custom Toast at screen top

问题:

Please read the question before answering with your standard routine to print a Toast :)

I'd like to display a Custom Toast at the top left corner of the screen. I use this code to create the Toast:

    Toast mFixedToast = new Toast(getApplicationContext());
    mFixedToast.setDuration(timeout);
    mFixedToast.setView(myInflatedLayout);
    mFixedToast.setGravity(Gravity.TOP|Gravity.FILL_HORIZONTAL, 0, 0);
    mFixedToast.setMargins(0,0);

However, in some devices, for example Samsung Galaxy S4, the toast is not positioned at (0,0), but with a margin like 40-50 pixels. Many other devices work as expected.

I am positive the margin is added by the WindowManager (The toast view is added as a View of type TYPE_TOAST to the WindowManager)

Why is that? Can it be modified? Please see the code below, I've cloned Toast.java into my own class and isolated the lines where the View is added to the WM:

 // LayoutParams for the TOAST view ... tried to change params.type but no luck.
 final WindowManager.LayoutParams params = mParams;
 params.height = WindowManager.LayoutParams.WRAP_CONTENT;
 params.width = WindowManager.LayoutParams.WRAP_CONTENT;
 params.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
              | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE
              | WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON;
            params.format = PixelFormat.TRANSLUCENT;
 params.windowAnimations = android.R.style.Animation_Toast;
 params.type = WindowManager.LayoutParams.TYPE_TOAST;

 mWM = (WindowManager)mView.getContext().getApplicationContext().getSystemService(Context.WINDOW_SERVICE);
 mParams.gravity = gravity;

 // CHECKED these all are 0 !!!
 mParams.x = mX; mParams.y = mY;
 mParams.verticalMargin = mVerticalMargin;
 mParams.horizontalMargin = mHorizontalMargin;
 .
 .
 if (localLOGV) Log.v(TAG, "ADD! " + mView + " in " + this+" with "+mX+","+mY+","+mVerticalMargin+","+mHorizontalMargin);
 mWM.addView(mView, mParams);

So it looks like it's the WindowManager who is adding this margin on those devices. Looks like a safe area or something like that, but I cant find where (or if) this can be changed.

Help appreciated.

回答1:

I figured this out.

Starting 4.4+ you have to add the following flag:

if (Build.VERSION.SDK_INT > Build.VERSION_CODES.JELLY_BEAN_MR2) {
        mParams.flags = mParams.flags | WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN;
}

This will allow your toast to be positioned all the way to the top.

回答2:

Please try the following :

mFixedToast.setGravity(Gravity.TOP, 0, 0);

Also check the inflated layout, that might be causing the issue. You might be using the MatchParent for that view and gravity center.

回答3:

private void Toast(String string) {
        // TODO Auto-generated method stub
        LinearLayout layout = new LinearLayout(this);
        layout.setBackgroundResource(R.color.Orange);
        TextView tv = new TextView(this);
        tv.setTextColor(Color.YELLOW);
        tv.setTextSize(25);
        tv.setGravity(Gravity.Top);
        tv.setText(string);
        ImageView img = new ImageView(this);
        img.setImageResource(R.drawable.ic_launcher2);
        layout.addView(img);
        layout.addView(tv);
        Toast toast = new Toast(this); // context is object of Context write
        tts.speak(string, TextToSpeech.QUEUE_FLUSH, null); // "this" if you are
                                                            // an Activity
        toast.setView(layout);
        toast.setGravity(Gravity.CENTER_VERTICAL, 0, 0);
        toast.show();
    }

回答4:

You can try this method to display toast in center of screen. If you want to display toast on top.you can change the msg.getYOffset(). Here is code. Try this

public static void displyToast(Context c, String str) {
        Toast msg = Toast.makeText(c, str, Toast.LENGTH_SHORT);
        msg.setGravity(Gravity.CENTER, msg.getXOffset() / 2,
                msg.getYOffset() / 2);
        msg.show();
    }

msg.getXOffset() / 2 take toast on center of screen horizintallly, whereas `msg.getYOffset() / 2` takes toast on center of screen vertically.

I hope this will help you. Happy Coding :)