Android学习笔记---自定义TextView实现阴影效果

直接上代码

SGTextView.java

package com.example.tv.view;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.Shader;
import android.graphics.Shader.TileMode;
import android.util.AttributeSet;
import android.widget.TextView;

public class SGTextView extends TextView {
    private Paint strokPaint = new Paint();
    private Paint gradientPaint = new Paint();

    public SGTextView(Context context) {
        this(context, null);
    }

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

    public void setStyle(String strokeColor, String startColor,
            String endColor, float strokewidthDp, int gradientHeighDp) {
        setStyle(
                Color.parseColor(strokeColor),
                DimensUtils.dip2px(getContext(), strokewidthDp),
                new LinearGradient(0, 0, 0, DimensUtils.dip2px(getContext(),
                        gradientHeighDp), new int[] {
                        Color.parseColor(startColor),
                        Color.parseColor(endColor) }, null, TileMode.CLAMP));
    }

    public void setStyle(int strokeColor, float strokewidth, Shader shader) {

        strokPaint.setAntiAlias(true);
        // 设定是否使用图像抖动处理，会使绘制出来的图片颜色更加平滑和饱满，图像更加清晰
        strokPaint.setDither(true);
        // 如果该项设置为true，则图像在动画进行中会滤掉对Bitmap图像的优化操作，加快显示
        // 速度，本设置项依赖于dither和xfermode的设置
        strokPaint.setFilterBitmap(true);

        strokPaint.setStrokeWidth(strokewidth);
        strokPaint.setColor(strokeColor);
        // 设置绘制时各图形的结合方式，如平滑效果等
        strokPaint.setStrokeJoin(Paint.Join.ROUND);
        // 当画笔样式为STROKE或FILL_OR_STROKE时，设置笔刷的图形样式，如圆形样式
        // Cap.ROUND,或方形样式Cap.SQUARE
        strokPaint.setStrokeCap(Paint.Cap.ROUND);
        strokPaint.setStyle(Paint.Style.STROKE);

        gradientPaint.setAntiAlias(true);
        gradientPaint.setDither(true);
        gradientPaint.setFilterBitmap(true);
        gradientPaint.setShader(shader);
        gradientPaint.setStrokeJoin(Paint.Join.ROUND);
        gradientPaint.setStrokeCap(Paint.Cap.ROUND);
        gradientPaint.setStyle(Paint.Style.FILL_AND_STROKE);

        float textsize = getTextSize();
        strokPaint.setTextSize(textsize);
        gradientPaint.setTextSize(textsize);

    }

    public void setShadowLayer(float radius, float dx, float dy, String color) {
        strokPaint.setShadowLayer(radius, dx, dy, Color.parseColor(color));
    }

    @Override
    protected void onDraw(Canvas canvas) {

        String text = getText().toString();
        int width = getMeasuredWidth();
        if (width == 0) {
            measure(0, 0);
            width = (int) (getMeasuredWidth() + strokPaint.getStrokeWidth() * 2);
            setWidth(width);
        }

        float y = getBaseline();
        float x = (width - strokPaint.measureText(text)) / 2;

        canvas.drawText(text, x, y, strokPaint);
        canvas.drawText(text, x, y, gradientPaint);
    }
}

DimensUtils.java

package com.example.tv.view;

import android.content.Context;

public final class DimensUtils {
    private DimensUtils() {
    }

    public static int px2dip(Context context, float pxValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (pxValue / scale + 0.5f);
    }

    public static int dip2px(Context context, float dipValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dipValue * scale + 0.5f);
    }

    public static int px2sp(Context context, float pxValue) {
        final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;
        return (int) (pxValue / fontScale + 0.5f);
    }

    public static int sp2px(Context context, float spValue) {
        final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;
        return (int) (spValue * fontScale + 0.5f);
    }

}

下面在布局中使用它

        <com.example.tv.view.SGTextView
            android:id="@+id/tv_tishis"
            android:layout_width="wrap_content"
            android:text="换台中"
            android:layout_height="match_parent"
            android:textSize="15sp"
            android:gravity="center"
            android:visibility="gone"
            android:layout_centerHorizontal="true" />

在代码中设置颜色以及阴影

        tvMainPeogressBar = (SGTextView) findViewById(R.id.tv_tishis);
        tvMainPeogressBar.setTextSize(43);//字体大小
        tvMainPeogressBar.setText("换台中……");//文本内容
        tvMainPeogressBar.setStyle("#ded8cd", "#7d7a74", "#a1969d", 3, 9);//渐变颜色
        tvMainPeogressBar.setShadowLayer(2, 0, 2, "#000000");//阴影