圆角imageview android,Android ImageView绘制圆角效果_Android_脚本之家

于 2021-05-27 11:09:05 发布
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文章标签： 圆角imageview android

前言

Android 开发中，我们经常需要实现图片的圆形/圆角的效果，我们可以使用两种方式来实现这样的效果。一种是使用Xfermode，另一种是BitmapShader来实现。下面我将分别介绍这两种用法。

使用Xfermode的方式实现

使用该方式的关键代码，如下：

private Bitmap creataBitmap(Bitmap bitmap) {

//用指定的一个Bitmap来构建一个画布

Bitmap target = Bitmap.createBitmap(1000,1000, Bitmap.Config.ARGB_8888);

Canvas canvas = new Canvas(target);

final Paint paint = new Paint();

paint.setColor(Color.GREEN);

paint.setAntiAlias(true);

//在刚才的画布上绘制一个圆形区域

canvas.drawCircle(500,500,500,paint);

//设置Xfermode，使用SRC_IN模式,这样可以取到第二张图片重叠后的区域

paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));

//在画布上绘制第二个需要显示的bitmap

canvas.drawBitmap(bitmap,0,0,paint);

return target;

}

上面代码中看出在指定的画布上绘制了两层图像，一个是半径为500像素的圆形，一个是将目标Bitmap绘制在上面。之间还调用了paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));作用是这两个绘制的效果图叠加后，取得第二个图的交集图。所以，我们先绘制一个圆形，然后绘制Bitmap，交集为圆形，取出的就是圆形区域的Bitmap了。

PorterDuff.Mode中一共有16种效果显示，如下：

9f8bc4cbf59f54f6f4bbbcb1cdd79114.png

可以根据不同的Mode，控制显示的效果图。

开始应用

1.自定义属性在attrs.xml中

2.自定义View

public class RoundImageView extends View {

private int type;

private static final int TYPE_CIRCLE = 0;

private static final int TYPE_ROUND = 1;

//图片

private Bitmap mSrc;

//圆角大小

private int mRadius;

//高度

private int mWidth;

//宽度

private int mHeight;

public RoundImageView(Context context, AttributeSet attrs) {

super(context, attrs);

//获取自定义的属性

TypedArray a = context.obtainStyledAttributes(attrs,R.styleable.RoundImageView);

//获取自定以属性的数目

int count = a.getIndexCount();

for (int i=0 ; i

int attr = a.getIndex(i);

switch (attr){

case R.styleable.RoundImageView_borderRadius:

int defValue = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,10f,getResources().getDisplayMetrics());

mRadius = a.getDimensionPixelSize(attr, defValue);

break;

case R.styleable.RoundImageView_type:

type = a.getInt(attr,0);

break;

case R.styleable.RoundImageView_src:

mSrc = BitmapFactory.decodeResource(getResources(),a.getResourceId(attr,0));

break;

}

}

a.recycle();

}

@Override

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

super.onMeasure(widthMeasureSpec, heightMeasureSpec);

//设置宽度

int specMode = MeasureSpec.getMode(widthMeasureSpec);

int specSize = MeasureSpec.getSize(widthMeasureSpec);

if (specMode == MeasureSpec.EXACTLY){

mWidth = specSize;

}else {

int desireByImg = getPaddingLeft() + getPaddingRight() + mSrc.getWidth();

if (specMode == MeasureSpec.AT_MOST)// wrap_content

{

mWidth = Math.min(desireByImg, specSize);

} else

mWidth = desireByImg;

}

//设置高度

specMode = MeasureSpec.getMode(heightMeasureSpec);

specSize = MeasureSpec.getSize(heightMeasureSpec);

if (specMode == MeasureSpec.EXACTLY){

mHeight = specSize;

}else {

int desire = getPaddingTop() + getPaddingBottom() + mSrc.getHeight();

if (specMode == MeasureSpec.AT_MOST)// wrap_content

{

mHeight = Math.min(desire, specSize);

} else

mHeight = desire;

}

setMeasuredDimension(mWidth,mHeight);

}

@Override

protected void onDraw(Canvas canvas) {

super.onDraw(canvas);

switch (type){

case TYPE_CIRCLE:

int min = Math.min(mWidth,mHeight);

//从当前存在的Bitmap，按一定的比例创建一个新的Bitmap。

mSrc = Bitmap.createScaledBitmap(mSrc, min, min, false);

canvas.drawBitmap(createCircleImage(mSrc, min), 0, 0, null);

break;

case TYPE_ROUND:

mSrc = Bitmap.createScaledBitmap(mSrc, mWidth, mHeight, false);

canvas.drawBitmap(createRoundConerImage(mSrc), 0, 0, null);

break;

}

}

/**

* 绘制圆角

* @param source

* @return

*/

private Bitmap createRoundConerImage(Bitmap source) {

final Paint paint = new Paint();

paint.setAntiAlias(true);

Bitmap target = Bitmap.createBitmap(mWidth, mHeight, Bitmap.Config.ARGB_8888);

Canvas canvas = new Canvas(target);

