onClick, motion event, etc.) taking it all in has left me a bit confused. I am fine writing the interface itself, its the modification of ImageButton where I'm not too sure how to attack it.
So, I ask you all: What method/methods do I need to override to add this simple functionality, while not impacting the current behavior of ImageButton, nor screwing up the ability to set an onTouchListener for the button that will perform additional actions on click without compromising this built in radio button logic? If I need to override something that will mess with the default behavior I mentioned, what do I need to put in the new method to restore that functionality?
This is what I have so far:
public class RadioImageButton extends AppCompatImageButton implements RadioCheckable {
//Default constructor
public RadioImageButton(Context context) {
super(context);
initView();
}
//Constructor with defined attributes
public RadioImageButton(Context context, AttributeSet attrs) {
super(context, attrs);
parseAttributes();
initView();
}
//Constructor with defined attributes and attributes taken from style defaults that aren't defined
public RadioImageButton(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
//=========================================================================
// Setup
//=========================================================================
private void initView()
{
}
private void parseAttributes()
{
}
}
The approach I would like to take would be something like:
...All other code I already showed
mChecked = false;
#Overide
void onClick(...)
{
mChecked = true;
setImageSource(R.example.checked_image); // Or I can use a selector resource
*Call to Radio Interface*;
mOnTouchListener.onTouch(v, event); //Handle user onTouchListener
}
...
and leave all the other code alone, though I'm sure it isn't quite that simple.
I thought a good start would be trying to find the source code for the default ImageButton class and set mine up to be a near replica so I can understand how it works and then modify from there, but all I could really find was this:
https://android.googlesource.com/platform/frameworks/base/+/android-7.0.0_r35/core/java/android/widget/ImageButton.java
and there is no way that is the actual source because pressing Ctrl+O shows many more functions that ImageButton defines that are not inherited from another class; regardless, that link is not at all helpful as its basically a giant comment with little to no code.
Thanks for any suggestions that will help me accomplish this in the most straightforward way.
EDIT: #pskink - Looking through the code you provided, it seems like it is trying to generate a matrix in order to transform the provided drawable (src) so that it fits into a new rectangle (dst) while maintaining the aspect ratio and positioning (hence ScaleToFit.CENTER). I would assume the destination rectangle would be the bounds of the view the drawable is contained in, which in this case is the RadioButton, but while stepping through the override of the "draw()" method it doesn't quite seem to be doing that, though I'm not quite sure how cavas.concat(matrix) is resolved so I'm not positive. Regardless it doesn't seem to work as intended or I am somehow using it wrong.

While maybe not the most robust method, it seems like the most straightforward, yet effective way to handle what I wanted to do was to leverage the Matrix class and its powerful scaling/transformation tools, specifically "setRectToRect()". Creating a custom view that extends RadioButton instead of ImageButton allowed me to make use of the existing RadioGroup, while manipulating characteristics of the button's drawables in the new classes Constructor achieved the behavior I was looking for.
Custom RadioButton class:
public class RadioImageButton extends android.support.v7.widget.AppCompatRadioButton {
int stateDrawable; //Resource ID for RadioButton selector Drawable
D scaledDrawable; //Post-scaling drawable
public RadioImageButtonTwo(Context context) {
super(context);
initView();
}
public RadioImageButtonTwo(Context context, AttributeSet attrs) {
super(context, attrs);
parseAttributes(attrs);
initView();
}
private void parseAttributes(AttributeSet attrs)
{
TypedArray styledAttrs = getContext().obtainStyledAttributes(attrs,R.styleable.RadioImageButtonTwo);
try {
// Obtain selector drawable from attributes
stateDrawable = styledAttrs.getResourceId(R.styleable.RadioImageButtonTwo_button_sDrawable, R.drawable.test_draw2);
} finally {
styledAttrs.recycle(); //Required for public shared view
}
}
private void initView()
{
scaledDrawable = new D(getResources(),stateDrawable); // Create scaled drawable
setBackground(scaledDrawable); // Apply scaled drawable
setButtonDrawable(android.R.color.transparent); // "Disable" button graphic
}
}
See more on setting up a custom view here: https://developer.android.com/training/custom-views/create-view#customattr
Custom drawable class "D" that includes fitCenter scaling thanks to #pskink:
class D extends StateListDrawable {
private Rect bounds = new Rect();
private RectF src = new RectF();
private RectF dst = new RectF();
private Matrix matrix = new Matrix();
public D(Resources r, int resId) {
try {
XmlResourceParser parser = r.getXml(resId);
int type;
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT) {
if (type == XmlPullParser.START_TAG && parser.getName().equals("selector")) {
inflate(r, parser, Xml.asAttributeSet(parser));
break;
}
}
} catch (XmlPullParserException | IOException e) {
e.printStackTrace();
}
}
#Override
public void draw(Canvas canvas) {
Drawable current = getCurrent();
bounds.set(0, 0, current.getIntrinsicWidth(), current.getIntrinsicHeight());
current.setBounds(bounds);
src.set(bounds);
dst.set(getBounds());
matrix.setRectToRect(src, dst, Matrix.ScaleToFit.CENTER);
canvas.concat(matrix);
super.draw(canvas);
}
}
Note that for whatever reason setting the button drawable itself to this custom drawable breaks the scaling, so changing the background to the custom drawable and setting the button drawable to transparent was the only way this worked. This custom drawable could easily be expanded upon to have more scaling type options and another view attribute could be defined to allow the user to choose the scaling type through XML.
This custom ImageView that mimics the (pointed out by pskink aswell) could also prove helpful in this task, as it too utilizes the Matrix class to implement multiple types of image scaling: https://github.com/yqritc/Android-ScalableImageView

