? ?在View類中的onDraw方法的參數Canvas是View繪制的背景，要將View轉換為Bitmap實際上就是讓Canvas上的繪制操作繪制到Bitmap上。

? ?View轉化為Bitmap也稱為截屏，讓用戶看到的View視圖轉化為圖片的過程。

? ?關于View轉化Bitmap涉及到的View類中的方法有：

???protected?void?onDraw(Canvas?canvas)public?void?buildDrawingCache()public?void?destroyDrawingCache()public?Bitmap?getDrawingCache()public?void?setDrawingCacheEnabled(boolean?enabled)

? ?下面是常見的幾個View截屏的示例：

??

1.View轉Bitmap

? ?

public?final?Bitmap?screenShot(View?view)?{if?(null?==?view)?{throw?new?IllegalArgumentException("parameter?can't?be?null.");}view.measure(View.MeasureSpec.UNSPECIFIED,?View.MeasureSpec.UNSPECIFIED);view.layout(0,?0,?view.getMeasuredWidth(),?view.getMeasuredHeight());view.setDrawingCacheEnabled(true);view.buildDrawingCache();Bitmap?bitmap?=?view.getDrawingCache();return?bitmap;}

??

2. Activity轉Bitmap,不帶狀態欄

public?final?Bitmap?screenShot(Activity?activity)?{if?(null?==?activity)?{throw?new?IllegalArgumentException("parameter?can't?be?null.");}View?view?=?activity.getWindow().getDecorView();view.setDrawingCacheEnabled(true);view.buildDrawingCache();Bitmap?b1?=?view.getDrawingCache();Rect?frame?=?new?Rect();view.getWindowVisibleDisplayFrame(frame);int?statusBarHeight?=?frame.top;Point?point?=?new?Point();activity.getWindowManager().getDefaultDisplay().getSize(point);int?width?=?point.x;int?height?=?point.y;Bitmap?b2?=?Bitmap.createBitmap(b1,?0,?statusBarHeight,?width,?height?-?statusBarHeight);view.destroyDrawingCache();return?b2;}

3. ScrollView轉長Bitmap(類似錘子便簽的截長圖)

?public?final?Bitmap?screenShot(ScrollView?scrollView)?{if?(null?==?scrollView)?{throw?new?IllegalArgumentException("parameter?can't?be?null.");}int?height?=?0;Bitmap?bitmap;for?(int?i?=?0,?s?=?scrollView.getChildCount();?i?<?s;?i++)?{height?+=?scrollView.getChildAt(i).getHeight();scrollView.getChildAt(i).setBackgroundResource(android.R.drawable.screen_background_light);}bitmap?=?Bitmap.createBitmap(scrollView.getWidth(),?height,?Bitmap.Config.ARGB_8888);final?Canvas?canvas?=?new?Canvas(bitmap);scrollView.draw(canvas);return?bitmap;}

轉載于:https://blog.51cto.com/aiilive/1711443

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