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Android中自定义View(1)

2015-11-25 17:42 501 查看
自定义View属性:
最近项目中经常需要用到自定义控件,因此自定义属性也是经常要用到的,在此说明一下自定义属性的用法:

自定义属性都存在于/value/attr.xml文件中,以如下格式存在。

<resource>

<declare-styleable name="自定义属性名称">

<attr name="属性名称" format="属性种类"/>

......

</declare-styleable>

</resource>

对于自定义属性中的format的值及其含义如下:

format属性值:reference 、color、boolean、dimension、float、integer、string、fraction、enum、flag

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>

特别要注意:

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"

/>

下面说说AttributeSet与TypedArray在自定义控件中的作用:

AttributeSet 的作用就是在控件进行初始化的时候,解析布局文件中该控件的属性(key eg:background)与该值(value eg:@drawable/icon)的信息封装在AttributeSet中,传递给该控件(View)的构造函数。对于非Android自带的属性,在View类中处理时是无法识别的,因此需要我们自己解析。所以这就要用到另外一个类TypedArray。在AttributeSet中我们有属性名称,有属性值,但是控件如何知道哪个属性代表什么意思呢?这个工作就由TypedArray来做了。TypedArray对象封装了/values/attrs.xml中的styleable里定义的每个属性的类型信息,通过TypedArray我们就可以知道AttributeSet中封装的值到底是干什么的了,从而可以对这些数据进行应用。
AttributeSet就相当于一盒糖,TypedArray就相当于这盒糖上的标签说明,告诉用户每个糖的口味等。这盒糖有什么口味是由用户自己的styleable文件里面的内容来决定的。

例如:<?xml version="1.0" encoding="utf-8"?>

<resources>
<declare-styleable name="CustomTitleView">

<attr name="titleText"
format="string/>

<attr name="titleTextColor"
format="color/>

<attr name="titleTextSize"
format="dimension/>

</declare-styleable>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:custom="http://schemas.android.com/apk/res/com.example.customview01"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<com.example.customview01.view.CustomTitleView
android:layout_width="200dp"
android:layout_height="100dp"
custom:titleText="3712"
custom:titleTextColor="#ff0000"
custom:titleTextSize="40sp" />

</RelativeLayout>

/**
* 文本
*/
private String mTitleText;
/**
* 文本的颜色
*/
private int mTitleTextColor;
/**
* 文本的大小
*/
private int mTitleTextSize;

/**
* 绘制时控制文本绘制的范围
*/
private Rect mBound;
private Paint mPaint;

public CustomTitleView(Context context, AttributeSet attrs)
{
this(context, attrs, 0);
}

public CustomTitleView(Context context)
{
this(context, null);
}

/**
* 获得我自定义的样式属性
*
* @param context
* @param attrs
* @param defStyle
*/
public CustomTitleView(Context context, AttributeSet attrs, int defStyle)
{
super(context, attrs, defStyle);
/**
* 获得我们所定义的自定义样式属性
*/
TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.CustomTitleView, defStyle, 0);
int n = a.getIndexCount();
for (int i = 0; i < n; i++)
{
int attr = a.getIndex(i);
switch (attr)
{
case R.styleable.CustomTitleView_titleText:
mTitleText = a.getString(attr);
break;
case R.styleable.CustomTitleView_titleTextColor:
// 默认颜色设置为黑色
mTitleTextColor = a.getColor(attr, Color.BLACK);
break;
case R.styleable.CustomTitleView_titleTextSize:
// 默认设置为16sp,TypeValue也可以把sp转化为px
mTitleTextSize = a.getDimensionPixelSize(attr, (int) TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_SP, 16, getResources().getDisplayMetrics()));
break;

}

}
a.recycle();

/**
* 获得绘制文本的宽和高
*/
mPaint = new Paint();
mPaint.setTextSize(mTitleTextSize);
// mPaint.setColor(mTitleTextColor);
mBound = new Rect();
mPaint.getTextBounds(mTitleText, 0, mTitleText.length(), mBound);

}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

@Override
protected void onDraw(Canvas canvas)
{
mPaint.setColor(Color.YELLOW);
canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredHeight(), mPaint);

mPaint.setColor(mTitleTextColor);
canvas.drawText(mTitleText, getWidth() / 2 - mBound.width() / 2, getHeight() / 2 + mBound.height() / 2, mPaint);
}

系统帮我们测量的高度和宽度都是MATCH_PARNET,当我们设置明确的宽度和高度时,系统帮我们测量的结果就是我们设置的结果,当我们设置为WRAP_CONTENT,或者MATCH_PARENT系统帮我们测量的结果就是MATCH_PARENT的长度。

所以,当设置了WRAP_CONTENT时,我们需要自己进行测量,即重写onMesure方法”:

重写之前先了解MeasureSpec的specMode,一共三种类型:

EXACTLY:一般是设置了明确的值或者是MATCH_PARENT

AT_MOST:表示子布局限制在一个最大值内,一般为WARP_CONTENT

UNSPECIFIED:表示子布局想要多大就多大,很少使用
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