android what should be pivot point to rotate image around its center of base

问题

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I want to rotate a image(specifically arrow image) around its center point of base.

e.g. At start my image will be like second hand in a clock on 9. And suppose if I rotate that image by 30 degree, it should look like clock second hand on 10 and if 120 degree the clock second hand on 1.

So I want to rotate that image around it's center(along x axis) of base.

So what should I pass as pivot(X & Y) if I first code

imageView.setPivotX(1f);
            imageView.setPivotY(1f);
            imageView.setRotation(-30);

or second code

Matrix matrix = new Matrix();
    imageView.setScaleType(ScaleType.MATRIX);
    matrix.postRotate((float) 20, 0f, 0f);
    imageView.setImageMatrix(matrix);

or third code

Bitmap myImg = BitmapFactory.decodeResource(getResources(), R.drawable.arrow_0_degree);
    Matrix matrix = new Matrix();
    matrix.postRotate(30);
    Bitmap rotated = Bitmap.createBitmap(myImg, 0, 1, myImg.getWidth(), myImg.getHeight(), matrix, true);
    imageView.setImageBitmap(rotated);

or fourth code

final RotateAnimation rotateAnim = new RotateAnimation(0.0f, degree,
        RotateAnimation.RELATIVE_TO_SELF, 0.5f,
        RotateAnimation.RELATIVE_TO_SELF, 0.5f);

rotateAnim.setDuration(0);
rotateAnim.setFillAfter(true);
imgview.startAnimation(rotateAnim);

Added an image for better understanding which rotated in 90 degrees along clockwise.

And I hope in future google will add more and clear documentation about the pivot points.

Thanks in advance.

回答1:

You were almost right with the fourth code ^^

You can achieve this like that :

    final RotateAnimation rotateAnim = new RotateAnimation(0.0f, 30,
            RotateAnimation.RELATIVE_TO_SELF, 0.5f,
            RotateAnimation.RELATIVE_TO_SELF, 1f);
    rotateAnim.setDuration(0);
    rotateAnim.setFillAfter(true);
    mImageView.setAnimation(rotateAnim);
    rotateAnim.start();

来源：https://stackoverflow.com/questions/29279563/android-what-should-be-pivot-point-to-rotate-image-around-its-center-of-base

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