Android学习笔记---自定义TextView实现阴影效果

Posted 2020-09-04 纯属浪费8818

直接上代码

SGTextView.java

 1 package com.example.tv.view;
 2 
 3 import android.content.Context;
 4 import android.graphics.Canvas;
 5 import android.graphics.Color;
 6 import android.graphics.LinearGradient;
 7 import android.graphics.Paint;
 8 import android.graphics.Shader;
 9 import android.graphics.Shader.TileMode;
10 import android.util.AttributeSet;
11 import android.widget.TextView;
12 
13 public class SGTextView extends TextView {
14     private Paint strokPaint = new Paint();
15     private Paint gradientPaint = new Paint();
16 
17     public SGTextView(Context context) {
18         this(context, null);
19     }
20 
21     public SGTextView(Context context, AttributeSet attrs) {
22         super(context, attrs);
23     }
24 
25     public void setStyle(String strokeColor, String startColor,
26             String endColor, float strokewidthDp, int gradientHeighDp) {
27         setStyle(
28                 Color.parseColor(strokeColor),
29                 DimensUtils.dip2px(getContext(), strokewidthDp),
30                 new LinearGradient(0, 0, 0, DimensUtils.dip2px(getContext(),
31                         gradientHeighDp), new int[] {
32                         Color.parseColor(startColor),
33                         Color.parseColor(endColor) }, null, TileMode.CLAMP));
34     }
35 
36     public void setStyle(int strokeColor, float strokewidth, Shader shader) {
37 
38         strokPaint.setAntiAlias(true);
39         // 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
40         strokPaint.setDither(true);
41         // 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
42         // 速度，本设置项依赖于dither和xfermode的设置
43         strokPaint.setFilterBitmap(true);
44 
45         strokPaint.setStrokeWidth(strokewidth);
46         strokPaint.setColor(strokeColor);
47         // 设置绘制时各图形的结合方式，如平滑效果等
48         strokPaint.setStrokeJoin(Paint.Join.ROUND);
49         // 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
50         // Cap.ROUND,或方形样式Cap.SQUARE
51         strokPaint.setStrokeCap(Paint.Cap.ROUND);
52         strokPaint.setStyle(Paint.Style.STROKE);
53 
54         gradientPaint.setAntiAlias(true);
55         gradientPaint.setDither(true);
56         gradientPaint.setFilterBitmap(true);
57         gradientPaint.setShader(shader);
58         gradientPaint.setStrokeJoin(Paint.Join.ROUND);
59         gradientPaint.setStrokeCap(Paint.Cap.ROUND);
60         gradientPaint.setStyle(Paint.Style.FILL_AND_STROKE);
61 
62         float textsize = getTextSize();
63         strokPaint.setTextSize(textsize);
64         gradientPaint.setTextSize(textsize);
65 
66     }
67 
68     public void setShadowLayer(float radius, float dx, float dy, String color) {
69         strokPaint.setShadowLayer(radius, dx, dy, Color.parseColor(color));
70     }
71 
72     @Override
73     protected void onDraw(Canvas canvas) {
74 
75         String text = getText().toString();
76         int width = getMeasuredWidth();
77         if (width == 0) {
78             measure(0, 0);
79             width = (int) (getMeasuredWidth() + strokPaint.getStrokeWidth() * 2);
80             setWidth(width);
81         }
82 
83         float y = getBaseline();
84         float x = (width - strokPaint.measureText(text)) / 2;
85 
86         canvas.drawText(text, x, y, strokPaint);
87         canvas.drawText(text, x, y, gradientPaint);
88     }
89 }

DimensUtils.java

 1 package com.example.tv.view;
 2 
 3 import android.content.Context;
 4 
 5 public final class DimensUtils {
 6     private DimensUtils() {
 7     }
 8 
 9     public static int px2dip(Context context, float pxValue) {
10         final float scale = context.getResources().getDisplayMetrics().density;
11         return (int) (pxValue / scale + 0.5f);
12     }
13 
14     public static int dip2px(Context context, float dipValue) {
15         final float scale = context.getResources().getDisplayMetrics().density;
16         return (int) (dipValue * scale + 0.5f);
17     }
18 
19     public static int px2sp(Context context, float pxValue) {
20         final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;
21         return (int) (pxValue / fontScale + 0.5f);
22     }
23 
24     public static int sp2px(Context context, float spValue) {
25         final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;
26         return (int) (spValue * fontScale + 0.5f);
27     }
28 
29 }

 

下面在布局中使用它

1         <com.example.tv.view.SGTextView
2             android:id="@+id/tv_tishis"
3             android:layout_width="wrap_content"
4             android:text="换台中"
5             android:layout_height="match_parent"
6             android:textSize="15sp"
7             android:gravity="center"
8             android:visibility="gone"
9             android:layout_centerHorizontal="true" />

 

在代码中设置颜色以及阴影

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