ImageView設定手指滑動縮放

本來就是我平時的兩篇練習,但是昨天看了一下感覺其實還挺有用的.就把他拿出了獻醜了,還有另外一篇關於控制元件抖動效果的部落格大家可以關注.

實現步驟

1, imageview設定scaletype為 android:scaleType=”matrix”

2, 設定imageview的setOnTouchListener,重寫裡面的程式碼

3, 新建一個matrix,
matrix.postScale(scale,scale,縮放中心,縮放中心);
image.setImageMatrix(matrix);

這樣image的大小就會改變了.

需要注意的幾點是 imageview一定要設定scaletype為matrix,否則圖片不能進行縮放.而且Bitmap也可以通過Matrix改變大小.

也可以用自定義控制元件imageview,重寫裡面的onTouchEvent,本文就是用的自定義控制元件得到方式實現的.

程式碼

自定義控制元件的程式碼,主要是重寫的onTouchEvent的程式碼

package com.test.administrator.imageviewscale;

import android.content.Context;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.renderscript.Float2;
import android.renderscript.Float4;
import android.util.AttributeSet;
import android.util.FloatMath;
import android.view.MotionEvent;
import android.widget.ImageView;

/**
 * Created by Administrator on 2016/3/21.
 */
public class MyImageView extends ImageView {
private PointF centerPoint;
private float firstdistance;
private Matrix matrix;

public MyImageView(Context context) {
super(context);
initParams();
}

private void initParams() {
matrix = new Matrix();
setImageMatrix(matrix);
}

public MyImageView(Context context, AttributeSet attrs) {
super(context, attrs);
initParams();
}

public MyImageView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initParams();
}



@Override
public boolean onTouchEvent(MotionEvent event) {
int count = event.getPointerCount();
if(count == 1){
switch (event.getAction()){
case MotionEvent.ACTION_DOWN:
System.out.println("actiondown 1----");
break;
case MotionEvent.ACTION_MOVE:
System.out.println("actionmove 1----");
break;
case MotionEvent.ACTION_UP:
System.out.println("actionup 1----");
break;
default:
break;
}
}else if(count == 2){
switch (event.getAction()&MotionEvent.ACTION_MASK){
case MotionEvent.ACTION_POINTER_DOWN:
 firstdistance = getDistance(event);
centerPoint = getCenterPoint(event);
System.out.println("actiondown 2===");
break;
case MotionEvent.ACTION_MOVE:
float distance = getDistance(event);
float scale = distance / firstdistance;
matrix.postScale(scale,scale,centerPoint.x,centerPoint.y);
setImageMatrix(matrix);
System.out.println(scale + "====");
firstdistance = distance;
System.out.println("actionmove 2===");
break;
case MotionEvent.ACTION_UP:

break;
default:
break;
}
}


return true;
}

/**
 * 獲取兩個點的中心點座標
 * @param event
 */
private PointF getCenterPoint(MotionEvent event) {
PointF point = new PointF();
point.x = (event.getX()+event.getX(1))/2;
point.y = (event.getY()+event.getY(1))/2;
return point;
}

/**
 * 兩根手指時手指間的距離
 * @param event
 */
private float getDistance(MotionEvent event) {
float x1 = event.getX();
float y1 = event.getY();

float x2 = event.getX(1);
float y2 = event.getY(1);
float distance = (float) Math.sqrt((x1 - x2)*(x1 - x2)+(y1 - y2)*(y1- y2));

return distance;
}
}
 

imageview的程式碼

<com.test.administrator.imageviewscale.MyImageView
android:id="@+id/iv"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:focusable="true"
android:clickable="true"
android:scaleType="matrix"
   android:src="@drawable/qq" />