在Android中,ImageView默认是一个矩形。如何使它成为一个圆角矩形(剪辑我的位图的所有4个角为圆角矩形)在ImageView?
请注意,从2021年起,只需使用ShapeableImageView
在Android中,ImageView默认是一个矩形。如何使它成为一个圆角矩形(剪辑我的位图的所有4个角为圆角矩形)在ImageView?
请注意,从2021年起,只需使用ShapeableImageView
当前回答
罗曼盖伊就在那里。
缩小版如下。
Bitmap bitmap = ((BitmapDrawable) getResources().getDrawable(R.drawable.image)).getBitmap();
Bitmap bitmapRounded = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), bitmap.getConfig());
Canvas canvas = new Canvas(bitmapRounded);
Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setShader(new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP));
canvas.drawRoundRect((new RectF(0.0f, 0.0f, bitmap.getWidth(), bitmap.getHeight())), 10, 10, paint);
imageView.setImageBitmap(bitmapRounded);
其他回答
对于上面提到的乔治·沃尔特斯二世,我只是把他的答案扩展了一下,以支持不同的圆角。这可以进一步优化(一些目标矩形重叠),但不是很多。
我知道这个线程有点老了,但它是谷歌上关于如何在Android上圆角ImageViews的查询的顶级结果之一。
/**
* Use this method to scale a bitmap and give it specific rounded corners.
* @param context Context object used to ascertain display density.
* @param bitmap The original bitmap that will be scaled and have rounded corners applied to it.
* @param upperLeft Corner radius for upper left.
* @param upperRight Corner radius for upper right.
* @param lowerRight Corner radius for lower right.
* @param lowerLeft Corner radius for lower left.
* @param endWidth Width to which to scale original bitmap.
* @param endHeight Height to which to scale original bitmap.
* @return Scaled bitmap with rounded corners.
*/
public static Bitmap getRoundedCornerBitmap(Context context, Bitmap bitmap, float upperLeft,
float upperRight, float lowerRight, float lowerLeft, int endWidth,
int endHeight) {
float densityMultiplier = context.getResources().getDisplayMetrics().density;
// scale incoming bitmap to appropriate px size given arguments and display dpi
bitmap = Bitmap.createScaledBitmap(bitmap,
Math.round(endWidth * densityMultiplier),
Math.round(endHeight * densityMultiplier), true);
// create empty bitmap for drawing
Bitmap output = Bitmap.createBitmap(
Math.round(endWidth * densityMultiplier),
Math.round(endHeight * densityMultiplier), Config.ARGB_8888);
// get canvas for empty bitmap
Canvas canvas = new Canvas(output);
int width = canvas.getWidth();
int height = canvas.getHeight();
// scale the rounded corners appropriately given dpi
upperLeft *= densityMultiplier;
upperRight *= densityMultiplier;
lowerRight *= densityMultiplier;
lowerLeft *= densityMultiplier;
Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setColor(Color.WHITE);
// fill the canvas with transparency
canvas.drawARGB(0, 0, 0, 0);
// draw the rounded corners around the image rect. clockwise, starting in upper left.
canvas.drawCircle(upperLeft, upperLeft, upperLeft, paint);
canvas.drawCircle(width - upperRight, upperRight, upperRight, paint);
canvas.drawCircle(width - lowerRight, height - lowerRight, lowerRight, paint);
canvas.drawCircle(lowerLeft, height - lowerLeft, lowerLeft, paint);
// fill in all the gaps between circles. clockwise, starting at top.
