import com.carspeak.client.util.DensityUtils;

import android.content.Context;

import android.graphics.Paint;

import android.graphics.Paint.FontMetrics;

import android.util.AttributeSet;

import android.util.Log;

import android.view.ViewGroup.LayoutParams;

import android.widget.TextView;

public class ShadowTextView extends TextView {

    private static float DEFAULT_MIN_TEXT_SIZE = 10;

    private static float DEFAULT_MAX_TEXT_SIZE = 85;

    // Attributes

    private Paint testPaint;

    private float minTextSize, maxTextSize;

    private String TAG = "ShadowTextView";

    public ShadowTextView(Context context, AttributeSet attrs) {

        super(context, attrs);

        initialise();

    }

    public ShadowTextView(Context context) {

        super(context);

    }

    public ShadowTextView(Context context, AttributeSet attrs, int defStyle) {

        super(context, attrs, defStyle);

    }

    @Override

    protected void onTextChanged(CharSequence text, int start,int lengthBefore, int lengthAfter) {

        super.onTextChanged(text, start, lengthBefore, lengthAfter);

        refitText(text.toString(), this.getWidth(),this.getHeight());

    }

    private void initialise() {

        testPaint = new Paint();

        testPaint.set(this.getPaint());

        // max size defaults to the intially specified text size unless it is

        // too small

        maxTextSize = this.getTextSize();

        if (maxTextSize <= DEFAULT_MAX_TEXT_SIZE) {

            maxTextSize = DEFAULT_MAX_TEXT_SIZE;

        }

        minTextSize = DEFAULT_MIN_TEXT_SIZE;

    };

    @Override

    protected void onSizeChanged(int w, int h, int oldw, int oldh) {

        if (w != oldw) {

//            refitText(this.getText().toString(), w);  //原本是需要执行的

        }

    }

    /**

     * Re size the font so the specified text fits in the text box * assuming

     * the text box is the specified width.

     */

private void refitText(String text, int textWidth,int textHeight) {

        int Length = text.length();

        //直接根据字符长度来调整字体大小  最大长度为20

//        this.setTextSize(DensityUtils.dp2px(this.getContext(), trySize));

//        testPaint.set(this.getPaint());

        if (textWidth > 0) {

            int availableWidth = textWidth - this.getPaddingLeft() - this.getPaddingRight();  //获取改TextView的画布可用大小

            float trySize = maxTextSize;

            float scaled = getContext().getResources().getDisplayMetrics().scaledDensity;

//            Log.v(TAG, "availableWidth="+availableWidth + ";scaled="+scaled);

            testPaint.setTextSize(trySize*scaled);   //模拟 注意乘以scaled

            while ((trySize > minTextSize)&& (testPaint.measureText(text) > availableWidth))

            {

                trySize -= 2;

                FontMetrics fm = testPaint.getFontMetrics();

                double rowFontHeight = (Math.ceil(fm.descent - fm.top) + 2);

                float scaled1 = (float) (this.getHeight() /rowFontHeight );  //字体的行数   textview的总高度/每行字的高度

                float scaled2 = (float) ((testPaint.measureText(text) / availableWidth));  //也是行数  所有字的总长度/textview的有效宽度

//                Log.v(TAG, "trySize="+trySize + ";testPaint.measureText(text)="+testPaint.measureText(text)+";scaled1="+scaled1+";scaled2="+scaled2+";rowFontHeight="+rowFontHeight);

                if((scaled2*rowFontHeight*1.9)<this.getHeight())  //1.9代表是1.9的行高（1个字体本身，0.9的行距 ，大致差不多，没有实际测过）

                    break;

                if (trySize <= minTextSize) {

                    trySize = minTextSize;

                    break;

                }

                testPaint.setTextSize(trySize*scaled);

            }

            this.setTextSize(trySize);

//            Log.v(TAG, "trySize="+trySize+";maxTextSize="+maxTextSize+";minTextSize="+minTextSize);

        }

}

//    private void refitText(String text, int textWidth,int textHeight) {

////        if (textWidth > 0) {

////            int availableWidth = textWidth - this.getPaddingLeft() - this.getPaddingRight();  //获取改TextView的画布可用大小

////            float trySize = maxTextSize;

////            float scaled = getContext().getResources().getDisplayMetrics().scaledDensity;

////            testPaint.setTextSize(trySize*scaled);   //模拟 注意乘以scaled

////            while ((trySize > minTextSize)&& (testPaint.measureText(text) > availableWidth)) {

////                trySize -= 2;

////                FontMetrics fm = testPaint.getFontMetrics();

////                float scaled1 = (float) (this.getHeight() / (Math.ceil(fm.descent - fm.top) + 2));

////                float scaled2 = (float) ((testPaint.measureText(text) / availableWidth));

////                if (scaled1 >= 1.75 & scaled1 >= scaled2) { // 注意1.75是三星s4 小米3  的适合数值（当然包括我的联想了)

////                    break;

////                }

////            if (trySize <= minTextSize) {

////                trySize = minTextSize;

////                break;

////            }

////            testPaint.setTextSize(trySize*scaled);

////            }

////            this.setTextSize(trySize);      //等同于this.getPaint().set(trySize*scaled);

////        }

//    }

}

<com.carspeak.client.view.ShadowTextView

                    android:id="@+id/tv_shadow_preview"

                    android:layout_width="@dimen/projection_screen_width_4_3"

                    android:layout_height="@dimen/projection_screen_height_4_3"

                    android:layout_centerHorizontal="true"

                    android:background="#000"

                    android:text="字幕"

                    android:gravity="center"

                    android:textColor="#fff" />