我在一个适配器中使用getView,我正在创建一个imageview,并使其等于convertView之前已经初始化了视图。它包含图像缩略图,其中一些代表视频。
@Override
public View getView(int position, View convertView, ViewGroup container) {
// First check if this is the top row
if (position < mNumColumns) {
if (convertView == null) {
convertView = new View(mContext);
}
// Set empty view with height of ActionBar
//convertView.setLayoutParams(new AbsListView.LayoutParams(
// LayoutParams.MATCH_PARENT, mActionBarHeight));
return convertView;
}
// Now handle the main ImageView thumbnails
ImageView imageView;
if (convertView == null) { // if it's not recycled, instantiate and initialize
imageView = new RecyclingImageView(mContext);
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setLayoutParams(mImageViewLayoutParams);
} else { // Otherwise re-use the converted view
imageView = (ImageView) convertView;
}
// Check the height matches our calculated column width
if (imageView.getLayoutParams().height != mItemHeight) {
imageView.setLayoutParams(mImageViewLayoutParams);
}
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
if(images.get(position - mNumColumns).getUriString().contains("video")){
//display video icon
}
else
{
//don't display video icon
}
// Finally load the image asynchronously into the ImageView, this also takes care of
// setting a placeholder image while the background thread runs
if (images != null && !images.isEmpty())
mImageFetcher.loadImage(images.get(position - mNumColumns).getUriString()/*.imageUrls[position - mNumColumns]*/, imageView);
return imageView;
}
缩略图上没有“播放”按钮来指定它们是视频,因此在这些情况下我需要以编程方式添加播放按钮。
通常我使用带有膨胀布局的视图模式,在这种情况下我没有这样做,因为我实际上不想在内存中存在某些东西。
所以我想以编程方式将RelativeLayout作为每个单元格的根视图(mRelativeLayout = (RelativeLayout)convertView
),并将imageview和playbutton imageview添加到该转换视图中
我该怎么做?它需要修改此语句,但我不确定如何初始化所有重用的视图
} else { // Otherwise re-use the converted view
imageView = (ImageView) convertView;
}
答案 0 :(得分:3)
我认为这里最好的方法是使用一个返回不同类型视图的适配器(通过覆盖getViewTypeCount()
和getItemViewType()
),例如{ {3}}
这样,您根本不需要以编程方式更改返回的视图。只需定义两个XML布局,并根据该位置的项目是否有视频来膨胀/重用其中一个或另一个。
这不仅会更加清晰,而且还会导致“转换”的性能损失。每当视频行作为convertView
提供给另一个没有一个的项目时,一个视图到另一个视图,反之亦然
答案 1 :(得分:2)
我会让您的getView()
始终返回RelativeLayout
对象(我在下面称之为containerView
),并将ImageView(s)
作为子项添加到该对象中。
这里唯一的复杂因素是您需要为这些子标识符提供标识符,以便以后可以从回收的convertView
中检索它们。请注意,我使用了内置的静态View.generateViewId()
,这是API级别17.如果您需要它在API级别17之前工作,您可以使用唯一的整数创建自己的ID(例如1 ,2等) - 只要确保它们不大于0x0FFFFFF
。 更新:我添加了以下用于此目的的代码。
请参阅我在下面的几点中添加的评论。
@Override
public View getView(int position, View convertView, ViewGroup container) {
// First check if this is the top row
if (position < mNumColumns) {
if (convertView == null) {
convertView = new View(mContext);
}
// Set empty view with height of ActionBar
//convertView.setLayoutParams(new AbsListView.LayoutParams(
// LayoutParams.MATCH_PARENT, mActionBarHeight));
return convertView;
}
// Now handle the main ImageView thumbnails
RelativeLayout containerView;
ImageView imageView;
ImageView videoIconView; // TODO: or whatever type you want to use for this...
if (convertView == null) { // if it's not recycled, instantiate and initialize
containerView = new RelativeLayout(mContext);
// TODO: The layout params that you used for the image view you probably
// now want to use for the container view instead...
imageView.setLayoutParams(mImageViewLayoutParams); // If so, you can change their name...
imageView = new RecyclingImageView(mContext);
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
//imageView.setLayoutParams(mImageViewLayoutParams); // This probably isn't needed any more.
// Generate an Id to use for later retrieval of the imageView...
// This assumes it was initialized to -1 in the constructor to mark it being unset.
// Note, this could be done elsewhere in this adapter class (such as in
// the constructor when mImageId is initialized, since it only
// needs to be done once (not once per view) -- I'm just doing it here
// to avoid having to show any other functions.
if (mImageId == -1) {
mImageId = View.generateViewId();
}
imageView.setId(mImageId);
containerView.addView(imageView, RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);
// NOTE: At this point, I would personally always just add the video icon
// as a child of containerView here no matter what (generating another unique
// view Id for it, mVideoIconId, similar to how was shown above for the imageView)
// and then set it to either VISIBLE or INVISIBLE/GONE below depending on whether
// the URL contains the word "video" or not.
// For example:
vidoIconView = new <whatever>;
// TODO: setup videoIconView with the proper drawable, scaling, etc. here...
if (mVideoIconId == -1) {
mVideoIconId = View.generateViewId();
}
videoIconView.setId(mVideoIconId);
containerView.addView(videoIconView, RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
final RelativeLayout.LayoutParams layout = ((RelativeLayout.LayoutParams)containerView.getLayoutParams());
layout.addRule(RelativeLayout.LayoutParams.CENTER_HORIZONTAL); // ... or whatever else you want
layout.addRule(RelativeLayout.LayoutParams.ALIGN_PARENT_BOTTOM); // ... or whatever else you want
} else {
// Otherwise re-use the converted view
containerView = (RelativeLayout) convertView;
imageView = containerView.findViewById(mImageId);
videoIconView = containerView.findViewById(mVideoIconId); // see comment above
}
// Check the height matches our calculated column width
if (containerView.getLayoutParams().height != mItemHeight) {
containerView.setLayoutParams(mImageViewLayoutParams);
}
if(images.get(position - mNumColumns).getUriString().contains("video")){
//display video icon
// see comment above, here you can probably just do something like:
videoIconView.setVisibility(View.VISIBLE);
}
else
{
//don't display video icon
videoIconView.setVisibility(View.GONE); // could also use INVISIBLE here... up to you.
}
// Finally load the image asynchronously into the ImageView, this also takes care of
// setting a placeholder image while the background thread runs
if (images != null && !images.isEmpty())
mImageFetcher.loadImage(images.get(position - mNumColumns).getUriString()/*.imageUrls[position - mNumColumns]*/, imageView);
return containerView;
}
<强>更新强>
在回答评论中的问题时,我使用类似的东西(在我的自定义“ViewController”基类中):
private static int s_nextGeneratedId = 1;
/**
* Try to do the same thing as View.generateViewId() when using API level < 17.
* @return Unique integer that can be used with setId() on a View.
*/
protected static int generateViewId() {
// AAPT-generated IDs have the high byte nonzero; clamp to the range under that.
if (++s_nextGeneratedId > 0x00FFFFFF)
s_nextGeneratedId = 1; // Roll over to 1, not 0.
return s_nextGeneratedId;
}
请注意,网格中的每个单元格都不需要唯一的视图ID。相反,您只需要为可能想要使用findViewById()
访问的每种类型的子视图使用它。因此,在您的情况下,您可能只需要两个唯一ID。由于从您的xml布局文件自动生成的视图ID到R.java
通常非常大,我发现只需对我的手工生成的ID使用较小的数字(如上所示)。