RectF rectT = new RectF(upperLeft, 0, width - upperRight, height / 2);
RectF rectR = new RectF(width / 2, upperRight, width, height - lowerRight);
RectF rectB = new RectF(lowerLeft, height / 2, width - lowerRight, height);
RectF rectL = new RectF(0, upperLeft, width / 2, height - lowerLeft);
canvas.drawRect(rectT, paint);
canvas.drawRect(rectR, paint);
canvas.drawRect(rectB, paint);
canvas.drawRect(rectL, paint);
// set up the rect for the image
Rect imageRect = new Rect(0, 0, width, height);
// set up paint object such that it only paints on Color.WHITE
paint.setXfermode(new AvoidXfermode(Color.WHITE, 255, AvoidXfermode.Mode.TARGET));
// draw resized bitmap onto imageRect in canvas, using paint as configured above
canvas.drawBitmap(bitmap, imageRect, imageRect, paint);
return output;
}
下面是一个覆盖imageView的简单示例,然后你也可以在布局设计器中使用它来预览。
public class RoundedImageView extends ImageView {
public RoundedImageView(Context context) {
super(context);
}
public RoundedImageView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public RoundedImageView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public RoundedImageView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
@Override
public void setImageDrawable(Drawable drawable) {
float radius = 0.1f;
Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap();
RoundedBitmapDrawable rid = RoundedBitmapDrawableFactory.create(getResources(), bitmap);
rid.setCornerRadius(bitmap.getWidth() * radius);
super.setImageDrawable(rid);
}
}
这是为了快速解决问题。半径用于所有角落,并基于位图宽度的百分比。
我只是覆盖了setImageDrawable,并使用支持v4方法绘制圆角位图。
用法:
<com.example.widgets.RoundedImageView
android:layout_width="39dp"
android:layout_height="39dp"
android:src="@drawable/your_drawable" />
使用imageView和自定义imageView预览:
/**
* Background Async task to load user profile picture from url
*/
private class LoadProfileImage extends AsyncTask<String, Void, RoundedBitmapDrawable> {
ImageView profileImageView;
public LoadProfileImage(ImageView profileImageView) {
this.profileImageView = profileImageView;
}
protected RoundedBitmapDrawable doInBackground(String... urls) {
String photoUrl = urls[0];
RoundedBitmapDrawable profileRoundedDrawable = null;
try {
InputStream inputStream = new java.net.URL(photoUrl).openStream();
Resources res = getResources();
profileRoundedDrawable = RoundedBitmapDrawableFactory.create(res, inputStream);
profileRoundedDrawable.setCircular(true);
} catch (Exception e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
return profileRoundedDrawable;
}
protected void onPostExecute(RoundedBitmapDrawable result) {
profileImageView.setImageDrawable(result);
}
}
您应该扩展ImageView并绘制自己的圆角矩形。
如果你想在图像周围添加一个框架,你也可以在布局中将圆形框架叠加在图像视图的顶部。
例如,通过使用FrameLayout将帧叠加到原始图像上。FrameLayout的第一个元素将是你想要显示的图像。然后添加另一个ImageView与框架。第二个ImageView将显示在原始ImageView的顶部,因此Android将在原始ImageView上方绘制它的内容。
为什么不在draw()中进行剪辑?
以下是我的解决方案:
用剪切扩展RelativeLayout 将ImageView(或其他视图)放入布局中:
代码:
public class RoundRelativeLayout extends RelativeLayout {
private final float radius;
public RoundRelativeLayout(Context context, AttributeSet attrs) {
super(context, attrs);
TypedArray attrArray = context.obtainStyledAttributes(attrs,
R.styleable.RoundRelativeLayout);
radius = attrArray.getDimension(
R.styleable.RoundRelativeLayout_radius, 0);
}
private boolean isPathValid;
private final Path path = new Path();
private Path getRoundRectPath() {
if (isPathValid) {
return path;
}
path.reset();
int width = getWidth();
int height = getHeight();
RectF bounds = new RectF(0, 0, width, height);
path.addRoundRect(bounds, radius, radius, Direction.CCW);
isPathValid = true;
return path;
}
@Override
protected void dispatchDraw(Canvas canvas) {
canvas.clipPath(getRoundRectPath());
super.dispatchDraw(canvas);
}
@Override
public void draw(Canvas canvas) {
canvas.clipPath(getRoundRectPath());
super.draw(canvas);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int oldWidth = getMeasuredWidth();
int oldHeight = getMeasuredHeight();
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int newWidth = getMeasuredWidth();
int newHeight = getMeasuredHeight();
if (newWidth != oldWidth || newHeight != oldHeight) {
isPathValid = false;
}
}
}