圓形圖片的實現方式有很多種,首先我分享下自己所知道的一種實現方式,這種方式的實現對角度的控制很靈活,可以在xml中自由的設置,實現的過程中使用到了PorterDuffXfermode這個類,網絡上對PorterDuffXfermode的解釋:
類android.graphics.PorterDuffXfermode繼承自android.graphics.Xfermode。在用Android中的Canvas進行繪圖時,可以通過使用PorterDuffXfermode將所繪製的圖形的像素與Canvas中對應位置的像素按照一定規則進行混合,形成新的像素值,從而更新Canvas中最終的像素顏色值,這樣會創建很多有趣的效果。當使用PorterDuffXfermode時,需要將其作爲參數傳給Paint.setXfermode(Xfermode xfermode)方法,這樣在用該畫筆paint進行繪圖時,Android就會使用傳入的PorterDuffXfermode,如果不想再使用Xfermode,那麼可以執行Paint.setXfermode(null)。
我的理解是canva在繪製倆個圖像有重疊時,會以什麼樣的形式顯示出來,只需要取決於你給它傳入的什麼模式就行了(其中總共16種模式,十六種模式圖像網絡上也有);PorterDuffXfermode功能挺強大的,想了解可以百度
效果圖:
一、該自定義View同樣繼承ImageView,重寫onDraw方法
@Override
protected void onDraw(Canvas canvas) {
//創建同等大小的位圖
Bitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_4444);
//創建帶有位圖的畫布
mCanvas=new Canvas(bitmap);
super.onDraw(mCanvas);
//繪製矩形內接圓(橢圓)外部分,簡單就是去掉的四個角所組成的圖形
drawGraphical();
canvas.drawBitmap(bitmap,0,0,mPaintBitmap);
}
代碼中創建了一個帶有位圖的畫布,以參數的形式,通過super.onDraw(mCanvas)傳給父類,我的理解是相當於兩個畫布mCanvas和canvas重疊在一起,mCanvas在上面,各自在自己上面繪製圖形,上面的PorterDuffXfermode就使用在mCanvas上,來約束mCanvas繪製顯示的區域
private void drawGraphical() {
//限制mRadius值的規範性
checkRadius();
//左上
mPath.moveTo(0, mRadius);
mPath.lineTo(0, 0);
mPath.lineTo(mRadius, 0);
//圓弧路徑
mPath.arcTo(new RectF(0, 0, mRadius * 2, mRadius * 2), 270, -90);
//左下
mPath.moveTo(0, getHeight() - mRadius);
mPath.lineTo(0, getHeight());
mPath.lineTo(mRadius, getHeight());
mPath.arcTo(new RectF(0, getHeight() - mRadius * 2, mRadius * 2, getHeight()), 90, 90);
//右下
mPath.moveTo(getWidth() - mRadius, getHeight());
mPath.lineTo(getWidth(), getHeight());
mPath.lineTo(getWidth(), getHeight() - mRadius);
mPath.arcTo(new RectF(getWidth() - mRadius * 2, getHeight() - mRadius * 2, getWidth(), getHeight()), 0, 90);
//右上
mPath.moveTo(getWidth(), mRadius);
mPath.lineTo(getWidth(), 0);
mPath.lineTo(getWidth() - mRadius, 0);
mPath.arcTo(new RectF(getWidth() - mRadius * 2, 0, getWidth(),mRadius * 2), 270, 90);
mCanvas.drawPath(mPath, mPaintPath);
}
繪製需要遮擋的圖形區域,moveTo(x,y)從哪個點開始,lineTo(x,y)到哪個點,arcTo(new RectF())繪製圓弧路徑,drawPath()根據規定的路徑開始繪製,繪製完,大概的樣子就是一個矩形去掉內接圓(長和寬相等)剩下的部分就是的了,自己不會畫圖,自己想象下吧private void init(Context context, AttributeSet attrs) {
TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.CornerImageView);
mRadius = typedArray.getDimension(R.styleable.CornerImageView_cornerRadius, -1);
mPaintBitmap=new Paint();
mPaintBitmap.setAntiAlias(true);
mPaintPath=new Paint();
mPaintPath.setAntiAlias(true);
mPorterDuffXfermode=new PorterDuffXfermode(PorterDuff.Mode.DST_OUT);
mPaintPath.setXfermode(mPorterDuffXfermode);
//圖形對象
mPath=new Path();
}
初始化代碼,PorterDuff.Mode.DST_OUT
取底部相交圖形之外的部分
二、全部代碼
package com.yufs.myimageview.view;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.widget.ImageView;
import com.yufs.myimageview.R;
/**
* Created by yufs on 2017/5/22.
