TextView (getDrawingCache) 中的位图始终为 null

发布于 2024-10-30 05:09:47 字数 304 浏览 2 评论 0原文

我试图提取与显示的 TextView 实例关联的位图，但它总是返回空值。我做错了什么？我应该使用 textview.draw(canvas) 代替吗？

    TextView textview = (TextView) findViewById(R.id.text_title);
    textview.setDrawingCacheEnabled(true);
    textview.buildDrawingCache();        
    Bitmap bmp = textview.getDrawingCache();

原文

I am trying to extract the bitmap associated to the displayed TextView instance, but it always returns a null value. What Am I doing wrong? Should I use textview.draw(canvas) instead?

    TextView textview = (TextView) findViewById(R.id.text_title);
    textview.setDrawingCacheEnabled(true);
    textview.buildDrawingCache();        
    Bitmap bmp = textview.getDrawingCache();

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鞋纸虽美，但不合脚ㄋ〞 2024-11-06 05:09:47

在获取绘图缓存之前执行此操作将解决问题

view.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), 
            MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
view.layout(0, 0, view.getMeasuredWidth(), view.getMeasuredHeight());

，然后 getDrawingCache() 将返回一个位图并将该位图绘制在画布上。

如果您在应用程序中使用位图，则更愿意通过调用它们的 recycle() 方法来从内存中清除它们，以便从内存中清除位图以确保安全，以避免 outOfMemoryException

Do this before getting drawing cache it will solve the problem

view.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), 
            MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
view.layout(0, 0, view.getMeasuredWidth(), view.getMeasuredHeight());

and then getDrawingCache() will return a bitmap and draw that bitmap on your canvas.

and if you are using bitmaps in your app prefer to clear them from memory by calling recycle() method on them so that bitmap get cleared from the memory for your safe side to avoid outOfMemoryException

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