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【Android】解析Paint类中MaskFilter的使用

时间:2018-09-29 01:20:18      阅读:221      评论:0      收藏:0      [点我收藏+]

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目录结构:

contents structure [+]

MaskFilter可以用来指定画笔的边缘效果。如果引用开启硬件加速的话,那么MaskFilter将不会起作用。
关闭硬件加速:

android:hardwareAccelerated="false"

Android中有两个已知的MaskFilter实现类,分别是:BlurMaskFilter和EmbossMaskFilter:
BlurMaskFilter:指定模糊样式和影响半径。
EmbossMaskFilter:指定浮雕的光源方向和周围光强度。

1.EmbossMaskFilter

EmbossMaskFilter用于完成浮雕效果,通过PS可以更简单的完成类似的效果。EmbossMaskFilter的唯一构造方法是:

public EmbossMaskFilter (float[] direction,float ambient,float specular,float blurRadius)

这个构造方法在API 28(Android 9.0)中已经被废弃了。

在指定参数的时候需要指定光源方向(direction)、环境光强度(ambient)、镜面反射系数(specular)和模糊半径(blurRadius)。

float[] direction=new float[]{1,1,1};//指定光源方向
float light=0.4f;//指定环境光强度(0~1),0~1表示环境从暗到亮
float specular=6f;//指定镜面反射系数,越接近0,反射光越强。
float blur=3f;//指定模糊半径,值越大,越清晰。

EmbossMaskFilter emboss=new EmbossMaskFilter(direction,light,specular,blur);
if(!canvas.isHardwareAccelerated()){//在未硬件加速的情况下设置效果
    myPaint.setMaskFilter(emboss);
}

如下代码:

protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    Paint paint=new Paint();
    paint.setColor(Color.RED);
    paint.setStyle(Style.FILL);
    paint.setTextSize(70);

    float[] direction=new float[]{1,1,1};//指定光源方向
    float light=0.3f;//指定环境光强度
    float specular=5;//指定镜面反射强度
    float blur=5f;//指定模糊程度

    EmbossMaskFilter emboss=new EmbossMaskFilter(direction,light,specular,blur);
    
    if(!canvas.isHardwareAccelerated()){//如果没有开启硬件加速,就设置浮雕效果
        paint.setMaskFilter(emboss);
    }
    canvas.drawText("test测试", 200,200, paint);//绘制文本
}

效果图:
技术分享图片

通过改变为不同的参数,可以得到不同的效果。

2.BlurMaskFilter

BlurMaskFilter有一个构造方法如下:

BlurMaskFilter(float radius, BlurMaskFilter.Blur style)

在构建BlurMaskFilter时,需要传入BlurMaskFilter.Blur枚举值,该枚举值有如下4种:

BlurMaskFilter.Blur.INNER 在边界内模糊,边界外不模糊
BlurMaskFilter.Blur.NORMAL 在边界内和边界外都模糊
BlurMaskFilter.Blur.OUTER 在边界外模糊,边界内不模糊
BlurMaskFilter.Blur.SOLID 在边边界内使用solid边框,边界外模糊


下面是使用示例:
activity_main.xml

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/rl"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    tools:context=".MainActivity"
    android:background="#ffffff"
    >
    <TextView
        android:id="@+id/tv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="ANDROID"
        android:textSize="100dp"
        android:textStyle="bold"
        android:textColor="#ff0000"
        android:gravity="center"
        />
    <RadioGroup
        android:id="@+id/rg"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        >
        <RadioButton
            android:id="@+id/rb_none"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="No blur"
            />
        <RadioButton
            android:id="@+id/rb_inner"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Inner blur"
            />
        <RadioButton
            android:id="@+id/rb_normal"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Normal blur"
            />
        <RadioButton
            android:id="@+id/rb_outer"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Outer blur"
            />
        <RadioButton
            android:id="@+id/rb_solid"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Solid blur"
            />
    </RadioGroup>
</RelativeLayout>

MainActivity.jave

import android.app.Activity;
import android.content.Context;
import android.content.pm.ActivityInfo;
import android.content.res.Resources;
import android.graphics.BlurMaskFilter;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.RadioGroup;
import android.widget.RelativeLayout;
import android.widget.TextView;

public class MainActivity extends Activity {
    Context mContext=null;
    Resources mResources=null;
    RelativeLayout mRelativeLayout=null;
    TextView mTextView=null;
    RadioGroup mRadioGroup=null;
    
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);//设置横屏
        
        mContext = getApplicationContext();

        mResources = getResources();

        mRelativeLayout = (RelativeLayout) findViewById(R.id.rl);
        mTextView = (TextView) findViewById(R.id.tv);
        mRadioGroup = (RadioGroup) findViewById(R.id.rg);

        // Set a checked change listener for RadioGroup
        mRadioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup radioGroup, int i) {
                if (i == R.id.rb_none) {
                    // If no blur is checked
                    // Set the TextView layer type
                    mTextView.setLayerType(View.LAYER_TYPE_SOFTWARE,null);
                    // Clear any previous MaskFilter
                    mTextView.getPaint().setMaskFilter(null);
                }
                if(i == R.id.rb_inner){
                    // If inner blur checked
                    applyBlurMaskFilter(mTextView, BlurMaskFilter.Blur.INNER);
                }
                if(i == R.id.rb_normal){
                    // If normal blur checked
                    applyBlurMaskFilter(mTextView, BlurMaskFilter.Blur.NORMAL);
                }
                if(i == R.id.rb_outer){
                    // If outer blur checked
                    applyBlurMaskFilter(mTextView, BlurMaskFilter.Blur.OUTER);
                }
                if(i == R.id.rb_solid){
                    // If solid blur checked
                    applyBlurMaskFilter(mTextView, BlurMaskFilter.Blur.SOLID);
                }
            }
        });
    }

    // Custom method to apply BlurMaskFilter to a TextView text
    protected void applyBlurMaskFilter(TextView tv, BlurMaskFilter.Blur style){

        // Define the blur effect radius
        float radius = tv.getTextSize()/10;

        // Initialize a new BlurMaskFilter instance
        BlurMaskFilter filter = new BlurMaskFilter(radius,style);

        /*
            public void setLayerType (int layerType, Paint paint)
                Specifies the type of layer backing this view. The layer can be LAYER_TYPE_NONE,
                LAYER_TYPE_SOFTWARE or LAYER_TYPE_HARDWARE.

                A layer is associated with an optional Paint instance that controls how the
                layer is composed on screen.
                
            Parameters
                layerType : The type of layer to use with this view, must be one of
                    LAYER_TYPE_NONE, LAYER_TYPE_SOFTWARE or LAYER_TYPE_HARDWARE
                paint : The paint used to compose the layer. This argument is optional and can be null. It is ignored when the layer type is LAYER_TYPE_NONE
        */
        /*
            public static final int LAYER_TYPE_SOFTWARE
                Indicates that the view has a software layer. A software layer is backed by
                a bitmap and causes the view to be rendered using Android‘s software rendering
                pipeline, even if hardware acceleration is enabled.
        */
        
        // Set the TextView layer type
        tv.setLayerType(View.LAYER_TYPE_SOFTWARE, new Paint());//取消硬件加速

        tv.getPaint().setMaskFilter(filter);
    }
}

效果图:
技术分享图片

技术分享图片

技术分享图片

技术分享图片

技术分享图片

 

参考文章:

How to use BlurMaskFilter In Android

 

【Android】解析Paint类中MaskFilter的使用

标签:context   can   12px   ima   ring   图片   textview   too   save   

原文地址:https://www.cnblogs.com/HDK2016/p/9721633.html

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