Android关于布局的经典面试题及解答(一)

1、RelativeLayout中如何获取控件相对于屏幕的坐标?

用View.getLocationOnScreen（）方法。

2、如何用代码给RelativeLayout中的控件添加布局属性?

用addRule()的方法。

textView = (TextView)findViewById(R.id.text_view);RelativeLayout.LayoutParams para = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,ViewGroup.LayoutParams.WRAP_CONTENT);para.addRule(RelativeLayout.CENTER_IN_PARENT, RelativeLayout.TRUE);textView.setLayoutParams(para);

前提是textView的母布局是个RelativeLayout。

3、GridLayout和TableLayout的区别，有变化。

参见 http://blog.csdn.net/runninglion/article/details/10813929

4、如何实现截图?

利用/**
* 若要截图，在getDrawingCache前必须要measure和layout
* */
int widthMeasure = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
int heightMeasure = widthMeasure;
parent.measure(widthMeasure, heightMeasure);
parent.layout(0, 0, widthMeasure, heightMeasure);

这是骗人的，根本截不了。正确如下:

private void getDrawBitmap(){View parent = this.getWindow().getDecorView();//getLayoutInflater().inflate(R.layout.activity_main, null);if(parent == null){return;}parent.setDrawingCacheEnabled(true);//parent.buildDrawingCache();/** * 若要截图，在getDrawingCache前必须要measure和layout * */int widthMeasure = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);int heightMeasure = widthMeasure;parent.measure(widthMeasure, heightMeasure);parent.layout(0, 0, widthMeasure, heightMeasure);Bitmap b = parent.getDrawingCache();saveBitmap(b,"/storage/sdcard0/Download", "ttt.jpg");}/** * @param b * @param path * @param name * 保存图片 */private void saveBitmap(Bitmap b, String path,String name){File file = new File(path);if (!file.exists()){file.mkdir();}try {FileOutputStream fos = new FileOutputStream(path + "/" + name);b.compress(CompressFormat.JPEG, 85, fos);fos.close();} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}

参见： http://blog.csdn.net/developer_jiangqq/article/details/12164239 http://whithin.blog.51cto.com/690417/1159072

5、如何设置Activity或View的背景颜色为渐变色？？

//设置Activity从上到下的渐变色GradientDrawable gradientDraw = new GradientDrawable(Orientation.TOP_BOTTOM,new int[]{Color.RED, Color.YELLOW});getWindow().setBackgroundDrawable(gradientDraw);

效果：

更多关于GradientDrawable的用法: http://blog.csdn.net/qq315297923/article/details/8539736

6、android 的layout_weight的含义：

表示view的原布局宽度再加上剩余空间的程度的比重，所以当两个View的宽度设为wrap_content和match_parent时设同样的weight得效果刚好相反的原因。

参见:

http://www.xiaoyunduo.org/article/97/

http://blog.csdn.net/jincf2011/article/details/6598256

http://yulongsheng.blog.51cto.com/3804293/1260876

更多相关文章

随机推荐