Android 自定义View (二) 进阶

Android 自定义View (二) 进阶，继续自定义View之旅，前面已经介绍过一个自定义View的基础的例子，Android 自定义View (一)，如果你还对自定义View不了解可以去看看。今天给大家带来一个稍微复杂点的例子。

自定义View显示一张图片，下面包含图片的文本介绍，类似相片介绍什么的，不过不重要，主要是学习自定义View的用法么。

还记得上一篇讲的4个步骤么:

1、自定义View的属性
2、在View的构造方法中获得我们自定义的属性
[ 3、重写onMesure ]
4、重写onDraw

直接切入正题：

1、在res/values/attr.xml

*初始化所特有自定义类型
*@paramcontext
*@paramdefStyle
publicCustomImageView(Contextcontext,AttributeSetattrs,intdefStyle)
super(context,attrs,defStyle);
TypedArraya=context.getTheme().obtainStyledAttributes(attrs,R.styleable.CustomImageView,defStyle,0);
intn=a.getIndexCount();
for(inti=0;i<>

{

intattr=a.getIndex(i);

 

switch(attr)

{

caseR.styleable.CustomImageView_image:

mImage=BitmapFactory.decodeResource(getResources(),a.getResourceId(attr,0));

break;

caseR.styleable.CustomImageView_imageScaleType:

mImageScale=a.getInt(attr,0);

break;

caseR.styleable.CustomImageView_titleText:

mTitle=a.getString(attr);

break;

caseR.styleable.CustomImageView_titleTextColor:

mTextColor=a.getColor(attr,Color.BLACK);

break;

caseR.styleable.CustomImageView_titleTextSize:

mTextSize=a.getDimensionPixelSize(attr,(int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,

16,getResources().getDisplayMetrics()));

break;

}

}

a.recycle();

rect=newRect();

mPaint=newPaint();

mTextBound=newRect();

mPaint.setTextSize(mTextSize);

//计算了描绘字体需要的范围

mPaint.getTextBounds(mTitle,0,mTitle.length(),mTextBound);

}
3、重写onMeasure

@Override

protectedvoidonMeasure(intwidthMeasureSpec,intheightMeasureSpec)

{

//super.onMeasure(widthMeasureSpec,heightMeasureSpec);

 

/**

*设置宽度

*/

intspecMode=MeasureSpec.getMode(widthMeasureSpec);

intspecSize=MeasureSpec.getSize(widthMeasureSpec);

 

if(specMode==MeasureSpec.EXACTLY)//match_parent,accurate

{

Log.e("xxx","EXACTLY");

mWidth=specSize;

}else

{

//由图片决定的宽

intdesireByImg=getPaddingLeft()+getPaddingRight()+mImage.getWidth();

//由字体决定的宽

intdesireByTitle=getPaddingLeft()+getPaddingRight()+mTextBound.width();

if(specMode==MeasureSpec.AT_MOST)//wrap_content

{

intdesire=Math.max(desireByImg,desireByTitle);

mWidth=Math.min(desire,specSize);

Log.e("xxx","AT_MOST");

}

}

/***

*设置高度

*/

specMode=MeasureSpec.getMode(heightMeasureSpec);

specSize=MeasureSpec.getSize(heightMeasureSpec);

if(specMode==MeasureSpec.EXACTLY)//match_parent,accurate

{

mHeight=specSize;

}else

{

intdesire=getPaddingTop()+getPaddingBottom()+mImage.getHeight()+mTextBound.height();

if(specMode==MeasureSpec.AT_MOST)//wrap_content

{

mHeight=Math.min(desire,specSize);

}

}

setMeasuredDimension(mWidth,mHeight);

 

}
4、重写onDraw

 

@Override

protectedvoidonDraw(Canvascanvas)

{

//super.onDraw(canvas);

/**

*边框

*/

mPaint.setStrokeWidth(4);

mPaint.setStyle(Paint.Style.STROKE);

mPaint.setColor(Color.CYAN);

canvas.drawRect(0,0,getMeasuredWidth(),getMeasuredHeight(),mPaint);

rect.left=getPaddingLeft();

rect.right=mWidth-getPaddingRight();

rect.top=getPaddingTop();

rect.bottom=mHeight-getPaddingBottom();

 

mPaint.setColor(mTextColor);

mPaint.setStyle(Style.FILL);

/**

*当前设置的宽度小于字体需要的宽度，将字体改为xxx...

*/

if(mTextBound.width()>mWidth)

{

TextPaintpaint=newTextPaint(mPaint);

Stringmsg=TextUtils.ellipsize(mTitle,paint,(float)mWidth-getPaddingLeft()-getPaddingRight(),

TextUtils.TruncateAt.END).toString();

canvas.drawText(msg,getPaddingLeft(),mHeight-getPaddingBottom(),mPaint);

 

}else

{

//正常情况，将字体居中

canvas.drawText(mTitle,mWidth/2-mTextBound.width()*1.0f/2,mHeight-getPaddingBottom(),mPaint);

}

 

//取消使用掉的快

rect.bottom-=mTextBound.height();

if(mImageScale==IMAGE_SCALE_FITXY)

{

canvas.drawBitmap(mImage,null,rect,mPaint);

}else

{

//计算居中的矩形范围

rect.left=mWidth/2-mImage.getWidth()/2;

rect.right=mWidth/2+mImage.getWidth()/2;

rect.top=(mHeight-mTextBound.height())/2-mImage.getHeight()/2;

rect.bottom=(mHeight-mTextBound.height())/2+mImage.getHeight()/2;

 

canvas.drawBitmap(mImage,null,rect,mPaint);

}

}
代码，结合注释和第一篇View的使用，应该可以看懂，不明白的留言。下面我们引入我们的自定义View: 

 

xmlns:zhy="http://schemas.android.com/apk/res/com.zhy.customview02"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical">

 

<>

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_margin="10dp"

android:padding="10dp"

zhy:image="@drawable/ic_launcher"

zhy:imageScaleType="center"

zhy:titleText="helloandorid!"

zhy:titleTextColor="#ff0000"

zhy:titleTextSize="30sp"/>

<>

android:layout_width="100dp"