RectF rect = new RectF(0, 0, mWidth, mHeight);

canvas.drawRoundRect(rect, mRadius, mRadius, paint);

paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));

canvas.drawBitmap(source, 0, 0, paint);

return target;

}

/**

* 绘制圆形

* @param source

* @param min

* @return

*/

private Bitmap createCircleImage(Bitmap source, int min) {

final Paint paint = new Paint();

paint.setAntiAlias(true);

Bitmap target = Bitmap.createBitmap(min, min, Bitmap.Config.ARGB_8888);

Canvas canvas = new Canvas(target);

canvas.drawCircle(min/2,min/2,min/2,paint);

paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));

canvas.drawBitmap(source, 0, 0, paint);

return target;

}

}

3.布局文件

xmlns:roundview="http://schemas.android.com/apk/res-auto"

xmlns:tools="http://schemas.android.com/tools"

android:id="@+id/activity_main"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical"

android:padding="10dp"

tools:context="mo.yumf.com.myviews.MainActivity">

android:layout_width="200dp"

android:layout_height="200dp"

android:layout_marginTop="20dp"

roundview:borderRadius="10dp"

roundview:src="@drawable/ac_default_icon"

roundview:type="round"/>

android:layout_width="200dp"

android:layout_height="200dp"

android:layout_marginTop="20dp"

roundview:src="@drawable/ac_default_icon"

roundview:type="circle"/>

上面的自定义View中，存在一个局限，那就是只能在布局中设置要加载的图片资源，不能在代码中设置图片。下面我们使用同样的方式，选择自定义ImageView来实现。

public class RoundImageView extends ImageView {

private int type;

private static final int TYPE_CIRCLE = 0;

private static final int TYPE_ROUND = 1;

//图片

private Bitmap mSrc;

//圆角大小

private int mRadius;

public RoundImageView(Context context, AttributeSet attrs) {

super(context, attrs);

//获取自定义的属性

TypedArray a = context.obtainStyledAttributes(attrs,R.styleable.RoundImageView);

//获取自定以属性的数目

int count = a.getIndexCount();

for (int i=0 ; i

int attr = a.getIndex(i);

switch (attr){

case R.styleable.RoundImageView_borderRadius:

int defValue = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,10f,getResources().getDisplayMetrics());

mRadius = a.getDimensionPixelSize(attr, defValue);

break;

case R.styleable.RoundImageView_type:

type = a.getInt(attr,0);

break;

}

}

a.recycle();

}

@Override

protected void onDraw(Canvas canvas) {

if (getDrawable() != null){

Bitmap bitmap = getBitmap(getDrawable());

if (bitmap != null){

switch (type){

case TYPE_CIRCLE:

//获取ImageView中的宽高，取最小值

int min = Math.min(getMeasuredWidth(),getMeasuredHeight());

//从当前存在的Bitmap，按一定的比例创建一个新的Bitmap。

mSrc = Bitmap.createScaledBitmap(bitmap, min, min, false);

canvas.drawBitmap(createCircleImage(mSrc, min), 0, 0, null);

break;

case TYPE_ROUND:

mSrc = Bitmap.createScaledBitmap(bitmap, getMeasuredWidth(), getMeasuredHeight(), false);

canvas.drawBitmap(createRoundConerImage(mSrc), 0, 0, null);

break;

}

}

}else {

super.onDraw(canvas);

}

}

private Bitmap getBitmap(Drawable drawable) {

if (drawable instanceof BitmapDrawable){

return ((BitmapDrawable)drawable).getBitmap();

}else if (drawable instanceof ColorDrawable){

Rect rect = drawable.getBounds();

int width = rect.right - rect.left;

int height = rect.bottom - rect.top;

int color = ((ColorDrawable)drawable).getColor();

Bitmap bitmap = Bitmap.createBitmap(width,height, Bitmap.Config.ARGB_8888);

Canvas canvas = new Canvas(bitmap);

canvas.drawARGB(Color.alpha(color),Color.red(color), Color.green(color), Color.blue(color));

return bitmap;

}else {

return null;

}

}

/**

* 绘制圆角

* @param source

* @return

*/

private Bitmap createRoundConerImage(Bitmap source) {

final Paint paint = new Paint();

paint.setAntiAlias(true);

Bitmap target = Bitmap.createBitmap(getMeasuredWidth(), getMeasuredHeight(), Bitmap.Config.ARGB_8888);

Canvas canvas = new Canvas(target);

RectF rect = new RectF(0, 0, getMeasuredWidth(), getMeasuredHeight());

canvas.drawRoundRect(rect, mRadius, mRadius, paint);

paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));

canvas.drawBitmap(source, 0, 0, paint);

return target;

}

/**

* 绘制圆形

* @param source

* @param min

* @return

*/

private Bitmap createCircleImage(Bitmap source, int min) {

final Paint paint = new Paint();

paint.setAntiAlias(true);

Bitmap target = Bitmap.createBitmap(min, min, Bitmap.Config.ARGB_8888);

Canvas canvas = new Canvas(target);

canvas.drawCircle(min/2,min/2,min/2,paint);

paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));

canvas.drawBitmap(source, 0, 0, paint);

return target;

}

}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。

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