围绕其中心旋转imageview

Question

i want to create an analog clock and i have a problem. i use 3 imageview for sec, min and hour hands. and now i want to each of them rotate around center but i can't. how can i rotate an imageview by giving the angle around the center?

Answer 1

Assuming you're targeting API 11, the easiest way is:

view.setPivotX(view.getWidth() / 2);
view.setPivotY(view.getHeight() / 2);

float rotation = //some value between 0f and 360f
view.setRotation(rotation);

Answer 2

The View class has a .setRoatation() method that would work perfectly. Just pass it a number of degrees to rotate and it will, by default, rotate around the center.

EDIT:

For rotating images in API levels below 11, see this post.

Answer 3

Below is the code for rotating textview. it works API 8 as well. It is just customized text view you need to create the object of it. And need to set rotation angel (also translation too if needed.)

public class VerticalTextView extends ImageView { final boolean topDown=true;

    float iRotateAngel, iSetX, iSetY;

    int iIndex;

    Context context;

    public int getiIndex()
        {
            return iIndex;
        }

    public void setiIndex(int iIndex)
        {
            this.iIndex = iIndex;
        }

    public float getiRotateAngel()
        {
            return iRotateAngel;
        }

    public void setiRotateAngel(float iRotateAngel)
        {
            this.iRotateAngel = iRotateAngel;
        }

    public float getiSetX()
        {
            return iSetX;
        }

    public void setiSetX(float iSetX)
        {
            this.iSetX = iSetX;
        }

    public float getiSetY()
        {
            return iSetY;
        }

    public void setiSetY(float iSetY)
        {
            this.iSetY = iSetY;
        }

    public boolean isTopDown()
        {
            return topDown;
        }



    public VerticalTextView(Context context)
        {
            super(context);
            this.context = context;
        }

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

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
        {
            super.onMeasure(heightMeasureSpec, widthMeasureSpec);
            setMeasuredDimension(getMeasuredHeight(), getMeasuredWidth());
        }

    @Override
    protected boolean setFrame(int l, int t, int r, int b)
        {
            return super.setFrame(l+32, t+12, l + (b - t)+32, t + (r - l)+12);
        }
    @Override
    public void draw(Canvas canvas)
        {
            if (topDown)
                {

                    canvas.translate(this.iSetX, this.iSetY);
                    canvas.rotate(this.iRotateAngel);
                }
            else
                {

                    canvas.translate(this.iSetX, this.iSetY);
                    canvas.rotate(this.iRotateAngel);
                }
            canvas.clipRect(0,0,getWidth(), getHeight(), android.graphics.Region.Op.REPLACE);
            super.draw(canvas);

        }
}