Android AnimationDrawable Recycling issue

I have a AnimationDrawable that i initialise before starting the animation and recycle it right as it finishes.. the problem is that when i want to start the animation again, i reinitialise everything but still gives an exception
java.lang.RuntimeException: Canvas: trying to use a recycled bitmap android.graphics.Bitmap#2bbad018
here's my code
public ImageView radarImageView;
public AnimationDrawable animationDrawable;
public void animationStart() {
// animationStop();
radarImageView = (ImageView) findViewById(R.id.radarIV);
radarImageView.setBackgroundResource(R.drawable.sensor_animation);
animationDrawable = (AnimationDrawable) radarImageView.getBackground();
animationDrawable.start();
}
public void animationStop() {
animationDrawable.stop();
for (int i = 0; i < animationDrawable.getNumberOfFrames(); ++i){
Drawable frame = animationDrawable.getFrame(i);
if (frame instanceof BitmapDrawable) {
((BitmapDrawable)frame).getBitmap().recycle();
}
frame.setCallback(null);
}
animationDrawable.setCallback(null);
// animationDrawable = null;
// radarImageView.setBackgroundResource(0);
}
Why does it not reinitialise the whole thing again?

The problem is because when you Bitmap.recycle() is called on the bitmap you cannot reuse it.
Also as you are calling setBackgroundResources(R.drawable.sensor_animation) you are referring to the same object which its bitmaps were recycled previously.
As a solution, you either have to create a new drawable every time or do not recycle that instance.
If you are worries about the memory usage try to use smaller bitmaps. Also using the correct sizes for different screen densities would help.

TextView does not refresh the bitmap for getDrawingCache

I have done quite some research on this and answers did not help 100%, I did find a way to make it work but it's awful and I don't understand the behavior.
This is what I finally have:
private Bitmap generateBitmapFromTxt() {
mTxtEmojicon.setDrawingCacheEnabled(true);
Bitmap bmap = Bitmap.createBitmap(mTxtEmojicon.getDrawingCache());
mTxtEmojicon.setDrawingCacheEnabled(false);
}
But the bitmap is not refreshing. I also did try:
invalidate()
buildDrawingCache() destroyDrawingCache()
...
I have a custom class that extends from TextView and the bitmap generated did NOT wrap words unless dynamically forcing to calculate it's size. Like this:
private void prepareTxtViewSize() {
int specWidth = View.MeasureSpec.makeMeasureSpec(mEdt.getMeasuredWidth(), View.MeasureSpec.AT_MOST);
int specHeight = View.MeasureSpec.makeMeasureSpec(mEdt.getMeasuredHeight(), View.MeasureSpec.AT_MOST);
mTxt.measure(specWidth, specHeight);
mTxt.layout(0, 0, mTxt.getMeasuredWidth(), mTxt.getMeasuredHeight());
}
My custom TextView class does NOT override onDraw().
Now, my solution, awful solution, was to call prepareTxtViewSize() twice before calling generateBitmapFromTxt() and it works, the bitmap is refreshed and I always get the correct one.
But I am sure there is something I am missing and I am just lucky it works. So does somebody know what am I missing and/or why calling prepareTxtViewSize() twice actually makes the drawingCache refresh?

