android,利用layoutParams代碼動态布局空間位置

本文借鑒優秀文章：http://www.cnblogs.com/shaweng/archive/2012/07/10/2585134.html

Android開發：LayoutParams的用法

LayoutParams繼承于Android.View.ViewGroup.LayoutParams.

       LayoutParams相當于一個Layout的資訊包，它封裝了Layout的位置、高、寬等資訊。假設在螢幕上一塊區域是由一個Layout占領的，如果将一個View添加到一個Layout中，最好告訴Layout使用者期望的布局方式，也就是将一個認可的layoutParams傳遞進去。

       可以這樣去形容LayoutParams，在象棋的棋盤上，每個棋子都占據一個位置，也就是每個棋子都有一個位置的資訊，如這個棋子在4行4列，這裡的“4行4列”就是棋子的LayoutParams。

       但LayoutParams類也隻是簡單的描述了寬高，寬和高都可以設定成三種值：

       1，一個确定的值；

       2，FILL_PARENT，即填滿（和父容器一樣大小）；

       3，WRAP_CONTENT，即包裹住元件就好。

在JAVA中動态建構的布局，常常這樣寫：

setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));      

上面這一句話其實是子對父的，也就是說，父布局下的子控件要設定這句話。


因為布局很多，雖然都繼承至ViewGroup但是各個布局還是有很大的不同。


很顯然上面這句應該這樣寫才算準确：
      

setLayoutParams(new TableRow.LayoutParams(TableRow.LayoutParams.FILL_PARENT,TableRow.LayoutParams.FILL_PARENT));      

這表示這個子控件的父布局是一個TableRow , 這樣的LayoutParams 太多，是以應明确指明。

下面分别說下兩個常用到布局:
1. FrameLayout下動态設定子控件居中，動态用JAVA代碼要這樣實作:這表示這個子控件的父布局是一個TableRow , 這樣的LayoutParams 太多，是以應明确指明。
下面分别說下兩個常用到布局:
1. FrameLayout下動态設定子控件居中，動态用JAVA代碼要這樣實作:
      

FrameLayout.LayoutParams lytp = new FrameLayout.LayoutParams(80,LayoutParams.WRAP_CONTENT);
lytp .gravity = Gravity.CENTER;
btn.setLayoutParams(lytp);      

2. RelativeLayout下動态設定子控件居中：
      

RelativeLayout.LayoutParams lp=new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT); 
lp.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, RelativeLayout.TRUE); 
lp.addRule(RelativeLayout.ALIGN_PARENT_TOP, RelativeLayout.TRUE); 
btn1.setLayoutParams(lp);      

執行個體：

   從網頁響應擷取Json 對象，并解析

@SuppressWarnings("unchecked")
		Map<String,Object> markJsonMap = (Map<String, Object>) mapJson.get("adlogo");
		if(markJsonMap != null){
			String position = (String) markJsonMap.get("position");
			String markTumbString = (String) markJsonMap.get("thumb");
			String smlscreen = (String) markJsonMap.get("smlscreen");
			String bigscreen = (String) markJsonMap.get("bigscreen");
			HomeActivity.mCornerMark.setPosition(position);
			HomeActivity.mCornerMark.setThumb(markTumbString);
			HomeActivity.mCornerMark.setSmlscreen(smlscreen);
			HomeActivity.mCornerMark.setBigscreen(bigscreen);
			setCornerMark();
		}           

解析後代碼設定角标圖檔的大小，位置，異步下載下傳圖檔

/**
	 * 動态設定角标位置
	 * */
	private void setCornerMark(){
		if(!HomeActivity.mCornerMark.getThumb().equals("") && HomeActivity.mCornerMark.getThumb().length() != 0)
		{
//			WindowManager wm = (WindowManager) mContex
//					.getSystemService(Context.WINDOW_SERVICE);
//
//			int width = wm.getDefaultDisplay().getWidth();
//			int height = wm.getDefaultDisplay().getHeight();

