Question

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，就是每当我在viewpager中刷图像时，viewpager每次都会在左上角加载下一个图像看起来很糟糕，但是我希望下一个图像的位置和大小与上一个图像是，并且拖动应该从它停止的地方开始：我怎么能完成这个？

注意：我不能使用MATRIX以外的scaletype

我也尝试过stackoverflow的所有解决方案，但没有成功

在ViewPager问题中使用Matrix缩放的ImageView

0 个答案: