【移動應用開發技術】Android中怎么利用ImageView設置手指滑動控件縮放

Android中怎么利用ImageView設置手指滑動控件縮放，相信很多沒有經驗的人對此束手無策，為此本文總結了問題出現的原因和解決方法，通過這篇文章希望你能解決這個問題。實現步驟1,imageview設置scaletype為android:scaleType=”matrix”2,設置imageview的setOnTouchListener,重寫里面的代碼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一定要設置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.也可以用自定義控件imageview,重寫里面的onTouchEvent,本文就是用的自定義控件得到方式實現的.代碼自定義控件的代碼,主要是重寫的onTouchEvent的代碼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坐標

*

@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的代碼<com.test.administrator.imageviewscale.MyImageView

android:id="@+id/iv"

android:layout_width="mat