在做分享功能的时候，需要截取全屏内容，一屏展示不完的内容，一般我们会用到 ListView ，ScrollView或Recyclerview
一： 普通截屏的实现
获取当前Window 的 DrawingCache 的方式，即decorView的DrawingCache
/**
* shot the current screen ,with the status but the status is trans *
*
* @param ctx current activity
*/
public static Bitmap shotActivity(Activity ctx) { View view = ctx.getWindow().getDecorView();
view.setDrawingCacheEnabled(true);
view.buildDrawingCache(); Bitmap bp = Bitmap.createBitmap(view.getDrawingCache(), , , view.getMeasuredWidth(),
view.getMeasuredHeight()); view.setDrawingCacheEnabled(false);
view.destroyDrawingCache(); return bp;
}
获取当前View的DrawingCache
public static Bitmap getViewBp(View v) {
if (null == v) {
return null;
}
v.setDrawingCacheEnabled(true);
v.buildDrawingCache();
if (Build.VERSION.SDK_INT >= ) {
v.measure(MeasureSpec.makeMeasureSpec(v.getWidth(),
MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(
v.getHeight(), MeasureSpec.EXACTLY));
v.layout((int) v.getX(), (int) v.getY(),
(int) v.getX() + v.getMeasuredWidth(),
(int) v.getY() + v.getMeasuredHeight());
} else {
v.measure(MeasureSpec.makeMeasureSpec(, MeasureSpec.UNSPECIFIED),
MeasureSpec.makeMeasureSpec(, MeasureSpec.UNSPECIFIED));
v.layout(, , v.getMeasuredWidth(), v.getMeasuredHeight());
}
Bitmap b = Bitmap.createBitmap(v.getDrawingCache(), , , v.getMeasuredWidth(), v.getMeasuredHeight());
v.setDrawingCacheEnabled(false);
v.destroyDrawingCache();
return b;
}
二：开源方案
在滚动视图中，如果当前View并没有在视图中全部绘制出来，我们可以利用View的ScrollTo()和ScrollBy()方法来移动画布，同时获取当前View的可视部分的DrawingCache，最后进行拼接得到其Bitmap，参考:PGSSoft/scrollscreenshot@[Github]，原理图如下：
三： ScrollView截屏
三个截屏中，ScrollView最简单，因为ScrollView只有一个childView，虽然没有全部显示在界面上，但是已经全部渲染绘制，因此可以直接 调用`scrollView.draw(canvas)`来完成截图，
/**
* http://blog.csdn.net/lyy1104/article/details/40048329
*/
public static Bitmap shotScrollView(ScrollView scrollView) {
int h = ;
Bitmap bitmap = null;
for (int i = ; i < scrollView.getChildCount(); i++) {
h += scrollView.getChildAt(i).getHeight();
scrollView.getChildAt(i).setBackgroundColor(Color.parseColor("#ffffff"));
}
bitmap = Bitmap.createBitmap(scrollView.getWidth(), h, Bitmap.Config.RGB_565);
final Canvas canvas = new Canvas(bitmap);
scrollView.draw(canvas);
return bitmap;
}
四： ListView截屏
而ListView就是会回收与重用Item，并且只会绘制在屏幕上显示的ItemView，根据*上大神的建议，采用一个List来存储Item的视图，这种方案依然不够好，当Item足够多的时候，可能会发生oom。
/**
* http://*.com/questions/12742343/android-get-screenshot-of-all-listview-items
*/
public static Bitmap shotListView(ListView listview) { ListAdapter adapter = listview.getAdapter();
int itemscount = adapter.getCount();
int allitemsheight = ;
List<Bitmap> bmps = new ArrayList<Bitmap>(); for (int i = ; i < itemscount; i++) { View childView = adapter.getView(i, null, listview);
childView.measure(
View.MeasureSpec.makeMeasureSpec(listview.getWidth(), View.MeasureSpec.EXACTLY),
View.MeasureSpec.makeMeasureSpec(, View.MeasureSpec.UNSPECIFIED)); childView.layout(, , childView.getMeasuredWidth(), childView.getMeasuredHeight());
childView.setDrawingCacheEnabled(true);
childView.buildDrawingCache();
bmps.add(childView.getDrawingCache());
allitemsheight += childView.getMeasuredHeight();
} Bitmap bigbitmap =
Bitmap.createBitmap(listview.getMeasuredWidth(), allitemsheight, Bitmap.Config.ARGB_8888);
Canvas bigcanvas = new Canvas(bigbitmap); Paint paint = new Paint();
int iHeight = ; for (int i = ; i < bmps.size(); i++) {
Bitmap bmp = bmps.get(i);
bigcanvas.drawBitmap(bmp, , iHeight, paint);
iHeight += bmp.getHeight(); bmp.recycle();
bmp = null;
} return bigbitmap;
}
五： RecyclerView截屏
我们都知道，在新的Android版本中，已经可以用RecyclerView来代替使用ListView的场景，相比较ListView，RecyclerView对Item View的缓存支持的更好。可以采用和ListView相同的方案，这里也是在*上看到的方案。
/**
* https://gist.github.com/PrashamTrivedi/809d2541776c8c141d9a
*/
public static Bitmap shotRecyclerView(RecyclerView view) {
RecyclerView.Adapter adapter = view.getAdapter();
Bitmap bigBitmap = null;
if (adapter != null) {
int size = adapter.getItemCount();
int height = ;
Paint paint = new Paint();
int iHeight = ;
final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / ); // Use 1/8th of the available memory for this memory cache.
