自定义View显示文本
网上就有达人采用自定义View来解决这个问题，我做了实验并总结了一下：
自定义View的步骤：
1）继承View类或其子类，例子继承了TextView类；
2）写构造函数，通过XML获取属性（这一步中可以自定义属性，见例程）；
3）重写父类的某些函数，一般都是以on开头的函数，例子中重写了onDraw()和onMeasure()函数；
=========================StartCustomTextView.java=============================
public class StartCustomTextView extends TextView {
public static int m_iTextHeight; //文本的高度
public static int m_iTextWidth;//文本的宽度
private Paint mPaint = null;
private String string="";
private float LineSpace = 0;//行间距
private int left_Margin;
private int right_Margin;
private int bottom_Margin;
public StartCustomTextView(Context context, AttributeSet set)
{
super(context,set);
DisplayMetrics displayMetrics = getResources().getDisplayMetrics();
TypedArray typedArray = context.obtainStyledAttributes(set, R.styleable.CYTextView);
int width = displayMetrics.widthPixels;
left_Margin = 29;
right_Margin = 29;
bottom_Margin = 29;
width = width - left_Margin -right_Margin;
float textsize = typedArray.getDimension(R.styleable.CYTextView_textSize, 34);
int textcolor = typedArray.getColor(R.styleable.CYTextView_textColor, getResources().getColor(R.color.white));
float linespace = typedArray.getDimension(R.styleable.CYTextView_lineSpacingExtra, 15);
int typeface = typedArray.getColor(R.styleable.CYTextView_typeface, 0);
typedArray.recycle();
//设置 CY TextView的宽度和行间距www.linuxidc.com
m_iTextWidth=width;
LineSpace=linespace;
// 构建paint对象
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setColor(textcolor);
mPaint.setTextSize(textsize);
switch(typeface){
case 0:
mPaint.setTypeface(Typeface.DEFAULT);
break;
case 1:
mPaint.setTypeface(Typeface.SANS_SERIF);
break;
case 2:
mPaint.setTypeface(Typeface.SERIF);
break;
case 3:
mPaint.setTypeface(Typeface.MONOSPACE);
break;
default:
mPaint.setTypeface(Typeface.DEFAULT);
break;
}
}
@Override
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
char ch;
int w = 0;
int istart = 0;
int m_iFontHeight;
int m_iRealLine=0;
int x=2;
int y=30;
Vector m_String=new Vector();
FontMetrics fm = mPaint.getFontMetrics();
m_iFontHeight = (int) Math.ceil(fm.descent - fm.top) + (int)LineSpace;//计算字体高度（字体高度＋行间距）
for (int i = 0; i < string.length(); i++)
{
ch = string.charAt(i);
float[] widths = new float[1];
String srt = String.valueOf(ch);
mPaint.getTextWidths(srt, widths);
if (ch == '\n'){
m_iRealLine++;
m_String.addElement(string.substring(istart, i));
istart = i + 1;
w = 0;
}else{
w += (int) (Math.ceil(widths[0]));
if (w > m_iTextWidth){
m_iRealLine++;
m_String.addElement(string.substring(istart, i));
istart = i;
i--;
w = 0;
}else{
if (i == (string.length() - 1)){
m_iRealLine++;
m_String.addElement(string.substring(istart, string.length()));
}
}
}
}
m_iTextHeight=m_iRealLine*m_iFontHeight+2;
canvas.setViewport(m_iTextWidth, m_iTextWidth);
for (int i = 0, j = 0; i < m_iRealLine; i++, j++)
{
canvas.drawText((String)(m_String.elementAt(i)), x, y+m_iFontHeight * j, mPaint);
}
}
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
int measuredHeight = measureHeight(heightMeasureSpec);
int measuredWidth = measureWidth(widthMeasureSpec);
this.setMeasuredDimension(measuredWidth, measuredHeight);
LayoutParams layout = new LinearLayout.LayoutParams(measuredWidth,measuredHeight);
layout.leftMargin= left_Margin;
layout.rightMargin= right_Margin;
layout.bottomMargin= bottom_Margin;
this.setLayoutParams(layout);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
private int measureHeight(int measureSpec)
{
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);
// Default size if no limits are specified.
initHeight();
int result = m_iTextHeight;
if (specMode == MeasureSpec.AT_MOST){
// Calculate the ideal size of your
// control within this maximum size.
