Android自定义xml中控件属性的学习
前言:
在做大型应用开发的过程中,为了满足各种UI风格,必须要求自己的应用程序有一套自己统一风格的界面风格。否则援用系统的风格时,会出现意想不到的效果。
比如:button控件,可能在android2.3是黑底白字,android2.4是白底黑字,那么我们在UI设计的时候就无法去设计我的界面背景到底是采用黑底还是采用白底,于是就顺其自然的会想设计自己的button UI 。即就有自己开发UI控件的情况出现。在读android api的时候总会看到方法的参数里有AttributeSet attrs。这个属性参数却不知道是干嘛的。从网上找来一些相关资料经过整理形成了该文档。
一、在xml 文件里定义控件的属性
我们已经习惯了android:attrs="" ,那么我们能不能定义自己的属性能,比如:test:attrs="" 呢?答案是肯定的.例如:
在res/values文件下定义一个attrs.xml文件.代码如下:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="MyView">
<attr name="textColor" format="color" />
<attr name="textSize" format="dimension" />
</declare-styleable>
</resources>
二、在java代码中实现构造方法
我们在MyView.java 代码修改如下:
public MyView(Context context,AttributeSet attrs)
{
super(context,attrs);
mPaint = new Paint();
TypedArray a = context.obtainStyledAttributes(attrs,
R.styleable.MyView);
int textColor = a.getColor(R.styleable.MyView_textColor,
0XFFFFFFFF);
float textSize = a.getDimension(R.styleable.MyView_textSize, 36);
mPaint.setTextSize(textSize);
mPaint.setColor(textColor);
a.recycle();
}
MyView.java 全部代码如下:
package com.android.tutor;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.Paint.Style;
import android.util.AttributeSet;
import android.view.View;
public class MyView extends View {
private Paint mPaint;
private Context mContext;
private static final String mString = "Welcome to Mr Wei's blog";
public MyView(Context context) {
super(context);
mPaint = new Paint();
}
public MyView(Context context,AttributeSet attrs)
{
super(context,attrs);
mPaint = new Paint();
TypedArray a = context.obtainStyledAttributes(attrs,
R.styleable.MyView);
int textColor = a.getColor(R.styleable.MyView_textColor,
0XFFFFFFFF);
float textSize = a.getDimension(R.styleable.MyView_textSize, 36);
mPaint.setTextSize(textSize);
mPaint.setColor(textColor);
a.recycle();
}
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
//设置填充
mPaint.setStyle(Style.FILL);
//画一个矩形,前俩个是矩形左上角坐标,后面俩个是右下角坐标
canvas.drawRect(new Rect(10, 10, 100, 100), mPaint);
mPaint.setColor(Color.BLUE);
//绘制文字
canvas.drawText(mString, 10, 110, mPaint);
}
}
我们获取定义的属性我们R.sytleable.MyView_textColor, 获取方法中后面通常设定默认值(float textSize = a.getDimension(R.styleable.MyView_textSize, 36 ); ), 防止我们在xml 文件中没有定义.从而使用默认值!获取MyView 就是定义在<declare-styleable name="MyView "></declare-styleable> 里的名字,获取里面属性用 名字_ 属性 ;连接起来就可以.TypedArray ;通常最后调用 .recycle() 方法,为了保持以后使用该属性一致性!
三、引用自定义属性
将我们自定义的MyView 加入布局main.xml 文件中,平且使用自定义属性,自定义属性必须加上:
xmlns:test ="http://schemas.android.com/apk/res/com.android.tutor"蓝色 是自定义属性的前缀,红色 是我们包名.
