Android 自定义View (二) 进阶

转载请标明出处：http://blog.csdn.net/lmj623565791/article/details/24300125

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

<?xml version="1.0" encoding="utf-8"?><resources>    <attr name="titleText" format="string" />    <attr name="titleTextSize" format="dimension" />    <attr name="titleTextColor" format="color" />    <attr name="image" format="reference" />    <attr name="imageScaleType">        <enum name="fillXY" value="0" />        <enum name="center" value="1" />    </attr>    <declare-styleable name="CustomImageView">        <attr name="titleText" />        <attr name="titleTextSize" />        <attr name="titleTextColor" />        <attr name="image" />        <attr name="imageScaleType" />    </declare-styleable></resources>

2、在构造中获得我们的自定义属性：

/** * 初始化所特有自定义类型 *  * @param context * @param attrs * @param defStyle */public CustomImageView(Context context, AttributeSet attrs, int defStyle){super(context, attrs, defStyle);TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.CustomImageView, defStyle, 0);int n = a.getIndexCount();for (int i = 0; i < n; i++){int attr = a.getIndex(i);switch (attr){case R.styleable.CustomImageView_image:mImage = BitmapFactory.decodeResource(getResources(), a.getResourceId(attr, 0));break;case R.styleable.CustomImageView_imageScaleType:mImageScale = a.getInt(attr, 0);break;case R.styleable.CustomImageView_titleText:mTitle = a.getString(attr);break;case R.styleable.CustomImageView_titleTextColor:mTextColor = a.getColor(attr, Color.BLACK);break;case R.styleable.CustomImageView_titleTextSize:mTextSize = a.getDimensionPixelSize(attr, (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,16, getResources().getDisplayMetrics()));break;}}a.recycle();rect = new Rect();mPaint = new Paint();mTextBound = new Rect();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

@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){// super.onMeasure(widthMeasureSpec, heightMeasureSpec);/** * 设置宽度 */int specMode = MeasureSpec.getMode(widthMeasureSpec);int specSize = MeasureSpec.getSize(widthMeasureSpec);if (specMode == MeasureSpec.EXACTLY)// match_parent , accurate{Log.e("xxx", "EXACTLY");mWidth = specSize;} else{// 由图片决定的宽int desireByImg = getPaddingLeft() + getPaddingRight() + mImage.getWidth();// 由字体决定的宽int desireByTitle = getPaddingLeft() + getPaddingRight() + mTextBound.width();if (specMode == MeasureSpec.AT_MOST)// wrap_content{int desire = 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{int desire = 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

@Overrideprotected void onDraw(Canvas canvas){// 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){TextPaint paint = new TextPaint(mPaint);String msg = 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:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    xmlns:zhy="http://schemas.android.com/apk/res/com.zhy.customview02"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <com.zhy.customview02.view.CustomImageView        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="hello andorid ! "        zhy:titleTextColor="#ff0000"        zhy:titleTextSize="30sp" />    <com.zhy.customview02.view.CustomImageView        android:layout_width="100dp"        android:layout_height="wrap_content"        android:layout_margin="10dp"        android:padding="10dp"        zhy:image="@drawable/ic_launcher"        zhy:imageScaleType="center"        zhy:titleText="helloworldwelcome"        zhy:titleTextColor="#00ff00"        zhy:titleTextSize="20sp" />    <com.zhy.customview02.view.CustomImageView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_margin="10dp"        android:padding="10dp"        zhy:image="@drawable/lmj"        zhy:imageScaleType="center"        zhy:titleText="妹子~"        zhy:titleTextColor="#ff0000"        zhy:titleTextSize="12sp" /></LinearLayout>

我特意让显示出现3中情况：

1、字体的宽度大于图片，且View宽度设置为wrap_content

2、View宽度设置为精确值，字体的长度大于此宽度

3、图片的宽度大于字体，且View宽度设置为wrap_content

看看显示效果：

怎么样，对于这三种情况所展示的效果都还不错吧。

好了，就到这里，各位看官，没事留个言，顶一个呗~

源码点击下载