Levenlol Levenlol - 5 months ago 25
Android Question

Android cannot add children to a custom Layout (inherit from ViewGroup)

hi I'm pretty new to android developing and I'm trying to create my own custom layout:

public class EqLayout extends ViewGroup {

public EqLayout(Context context){
super(context);
}

public EqLayout(Context context, AttributeSet attrs){
super(context, attrs);
}

public EqLayout(Context context, AttributeSet attrs, int defstyle){
super(context, attrs, defstyle);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int lato = getLato();
int w = getMeasuredWidth()/lato;
int h = getMeasuredHeight()/lato;
int ws = MeasureSpec.makeMeasureSpec(w, MeasureSpec.EXACTLY);
int hs = MeasureSpec.makeMeasureSpec(h, MeasureSpec.EXACTLY);

for(int i = 0; i < getChildCount(); i++){
View v = getChildAt(i);
v.measure(ws, hs);
}
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
int lato = getLato();
int w = (r - l)/lato;
int h = (t - b)/lato;

for(int i = 0; i < getChildCount(); i++){
View v = getChildAt(i);
int x = i%lato, y = i/lato;
v.layout(x*w, y*h, (x+1)*w, (y+1)*h);
}

}

private int getLato(){
int r = (int) Math.ceil(Math.sqrt(getChildCount()));
r = (r > 0) ? r : r+1;
return r;
}
}


MainActivity:

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
EqLayout eql = (EqLayout) findViewById(R.id.eqlviewlayout);
for(int i = 0; i < 14; i++){
Button b = new Button(this);
b.setText("#"+i);
eql.addView(b);
}
}
}


and that's the xml:

XML file

All seems to works fine but I cannot add a child to it.
I tried on runtime and from Android Studio by drag and drop a button but without success.

Anybody knows why that happens ? Thanks for you time, ask if you need any more info.

Answer

You have a negative height for your children.

Just replace in your onLayout this line:

int h = (t - b)/lato;

with

int h = (b - t)/lato;

and you're good!

Screenshot