自定义布局RelativeLayout 画网格线

在Android中画线必须由一个载体，要么是一个控件，要么是一个布局，其实他们都是继承自View，通过自定义控件或布局的方式画线是最常见的。下面的小例子实现了在自定义RelativeLayout中画网格线

代码下载：http://download.csdn.net/detail/yxg190221/7589287

自定义控件代码：

package layout.layout.ex;import android.content.Context;import android.graphics.Canvas;import android.graphics.Paint;import android.util.AttributeSet;import android.widget.RelativeLayout;public class GridRelativeLayout extends RelativeLayout {private Canvas myCanvas;private int horGrid = 100, verGrid = 100;//水平网格和竖直网格private int screenW, screenH;//屏幕宽和高private boolean initOver = false;//初始化标签public GridRelativeLayout(Context context) {super(context);setWillNotDraw(false);}public GridRelativeLayout(Context context, AttributeSet attrs) {super(context, attrs);setWillNotDraw(false);}public GridRelativeLayout(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);setWillNotDraw(false);}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);this.myCanvas = canvas;Paint paint = new Paint();paint.setColor(android.graphics.Color.YELLOW);//颜色paint.setStrokeWidth(3);//线宽int verNum = (int)(screenH / verGrid) + 1;int horNum = (int)(screenW / horGrid) + 1;if (initOver) {for (int i = 0; i < verNum; i++) {canvas.drawLine(0, i * verGrid - 1, screenW, i * verGrid - 1,paint);}for (int i = 0; i < horNum; i++) {canvas.drawLine(i * horGrid - 1, 0, i * horGrid - 1, screenH,paint);}}}/**设置网格线参数**/public void setInf(int vergrid, int horgrid, int screenW, int screenH) {this.verGrid = vergrid;this.horGrid = horgrid;this.screenW = screenW;this.screenH = screenH;initOver = true;postInvalidate();}/**擦除网格线**/public void clearLine(){initOver = false;postInvalidate();}}

主程序代码：

package com.example.test005;import layout.layout.ex.GridRelativeLayout;import android.app.Activity;import android.os.Bundle;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class MainActivity extends Activity {private GridRelativeLayout rl;private Button btnDraw,btnClear;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);rl=(GridRelativeLayout)findViewById(R.id.rl);btnDraw=(Button)findViewById(R.id.button1);btnClear=(Button)findViewById(R.id.button2);btnDraw.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View arg0) {rl.setInf(100, 100, 1280, 720);//画网格线}});btnClear.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View arg0) {rl.clearLine();//擦除网格线}});}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {getMenuInflater().inflate(R.menu.main, menu);return true;}}

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