Android开发-Android中设置图片为圆角，Drawable转化为Bitmap

谁借莪１个温暖的怀抱￠ 2023-10-16 20:48 94阅读 0赞

#### 1 简介 ####

图片处理是Android应用程序开发时经常需要进行的操作，例如图片的放大，缩小，拉升，圆角，倒影.......等等。

Android中，和图片相关的类，最主要的两个是Drawable转化为Bitmap。经常需要进行二者的转换。本篇介绍，图片相关的操作，给出一个工具类的实现。

#### 2 工具类的实现和使用： ####

这个工具类主要提供以下功能：

>     图片的缩放（缩小和放大）；
>     把Drawable转化为Bitmap；
>     通过Bitmap，获得圆角图片；
>     通过Bitmap，获得带倒影的图片；

代码：

package com.bangcle.myglibtestapp.utils;
    
    import android.graphics.Bitmap;
    import android.graphics.Canvas;
    import android.graphics.LinearGradient;
    import android.graphics.Matrix;
    import android.graphics.Paint;
    import android.graphics.PixelFormat;
    import android.graphics.PorterDuffXfermode;
    import android.graphics.Rect;
    import android.graphics.RectF;
    import android.graphics.Bitmap.Config;
    import android.graphics.PorterDuff.Mode;
    import android.graphics.Shader.TileMode;
    import android.graphics.drawable.Drawable;
    public class ImageTools {
    
        //放大缩小图片
        public static Bitmap zoomBitmap(Bitmap bitmap,int w,int h){
            int width = bitmap.getWidth();
            int height = bitmap.getHeight();
            Matrix matrix = new Matrix();
            float scaleWidht = ((float)w / width);
            float scaleHeight = ((float)h / height);
            matrix.postScale(scaleWidht, scaleHeight);
            Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);
            return newbmp;
        }
        //将Drawable转化为Bitmap
        public static Bitmap drawableToBitmap(Drawable drawable){
            int width = drawable.getIntrinsicWidth();
            int height = drawable.getIntrinsicHeight();
            Bitmap bitmap = Bitmap.createBitmap(width, height,
                    drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
                            : Bitmap.Config.RGB_565);
            Canvas canvas = new Canvas(bitmap);
            drawable.setBounds(0,0,width,height);
            drawable.draw(canvas);
            return bitmap;
    
        }
    
        //获得圆角图片的方法
        public static Bitmap getRoundedCornerBitmap(Bitmap bitmap,float roundPx){
    
            Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap
                    .getHeight(), Config.ARGB_8888);
            Canvas canvas = new Canvas(output);
    
            final int color = 0xff424242;
            final Paint paint = new Paint();
            final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
            final RectF rectF = new RectF(rect);
    
            paint.setAntiAlias(true);
            canvas.drawARGB(0, 0, 0, 0);
            paint.setColor(color);
            canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
    
            paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
            canvas.drawBitmap(bitmap, rect, rect, paint);
    
            return output;
        }
        //获得带倒影的图片方法
        public static Bitmap createReflectionImageWithOrigin(Bitmap bitmap){
            final int reflectionGap = 4;
            int width = bitmap.getWidth();
            int height = bitmap.getHeight();
    
            Matrix matrix = new Matrix();
            matrix.preScale(1, -1);
    
            Bitmap reflectionImage = Bitmap.createBitmap(bitmap,
                    0, height/2, width, height/2, matrix, false);
    
            Bitmap bitmapWithReflection = Bitmap.createBitmap(width, (height + height/2), Config.ARGB_8888);
    
            Canvas canvas = new Canvas(bitmapWithReflection);
            canvas.drawBitmap(bitmap, 0, 0, null);
            Paint deafalutPaint = new Paint();
            canvas.drawRect(0, height,width,height + reflectionGap,
                    deafalutPaint);
    
            canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);
    
            Paint paint = new Paint();
            LinearGradient shader = new LinearGradient(0,
                    bitmap.getHeight(), 0, bitmapWithReflection.getHeight()
                    + reflectionGap, 0x70ffffff, 0x00ffffff, TileMode.CLAMP);
            paint.setShader(shader);
            // Set the Transfer mode to be porter duff and destination in
            paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
            // Draw a rectangle using the paint with our linear gradient
            canvas.drawRect(0, height, width, bitmapWithReflection.getHeight()
                    + reflectionGap, paint);
    
            return bitmapWithReflection;
        }
    
    }

说明：

Bitmap.createBitmap： 创建Bitemap对象；  
bitmap.getWidth()/getHeight()：获取宽高；  
Rect rect = new Rect（）:创建一个矩形框；

**工具类的使用：**

package com.bangcle.myglibtestapp;
    
    import android.app.Activity;
    import android.graphics.Bitmap;
    import android.graphics.drawable.Drawable;
    import android.os.Bundle;
    import android.widget.ImageView;
    
    import androidx.core.content.ContextCompat;
    
    import com.bangcle.myglibtestapp.utils.ImageTools;
    
    public class MainActivity extends Activity {
        private ImageView mImageView01,mImageView02;
    
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_image_test);
            setupViews();
        }
    
        private void setupViews(){
            mImageView01 = (ImageView)findViewById(R.id.image01);
            mImageView02 = (ImageView)findViewById(R.id.image02);
    
            //从文件实例化Drawable对象
            Drawable drawable = ContextCompat.getDrawable(this, R.drawable.dongwu_image01);
    
            //将Drawable转化为Bitmap
            Bitmap bitmap = ImageTools.drawableToBitmap(drawable);
            //缩放图片
            Bitmap zoomBitmap = ImageTools.zoomBitmap(bitmap, 100, 100);
            //获取圆角图片
            Bitmap roundBitmap = ImageTools.getRoundedCornerBitmap(zoomBitmap, 10.0f);
            //获取倒影图片
            Bitmap reflectBitmap = ImageTools.createReflectionImageWithOrigin(zoomBitmap);
            //这里可以让Bitmap再转化为Drawable
    //    	Drawable roundDrawable = new BitmapDrawable(roundBitmap);
    //    	Drawable reflectDrawable = new BitmapDrawable(reflectBitmap);
    //    	mImageView01.setBackgroundDrawable(roundDrawable);
    //    	mImageView02.setBackgroundDrawable(reflectDrawable);
    
            mImageView01.setImageBitmap(roundBitmap);
            mImageView02.setImageBitmap(reflectBitmap);
        }
    
    
    }

说明：

通过dongwu\_image01.png文件，创建一个Drawable对象：

>     Drawable drawable = ContextCompat.getDrawable(this, R.drawable.dongwu_image01);：

将drawable转换为bitmap：

>     ImageTools.drawableToBitmap(drawable);

按照100%缩放图片：

>     ImageTools.zoomBitmap(bitmap, 100, 100);

布局文件xml：

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        >
        <ImageView
            android:id="@+id/image01"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:padding="10px"
            />
        <ImageView
            android:id="@+id/image02"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:padding="10px"
            />
    </LinearLayout>

运行效果图：

![1c87667965a7415da9a12279e0061097.png][]

说明：

上面的控件是圆角，下面的是直角。

[1c87667965a7415da9a12279e0061097.png]: https://img-blog.csdnimg.cn/1c87667965a7415da9a12279e0061097.png