开发一个程序，实现通过 Image View 显示带边框的图片。安卓知识

开发一个程序，实现通过 Image View 显示带边框的图片。安卓知识解答

边框都是一样的吗

• 帮你找了个相似的问题, 你可以看下: https://ask.csdn.net/questions/7671953
• 你也可以参考下这篇文章：安卓自定义ImageView，实现宽高比为1（正方形图片）
• 除此之外, 这篇博客: ImageView 缩放 等比例裁剪显示中的 ImageView 缩放 等比例裁剪显示 部分也许能够解决你的问题, 你可以仔细阅读以下内容或跳转源博客中阅读:
  

• 需求控件加载图片,先进行宽度等比例缩放 然后进行超出部分裁剪
  

  import android.content.Context;
  import android.content.res.TypedArray;
  import android.graphics.Bitmap;
  import android.graphics.BitmapFactory;
  import android.graphics.Canvas;
  import android.graphics.Color;
  import android.graphics.Matrix;
  import android.graphics.Paint;
  import android.graphics.Point;
  import android.graphics.RectF;
  import android.os.Build;
  import android.support.v7.widget.AppCompatImageView;
  import android.util.AttributeSet;
  import android.view.View;
  
  import com.swkj.share_earn.R;
  
  import static java.lang.Integer.SIZE;
  
  public class TailorImageView extends AppCompatImageView {
      float width, height;
      private int resourceId;
      private Bitmap mBitmapOuter;
      private float mWidth;
      private int mHeight;
      private Paint paint;
      private Point center;
      private Point bmpCenter;
      private RectF oval;
      public TailorImageView(Context context) {
          this(context, null);
          init(context, null);
      }
      public TailorImageView(Context context, AttributeSet attrs) {
          this(context, attrs, 0);
          init(context, attrs);
      }
      public TailorImageView(Context context, AttributeSet attrs, int defStyleAttr) {
          super(context, attrs, defStyleAttr);
          TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.TailorImageView, defStyleAttr, R.style.AppTheme);
          //拿到resourceid属性
          resourceId = typedArray.getResourceId(R.styleable.TailorImageView_resourceid, SIZE);
          init(context, attrs);
          typedArray.recycle();
      }
      private void init(Context context, AttributeSet attrs) {
          if (Build.VERSION.SDK_INT < 18) {
              setLayerType(View.LAYER_TYPE_SOFTWARE, null);
          }
      }
      @Override
      protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
          super.onLayout(changed, left, top, right, bottom);
          width = getWidth();
          height = getHeight();
      }
      @Override
      protected void onSizeChanged(int w, int h, int oldw, int oldh) {
          super.onSizeChanged(w, h, oldw, oldh);
          this.mWidth = w;
          this.mHeight = h;
      }
      @Override
      protected void onDraw(Canvas canvas) {
          super.onDraw(canvas);
          BitmapFactory.Options options = new BitmapFactory.Options();
          options.inSampleSize = 2;//1/4
          mBitmapOuter = BitmapFactory.decodeResource(getResources(), resourceId);
          paint = new Paint();
          paint.setColor(Color.GREEN);
          paint.setAntiAlias(true);
          int bbw = mBitmapOuter.getWidth();
          int bbh = mBitmapOuter.getHeight();
          bmpCenter = new Point(bbw / 2, bbh / 2);
          float ww = width / bbw;
          mBitmapOuter = scaleBitmap(mBitmapOuter, mWidth / bbw);
          canvas.drawBitmap(mBitmapOuter, 0, 0, new Paint());
      }
      private Bitmap scaleBitmap(Bitmap origin, float scale) {
          if (origin == null) {
              return null;
          }
          int height = origin.getHeight();
          int width = origin.getWidth();
          Matrix matrix = new Matrix();
          matrix.postScale(scale, scale);// 使用后乘
          Bitmap newBM = Bitmap.createBitmap(origin, 0, 0, width, height, matrix, false);
          if (!origin.isRecycled()) {
              origin.recycle();
          }
          return newBM;
      }
      public int getResourceId() {
          return resourceId;
      }
      public void setResourceId(int resourceId) {
          this.resourceId = resourceId;
          postInvalidate();
      }
  }

  attrs文件

  < ?xml version="1.0" encoding="utf-8"?>
  < resources>
      < declare-styleable name="TailorImageView">
          < attr name="resourceid" format="dimension">< /attr>
      < /declare-styleable>
  < /resources>
  

  布局文件

  Res-->Layout-->xml
      com.swkj.share_earn.ui.view.TailorImageView
      android:id="@+id/iv_poster"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:padding="10px"
      android:scaleType="fitXY"
      android:src="@drawable/poster_bg"