自定义view，实现TextView上文本的自动换行

package com.orgcent.demo.view; import java.util.Arrays; import android.content.Context; import android.content.res.Resources; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Paint.FontMetrics; import android.graphics.Paint.Style; import android.util.AttributeSet; import android.util.TypedValue; import android.view.View; //自定义文本标签，自动换行 public class MyView extends View { private Paint mPaint = new Paint(); public MyView(Context context) { this(context,null); } public MyView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); init(); } public MyView(Context context, AttributeSet attrs) { this(context,attrs,0); } private void init() { mPaint.setAntiAlias(true); mPaint.setColor(Color.RED); mPaint.setStyle(Style.STROKE); mPaint.setTextSize(getRawSize(TypedValue.COMPLEX_UNIT_DIP, 15)); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); // setMeasuredDimension(300, 200); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); //view.draw()绘制了控件的背景 //控件的绘制操作及顺序： /* * Draw traversal performs several drawing steps which must be executed * in the appropriate order: * * 1. Draw the background （绘制控件设置的背景） * 2. If necessary, save the canvas' layers to prepare for fading * 3. Draw view's content (可以重写， onDraw(canvas);) * 4. Draw children (可重写，用来分发画布到子控件，具体看ViewGroup。对应方法dispatchDraw(canvas);此方法依次调用了子控件的draw()方法) * 5. If necessary, draw the fading edges and restore layers （绘制控件四周的阴影渐变效果） * 6. Draw decorations (scrollbars for instance) （用来绘制滚动条，对应方法onDrawScrollBars(canvas);。 * 可以重写onDrawHorizontalScrollBar()和onDrawVerticalScrollBar()来自定义滚动条） */ //可以绘制内容和滚动条。 //draw backgroud canvas.drawColor(Color.WHITE); //draw text FontMetrics fm = mPaint.getFontMetrics(); float baseline = fm.descent - fm.ascent; float x = 0; float y = baseline; //由于系统基于字体的底部来绘制文本，所有需要加上字体的高度。 String txt = getResources().getString(com.orgcent.demo.R.string.hello); //文本自动换行 String[] texts = autoSplit(txt, mPaint, getWidth() - 5); System.out.printf("line indexs: %s\n", Arrays.toString(texts)); for(String text : texts) { canvas.drawText(text, x, y, mPaint); //坐标以控件左上角为原点 y += baseline + fm.leading; //添加字体行间距 } } /** * 自动分割文本 * @param content 需要分割的文本 * @param p 画笔，用来根据字体测量文本的宽度 * @param width 指定的宽度 * @return 一个字符串数组，保存每行的文本 */ private String[] autoSplit(String content, Paint p, float width) { int length = content.length(); float textWidth = p.measureText(content); if(textWidth <= width) { return new String[]{content}; } int start = 0, end = 1, i = 0; int lines = (int) Math.ceil(textWidth / width); //计算行数 String[] lineTexts = new String[lines]; while(start < length) { if(p.measureText(content, start, end) > width) { //文本宽度超出控件宽度时 lineTexts[i++] = (String) content.subSequence(start, end); start = end; } if(end == length) { //不足一行的文本 lineTexts[i] = (String) content.subSequence(start, end); break; } end += 1; } return lineTexts; } /** * 获取指定单位对应的原始大小（根据设备信息） * px,dip,sp -> px * * Paint.setTextSize()单位为px * * 代码摘自：TextView.setTextSize() * * @param unit TypedValue.COMPLEX_UNIT_* * @param size * @return */ public float getRawSize(int unit, float size) { Context c = getContext(); Resources r; if (c == null) r = Resources.getSystem(); else r = c.getResources(); return TypedValue.applyDimension(unit, size, r.getDisplayMetrics()); } }