Android 自己定义View (二) 进阶

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

继续自己定义View之旅。前面已经介绍过一个自己定义View的基础的样例，Android
自己定义View (一)，假设你还对自己定义View不了解能够去看看。今天给大家带来一个略微复杂点的样例。

自己定义View显示一张图片，以下包括图片的文本介绍，类似相片介绍什么的，只是不重要，主要是学习自己定义View的使用方法么。

还记得上一篇讲的4个步骤么:

1、自己定义View的属性

2、在View的构造方法中获得我们自己定义的属性

[ 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己定义属性：

/**
* 初始化所特有自己定义类型
*
* @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);
// 计算了描绘字体须要的范围
mPaint.getTextBounds(mTitle, 0, mTitle.length(), mTextBound);}

3、重写onMeasure

@Override
protected 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

@Override
protected 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须要的宽度。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);
}}