Android - ToDoList(定制样式) 详解

ToDoList(定制样式) 详解

本文地址: http://blog.csdn.net/caroline_wendy/article/details/21330733

Android允许从已有的视图工具箱(Widget Tool Box)派生子类 或 实现自己的视图控件;

通过重写事件处理程序 和onDraw()方法, 但是仍然回调超类(super)的方法, 可以对视图进行定制, 而不必实心它的功能;

前置步骤参见: http://blog.csdn.net/caroline_wendy/article/details/21246963

步骤: 

1. 创建ToDoListItemView类, 定制Item项的外观:

位置: java->package->ToDoListItemView.java

package mzx.spike.todolist.app;  import android.content.Context; import android.content.res.Resources; import android.graphics.Canvas; import android.graphics.Paint; import android.util.AttributeSet; import android.widget.TextView;  /**  * Created by C.L.Wang on 14-3-16.  */ public class ToDoListItemView extends TextView{      private Paint marginPaint;     private Paint linePaint;     private int paperColor;     private float margin;      public ToDoListItemView (Context context, AttributeSet ats, int ds) {         super(context, ats, ds);         init();     }      public  ToDoListItemView (Context context) {         super(context);         init();     }      public ToDoListItemView (Context context, AttributeSet ats) {         super(context, ats);         init();     }      private void init() {          //获得对资源列表的引用         Resources myResources = getResources();          marginPaint = new Paint(Paint.ANTI_ALIAS_FLAG);         marginPaint.setColor(myResources.getColor(R.color.notepad_margin));          linePaint = new Paint(Paint.ANTI_ALIAS_FLAG);         linePaint.setColor(myResources.getColor(R.color.notepad_lines));          paperColor = myResources.getColor(R.color.notepad_paper);         margin = myResources.getDimension(R.dimen.notepad_margin);     }      @Override     public void onDraw(Canvas canvas) {          canvas.drawColor(paperColor);          canvas.drawLine(0, 0, 0, getMeasuredHeight(), linePaint);         canvas.drawLine(0, getMeasuredHeight(), getMeasuredWidth(), getMeasuredHeight(), linePaint);          canvas.drawLine(margin, 0, margin, getMeasuredHeight(), marginPaint);          canvas.save();         canvas.translate(margin, 0);          super.onDraw(canvas);         canvas.restore();     }  } 

详解:

1. 继承TextView类, 是文本视图的定制;

2. 重载构造函数, 包含三个参数的重载版本,回调超类(super)之后,初始化资源私有变量(init);

3. 在Init()中, 获得资源列表的引用(getResource), 将资源文件转换为可以调用的参数(myResource.getXXX), 初始化资源私有变量;

4. 重写(Override)OnDraw方法, 设置颜色, 画线, 指定写入格式;

5. canvas.translate(), 使输出文件, 后移margin距离;

2. 创建颜色(colors)资源文件

位置: res->values->colors.xml

<?xml version="1.0" encoding="utf-8"?> <resources>     <color name="notepad_paper">#EEF8E0A0</color>     <color name="notepad_lines">#FF0000FF</color>     <color name="notepad_margin">#90FF0000</color>     <color name="notepad_text">#AA0000FF</color> </resources>

颜色资源文件, 以color标签, Android Studio会显示颜色;

3. 修改尺寸(dimen)资源文件:

位置: res->values->dimen.xml

<resources>     <!-- Default screen margins, per the Android Design guidelines. -->     <dimen name="activity_horizontal_margin">16dp</dimen>     <dimen name="activity_vertical_margin">16dp</dimen>     <dimen name="notepad_margin">30dp</dimen> </resources>

补充即可;

4. 创建todolist_item布局文件:

位置: res->layout->todolist_item.xml

<?xml version="1.0" encoding="utf-8"?>  <mzx.spike.todolist.app.ToDoListItemView     xmlns:android="http://schemas.android.com/apk/res/android"     android:orientation="vertical"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:padding="10dp"     android:scrollbars="vertical"     android:textColor="@color/notepad_text"     android:fadingEdge="vertical" />

详解:

1. 标签为类名, 即ToDoListItemView类, 重载了TextView的方法;

2. 设置相应的属性标签;

5. 修改适配器(Adapter), 使用定制的TextView:

位置: java->package->ToDoListActivity

......         int resID = R.layout.todolist_item;         //三个参数         aa = new ArrayAdapter<String>(this, resID, toDoItems);          toDoListFragment.setListAdapter(aa); ......

详解:

找到资源文件的ID, 传入适配器;

6. 执行程序:

代码下载: http://download.csdn.net/detail/u012515223/7050371