ImageSpan

自定义ImageSpan继承类，可以设置图片大小和位置

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Paint.FontMetricsInt;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.text.style.ImageSpan;

import com.xuehu365.xuehu.utils.LogHelp;

/**
 * Created by Administrator on 2016/10/20.
 */
public class MyImageSpan extends ImageSpan {
    public MyImageSpan(Context arg0, int arg1) {
        super(arg0, arg1);
    }

    public int getSize(Paint paint, CharSequence text, int start, int end,
                       Paint.FontMetricsInt fm) {
        Drawable d = getDrawable();
//        Drawable d2 = zoomDrawable(d, 50, 50);
        Rect rect = d.getBounds();
        if (fm != null) {
            FontMetricsInt fmPaint = paint.getFontMetricsInt();
            int fontHeight = fmPaint.bottom - fmPaint.top;
            int drHeight = rect.bottom - rect.top;

            int top = drHeight / 2 - fontHeight / 4;
            int bottom = drHeight / 2 + fontHeight / 4;

            fm.ascent = -bottom;
            fm.top = -bottom;
            fm.bottom = top;
            fm.descent = top;
        }
        return rect.right;
    }

    @Override
    public void draw(Canvas canvas, CharSequence text, int start, int end,
                     float x, int top, int y, int bottom, Paint paint) {
        Drawable b = getDrawable();
        canvas.save();
        int transY = 0;
        transY = ((bottom - top) - b.getBounds().bottom) / 2 + top;
        canvas.translate(x, transY);
        b.draw(canvas);
        canvas.restore();
    }

    public Drawable zoomDrawable(Drawable drawable, int w, int h) {
        int width = drawable.getIntrinsicWidth();
        int height = drawable.getIntrinsicHeight();
        Bitmap oldbmp = drawableToBitmap(drawable);// drawable转换成bitmap
        Matrix matrix = new Matrix();   // 创建操作图片用的Matrix对象
        float scaleWidth = ((float) w / width);   // 计算缩放比例
        LogHelp.i("move", "width:" + width + ";;w:" + w + ";;scaleWidth:" + scaleWidth);
        float scaleHeight = ((float) h / height);
        matrix.postScale(scaleWidth, scaleHeight);         // 设置缩放比例
        Bitmap newbmp = Bitmap.createBitmap(oldbmp, 0, 0, width, height, matrix, true);       // 建立新的bitmap，其内容是对原bitmap的缩放后的图
        return new BitmapDrawable(newbmp);       // 把bitmap转换成drawable并返回
    }

    public Bitmap drawableToBitmap(Drawable drawable)// drawable 转换成bitmap
    {
        int width = drawable.getIntrinsicWidth();   // 取drawable的长宽
        int height = drawable.getIntrinsicHeight();
        Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565;         // 取drawable的颜色格式
        Bitmap bitmap = Bitmap.createBitmap(width, height, config);     // 建立对应bitmap
        Canvas canvas = new Canvas(bitmap);         // 建立对应bitmap的画布
        drawable.setBounds(0, 0, width, height);
        drawable.draw(canvas);      // 把drawable内容画到画布中
        return bitmap;
    }
}