How to get the button's border size in Android

问题:

How can I get the border width of a stand Android button programmatically? I simply need to resize the text to fit to the gray area and need to position other objects inline with the buttons, but I cannot do that without knowing the size of the border. I need this to work in all API's 7+. The red arrows in the image below show what I am trying to get:

Here is the code I use for creating my button:

cmdView = new Button(this);
params = new RelativeLayout.LayoutParams(widthLblViewVerbs , (int) fieldHeight);
params.leftMargin = (int) (screenWidth - params.width);
params.topMargin = (int) yPos;
cmdView.setSingleLine();
cmdView.setText("View");
cmdView.setPadding(0, 0, 0, 0);
cmdView.setTextSize(TypedValue.COMPLEX_UNIT_PX, SetTextSize(cmdView.getText().toString(), params.width, params.height));
layout.addView(cmdView, params);

NB. I've had to ask this question again because someone downvoted my question last time and I am desperate for a solution. I have made absolutely no progress with my program in weeks because I have been stuck with this and another problem. If there is something unclear about my question, please let me know and I will edit it. Thank you

回答1:

My initial code recommendation from the comments can be found here. The implementation done by Dan Bray is:

final Button button = new Button(this);
params = new RelativeLayout.LayoutParams(50, 50);
layout.addView(button, params);
button.post(new Runnable()
{
@Override
public void run()
{
    button.buildDrawingCache();
    Bitmap viewCopy = button.getDrawingCache();

    boolean stillBorder = true;
    PaddingLeft = 0;
    PaddingTop = 0;
    while (stillBorder)
    {
        int color = viewCopy.getPixel(PaddingLeft, button.getHeight() / 2);
        if (color != Color.TRANSPARENT)
            stillBorder = false;
        else
            PaddingLeft++;
    }              
    stillBorder = true;
    while (stillBorder)
    {
        int color = viewCopy.getPixel(button.getWidth() / 2, PaddingTop);
        if (color != Color.TRANSPARENT)
            stillBorder = false;
        else
            PaddingTop++;
    }
}
});

回答2:

Not really clear on the question - you want the margins of the underlying view and then the set the size of the button to match ? Then Have you tried

ViewGroup.MarginLayoutParams lp = (ViewGroup.MarginLayoutParams) view.getLayoutParams();

margins are accessible via

lp.leftMargin;
lp.rightMargin;
lp.topMargin;
lp.bottomMargin;

Details here:http://developer.android.com/reference/android/view/ViewGroup.MarginLayoutParams.html

回答3:

This gets the width and height of the button's border:

final Button button = new Button(this);
params = new RelativeLayout.LayoutParams(50, 50);
layout.addView(button, params);
button.post(new Runnable()
{
    @Override
    public void run()
    {
        button.buildDrawingCache();
        Bitmap viewCopy = button.getDrawingCache();

        boolean stillBorder = true;
        PaddingLeft = 0;
        PaddingTop = 0;
        while (stillBorder)
        {
            int color = viewCopy.getPixel(PaddingLeft, button.getHeight() / 2);
            if (color != Color.TRANSPARENT)
                stillBorder = false;
            else
                PaddingLeft++;
        }              
        stillBorder = true;
        while (stillBorder)
        {
            int color = viewCopy.getPixel(button.getWidth() / 2, PaddingTop);
            if (color != Color.TRANSPARENT)
                stillBorder = false;
            else
                PaddingTop++;
        }
    }
});

回答4:

Assuming you are using a nine patch background image, there is a much easier way.

In the nine patch image, you can define a padding box. This padding box will automatically be applied to the contents you set. No need to recalculate the paddings manually in that case.

Note that you should not set a padding on views using a nine patch as a background as the padding from the nine patch will be ignored.