今天下载传智播客黎活明老师的Android视频看了图片拖动和缩放，放上去以后学习用。
package com.example.test_pictrue_move_drag;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Matrix;import android.graphics.PointF;import android.os.Bundle;import android.util.FloatMath;import android.view.MotionEvent;import android.view.View;import android.widget.ImageView;public class MainActivity extends Activity { private ImageView imageView ; private PointF startPoint = new PointF(); private Matrix matrix = new Matrix() ; private Matrix saveCurrentMatrix = new Matrix(); // 初始状态 private final static int NONE = 0; // 拖动 private final static int DRAG = 1; // 缩放 private final static int ZOOM = 2; // 记录当前模式 private int MODE = NONE ; // 计算两点之间的距离 private float startDistance ; // 计算两点之间的中心点 private PointF midPoint ; // private Bitmap bitmap ; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); imageView = (ImageView) findViewById(R.id.imageView); imageView.setOnTouchListener(new View.OnTouchListener() { @Override public boolean onTouch(View v, MotionEvent event) { // TODO Auto-generated method stub switch (event.getAction() & MotionEvent.ACTION_MASK) { case MotionEvent.ACTION_DOWN: // 手指按下屏幕 saveCurrentMatrix.set(imageView.getImageMatrix()); // 记录imageView的当前移动位置 startPoint.set(event.getX(), event.getY()); // 记录开始按下的点坐标 MODE = DRAG ; break; case MotionEvent.ACTION_POINTER_DOWN: // 屏幕上已经有一个触点，再有一个手指按下屏幕 MODE = ZOOM ; startDistance = distance(event); if(startDistance > 10f){ midPoint = mid(event); saveCurrentMatrix.set(imageView.getImageMatrix());//记录ImageView当前的缩放倍数 } break ; case MotionEvent.ACTION_MOVE: if(MODE == DRAG ){ // 移动距离 float dx = event.getX() - startPoint.x; float dy = event.getY() - startPoint.y; matrix.set(saveCurrentMatrix); //在上一次移动位置的基础上进行移动 // 进行拖动 matrix.postTranslate(dx, dy); } else if (MODE == ZOOM){ float endDis = distance(event);//结束距离 if(endDis > 10f){ float scale = endDis / startDistance;//得到缩放倍数 matrix.set(saveCurrentMatrix);//在上一次缩放位置的基础上进行缩放 matrix.postScale(scale, scale, midPoint.x, midPoint.y); } } break ; case MotionEvent.ACTION_UP:// 手指离开屏幕 case MotionEvent.ACTION_POINTER_UP: // 有手指离开屏幕，但还屏幕还有触点 MODE = NONE ; break; } imageView.setImageMatrix(matrix); return true; } }); // bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.test_20150119100930); } /** * 计算两点之间的距离 * @param event * @return */ public static float distance(MotionEvent event) { float dx = event.getX(1) - event.getX(0); float dy = event.getY(1) - event.getY(0); return FloatMath.sqrt(dx*dx + dy*dy); } /** * 计算两点之间的中间点 * @param event * @return */ public static PointF mid(MotionEvent event){ float midX = (event.getX(1) + event.getX(0)) / 2; float midY = (event.getY(1) + event.getY(0)) / 2; return new PointF(midX, midY); } // /** // * 横向、纵向居中 // */ // protected void center(boolean horizontal, boolean vertical) { // Matrix m = new Matrix(); // m.set(matrix); // RectF rect = new RectF(0, 0, bitmap.getWidth(), bitmap.getHeight()); // m.mapRect(rect); // float height = rect.height(); // float width = rect.width(); // float deltaX = 0, deltaY = 0; // if (vertical) { // // 图片小于屏幕大小，则居中显示。大于屏幕，上方留空则往上移，下放留空则往下移 // int screenHeight = getResources().getDisplayMetrics().heightPixels; // if (height < screenHeight) { // deltaY = (screenHeight - height) / 2 - rect.top; // } else if (rect.top > 0) { // deltaY = -rect.top; // } else if (rect.bottom < screenHeight) { // deltaY = imageView.getHeight() - rect.bottom; // } // } // if (horizontal) { // int screenWidth = getResources().getDisplayMetrics().widthPixels; // if (width < screenWidth) { // deltaX = (screenWidth - width) / 2 - rect.left; // } else if (rect.left > 0) { // deltaX = -rect.left; // } else if (rect.right < screenWidth) { // deltaX = screenWidth - rect.right; // } // } // matrix.postTranslate(deltaX, deltaY); // } }?
? ? xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center" > <ImageView android:id="@+id/imageView" android:layout_width="fill_parent" android:layout_height="fill_parent" android:contentDescription="@null" android:layout_centerInParent="true" android:src="@drawable/test_20150119100930" android:scaleType="matrix" /> </RelativeLayout>
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? ?附件还有一个另一种拖动的实现方式
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