*/
public class CornerImageView extends ImageView{
private Canvas mCanvas;
private Paint mPaintBitmap;//繪製bitmap的畫筆
private Paint mPaintPath;//繪製path的畫筆
private Path mPath;//path對象
private float mRadius=0;//圓角弧度
private PorterDuffXfermode mPorterDuffXfermode;//
public CornerImageView(Context context) {
super(context);
init(context, null);
}
public CornerImageView(Context context, AttributeSet attrs) {
this(context,attrs,0);
}
public CornerImageView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context,attrs);
}
private void init(Context context, AttributeSet attrs) {
TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.CornerImageView);
mRadius = typedArray.getDimension(R.styleable.CornerImageView_cornerRadius, -1);
mPaintBitmap=new Paint();
mPaintBitmap.setAntiAlias(true);
mPaintPath=new Paint();
mPaintPath.setAntiAlias(true);
mPorterDuffXfermode=new PorterDuffXfermode(PorterDuff.Mode.DST_OUT);
mPaintPath.setXfermode(mPorterDuffXfermode);
//圖形對象
mPath=new Path();
}
@Override
protected void onDraw(Canvas canvas) {
//創建同等大小的位圖
Bitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_4444);
//創建帶有位圖的畫布
mCanvas=new Canvas(bitmap);
super.onDraw(mCanvas);
//繪製矩形內接圓(橢圓)外部分,簡單就是去掉的四個角所組成的圖形
drawGraphical();
canvas.drawBitmap(bitmap,0,0,mPaintBitmap);
}
private void drawGraphical() {
//限制mRadius值的規範性
checkRadius();
//左上
mPath.moveTo(0, mRadius);
mPath.lineTo(0, 0);
mPath.lineTo(mRadius, 0);
//圓弧路徑
mPath.arcTo(new RectF(0, 0, mRadius * 2, mRadius * 2), 270, -90);
//左下
mPath.moveTo(0, getHeight() - mRadius);
mPath.lineTo(0, getHeight());
mPath.lineTo(mRadius, getHeight());
mPath.arcTo(new RectF(0, getHeight() - mRadius * 2, mRadius * 2, getHeight()), 90, 90);
//右下
mPath.moveTo(getWidth() - mRadius, getHeight());
mPath.lineTo(getWidth(), getHeight());
mPath.lineTo(getWidth(), getHeight() - mRadius);
mPath.arcTo(new RectF(getWidth() - mRadius * 2, getHeight() - mRadius * 2, getWidth(), getHeight()), 0, 90);
//右上
mPath.moveTo(getWidth(), mRadius);
mPath.lineTo(getWidth(), 0);
mPath.lineTo(getWidth() - mRadius, 0);
mPath.arcTo(new RectF(getWidth() - mRadius * 2, 0, getWidth(),mRadius * 2), 270, 90);
mCanvas.drawPath(mPath, mPaintPath);
}
/**
* 如果未設置cornerRadius屬性,或者設置的非法,默認是圓形
*/
private void checkRadius() {
float minValues;
if(getWidth()>getHeight()){
minValues=getHeight();
}else{
minValues=getWidth();
}
if(mRadius>minValues/2||mRadius<0){
mRadius=minValues/2;
}
}
}
attrs文件
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="CornerImageView">
<attr name="cornerRadius" format="dimension"></attr>
</declare-styleable>
</resources>
xml中使用
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:mimage="http://schemas.android.com/apk/res-auto"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.yufs.myimageview.MainActivity">
<ScrollView
android:layout_width="match_parent"
android:layout_height="wrap_content">
<LinearLayout
android:layout_width="match_parent"
android:orientation="vertical"
android:gravity="center_horizontal"
android:layout_height="wrap_content">
<com.yufs.myimageview.view.CornerImageView
android:layout_width="150dp"
android:layout_height="50dp"
android:layout_marginTop="24dp"
android:scaleType="centerCrop"
android:src="@mipmap/green"
mimage:cornerRadius="12dp"
/>
<com.yufs.myimageview.view.CornerImageView
android:layout_width="90dp"
android:layout_height="90dp"
android:layout_marginTop="12dp"
android:scaleType="centerCrop"
android:src="@mipmap/green"
/>
<com.yufs.myimageview.view.CornerImageView
android:layout_width="90dp"
android:layout_height="90dp"
android:layout_marginTop="12dp"
android:scaleType="centerCrop"
mimage:cornerRadius="12dp"
android:src="@mipmap/green"
/>
<com.yufs.myimageview.view.CornerImageView
android:layout_width="120dp"
android:layout_height="45dp"
android:layout_marginTop="12dp"
android:scaleType="centerCrop"
android:src="@mipmap/green"
/>
</LinearLayout>
</ScrollView>
</RelativeLayout>
使用自定義屬性時別忘記在頂部加入聲明
xmlns:mimage="http://schemas.android.com/apk/res-auto"
mimage名字隨意
green是一張圖片,你可以用自己的演示看看,有什麼問題,或者我說的有哪不對的,希望大神幫忙指點下,謝謝