在res/values/下建立一个attrs.xml ,在里面定义我们的属性和声明我们的整个样式:
<?xml version="1.0" encoding="utf-8"?> <resources> <attr name="titleText" format="string" /> <attr name="titleTextColor" format="color" /> <attr name="titleTextSize" format="dimension" /> <declare-styleable name="CustomTitleView"> <attr name="titleText" /> <attr name="titleTextColor" /> <attr name="titleTextSize" /> </declare-styleable> </resources>
定义了字体,字体颜色,字体大小3个属性。format是值该属性的取值类型:一共有 string,color,demension,integer,enum,reference,float,boolean,fraction,flag 。
<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-auto" android:layout_width="match_parent" android:layout_height="match_parent" > <com.yydcdut.CustomTitleView android:layout_width="200dp" android:layout_height="100dp" custom:titleText="3712" custom:titleTextColor="#ff0000" custom:titleTextSize="40sp" /> </RelativeLayout>
xmlns:custom=http://schemas.android.com/apk/res-auto,命名空间,现在都是res-auto形式的了。
/** * 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); }
我们重写了3个构造方法,默认的布局文件调用的是两个参数的构造方法,所以记得让所有的构造调用我们的三个参数的构造,我们在三个参数的构造中获得自定义属性。
@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); }
此时长宽都是固定的,当长宽都设置为wrap_content,会发现效果:
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
@Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int widthMode = MeasureSpec.getMode(widthMeasureSpec); int widthSize = MeasureSpec.getSize(widthMeasureSpec); int heightMode = MeasureSpec.getMode(heightMeasureSpec); int heightSize = MeasureSpec.getSize(heightMeasureSpec); int width; int height ; if (widthMode == MeasureSpec.EXACTLY) { width = widthSize; } else { mPaint.setTextSize(mTitleTextSize); mPaint.getTextBounds(mTitle, 0, mTitle.length(), mBounds); float textWidth = mBounds.width(); int desired = (int) (getPaddingLeft() + textWidth + getPaddingRight()); width = desired; } if (heightMode == MeasureSpec.EXACTLY){ height = heightSize; } else { mPaint.setTextSize(mTitleTextSize); mPaint.getTextBounds(mTitle, 0, mTitle.length(), mBounds); float textHeight = mBounds.height(); int desired = (int) (getPaddingTop() + textHeight + getPaddingBottom()); height = desired; } setMeasuredDimension(width, height); }
布局修改一下
<com.yydcdut.CustomTitleView android:layout_width="wrap_content" android:layout_height="wrap_content" custom:titleText="3712" android:padding="10dp" custom:titleTextColor="#ff0000" android:layout_centerInParent="true" custom:titleTextSize="40sp" />
参考:http://blog.csdn.net/lmj623565791/article/details/24252901