main.xml 全部代码如下:
<?xml
version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:test="http://schemas.android.com/apk/res/com.android.tutor"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<com.android.tutor.MyView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
test:textSize="20px"
test:textColor="#fff"
/>
</LinearLayout>
四、Android中自定义属性的格式详解
1. reference:参考某一资源ID。
(1)属性定义:
<declare-styleable name = "名称">
<attr name = "background" format = "reference" />
</declare-styleable>
(2)属性使用:
<ImageView
android:layout_width = "42dip"
android:layout_height = "42dip"
android:background = "@drawable/图片ID"
/>
2. color:颜色值。
(1)属性定义:
<declare-styleable name = "名称">
<attr name = "textColor" format = "color" />
</declare-styleable>
(2)属性使用:
<TextView
android:layout_width = "42dip"
android:layout_height = "42dip"
android:textColor = "#00FF00"
/>
3. boolean:布尔值。
(1)属性定义:
<declare-styleable name = "名称">
<attr name = "focusable" format = "boolean" />
</declare-styleable>
(2)属性使用:
<Button
android:layout_width = "42dip"
android:layout_height = "42dip"
android:focusable = "true"
/>
4. dimension:尺寸值。
(1)属性定义:
<declare-styleable name = "名称">
<attr name = "layout_width" format = "dimension" />
</declare-styleable>
(2)属性使用:
<Button
android:layout_width = "42dip"
android:layout_height = "42dip"
/>
5. float:浮点值。
(1)属性定义:
<declare-styleable name = "AlphaAnimation">
<attr name = "fromAlpha" format = "float" />
<attr name = "toAlpha" format = "float" />
</declare-styleable>
(2)属性使用:
<alpha
android:fromAlpha = "1.0"
android:toAlpha = "0.7"
/>
6. integer:整型值。
(1)属性定义:
<declare-styleable name = "AnimatedRotateDrawable">
<attr name = "visible" />
<attr name = "frameDuration" format="integer" />
<attr name = "framesCount" format="integer" />
<attr name = "pivotX" />
<attr name = "pivotY" />
<attr name = "drawable" />
</declare-styleable>
(2)属性使用:
<animated-rotate
xmlns:android = "http://schemas.android.com/apk/res/android"
android:drawable = "@drawable/图片ID"
android:pivotX = "50%"
android:pivotY = "50%"
android:framesCount = "12"
android:frameDuration = "100" />
7. string:字符串。
(1)属性定义:
<declare-styleable name = "MapView">
<attr name = "apiKey" format = "string" />
</declare-styleable>
(2)属性使用:
<com.google.android.maps.MapView
android:layout_width = "fill_parent"
android:layout_height = "fill_parent"
android:apiKey = "0jOkQ80oD1JL9C6HAja99uGXCRiS2CGjKO_bc_g"
/>
8. fraction:百分数。
(1)属性定义:
<declare-styleable name="RotateDrawable">
<attr name = "visible" />
<attr name = "fromDegrees" format = "float" />
<attr name = "toDegrees" format = "float" />
<attr name = "pivotX" format = "fraction" />
<attr name = "pivotY" format = "fraction" />
<attr name = "drawable" />
</declare-styleable>
(2)属性使用:
<rotate
xmlns:android = "http://schemas.android.com/apk/res/android"
android:interpolator = "@anim/动画ID"
android:fromDegrees = "0"
android:toDegrees = "360"
android:pivotX = "200%"
android:pivotY = "300%"
android:duration = "5000"
android:repeatMode = "restart"
android:repeatCount = "infinite"
/>
9. enum:枚举值。
(1)属性定义:
<declare-styleable name="名称">
<attr name="orientation">
<enum name="horizontal" value="0" />
<enum name="vertical" value="1" />
</attr>
</declare-styleable>
(2)属性使用:
<LinearLayout
xmlns:android = "http://schemas.android.com/apk/res/android"
android:orientation = "vertical"
android:layout_width = "fill_parent"
android:layout_height = "fill_parent"
>
</LinearLayout>
10. flag:位或运算。
(1)属性定义:
<declare-styleable name="名称">
<attr name="windowSoftInputMode">
<flag name = "stateUnspecified" value = "0" />
<flag name = "stateUnchanged" value = "1" />
<flag name = "stateHidden" value = "2" />
<flag name = "stateAlwaysHidden" value = "3" />
<flag name = "stateVisible" value = "4" />
<flag name = "stateAlwaysVisible" value = "5" />
<flag name = "adjustUnspecified" value = "0x00" />
<flag name = "adjustResize" value = "0x10" />
<flag name = "adjustPan" value = "0x20" />
<flag name = "adjustNothing" value = "0x30" />
</attr>
</declare-styleable>
(2)属性使用:
<activity
android:name = ".StyleAndThemeActivity"
android:label = "@string/app_name"
android:windowSoftInputMode = "stateUnspecified | stateUnchanged | stateHidden">
<intent-filter>
<action android:name = "android.intent.action.MAIN" />
<category android:name = "android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
注意:
属性定义时可以指定多种类型值。
(1)属性定义:
<declare-styleable name = "名称">
<attr name = "background" format = "reference|color" />
</declare-styleable>
(2)属性使用:
<ImageView
android:layout_width = "42dip"
android:layout_height = "42dip"
android:background = "@drawable/图片ID|#00FF00"
/>