Using Google's ImageWorker to load images in ListView results in java.lang.RuntimeException

Recently, I started using Google ImageWorker class for loading bitmaps on a background thread. This class handles everything, including putting the bitmaps in the ImageView. Google talks about this class (and it's helper classes for Image manipulation and caching) here: http://developer.android.com/training/displaying-bitmaps/process-bitmap.html
The ImageView(s) in my case are parts of list items in a ListView. Here's the interesting part of getView on my ArrayAdapter:
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
View view = convertView == null ? inflater.inflate(R.layout.nodelist_item, null) : convertView;
NodeHolder holder = getHolder(view);
Node node = mList.get(position);
holder.txtTitle.setText(node.Title);
//Setting the rest of the different fields ...
//And finally loading the image
if(node.hasArt())
worker.loadImage(node.ImageID, holder.imgIcon);
}
The entire getView method can be seen here: http://pastebin.com/CJbtVfij
The worker object is a very simple implementation of the ImageWorker:
public class NodeArtWorker extends ImageWorker {
protected int width;
protected int height;
public NodeArtWorker(Context context) {
super(context);
addImageCache(context);
//Code for getting the approximate width and height of the ImageView, in order to scale to save memory.
}
#Override
protected Bitmap processBitmap(Object data) {
Bitmap b = getBitmap(data);
if(b == null) return null;
return Utils.resizeBitmap(b, width, height);
}
protected Bitmap getBitmap(Object data) {
//Downloads the bitmap from a server, and returns it.
}
}
This works very well, and the performance is much better now than before. However, if I change the ImageID on some of the items in the list, and call adapter.notifyDataSetChanged() to rebuild the view (and thereby start loading new bitmaps), I get a RuntimeException:
0 java.lang.RuntimeException: Canvas: trying to use a recycled bitmap android.graphics.Bitmap#41adf448
1 at android.graphics.Canvas.throwIfRecycled(Canvas.java:1058)
2 at android.graphics.Canvas.drawBitmap(Canvas.java:1159)
3 at android.graphics.drawable.BitmapDrawable.draw(BitmapDrawable.java:440)
4 at android.widget.ImageView.onDraw(ImageView.java:1025)
5 at android.view.View.draw(View.java:14126)
The full stacktrace can be seen in the following pastebin entry, but is probably uninteresting, as it is the typical Android view hierarchy redraw stacktrace: http://pastebin.com/DsWcidqw
I get that the Bitmaps are being recycled, but I don't understand exactly where and what can be done about it. As my code comes directly from Google, and is, as far as I understand, the recommended way of doing this, I am very confused.

On Android, Bitmaps can be recycled to be later re-used (much faster than re-creating a Bitmap).
The Bitmap#recycle()method will flag the Bitmap as recycled.
So if you try to set such a recycled bitmap to an ImageView or draw it on a Canvas, you will end up with this exception:
java.lang.RuntimeException: Canvas: trying to use a recycled bitmap
The official demo that you linked on your question is dealing with recycled Bitmaps.
It uses a dedicated method hasValidBitmap() and checks the Bitmap#isRecycled() value:
private synchronized boolean hasValidBitmap() {
Bitmap bitmap = getBitmap();
return bitmap != null && !bitmap.isRecycled();
}
So you need to do the same. When you're searching on your cache for a Bitmap, before applying it to an ImageView, check if it's recycled or not. If it's not you can directly set it, otherwise, you need to update the Bitmap.
To create a new Bitmap from a recycled Bitmap, you can use the Bitmap::createBitmap(Bitmap) method.
You can find more details on this page.

i think this is not the ImageWorker class bug, this is
com.mobeta.android.dslv.DragSortListView.dispatchDraw(DragSortListView.java:797)
issue. so in order to see my answer is correct or not just remove that library and see if it works or not. after that i think the best solutions are:
1- not use that library.
2- report issue on github.
3- solve it by your own and debugge it.
4- or you can set null for image holder bitmap
holder.imgIcon.setBitmapDrawble(null);
and then call worker.loadImage.

Android recycling Button backgroundDrawable still causes OutOfMemoryError

I have some CustomButton, and at some point, a background is drawn from a base64String into a BitmapDrawable, which is applied to the CustomButton. Within the total lifespan of the application, this can happen multiple times. This caused a OutOfMemoryError: bitmap size exceeds VM budget, and after some digging on StackOverflow, this happened because the Bitmaps were not recycled. So I tried to handle this with some code that is executed each time another background was applied (this code comes from the CustomButton class):
public void recycleBackground() {
BitmapDrawable bd = null;
Drawable bg = getBackground();
if (bg != null) {
bg.setCallback(null);
if (bg instanceof BitmapDrawable) {
bd = (BitmapDrawable) bg;
if (!bd.getBitmap().isRecycled()) bd.getBitmap().recycle();
}
bd = null; //just precautionous
bg = null; //also just a precaution
}
Yet, the memory is slowly (because background images are not all that large) but surely flooded. What am I missing or doing wrong? I combined the above code from some different questions/answers from SO. I can find a lot on recycling Bitmaps, not so much on the recycling of Drawables. Maybe that's what I'm doing wrong?