			FrameLayout.LayoutParams reParams = (android.widget.FrameLayout.LayoutParams) HomeActivity.home_surface_viewLyout.getLayoutParams();
			int width = reParams.width;
			int height = reParams.height;
			RelativeLayout.LayoutParams params;
			//width, height * 48 / 128
			//擷取控件布局參數
			Configuration config = mContex.getResources().getConfiguration();
			if (config.orientation == Configuration.ORIENTATION_LANDSCAPE)
			{
				String[] paramString = HomeActivity.mCornerMark.getBigscreen().split(",");
				int whidthString = Integer.parseInt(paramString[0]);
				int heightString = Integer.parseInt(paramString[1]);
				//轉dp
				whidthString = DensityUtil.px2dip(mContex,whidthString);
				heightString = DensityUtil.px2dip(mContex,heightString);
				params = new LayoutParams(whidthString,heightString);
			}else{
				String[] paramString = HomeActivity.mCornerMark.getSmlscreen().split(",");
				int whidthString = Integer.parseInt(paramString[0]);
				int heightString = Integer.parseInt(paramString[1]);
				//轉dp
				whidthString = (int) (width*0.005*whidthString);
				heightString = (int) (height*0.005*heightString);
				
				whidthString = DensityUtil.px2dip(mContex,whidthString);
				heightString = DensityUtil.px2dip(mContex,heightString);
				params = new RelativeLayout.LayoutParams(whidthString,heightString);
			}

			//動态指定控件大小,位置
			Log.v("Position", HomeActivity.mCornerMark.getPosition());
			if(HomeActivity.mCornerMark.getPosition().equals("1")){
				params.leftMargin=20;
				params.topMargin=20;
				params.addRule(RelativeLayout.ALIGN_PARENT_LEFT, RelativeLayout.TRUE);
				params.addRule(RelativeLayout.ALIGN_PARENT_TOP, RelativeLayout.TRUE);
			}
			else if(HomeActivity.mCornerMark.getPosition().equals("2")){
				params.rightMargin=20;
				params.topMargin=20;
				params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, RelativeLayout.TRUE);
				params.addRule(RelativeLayout.ALIGN_PARENT_TOP, RelativeLayout.TRUE);
			}else if (HomeActivity.mCornerMark.getPosition().equals("3")) {
				params.leftMargin=20;
				params.bottomMargin=20;
				params.addRule(RelativeLayout.ALIGN_PARENT_LEFT, RelativeLayout.TRUE);
				params.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM, RelativeLayout.TRUE);
			}else if(HomeActivity.mCornerMark.getPosition().equals("4")){
				params.rightMargin=20;
				params.bottomMargin=20;
				params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, RelativeLayout.TRUE);
				params.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM, RelativeLayout.TRUE);
			}


			HomeActivity.img_cornermark.setLayoutParams(params);

			DownLoadTask downLoadTask = new DownLoadTask(HomeActivity.img_cornermark);
			downLoadTask.execute(HomeActivity.mCornerMark.getThumb());

		}
	}
           

遇到的問題：

1. 在RelativeLayout裡的布局，圖檔不顯示？

      RelativeLayout 層次布局是通過xml 檔案 Relativelayout 由底層到外層進行布局的 ，應該在底層布局之上  

2.在RelativeLayout裡，代碼實作位置是用

<span style="white-space:pre">	</span>params.addRule(RelativeLayout.ALIGN_PARENT_LEFT, RelativeLayout.TRUE);
	params.addRule(RelativeLayout.ALIGN_PARENT_TOP, RelativeLayout.TRUE);           

3.不同手機分辨率等比列顯示：

String[] paramString = HomeActivity.mCornerMark.getSmlscreen().split(",");
				int whidthString = Integer.parseInt(paramString[0]);
				int heightString = Integer.parseInt(paramString[1]);
				//轉dp
				whidthString = (int) (width*0.005*whidthString);
				heightString = (int) (height*0.005*heightString);
				
				whidthString = DensityUtil.px2dip(mContex,whidthString);
				heightString = DensityUtil.px2dip(mContex,heightString);
				params = new RelativeLayout.LayoutParams(whidthString,heightString);