图片平移缩放

最新推荐文章于 2024-09-10 01:45:00 发布

Jack1378

最新推荐文章于 2024-09-10 01:45:00 发布

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分类专栏：移动互联

本文链接：https://blog.youkuaiyun.com/Jack20170316/article/details/74626900

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这篇博客介绍了如何在Android应用中实现图片的平移和缩放功能。通过设置ImageView的scaleType为matrix，并监听触摸事件，动态调整Matrix来实现图片的拖动和双指缩放。代码示例中，定义了MODE_DRAG、MODE_ZOOM和MODE_NONE三种模式，分别对应拖动、缩放和无操作状态，通过对MotionEvent的ACTION_DOWN、ACTION_POINTER_DOWN和ACTION_MOVE等事件的处理，实现了平移和缩放操作。

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    //布局文件
 <ImageView
    android:id="@+id/picture"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:scaleType="matrix"
    android:src="@drawable/dck"/>
//代码
            package com.example.lenovo_pc.mypicture;

import android.graphics.Matrix;
import android.graphics.PointF;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;

    public class MainActivity extends AppCompatActivity {

        private ImageView picture;
        private float xl;
        private float yl;
        private final int MODE_DRAG = 1;
        private final int MODE_ZOOM = 2;
        private final int MODE_NONE = 0;
        private int currentMode = MODE_NONE;
        private double distanceStart;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            initView();

        }

        Matrix matrix = new Matrix();
        Matrix matrixNew = new Matrix();

        private void initView() {
            picture = (ImageView) findViewById(R.id.picture);
            picture.setOnTouchListener(new View.OnTouchListener() {
                @Override
                public boolean onTouch(View v, MotionEvent event) {
                    switch (event.getAction() & MotionEvent.ACTION_MASK) {
                        case MotionEvent.ACTION_DOWN:
                            currentMode = MODE_DRAG;
                            xl = event.getX();
                            yl = event.getY();
                            matrix.set(picture.getImageMatrix());
                            break;
                        case MotionEvent.ACTION_POINTER_DOWN:
                            //计算两个手指间的距离
                            distanceStart = spacing(event);
                            if (distanceStart > 20) {
                                currentMode = MODE_ZOOM;
                                matrix.set(picture.getImageMatrix());
                            }
                            break;
                        case MotionEvent.ACTION_MOVE:
                            if (currentMode == MODE_DRAG) {
                                matrixNew.set(matrix);
                                float xn = event.getX();
                                float yn = event.getY();
                                //matrix.setTranslate(xn,yn);
                                matrixNew.postTranslate(xn - xl, yn - yl);
                            } else if (currentMode == MODE_ZOOM) {
                                if (spacing(event) > 20) {
                                    matrixNew.set(matrix);
                                    double distance = spacing(event);
                                    float scale = (float) (distance / distanceStart);
                                    PointF pointF = myPointF(event);
                                    matrixNew.postScale(scale, scale, pointF.x, pointF.y);
                                }
                            }

                            break;
                        case MotionEvent.ACTION_UP:
                            currentMode = MODE_NONE;
                            break;
                    }
                    picture.setImageMatrix(matrixNew);
                    return true;
                }
            });
        }

        //计算两点之间的距离
        private double spacing(MotionEvent event) {
            float x = 0;
            float y = 0;
            try {
                x = event.getX(0) - event.getX(1);
                y = event.getY(0) - event.getY(1);
            } catch (IllegalArgumentException e) {
            }
            return Math.sqrt(x * x + y * y);
        }

        public PointF myPointF(MotionEvent event) {
            float x1 = event.getX(0);
            float x2 = event.getX(1);
            float y1 = event.getY(0);
            float y2 = event.getY(1);

            float x = (x1 + x2) / 2;
            float y = (y1 + y2) / 2;
            PointF pointF = new PointF(x, y);
            return pointF;
        }
    }