imageview 放大旋转自定义 不能超出屏幕

你可以使用 Android 中的 Matrix 类来实现 ImageView 的放大和旋转，同时确保不超出屏幕的范围。以下是一个示例：

public class ZoomRotateImageView extends androidx.appcompat.widget.AppCompatImageView {
    private Matrix mMatrix = new Matrix();
    private float mScaleFactor = 1.f;
    private float mRotationDegrees = 0.f;
    private float mFocusX = 0.f;
    private float mFocusY = 0.f;
    private int mImageWidth;
    private int mImageHeight;
    private int mViewWidth;
    private int mViewHeight;

    public ZoomRotateImageView(Context context) {
        super(context);
        init(context);
    }

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

    public ZoomRotateImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context);
    }

    private void init(Context context) {
        setScaleType(ScaleType.MATRIX);
    }

    @Override
    protected boolean setFrame(int l, int t, int r, int b) {
        mViewWidth = r - l;
        mViewHeight = b - t;

        mMatrix.reset();
        mMatrix.setTranslate((mViewWidth - mImageWidth) / 2f, (mViewHeight - mImageHeight) / 2f);
        float scale = Math.min((float) mViewWidth / (float) mImageWidth, (float) mViewHeight / (float) mImageHeight);
        mMatrix.postScale(scale, scale, mViewWidth / 2f, mViewHeight / 2f);
        mMatrix.postRotate(mRotationDegrees, mViewWidth / 2f, mViewHeight / 2f);
        setImageMatrix(mMatrix);
        mScaleFactor = 1f;

        return super.setFrame(l, t, r, b);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction() & MotionEvent.ACTION_MASK) {
            case MotionEvent.ACTION_DOWN:
                mMatrix.set(getImageMatrix());
                mFocusX = event.getX();
                mFocusY = event.getY();
                break;

            case MotionEvent.ACTION_MOVE:
                float dx = event.getX() - mFocusX;
                float dy = event.getY() - mFocusY;
                mMatrix.postTranslate(dx, dy);
                setImageMatrix(mMatrix);
                break;

            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_POINTER_UP:
                break;

            case MotionEvent.ACTION_POINTER_DOWN:
                float oldDistance = spacing(event);
                if (oldDistance > 10f) {
                    mMatrix.set(getImageMatrix());
                    midPoint(mPointF, event);
                }
                break;

            case MotionEvent.ACTION_MOVE | MotionEvent.ACTION_POINTER_DOWN:
                float newDistance = spacing(event);
                if (newDistance > 10f) {
                    mMatrix.set(getImageMatrix());
                    float scale = newDistance / oldDistance;
                    mMatrix.postScale(scale, scale, mPointF.x, mPointF.y);
                    mScaleFactor *= scale;
                    setImageMatrix(mMatrix);
                }
                break;
        }

        return true;
    }

    private PointF mPointF = new PointF();

    private float spacing(MotionEvent event) {
        float x = event.getX(0) - event.getX(1);
        float y = event.getY(0) - event.getY(1);
        return (float) Math.sqrt(x * x + y * y);
    }

    private void midPoint(PointF point, MotionEvent event) {
        float x = event.getX(0) + event.getX(1);
        float y = event.getY(0) + event.getY(1);
        point.set(x / 2f, y / 2f);
    }

    public void setImageBitmap(Bitmap bm) {
        super.setImageBitmap(bm);
        mImageWidth = bm.getWidth();
        mImageHeight = bm.getHeight();
    }

    public void setRotationDegrees(float degrees) {
        mRotationDegrees = degrees;
        invalidate();
    }
}

这个自定义控件使用了 Matrix 类来处理 ImageView 的变换，包括平移、缩放和旋转。在 onTouchEvent() 中，我们只需要检测触摸事件的类型，然后更新相应的变换矩阵即可。在 setFrame() 中，我们会重新计算图片的缩放比例，并且确保图片不会超出屏幕的范围。你可以根据自己的需求修改代码来适应不同的场景。