// If your control fills the available
// space return the outer bound.
result = specSize;
}else if (specMode == MeasureSpec.EXACTLY){
// If your control can fit within these bounds return that value.
// result = specSize;
}
return result;
}
private void initHeight()
{
//设置 CY TextView的初始高度为0
m_iTextHeight=0;
//大概计算 CY TextView所需高度
FontMetrics fm = mPaint.getFontMetrics();
int m_iFontHeight = (int) Math.ceil(fm.descent - fm.top) + (int)LineSpace;
int line=0;
int istart=0;
int w=0;
for (int i = 0; i < string.length(); i++)
{
char ch = string.charAt(i);
float[] widths = new float[1];
String srt = String.valueOf(ch);
mPaint.getTextWidths(srt, widths);
if (ch == '\n'){
line++;
istart = i + 1;
w = 0;
}else{
w += (int) (Math.ceil(widths[0]));
if (w > m_iTextWidth){
line++;
istart = i;
i--;
w = 0;
}else{
if (i == (string.length() - 1)){
line++;
}
}
}
}
m_iTextHeight=(line)*m_iFontHeight+2;
}
private int measureWidth(int measureSpec)
{
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);
// Default size if no limits are specified.
int result = 500;
if (specMode == MeasureSpec.AT_MOST){
// Calculate the ideal size of your control
// within this maximum size.
// If your control fills the available space
// return the outer bound.
result = specSize;
}else if (specMode == MeasureSpec.EXACTLY){
// If your control can fit within these bounds return that value.
result = specSize;
}
return result;
}
public void SetText(String text)
{
string = text;
// requestLayout();
// invalidate();
}
}
=======================attrs.xml===============================
该文件是自定义的属性，放在工程的res/values下
<resources> <attr name="textwidth" format="integer"/> <attr name="typeface"> <enum name="normal" value="0"/> <enum name="sans" value="1"/> <enum name="serif" value="2"/> <enum name="monospace" value="3"/> </attr> <declare-styleable name="CYTextView"> <attr name="textwidth" /> <attr name="textSize" format="dimension"/> <attr name="textColor" format="reference|color"/> <attr name="lineSpacingExtra" format="dimension"/> <attr name="typeface" /> </declare-styleable> </resources>
=======================main.xml==========================
<?xml version="1.0" encoding="utf-8"?> <ScrollView xmlns:Android="http://schemas.android.com/apk/res/android" Android:layout_width="320px" Android:layout_height="320px" Android:background="#ffffffff" > <LinearLayout xmlns:Android="http://schemas.android.com/apk/res/android" Android:orientation="vertical" Android:layout_width="fill_parent" Android:layout_height="fill_parent"> <com.cy.CYTextView.CYTextView xmlns:cy="http://schemas.Android.com/apk/res/ com.cy.CYTextView " Android:id="@+id/mv" Android:layout_height="wrap_content" Android:layout_width="wrap_content" cy :textwidth="320" cy :textSize="24sp" cy :textColor="#aa000000" cy :lineSpacingExtra="15sp" cy :typeface="serif"> </com. cy .CYTextView.CYTextView> </LinearLayout> </ScrollView>
蓝色代码即为自定义View，其中以cy命名空间开头的属性是自定义属性；
=======================Main.java=============================
public class Main extends Activity {
CYTextView mCYTextView;
String text = "Android提供了精巧和有力的组件化模型构建用户的UI部分。主要是基于布局类：View和 ViewGroup。在此基础上，android平台提供了大量的预制的View和xxxViewGroup子 类，即布局（layout）和窗口小部件（widget）。可以用它们构建自己的UI。";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.main);
mCYTextView = (CYTextView)findViewById(R.id.mv);
mCYTextView.SetText(text);
}
}
http://blog.csdn.net/furongkang/article/details/7625814