final int cacheSize = maxMemory / ;
LruCache<String, Bitmap> bitmaCache = new LruCache<>(cacheSize);
for (int i = ; i < size; i++) {
RecyclerView.ViewHolder holder = adapter.createViewHolder(view, adapter.getItemViewType(i));
adapter.onBindViewHolder(holder, i);
holder.itemView.measure(
View.MeasureSpec.makeMeasureSpec(view.getWidth(), View.MeasureSpec.EXACTLY),
View.MeasureSpec.makeMeasureSpec(, View.MeasureSpec.UNSPECIFIED));
holder.itemView.layout(, , holder.itemView.getMeasuredWidth(),
holder.itemView.getMeasuredHeight());
holder.itemView.setDrawingCacheEnabled(true);
holder.itemView.buildDrawingCache();
Bitmap drawingCache = holder.itemView.getDrawingCache();
if (drawingCache != null) { bitmaCache.put(String.valueOf(i), drawingCache);
}
height += holder.itemView.getMeasuredHeight();
} bigBitmap = Bitmap.createBitmap(view.getMeasuredWidth(), height, Bitmap.Config.ARGB_8888);
Canvas bigCanvas = new Canvas(bigBitmap);
Drawable lBackground = view.getBackground();
if (lBackground instanceof ColorDrawable) {
ColorDrawable lColorDrawable = (ColorDrawable) lBackground;
int lColor = lColorDrawable.getColor();
bigCanvas.drawColor(lColor);
} for (int i = ; i < size; i++) {
Bitmap bitmap = bitmaCache.get(String.valueOf(i));
bigCanvas.drawBitmap(bitmap, 0f, iHeight, paint);
iHeight += bitmap.getHeight();
bitmap.recycle();
}
}
return bigBitmap;
}
六： 其他屏幕相关工具
1.获取状态来高度常见方式
/**
* get the height of status *
*/
public static int getStatusH(Activity ctx) {
Rect s = new Rect();
ctx.getWindow().getDecorView().getWindowVisibleDisplayFrame(s);
return s.top;
}
/**
* get the height of status *
*/
public static int getStatusH(Context ctx) {
int statusHeight = -;
try {
Class<?> clazz = Class.forName("com.android.internal.R$dimen");
Object object = clazz.newInstance();
int height = Integer.parseInt(clazz.getField("status_bar_height")
.get(object).toString());
statusHeight = ctx.getResources().getDimensionPixelSize(height);
} catch (Exception e) {
e.printStackTrace();
}
return statusHeight;
}
/**
* get the height of status *
*/
public static int getStatusHeight(Activity activity) {
int resourceId = activity.getResources().getIdentifier("status_bar_height", "dimen", "android");
return resourceId > ? activity.getResources().getDimensionPixelSize(resourceId) : ;
}
2.获取标题栏高度
/**
* get the height of title *
*/
public static int getTitleH(Activity ctx) {
int contentTop = ctx.getWindow()
.findViewById(Window.ID_ANDROID_CONTENT).getTop();
return contentTop - getStatusH(ctx);
}
3.获取屏幕宽高
/**
* get the width of screen **
*/
public static int getScreenW(Context ctx) {
int w = ;
if (Build.VERSION.SDK_INT > ) {
Point p = new Point();
((WindowManager) ctx.getSystemService(Context.WINDOW_SERVICE))
.getDefaultDisplay().getSize(p);
w = p.x;
} else {
w = ((WindowManager) ctx.getSystemService(Context.WINDOW_SERVICE))
.getDefaultDisplay().getWidth();
}
return w;
}
/**
* get the height of screen *
*/
public static int getScreenH(Context ctx) {
int h = ;
if (Build.VERSION.SDK_INT > ) {
Point p = new Point();
((WindowManager) ctx.getSystemService(Context.WINDOW_SERVICE))
.getDefaultDisplay().getSize(p);
h = p.y;
} else {
h = ((WindowManager) ctx.getSystemService(Context.WINDOW_SERVICE))
.getDefaultDisplay().getHeight();
}
return h;
}
/**
* 获得屏幕高度
*
* @param context
* @return
*/
public static int getScreenWidth(Context context) {
WindowManager wm = (WindowManager) context
.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics outMetrics = new DisplayMetrics();
wm.getDefaultDisplay().getMetrics(outMetrics);
return outMetrics.widthPixels;
}
相关源码：