Android 小工具--圆形图片

1.CircleImageView类代码

public class CircleImageView extends androidx.appcompat.widget.AppCompatImageView { //画笔 private Paint mPaint; //圆形图片的半径 private int mRadius; //图片的宿放比例 private float mScale; public CircleImageView(Context context) { super(context); } public CircleImageView(Context context, @Nullable AttributeSet attrs) { super(context, attrs); } public CircleImageView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); //由于是圆形，宽高应保持一致 int size = Math.min(getMeasuredWidth(), getMeasuredHeight()); mRadius = size / 2; setMeasuredDimension(size, size); } @SuppressLint("DrawAllocation") @Override protected void onDraw(Canvas canvas) { mPaint = new Paint(); Drawable drawable = getDrawable(); if (null != drawable) { Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap(); //初始化BitmapShader，传入bitmap对象 BitmapShader bitmapShader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP); //计算缩放比例 mScale = (mRadius * 2.0f) / Math.min(bitmap.getHeight(), bitmap.getWidth()); Matrix matrix = new Matrix(); matrix.setScale(mScale, mScale); bitmapShader.setLocalMatrix(matrix); mPaint.setShader(bitmapShader); //画圆形，指定好坐标，半径，画笔 canvas.drawCircle(mRadius, mRadius, mRadius, mPaint); } else { super.onDraw(canvas); } } }

2.布局文件中使用

代码

<?xml version="1.0" encoding="utf-8"?> <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <com.hnucm18jr.myapplication.CircleImageView android:layout_width="100dp" android:layout_height="100dp" android:src="@drawable/a1" app:layout_constraintLeft_toLeftOf="parent" app:layout_constraintRight_toRightOf="parent" app:layout_constraintTop_toTopOf="parent" android:layout_marginTop="200dp"/> </androidx.constraintlayout.widget.ConstraintLayout>