增加动画
可以先看[Android中的动画]
需要写4个动画
(https://blog.csdn.net/u010356768/article/details/80908163)
第一个
left2right_in.xml
<set xmlns:android="http://schemas.android.com/apk/res/android">
<translate
android:fromXDelta="-100%"
android:toXDelta="0"
android:duration="800"/>
</set>
第二个
left2right_out.xml
<set xmlns:android="http://schemas.android.com/apk/res/android">
<translate
android:fromXDelta="0"
android:toXDelta="100%"
android:duration="800"/>
</set>
第三个
right2left_in
<set xmlns:android="http://schemas.android.com/apk/res/android">
<translate
android:fromXDelta="100%"
android:toXDelta="0"
android:duration="800"/>
</set>
第四个
right2left_out
<set xmlns:android="http://schemas.android.com/apk/res/android">
<translate
android:fromXDelta="0"
android:toXDelta="-100%"
android:duration="800"/>
</set>
现在动画写好了,但是不能直接使用,因为我们在滑动的时候,会有2张图片同时出现在屏幕中,而我们现在屏幕上只有一个ImageView,是不能同时显示2张图的
因此,我们需要把屏幕上的ImageView,换成
activity_display_image
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.DisplayImageActivity"
android:gravity="center"
android:orientation="horizontal">
<Button
android:id="@+id/btn_previous"
android:layout_width="50dp"
android:layout_height="50dp"/>
<!-- <ImageView
android:id="@+id/img_thumb"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:src="@mipmap/ic_launcher"
android:scaleType="fitXY"
android:adjustViewBounds="true"
/>-->
<ImageSwitcher
android:id="@+id/image_switcher"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<Button
android:id="@+id/btn_next"
android:layout_width="50dp"
android:layout_height="50dp"/>
</LinearLayout>
DisplayImageActivity
public class DisplayImageActivity extends AppCompatActivity implements View.OnClickListener {
private Button btnPrevious;
private Button btnNext;
//private ImageView imgThumb;
private ImageSwitcher imageSwitcher;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_image);
btnPrevious = findViewById(R.id.btn_previous);
btnNext = findViewById(R.id.btn_next);
//imgThumb = findViewById(R.id.img_thumb);
imageSwitcher = findViewById(R.id.image_switcher);
//为imageSwitcher添加子集ImageView,只能增加2个Imageview
/*ImageView iv = new ImageView(this);
imageSwitcher.addView(iv);
iv = new ImageView(this);
imageSwitcher.addView(iv);*/
//除了上边添加ImageView的方法,我们可以使用以下代码,自动调用2次
imageSwitcher.setFactory(new ViewSwitcher.ViewFactory() {
@Override
public View makeView() {
ImageView iv = new ImageView(DisplayImageActivity.this);
FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT,FrameLayout.LayoutParams.MATCH_PARENT);
iv.setLayoutParams(params);
return iv;
}
});
btnPrevious.setOnClickListener(this);
btnNext.setOnClickListener(this);
//获取数据源
ImageStoreApplication application = (ImageStoreApplication) getApplication();
imageList = application.getImages();
//获取当前默认需要显示的图片的索引
currentImageIndex = getIntent().getIntExtra("position", 0);
//显示图片
displayImage();
}
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.btn_previous:
diaplayPrevious();
break;
case R.id.btn_next:
diaplayNext();
break;
}
}
//当前显示的图片的索引
private int currentImageIndex;
//数据源
private List<Image> imageList;
/**
* 显示图片
*/
private void displayImage() {
LoadImageTask task = new LoadImageTask();
task.execute();
}
/**
* 显示上一张
*/
private void diaplayPrevious() {
currentImageIndex--;
if (currentImageIndex < 0) {
currentImageIndex = imageList.size() - 1;
}
//设置动画,从左至右
imageSwitcher.setInAnimation(this,R.anim.left2right_in);
imageSwitcher.setOutAnimation(this,R.anim.left2right_out);
displayImage();
}
/**
* 显示下一张
*/
private void diaplayNext() {
currentImageIndex++;
if (currentImageIndex >= imageList.size()) {
currentImageIndex = 0;
}
//设置动画,从右至左
imageSwitcher.setInAnimation(this,R.anim.right2left_in);
imageSwitcher.setOutAnimation(this,R.anim.right2left_out);
displayImage();
}
private static final int IMAGE_MAX_SIZE = 200;
private Map<View,LoadImageTask> tasks = new HashMap<View, LoadImageTask>();
//参数;是否更新进度;结果
private class LoadImageTask extends AsyncTask<Void,Void,Bitmap> {
private Image image;
public LoadImageTask() {
super();
this.image = imageList.get(currentImageIndex);
}
@Override
protected Bitmap doInBackground(Void... voids) {
//判断是否需要解码图片
if(image.getBitmap() == null){
//判断并计算图片的缩放比
//200单位是px
int rate = 1;
if(image.getWidth()>IMAGE_MAX_SIZE&&image.getHeight()>IMAGE_MAX_SIZE){
if(image.getWidth()<image.getHeight()){
rate = image.getWidth()/IMAGE_MAX_SIZE;
}else {
rate = image.getHeight()/IMAGE_MAX_SIZE;
}
}
//创建解码图片选项参数
BitmapFactory.Options opts = new BitmapFactory.Options();
opts.inSampleSize = rate;
//解码图片得到图片的bitmap对象
Bitmap bitmap = BitmapFactory.decodeFile(image.getData(),opts);
Log.d("Image","解码完成,bitmap尺寸为"+bitmap.getWidth()+"x"+bitmap.getHeight()+"bitmap占用内存:"+bitmap.getByteCount());
//将解码得到的Bitmap封装到图片数据中
image.setBitmap(bitmap);
}
return null;
}
@Override
protected void onPostExecute(Bitmap bitmap) {
//imgThumb.setImageBitmap(image.getBitmap());
Drawable drawable = new BitmapDrawable(getResources(),image.getBitmap());
imageSwitcher.setImageDrawable(drawable);
}
}
private float downX;
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()){
case MotionEvent.ACTION_DOWN:
Log.d("Motion","ACTION_DOWN->"+event.getX()+","+event.getY());
downX = event.getX();
break;
case MotionEvent.ACTION_UP:
Log.d("Motion","ACTION_UP->"+event.getX()+","+event.getY());
if(event.getX()-downX>60){
Log.d("Motion","从左至右滑动");
diaplayPrevious();
}
if(downX - event.getX()>60){
Log.d("Motion","从右至左滑动");
diaplayNext();
}
break;
case MotionEvent.ACTION_MOVE:
Log.d("Motion","ACTION_MOVE->"+event.getX()+","+event.getY());
break;
}
return false;
}
}
效果图
其中
imageSwitcher.setFactory(new ViewSwitcher.ViewFactory() {
@Override
public View makeView() {
ImageView iv = new ImageView(DisplayImageActivity.this);
FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.MATCH_PARENT,FrameLayout.LayoutParams.MATCH_PARENT);
iv.setLayoutParams(params);
return iv;
}
});
FrameLayout.LayoutParams,之所以用FrameLayout,是因为