我一直没在Widgets上工作过,但是我有一些获取ImageView尺寸的经验。
这是我使用的一些代码:
public class ViewSizes {
public int width;
public int height;
public boolean isEmpty() {
boolean result = false;
if (0 >= width || 0 >= height) {
result = true;
}
return result;
}
}
那只是一个包含大小参数的虚拟类。
public static ViewSizes getSizes(View view) {
ViewSizes sizes = new ViewSizes();
sizes.width = view.getWidth();
sizes.height = view.getHeight();
if (sizes.isEmpty()) {
LayoutParams params = view.getLayoutParams();
if (null != params) {
int widthSpec = View.MeasureSpec.makeMeasureSpec(params.width, View.MeasureSpec.AT_MOST);
int heightSpec = View.MeasureSpec.makeMeasureSpec(params.height, View.MeasureSpec.AT_MOST);
view.measure(widthSpec, heightSpec);
}
sizes.width = view.getMeasuredWidth();
sizes.height = view.getMeasuredHeight();
}
return sizes;
}
该方法计算宽度,如果尚未发生测量周期,则强制进行测量。
public static boolean loadPhoto(ImageView view, String url, float aspectRatio) {
boolean processed = false;
ViewSizes sizes = ViewsUtils.getSizes(view);
if (!sizes.isEmpty()) {
int width = sizes.width - 2;
int height = sizes.height - 2;
if (ASPECT_RATIO_UNDEFINED != aspectRatio) {
if (height * aspectRatio > width) {
height = (int) (width / aspectRatio);
} else if (height * aspectRatio < width) {
width = (int) (height * aspectRatio);
}
}
processed = true;
}
return processed;
}
这个可能对你没什么用,我只是举个例子 - 我有一个ImageView和一个图片URL,需要将其参数化为图片和高度。
public class PhotoLayoutListener implements OnGlobalLayoutListener {
private ImageView view;
private String url;
private float aspectRatio;
public PhotoLayoutListener(ImageView view, String url, float aspectRatio) {
this.view = view;
this.url = url;
this.aspectRatio = aspectRatio;
}
boolean handled = false;
@Override
public void onGlobalLayout() {
if (!handled) {
PhotoUtils.loadPhoto(view, url, aspectRatio);
handled = true;
}
ViewTreeObserver viewTreeObserver = view.getViewTreeObserver();
if (viewTreeObserver.isAlive()) {
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
removeLayoutListenerPre16(viewTreeObserver, this);
} else {
removeLayoutListenerPost16(viewTreeObserver, this);
}
}
}
@SuppressWarnings("deprecation")
private void removeLayoutListenerPre16(ViewTreeObserver observer, OnGlobalLayoutListener listener){
observer.removeGlobalOnLayoutListener(listener);
}
@TargetApi(Build.VERSION_CODES.JELLY_BEAN)
private void removeLayoutListenerPost16(ViewTreeObserver observer, OnGlobalLayoutListener listener){
observer.removeOnGlobalLayoutListener(listener);
}
}
这只是一个布局监听器 - 我想在布局阶段完成后处理图像加载。
public static void setImage(ImageView view, String url, boolean forceLayoutLoading, float aspectRatio) {
if (null != view && null != url) {
final ViewTreeObserver viewTreeObserver = view.getViewTreeObserver();
if (forceLayoutLoading || !PhotoUtils.loadPhoto(view, url, aspectRatio)) {
if (viewTreeObserver.isAlive()) {
viewTreeObserver.addOnGlobalLayoutListener(new PhotoLayoutListener(view, url, aspectRatio));
}
}
}
}
这是我实际调用的方法。我给它视图和URL。如果该方法能够确定视图的大小,它会立即开始加载。否则,它只分配一个布局监听器,并在布局完成后启动加载过程。
你可以剥离一些参数 - forceLoading / aspectRatio 对你来说应该是无关紧要的。在更改
PhotoUtils.loadPhoto
方法之后,它将根据计算出的宽度/高度创建位图。