FloatImageTextView.java

package com.roboo.like.netease.view;

import java.util.ArrayList;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.FontMetrics;
import android.graphics.Rect;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.TypedValue;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Scroller;

/**
 * 模拟CSS中的float浮动效果
 */
public class FloatImageTextView extends View
{
	/**
	 * 文字环绕的图片
	 */
	private Bitmap mBitmap;
	/**
	 * 图片矩形大小
	 */
	private final Rect bitmapFrame = new Rect();
	private final Rect tmp = new Rect();
	/**
	 * view 默认采用的density
	 */
	private int mTargetDentity = DisplayMetrics.DENSITY_DEFAULT;
	/***
	 * 绘制文字的画笔
	 */
	private final Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
	/**
	 * 要显示的文字
	 */
	private String mText;
	/**
	 * 根据文字大小以确定文字应该显示的行数
	 */
	private ArrayList<TextLine> mTextLines;
	private final int[] textSize = new int[2];

	public FloatImageTextView(Context context)
	{
		super(context);
		init();
	}

	public FloatImageTextView(Context context, AttributeSet attrs, int defStyle)
	{
		super(context, attrs, defStyle);
		init();
	}

	public FloatImageTextView(Context context, AttributeSet attrs)
	{
		super(context, attrs);
		init();
	}

	private void init()
	{
		mTargetDentity = getResources().getDisplayMetrics().densityDpi;
		mTextLines = new ArrayList<TextLine>();
		mPaint.setTextSize(30);
		mPaint.setColor(Color.RED);

	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
	{
		int w = 0, h = 0;
		// 图片大小
		w += bitmapFrame.width();
		h += bitmapFrame.height();

		// 文本宽度
		if (null != mText && mText.length() > 0)//TextUtils.isEmpty(mText);
		{
			mTextLines.clear();
			int size = resolveSize(Integer.MAX_VALUE, widthMeasureSpec);
			 
			measureAndSplitText(mPaint, mText, size);
			final int textWidth = textSize[0], textHeight = textSize[1];
			w += textWidth; // 内容宽度
			if (h < textHeight)
			{ // 内容高度
				h = (int) textHeight;
			}
		}

		w = Math.max(w, getSuggestedMinimumWidth());
		h = Math.max(h, getSuggestedMinimumHeight());

		setMeasuredDimension(resolveSize(w, widthMeasureSpec), resolveSize(h, heightMeasureSpec));
	}

	@Override
	protected void onDraw(Canvas canvas)
	{
		// 绘制图片
		if (null != mBitmap)
		{
			canvas.drawBitmap(mBitmap, null, bitmapFrame, null);
		}

		// 绘制文本
		TextLine line;
		final int size = mTextLines.size();
		for (int i = 0; i < size; i++)
		{
			line = mTextLines.get(i);
			canvas.drawText(line.text, line.x, line.y, mPaint);
		}
		System.out.println(mTextLines);
	}

	public void setImageBitmap(Bitmap bm)
	{
		setImageBitmap(bm, null);
	}

	public void setImageBitmap(Bitmap bm, int left, int top)
	{
		setImageBitmap(bm, new Rect(left, top, 0, 0));
	}

	public void setImageBitmap(Bitmap bm, Rect bitmapFrame)
	{
		mBitmap = bm;
		computeBitmapSize(bitmapFrame);
		requestLayout();
		invalidate();
	}

	public void setText(String text)
	{
		mText = text;
		requestLayout();
		invalidate();
	}

	private void computeBitmapSize(Rect rect)
	{
		if (null != rect)
		{
			bitmapFrame.set(rect);
		}
		if (null != mBitmap)
		{
			if (rect.right == 0 && rect.bottom == 0)
			{
				final Rect r = bitmapFrame;
				r.set(r.left, r.top, r.left + mBitmap.getScaledHeight(mTargetDentity), r.top + mBitmap.getScaledHeight(mTargetDentity));
			}
		}
		else
		{
			bitmapFrame.setEmpty();
		}
	}
	/**
	 * 将文字拆分成多行进行绘制
	 * @param p
	 * @param content
	 * @param maxWidth
	 */
	private void measureAndSplitText(Paint p, String content, int maxWidth)
	{
		FontMetrics fm = mPaint.getFontMetrics();
		final int lineHeight = (int) (fm.bottom - fm.top);
		final Rect r = new Rect(bitmapFrame);
		// r.inset(-5, -5);
		final int length = content.length();
		int start = 0, end = 0, offsetX = 0, offsetY = 0;
		int availWidth = maxWidth;
		TextLine line;
		boolean onFirst = true;
		boolean newLine = true;
		while (start < length)
		{
			end++;
			if (end == length)
			{ // 剩余的不足一行的文本
				if (start <= length - 1)
				{
					if (newLine)
						offsetY += lineHeight;
					line = new TextLine();
					line.text = content.substring(start, end - 1);
					line.x = offsetX;
					line.y = offsetY;
					mTextLines.add(line);
				}
				break;
			}
			p.getTextBounds(content, start, end, tmp);
			if (onFirst)
			{ // 确定每个字符串的坐标
				onFirst = false;
				final int height = lineHeight + offsetY;
				if (r.top >= height)
				{ // 顶部可以放下一行文字
					offsetX = 0;
					availWidth = maxWidth;
					newLine = true;
				}
				else if (newLine && (r.bottom >= height && r.left >= tmp.width()))
				{ // 中部左边可以放文字
					offsetX = 0;
					availWidth = r.left;
					newLine = false;
				}
				else if (r.bottom >= height && maxWidth - r.right >= tmp.width())
				{ // 中部右边
					offsetX = r.right;
					availWidth = maxWidth - r.right;
					newLine = true;
				}
				else
				{ // 底部
					offsetX = 0;
					availWidth = maxWidth;
					if (offsetY < r.bottom)
						offsetY = r.bottom;
					newLine = true;
				}
			}

			if (tmp.width() > availWidth)
			{ // 保存一行能放置的最大字符串
				onFirst = true;
				line = new TextLine();
				line.text = content.substring(start, end - 1);
				line.x = offsetX;
				mTextLines.add(line);
				if (newLine)
				{
					offsetY += lineHeight;
					line.y = offsetY;
				}
				else
				{
					line.y = offsetY + lineHeight;
				}

				start = end - 1;
			}
		}
		textSize[1] = offsetY;
	}

	class TextLine
	{
		String text;
		int x;
		int y;

		@Override
		public String toString()
		{
			return "TextLine [text=" + text + ", x=" + x + ", y=" + y + "]";
		}
	}

}