android drawable 透明度,ImageView透明度 |
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ImageView 能显示的不仅仅是图片,任何Drawable对象都可以使用它来显示 xml android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> android:orientation="horizontal" android:layout_width="fill_parent" android:layout_height="wrap_content" android:gravity="center"> android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="增大透明度" /> android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="降低透明度" /> android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="下一张" /> android:layout_width="fill_parent" android:background="#0000ff" android:layout_height="240px" android:src="@drawable/shuangta" android:scaleType="fitCenter" /> android:layout_width="120dp" android:layout_height="120dp" android:background="#0000ff" android:layout_marginTop="10dp"/> Activity package org.crazyit.imageview; import android.app.Activity; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.drawable.BitmapDrawable; import android.os.Bundle; import android.view.MotionEvent; import android.view.View; import android.view.View.OnClickListener; import android.view.View.OnTouchListener; import android.widget.Button; import android.widget.ImageView; /** * Description: * site: crazyit.org * Copyright (C), 2001-2012, Yeeku.H.Lee * This program is protected by copyright laws. * Program Name: * Date: * @author Yeeku.H.Lee [email protected] * @version 1.0 */ public class ImageViewTest extends Activity { //定义一个访问图片的数组 int[] images = new int[]{ R.drawable.lijiang, R.drawable.qiao, R.drawable.shuangta, R.drawable.shui, R.drawable.xiangbi, }; //定义默认显示的图片 int currentImg = 2; //定义图片的初始透明度 private int alpha = 255; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); final Button plus = (Button)findViewById(R.id.plus); final Button minus = (Button)findViewById(R.id.minus); final ImageView image1 = (ImageView)findViewById(R.id.image1); final ImageView image2 = (ImageView)findViewById(R.id.image2); final Button next = (Button)findViewById(R.id.next); //定义查看下一张图片的监听器 next.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { if (currentImg >= 4) { currentImg = -1; } BitmapDrawable bitmapDrawable = (BitmapDrawable) image1 .getDrawable(); //如果图片还未回收,先强制回收该图片 if (!bitmapDrawable.getBitmap().isRecycled()) { bitmapDrawable.getBitmap().recycle(); } //改变ImageView显示的图片 image1.setImageBitmap(BitmapFactory.decodeResource(getResources() , images[++currentImg])); //try //{ 改变ImageView里显示的图片 //image1.setImageResource(images[++currentImg]); //} 捕捉内存溢出异常 //catch(OutOfMemoryError e) //{ //} } }); //定义改变图片透明度的方法 OnClickListener listener = new OnClickListener() { @Override public void onClick(View v) { if(v == plus) { alpha += 20; } if(v == minus) { alpha -= 20; } if(alpha >= 255) { alpha = 255; } if(alpha @Override public boolean onTouch(View view, MotionEvent event) { BitmapDrawable bitmapDrawable = (BitmapDrawable) image1 .getDrawable(); //获取第一个图片显示框中的位图 Bitmap bitmap = bitmapDrawable.getBitmap(); //bitmap图片实际大小与第一个ImageView的缩放比例 double scale = bitmap.getWidth() / 320.0; //获取需要显示的图片的开始点 int x = (int) (event.getX() * scale); int y = (int) (event.getY() * scale); if (x + 120 > bitmap.getWidth()) { x = bitmap.getWidth() - 120; } if (y + 120 > bitmap.getHeight()) { y = bitmap.getHeight() - 120; } //显示图片的指定区域 image2.setImageBitmap(Bitmap.createBitmap(bitmap, x, y, 120, 120)); image2.setAlpha(alpha); return false; } }); } } |
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