学步园

public class MyTextView extends TextView {

	private int textSize = 25;
	private int textColor = R.color.black;
	private String text;
	private Paint paint;
	private boolean hasDrawed = false;
	private List<String> lines;

	public DiskNameTextView(Context context, AttributeSet attrs) {
		super(context, attrs);
		textSize = attrs.getAttributeIntValue(
				"http://schemas.android.com/apk/res/android", "textSize", 28);
		textColor = attrs.getAttributeIntValue(
				"http://schemas.android.com/apk/res/android", "textColor", R.color.black);
		paint = new Paint();
		paint.setTextSize(textSize);
		paint.setColor(textColor);
		paint.setStyle(Style.FILL);
		paint.setAntiAlias(true);
	}

	@SuppressLint("DrawAllocation")
	@Override
	protected void onDraw(Canvas canvas) {
		super.onDraw(canvas);
		if (text != null && !text.trim().equals("")) {
			if(lines != null) {				//先把每行文字保存起来，重画的时候加快速度
				for(int i=0; i<lines.size(); i++) {
					canvas.drawText(lines.get(i), 0, (i+1) * textSize, paint);
				}
				return;
			}
			int viewWidth = this.getWidth();									// 得到view的宽度
			int textWidth = (int) paint.measureText(text, 0, text.length());	// 得到text的宽度
			int line = (int) Math.ceil(textWidth / viewWidth) + 1;				//得到行数
			if(!hasDrawed) {	//通过行数设置view的高度，最后加的1/2行高是为了把p、j这种跨行的字母显示完整
				this.setLayoutParams(new LayoutParams(viewWidth, textSize * line + textSize / 2));
			}
			if (textWidth < viewWidth) {
				canvas.drawText(text, 0, textSize, paint);
			} else {
				int currIndex = 0;
				int lineNum = 1;
				String lastLine = "";
				lines = new ArrayList<String>();
				int lineWords = (int) ((float)text.length() / ((float) textWidth / (float) viewWidth + 2));
				for (int i = lineWords; i < text.length(); i++) {
					String subStr = text.substring(currIndex, i);
					int width = (int) paint.measureText(subStr, 0, subStr.length());
					if (width < viewWidth) {
						lastLine = subStr;
						if (i == text.length() - 1) {
							lastLine = text.substring(currIndex, ++i);
							canvas.drawText(lastLine, 0, lineNum * textSize, paint);
							lines.add(lastLine);
						}
						continue;
					} else {
						canvas.drawText(lastLine, 0, lineNum * textSize, paint);
						lines.add(lastLine);
						currIndex = i - 1;
						lineNum++;
						i--;
						if(i + lineWords < text.length())
							i += lineWords;
					}
				}
				hasDrawed = true;
			}
		}

	}

	public String getText() {
		return text;
	}

	public void setText(String text) {
		this.text = text;
		hasDrawed = false;
		invalidate();
	}

}