玩转Android---UI篇---ZoomControls放大缩小图片

原址：http://hualang.iteye.com/category/143855

ZoomControls控件是一个可以缩放但控件，效果如下图

以下是它但一些主要但方法

hasFocus ()：判断焦点

hide ()：隐藏

onTouchEvent (MotionEvent event)：现这个方法来处理触摸屏移动事件

setIsZoomInEnabled (boolean isEnabled)：是否允许放大

setIsZoomOutEnabled (boolean isEnabled)：是否允许缩小

setOnZoomInClickListener (View.OnClickListener listener)：注册放大监听器

setOnZoomOutClickListener (View.OnClickListener listener)：注册缩小监听器

setZoomSpeed (long speed)：设置缩放速度

show ()：显示

这里面，如果将setIsZoomInEnabled()方法设置为false，那么这个放大的按钮就变成了灰色，不能用了，其实这个控件就是两个按钮而已，只是有外观，没有功能，如果你要放大图片或者缩小图片，还是要在监听事件中实现

开始看代码

main.xml

Java代码


<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:id="@+id/layout1"

>

<ImageView

android:id="@+id/imgview"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:src="@drawable/yuanyuan"

/>

<ZoomControls

android:id="@+id/zoomcontrol"

android:layout_gravity="bottom"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

/>

</LinearLayout>

ZoomExampleActivity.java

Java代码


package com.loulijun.zoomcontroltest;

import android.app.Activity;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.Matrix;

import android.os.Bundle;

import android.util.DisplayMetrics;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.ImageView;

import android.widget.LinearLayout;

import android.widget.ZoomControls;

public class ZoomExampleActivity extends Activity {

private LinearLayout layout1;

private ZoomControls zoom;

private ImageView img;

private int id=0;

private int displayWidth;

private int displayHeight;

private float scaleWidth = 1;

private float scaleHeight = 1;

private Bitmap bmp;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

layout1 = (LinearLayout)findViewById(R.id.layout1);

//取得屏幕分辨率大小

DisplayMetrics dm = new DisplayMetrics();

getWindowManager().getDefaultDisplay().getMetrics(dm);

displayWidth = dm.widthPixels;

//屏幕高度减去zoomControls的高度

displayHeight = dm.heightPixels;

bmp = BitmapFactory.decodeResource(getResources(), R.drawable.yuanyuan);

img = (ImageView)findViewById(R.id.imgview);

//zoom.hide();隐藏zoomControls

//zoom.show();显示zoomCOntrols

zoom = (ZoomControls)findViewById(R.id.zoomcontrol);

img = (ImageView)findViewById(R.id.imgview);

zoom.setIsZoomInEnabled(true);

zoom.setIsZoomOutEnabled(true);

//图片放大

zoom.setOnZoomInClickListener(new OnClickListener()

{

public void onClick(View v)

{

int bmpWidth = bmp.getWidth();

int bmpHeight = bmp.getHeight();

//设置图片放大但比例

double scale = 1.25;

//计算这次要放大的比例

scaleWidth = (float)(scaleWidth*scale);

scaleHeight = (float)(scaleHeight*scale);

//产生新的大小但Bitmap对象

Matrix matrix = new Matrix();

matrix.postScale(scaleWidth, scaleHeight);

Bitmap resizeBmp = Bitmap.createBitmap(bmp,0,0,bmpWidth,bmpHeight,matrix,true);

img.setImageBitmap(resizeBmp);

}

});

//图片减小

zoom.setOnZoomOutClickListener(new OnClickListener()

{

public void onClick(View v) {

int bmpWidth = bmp.getWidth();

int bmpHeight = bmp.getHeight();

//设置图片放大但比例

double scale = 0.8;

//计算这次要放大的比例

scaleWidth = (float)(scaleWidth*scale);

scaleHeight = (float)(scaleHeight*scale);

//产生新的大小但Bitmap对象

Matrix matrix = new Matrix();

matrix.postScale(scaleWidth, scaleHeight);

Bitmap resizeBmp = Bitmap.createBitmap(bmp,0,0,bmpWidth,bmpHeight,matrix,true);

img.setImageBitmap(resizeBmp);

}

});

}

}

效果如下：