本文實例為大家分享了Android圓形控件實現畫圓效果的具體代碼，供大家參考，具體內容如下

實現圓形控件

實現如下

package com.example.demo.util;import android.content.Context;import android.content.res.TypedArray;import android.graphics.Bitmap;import android.graphics.BitmapShader;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Matrix;import android.graphics.Paint;import android.graphics.RectF;import android.graphics.Shader;import android.graphics.drawable.BitmapDrawable;import android.graphics.drawable.ColorDrawable;import android.graphics.drawable.Drawable;import android.util.AttributeSet;import android.widget.ImageView;import androidx.annotation.Nullable;import com.example.demo.R;public class CircleImageView extends androidx.appcompat.widget.AppCompatImageView { private static final ScaleType SCALE_TYPE = ScaleType.CENTER_CROP; private static final Bitmap.Config BITMAP_CONFIG = Bitmap.Config.ARGB_8888; private static final int COLORDRAWABLE_DIMENSION = 1; private static final int DEFAULT_BORDER_WIDTH = 0; private static final int DEFAULT_BORDER_COLOR = Color.BLACK; private final RectF mDrawableRect = new RectF(); private final RectF mBorderRect = new RectF(); private final Matrix mShaderMatrix = new Matrix(); private final Paint mBitmapPaint = new Paint(); private final Paint mBorderPaint = new Paint(); private int mBorderColor = DEFAULT_BORDER_COLOR; private int mBorderWidth = DEFAULT_BORDER_WIDTH; private Bitmap mBitmap; private BitmapShader mBitmapShader; private int mBitmapWidth; private int mBitmapHeight; private float mDrawableRadius; private float mBorderRadius; private boolean mReady; private boolean mSetupPending; public CircleImageView(Context context) {super(context); } public CircleImageView(Context context, @Nullable AttributeSet attrs) {this(context,attrs,0); } public CircleImageView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);super.setScaleType(SCALE_TYPE);TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CircleImageView, defStyle, 0);mBorderWidth = a.getDimensionPixelSize(R.styleable.CircleImageView_border_width, DEFAULT_BORDER_WIDTH);mBorderColor = a.getColor(R.styleable.CircleImageView_border_color, DEFAULT_BORDER_COLOR);a.recycle();mReady = true;if (mSetupPending) { setup(); mSetupPending = false;} } @Override public ScaleType getScaleType() {return SCALE_TYPE; } @Override public void setScaleType(ScaleType scaleType) {if (scaleType != SCALE_TYPE) { throw new IllegalArgumentException(String.format('ScaleType %s not supported.', scaleType));} } @Override protected void onDraw(Canvas canvas) {if (getDrawable() == null) { return;}canvas.drawCircle(getWidth() / 2, getHeight() / 2, mDrawableRadius, mBitmapPaint);canvas.drawCircle(getWidth() / 2, getHeight() / 2, mBorderRadius, mBorderPaint); } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) {super.onSizeChanged(w, h, oldw, oldh);setup(); } public int getBorderColor() {return mBorderColor; } public void setBorderColor(int borderColor) {if (borderColor == mBorderColor) { return;}mBorderColor = borderColor;mBorderPaint.setColor(mBorderColor);invalidate(); } public int getBorderWidth() {return mBorderWidth; } public void setBorderWidth(int borderWidth) {if (borderWidth == mBorderWidth) { return;}mBorderWidth = borderWidth;setup(); } @Override public void setImageBitmap(Bitmap bm) {super.setImageBitmap(bm);mBitmap = bm;setup(); } @Override public void setImageDrawable(Drawable drawable) {super.setImageDrawable(drawable);mBitmap = getBitmapFromDrawable(drawable);setup(); } @Override public void setImageResource(int resId) {super.setImageResource(resId);mBitmap = getBitmapFromDrawable(getDrawable());setup(); } private Bitmap getBitmapFromDrawable(Drawable drawable) {if (drawable == null) { return null;}if (drawable instanceof BitmapDrawable) { return ((BitmapDrawable) drawable).getBitmap();}try { Bitmap bitmap; if (drawable instanceof ColorDrawable) {bitmap = Bitmap.createBitmap(COLORDRAWABLE_DIMENSION, COLORDRAWABLE_DIMENSION, BITMAP_CONFIG); } else {bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), BITMAP_CONFIG); } Canvas canvas = new Canvas(bitmap); drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight()); drawable.draw(canvas); return bitmap;} catch (OutOfMemoryError e) { return null;} } private void setup() {if (!mReady) { mSetupPending = true; return;}if (mBitmap == null) { return;}mBitmapShader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);mBitmapPaint.setAntiAlias(true);mBitmapPaint.setShader(mBitmapShader);mBorderPaint.setStyle(Paint.Style.STROKE);mBorderPaint.setAntiAlias(true);mBorderPaint.setColor(mBorderColor);mBorderPaint.setStrokeWidth(mBorderWidth);mBitmapHeight = mBitmap.getHeight();mBitmapWidth = mBitmap.getWidth();mBorderRect.set(0, 0, getWidth(), getHeight());mBorderRadius = Math.min((mBorderRect.height() - mBorderWidth) / 2, (mBorderRect.width() - mBorderWidth) / 2);mDrawableRect.set(mBorderWidth, mBorderWidth, mBorderRect.width() - mBorderWidth, mBorderRect.height() - mBorderWidth);mDrawableRadius = Math.min(mDrawableRect.height() / 2, mDrawableRect.width() / 2);updateShaderMatrix();invalidate(); } private void updateShaderMatrix() {float scale;float dx = 0;float dy = 0;mShaderMatrix.set(null);if (mBitmapWidth * mDrawableRect.height() > mDrawableRect.width() * mBitmapHeight) { scale = mDrawableRect.height() / (float) mBitmapHeight; dx = (mDrawableRect.width() - mBitmapWidth * scale) * 0.5f;} else { scale = mDrawableRect.width() / (float) mBitmapWidth; dy = (mDrawableRect.height() - mBitmapHeight * scale) * 0.5f;}mShaderMatrix.setScale(scale, scale);mShaderMatrix.postTranslate((int) (dx + 0.5f) + mBorderWidth, (int) (dy + 0.5f) + mBorderWidth);mBitmapShader.setLocalMatrix(mShaderMatrix); }}

使用如下

<com.example.demo.util.CircleImageViewandroid: android:layout_width='35dp'android:layout_height='35dp'app:border_color='#00000000'android:layout_gravity='center_vertical'android:src='http://www.gepszalag.com/bcjs/@drawable/ic_launcher_background'></com.example.demo.util.CircleImageView>

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持好吧啦網。