ShadowTextView 阴影字

package android.car.ui;

import android.content.Context;
import android.content.res.ColorStateList;
import android.graphics.BlurMaskFilter;
import android.graphics.BlurMaskFilter.Blur;
import android.graphics.Canvas;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.view.View;
import android.widget.TextView;

import java.lang.reflect.Field;

public class ShadowTextView extends TextView {

    static final String TAG = "ShadowTextView";

    ColorStateList mShadowColorList;
    BlurMaskFilter mMaskFilter;
    boolean mEnableFilter = false;
    int mShadowColor = 0;
    float mShadowSize = 0.0f;
    Blur mBlurType;

    Field mCurTextColorField;

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

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

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

    private void init() {
        mCurTextColorField = getField("mCurTextColor");
        setLayerType(View.LAYER_TYPE_SOFTWARE, null);
        if (mCurTextColorField != null) {
            mCurTextColorField.setAccessible(true);
        }
    }

    public void setEnableShadow(boolean enable) {
        mEnableFilter = enable;
    }

    public void setShadow(int color, float size, Blur type) {
        mShadowColor = color;
        mShadowSize = size;
        mBlurType = type;

        mMaskFilter = new BlurMaskFilter(mShadowSize, mBlurType);
    }

    private static Field getField(String name) {
        try {
            Field f = TextView.class.getDeclaredField(name);
            return f;
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        }
        return null;
    }

    void setCurrColor(int color) {
        if (mCurTextColorField != null) {
            try {
                mCurTextColorField.setInt(this, color);
            } catch (IllegalArgumentException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        if (mEnableFilter && mMaskFilter != null) {
            int oldColor = getCurrentTextColor();
            setCurrColor(mShadowColor);
            TextPaint tp = getPaint();
            tp.setMaskFilter(mMaskFilter);
            super.onDraw(canvas);
            tp.setMaskFilter(null);
            setCurrColor(oldColor);
        }
        super.onDraw(canvas);
    }
}