android textview - In Android, how do I set margins in dp programmatically?




6 Answers

You should use LayoutParams to set your button margins:

LayoutParams params = new LayoutParams(
        LayoutParams.WRAP_CONTENT,      
        LayoutParams.WRAP_CONTENT
);
params.setMargins(left, top, right, bottom);
yourbutton.setLayoutParams(params);

Depending on what layout you're using you should use RelativeLayout.LayoutParams or LinearLayout.LayoutParams.

And to convert your dp measure to pixel, try this:

Resources r = mContext.getResources();
int px = (int) TypedValue.applyDimension(
        TypedValue.COMPLEX_UNIT_DIP,
        yourdpmeasure, 
        r.getDisplayMetrics()
);
viewgroup kotlin

In this, this and this thread I tried to find an answer on how to set the margins on a single view. However, I was wondering if there isn't an easier way. I'll explain why I rather wouldn't want to use this approach:

I have a custom Button which extends Button. If the background is set to something else than the default background (by calling either setBackgroundResource(int id) or setBackgroundDrawable(Drawable d)), I want the margins to be 0. If I call this:

public void setBackgroundToDefault() {
    backgroundIsDefault = true;
    super.setBackgroundResource(android.R.drawable.btn_default);
    // Set margins somehow
}

I want the margins to reset to -3dp (I already read here how to convert from pixels to dp, so once I know how to set margins in px, I can manage the conversion myself). But since this is called in the CustomButton class, the parent can vary from LinearLayout to TableLayout, and I'd rather not have him get his parent and check the instanceof that parent. That'll also be quite inperformant, I imagine.

Also, when calling (using LayoutParams) parentLayout.addView(myCustomButton, newParams), I don't know if this adds it to the correct position (haven't tried however), say the middle button of a row of five.

Question: Is there any easier way to set the margin of a single Button programmatically besides using LayoutParams?

EDIT: I know of the LayoutParams way, but I'd like a solution that avoids handling each different container type:

ViewGroup.LayoutParams p = this.getLayoutParams();
    if (p instanceof LinearLayout.LayoutParams) {
        LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams)p;
        if (_default) lp.setMargins(mc.oml, mc.omt, mc.omr, mc.omb);
        else lp.setMargins(mc.ml, mc.mt, mc.mr, mc.mb);
        this.setLayoutParams(lp);
    }
    else if (p instanceof RelativeLayout.LayoutParams) {
        RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams)p;
        if (_default) lp.setMargins(mc.oml, mc.omt, mc.omr, mc.omb);
        else lp.setMargins(mc.ml, mc.mt, mc.mr, mc.mb);
        this.setLayoutParams(lp);
    }
    else if (p instanceof TableRow.LayoutParams) {
        TableRow.LayoutParams lp = (TableRow.LayoutParams)p;
        if (_default) lp.setMargins(mc.oml, mc.omt, mc.omr, mc.omb);
        else lp.setMargins(mc.ml, mc.mt, mc.mr, mc.mb);
        this.setLayoutParams(lp);
    }
}

Because this.getLayoutParams();returns a ViewGroup.LayoutParams, which do not have the attributes topMargin, bottomMargin, leftMargin, rightMargin. The mc instance you see is just a MarginContainer which contains offset (-3dp) margins and (oml, omr, omt, omb) and the original margins (ml, mr, mt, mb).




Best way ever:

private void setMargins (View view, int left, int top, int right, int bottom) {
    if (view.getLayoutParams() instanceof ViewGroup.MarginLayoutParams) {
        ViewGroup.MarginLayoutParams p = (ViewGroup.MarginLayoutParams) view.getLayoutParams();
        p.setMargins(left, top, right, bottom);
        view.requestLayout();
    }
}

How to call method:

setMargins(mImageView, 50, 50, 50, 50);

Hope this will help you.




layout_margin is a constraint that a view child tell to its parent. However it is the parent's role to choose whether to allow margin or not. Basically by setting android:layout_margin="10dp", the child is pleading the parent view group to allocate space that is 10dp bigger than its actual size. (padding="10dp", on the other hand, means the child view will make its own content 10dp smaller.)

Consequently, not all ViewGroups respect margin. The most notorious example would be listview, where the margins of items are ignored. Before you call setMargin() to a LayoutParam, you should always make sure that the current view is living in a ViewGroup that supports margin (e.g. LinearLayouot or RelativeLayout), and cast the result of getLayoutParams() to the specific LayoutParams you want. (ViewGroup.LayoutParams does not even have setMargins() method!)

The function below should do the trick. However make sure you substitute RelativeLayout to the type of the parent view.

private void setMargin(int marginInPx) {
    RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams) getLayoutParams();
    lp.setMargins(marginInPx,marginInPx, marginInPx, marginInPx);
    setLayoutParams(lp);
}



Here is the all-in-one answer with recent updates:

Step 1, to update margin

The basic idea is to get margin out and then update it. The update will be applies automatically and you do not need to set it back. To get the layout parameters, simply call this method:

LayoutParams layoutParams = (LayoutParams) yourView.findViewById(R.id.THE_ID).getLayoutParams();

The LayoutParams comes from the layout of your view. If the view is from a linear layout, you need to import LinearLayout.LayoutParams. If you use relative layout, import LinearLayout.LayoutParams , etc.

Now, if you set the margin using Layout_marginLeft, Right, etc, you need to update margin in this way

layoutParams.setMargins(left, top, right, bottom);

If you set margin using the new layout_marginStart, you need to update margin in this way

layoutParams.setMarginStart(start);
layoutParams.setMarginEnd(end);

Step 2, to update margin in dp

All two ways of updating margin above are updating in pixels. You need to do a translation of dp to pixels.

float dpRatio = context.getResources().getDisplayMetrics().density;
int pixelForDp = (int)dpValue * dpRatio;

Now put the calculated value to the above margin update functions and you should be all set




Use this method to set margin in dp

private void setMargins (View view, int left, int top, int right, int bottom) {
    if (view.getLayoutParams() instanceof ViewGroup.MarginLayoutParams) {
        ViewGroup.MarginLayoutParams p = (ViewGroup.MarginLayoutParams) view.getLayoutParams();

        final float scale = getBaseContext().getResources().getDisplayMetrics().density;
        // convert the DP into pixel
        int l =  (int)(left * scale + 0.5f);
        int r =  (int)(right * scale + 0.5f);
        int t =  (int)(top * scale + 0.5f);
        int b =  (int)(bottom * scale + 0.5f);

        p.setMargins(l, t, r, b);
        view.requestLayout();
    }
}

call the method :

setMargins(linearLayout,5,0,5,0);



When you are in a custom View, you can use getDimensionPixelSize(R.dimen.dimen_value), in my case, I added the margin in LayoutParams created on init method.

In Kotlin

init {
    LayoutInflater.from(context).inflate(R.layout.my_layout, this, true)
    layoutParams = LayoutParams(MATCH_PARENT, WRAP_CONTENT).apply {
    val margin = resources.getDimensionPixelSize(R.dimen.dimen_value)
    setMargins(0, margin, 0, margin)
}

in Java:

public class CustomView extends LinearLayout {

    //..other constructors

    public CustomView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        LayoutParams params = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
        int margin = getResources().getDimensionPixelSize(R.dimen.spacing_dime);
        params.setMargins(0, margin, 0, margin);
        setLayoutParams(params);
    }
}



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