android,利用layoutParams代碼動態布局空間位置

android,利用layoutParams代碼動態布局空間位置

 

 

Android開發：LayoutParams的用法

LayoutParams繼承於Android.View.ViewGroup.LayoutParams.
LayoutParams相當於一個Layout的資訊包，它封裝了Layout的位置、高、寬等資訊。假設在螢幕上一塊地區是由一個Layout佔領的，如果將一個View添加到一個Layout中，最好告訴Layout使用者期望的布局方式，也就是將一個認可的layoutParams傳遞進去。
可以這樣去形容LayoutParams，在象棋的棋盤上，每個棋子都佔據一個位置，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類也只是簡單的描述了寬高，寬和高都可以設定成三種值：
1，一個確定的值；
2，FILL_PARENT，即填滿（和父容器一樣大小）；
3，WRAP_CONTENT，即包裹住組件就好。


在JAVA中動態構建的布局，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，父布局下的子控制項要設定這句話。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確：

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

這表示這個子控制項的父布局是一個TableRow , 這樣的LayoutParams 太多，所以應明確指明。下面分別說下兩個常用到布局:1. FrameLayout下動態設定子控制項置中，動態用JAVA代碼要這樣實現:這表示這個子控制項的父布局是一個TableRow , 這樣的LayoutParams 太多，所以應明確指明。下面分別說下兩個常用到布局:1. FrameLayout下動態設定子控制項置中，動態用JAVA代碼要這樣實現:

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

2. RelativeLayout下動態設定子控制項置中：

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，並解析

 

@SuppressWarnings(unchecked)Map markJsonMap = (Map) 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();}

解析後代碼設定角標圖片的大小，位置，非同步下載圖片

 

 

/** * 動態設定角標位置 * */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//擷取控制項布局參數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dpwhidthString = 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dpwhidthString = (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);}//動態指定控制項大小,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，圖片不顯示？

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，代碼實現位置是用

params.addRule(RelativeLayout.ALIGN_PARENT_LEFT, RelativeLayout.TRUE);params.addRule(RelativeLayout.ALIGN_PARENT_TOP, RelativeLayout.TRUE);

 

3.不同手機解析度等比列顯示：

 

String[] paramString = HomeActivity.mCornerMark.getSmlscreen().split(,);int whidthString = Integer.parseInt(paramString[0]);int heightString = Integer.parseInt(paramString[1]);//轉dpwhidthString = (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);