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我有一个可以拖动、缩放和缩放的 ImageView，我正在使用以下类来执行此操作：

import android.content.Context;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;

/**
 * Created by ankitagrawal on 11/4/16.
 */
public class DragImageView extends ImageView {

    public DragImageView(Context context) {
        super(context);
        sharedConstructing(context);
    }

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

    public DragImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        sharedConstructing(context);
    }

    private void sharedConstructing(Context context) {
        super.setClickable(true);
        super.setOnTouchListener(new TouchListener());
    }

    private class TouchListener implements View.OnTouchListener {

        public TouchListener() {
            super();
        }
        Matrix matrix = new Matrix();
        Matrix savedMatrix = new Matrix();
        // We can be in one of these 3 states
        static final int NONE = 0;
        static final int DRAG = 1;
        static final int ZOOM = 2;
        int mode = NONE;
        // Remember some things for zooming
        PointF start = new PointF();
        PointF mid = new PointF();
        float oldDist = 1f;
        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 / 2, y / 2);
        }

        @Override
        public boolean onTouch(View v, MotionEvent event) {
            ImageView view = (ImageView) v;
            switch (event.getAction() & MotionEvent.ACTION_MASK) {
                case MotionEvent.ACTION_DOWN:
                    savedMatrix.set(matrix);
                    start.set(event.getX(), event.getY());
                    mode = DRAG;
                    break;
                case MotionEvent.ACTION_POINTER_DOWN:
                    oldDist = spacing(event);
                    if (oldDist > 10f) {
                        savedMatrix.set(matrix);
                        midPoint(mid, event);
                        mode = ZOOM;
                    }
                    break;
                case MotionEvent.ACTION_UP:
                case MotionEvent.ACTION_POINTER_UP:
                    mode = NONE;
                    break;
                case MotionEvent.ACTION_MOVE:
                    if (mode == DRAG) {
                        // ...
                        matrix.set(savedMatrix);
                        matrix.postTranslate(event.getX() - start.x,
                                event.getY() - start.y);
                    }
                    else if (mode == ZOOM) {
                        float newDist = spacing(event);
                        if (newDist > 10f) {
                            matrix.set(savedMatrix);
                            float scale = newDist / oldDist;
                            matrix.postScale(scale, scale, mid.x, mid.y);
                        }
                    }
                    break;
            }

            view.setImageMatrix(matrix);
            return true; // indicate event was handled
        }
    }
}

但我有一个问题，即每当我在 viewpager 中滑动图像时，viewpager 每次都会在左上角加载下一个图像，这看起来很糟糕，但我希望下一个图像的位置和大小与前一个图像完全相同是并且也拖动应该从它停止的地方开始：我怎么能做到这一点？

注意：我不能使用 MATRIX 以外的 scaletype

我也尝试了stackoverflow答案的所有解决方案，但没有成功

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0 回答 0