android应该是枢轴点以围绕其中心旋转图像 [英] android what should be pivot point to rotate image around its center of base

问题描述

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我要旋转图像（特别是箭头图像）在其中心点附近。

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

例如开始时，我的图像就像是9时针上的秒针。
并且假设如果我将图像旋转30度，它应该看起来像是10时针的秒针，如果是120时则是1针的秒针。

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.

所以我想围绕该图像的中心（沿x轴）旋转图像。

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

那又怎样？如果我先编写代码

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

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

或第二个代码

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

或第三个代码

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);

或第四个代码

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);

添加了一个图像以便更好地理解，该图像沿顺时针方向旋转了90度。

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

我希望以后的Google会添加更多和清晰的有关枢轴点的文档。

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

预先感谢。

推荐答案

使用第四个代码^^

您可以实现以下目标：

    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();

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