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
我使用了一个自定义视图，我在其他视图的顶部布局，它只是画了4个小倒角，颜色与背景相同。
优点:
不分配位图。 适用于任何你想要应用圆角的视图。 适用于所有API级别;)
代码:
public class RoundedCornersView extends View {
private float mRadius;
private int mColor = Color.WHITE;
private Paint mPaint;
private Path mPath;
public RoundedCornersView(Context context) {
super(context);
init();
}
public RoundedCornersView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
TypedArray a = context.getTheme().obtainStyledAttributes(
attrs,
R.styleable.RoundedCornersView,
0, 0);
try {
setRadius(a.getDimension(R.styleable.RoundedCornersView_radius, 0));
setColor(a.getColor(R.styleable.RoundedCornersView_cornersColor, Color.WHITE));
} finally {
a.recycle();
}
}
private void init() {
setColor(mColor);
setRadius(mRadius);
}
private void setColor(int color) {
mColor = color;
mPaint = new Paint();
mPaint.setColor(mColor);
mPaint.setStyle(Paint.Style.FILL);
mPaint.setAntiAlias(true);
invalidate();
}
private void setRadius(float radius) {
mRadius = radius;
RectF r = new RectF(0, 0, 2 * mRadius, 2 * mRadius);
mPath = new Path();
mPath.moveTo(0,0);
mPath.lineTo(0, mRadius);
mPath.arcTo(r, 180, 90);
mPath.lineTo(0,0);
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
/*This just draws 4 little inverted corners */
int w = getWidth();
int h = getHeight();
canvas.drawPath(mPath, mPaint);
canvas.save();
canvas.translate(w, 0);
canvas.rotate(90);
canvas.drawPath(mPath, mPaint);
canvas.restore();
canvas.save();
canvas.translate(w, h);
canvas.rotate(180);
canvas.drawPath(mPath, mPaint);
canvas.restore();
canvas.translate(0, h);
canvas.rotate(270);
canvas.drawPath(mPath, mPaint);
}
}
其他回答
如果你不希望边框影响图像，使用这个类。不幸的是，我没有找到任何方法来绘制画布上的透明区域来到onDraw()。这里创建了一个新的位图它是画在一个真实的画布上的。
如果您想要创建一个消失的边界，该视图非常有用。如果你将borderWidth设置为0，边框将会消失，图像仍然保持圆角，就像边界一样。也就是说，它看起来就像边界完全由图像边缘绘制。
import android.annotation.SuppressLint
import android.content.Context
import android.graphics.Bitmap
import android.graphics.Canvas
import android.graphics.Color
import android.graphics.Paint
import android.graphics.PorterDuff
import android.graphics.PorterDuffXfermode
import android.graphics.RectF
import android.util.AttributeSet
import androidx.appcompat.widget.AppCompatImageView
class RoundedImageViewWithBorder @JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0) : AppCompatImageView(context, attrs, defStyleAttr) {
var borderColor: Int = 0
set(value) {
invalidate()
field = value
}
var borderWidth: Int = 0
set(value) {
invalidate()
field = value
}
var cornerRadius: Float = 0f
set(value) {
invalidate()
field = value
}
private var bitmapForDraw: Bitmap? = null
private var canvasForDraw: Canvas? = null
private val transparentPaint = Paint().apply {
isAntiAlias = true
color = Color.TRANSPARENT
style = Paint.Style.STROKE
xfermode = PorterDuffXfermode(PorterDuff.Mode.SRC)
}
private val borderPaint = Paint().apply {
isAntiAlias = true
style = Paint.Style.STROKE
}
private val transparentAreaRect = RectF()
private val borderRect = RectF()
init {
val typedArray = context.obtainStyledAttributes(attrs, R.styleable.RoundedImageViewWithBorder)
try {
borderWidth = typedArray.getDimensionPixelSize(R.styleable.RoundedImageViewWithBorder_border_width, 0)
borderColor = typedArray.getColor(R.styleable.RoundedImageViewWithBorder_border_color, 0)
cornerRadius = typedArray.getDimensionPixelSize(R.styleable.RoundedImageViewWithBorder_corner_radius, 0).toFloat()
} finally {
typedArray.recycle()
}
}
@SuppressLint("CanvasSize", "DrawAllocation")
override fun onDraw(canvas: Canvas) {
if (canvas.height <=0 || canvas.width <=0) {
return
}
if (canvasForDraw?.height != canvas.height || canvasForDraw?.width != canvas.width) {
val newBitmap = Bitmap.createBitmap(canvas.width, canvas.height, Bitmap.Config.ARGB_8888)
bitmapForDraw = newBitmap
canvasForDraw = Canvas(newBitmap)
}
bitmapForDraw?.eraseColor(Color.TRANSPARENT)
// Draw existing content
super.onDraw(canvasForDraw)
if (borderWidth > 0) {
canvasForDraw?.let { drawWithBorder(it) }
} else {
canvasForDraw?.let { drawWithoutBorder(it) }
}
// Draw everything on real canvas
bitmapForDraw?.let { canvas.drawBitmap(it, 0f, 0f, null) }
}
private fun drawWithBorder(canvas: Canvas) {
// Draw transparent area
transparentPaint.strokeWidth = borderWidth.toFloat() * 4
transparentAreaRect.apply {
left = -borderWidth.toFloat() * 1.5f
top = -borderWidth.toFloat() * 1.5f
right = canvas.width.toFloat() + borderWidth.toFloat() * 1.5f
bottom = canvas.height.toFloat() + borderWidth.toFloat() * 1.5f
}
canvasForDraw?.drawRoundRect(transparentAreaRect, borderWidth.toFloat() * 2 + cornerRadius, borderWidth.toFloat() * 2 + cornerRadius, transparentPaint)
// Draw border
borderPaint.color = borderColor
borderPaint.strokeWidth = borderWidth.toFloat()
borderRect.apply {
left = borderWidth.toFloat() / 2
top = borderWidth.toFloat() / 2
right = canvas.width.toFloat() - borderWidth.toFloat() / 2
bottom = canvas.height.toFloat() - borderWidth.toFloat() / 2
}
canvas.drawRoundRect(borderRect, cornerRadius - borderWidth.toFloat() / 2, cornerRadius - borderWidth.toFloat() / 2, borderPaint)
}
private fun drawWithoutBorder(canvas: Canvas) {
// Draw transparent area
transparentPaint.strokeWidth = cornerRadius * 4
transparentAreaRect.apply {
left = -cornerRadius * 2
top = -cornerRadius * 2
right = canvas.width.toFloat() + cornerRadius * 2
bottom = canvas.height.toFloat() + cornerRadius * 2
}
canvasForDraw?.drawRoundRect(transparentAreaRect, cornerRadius * 3, cornerRadius * 3, transparentPaint)
}
}
值:
<declare-styleable name="RoundedImageViewWithBorder">
<attr name="corner_radius" format="dimension|string" />
<attr name="border_width" format="dimension|reference" />
<attr name="border_color" format="color|reference" />
</declare-styleable>
它可以用ShapeableImageView使用ShapeAppearanceOverlay完成:
<com.google.android.material.imageview.ShapeableImageView
android:id="@+id/avatar"
android:layout_width="64dp"
android:layout_height="64dp"
android:padding="4dp"
app:shapeAppearance="@style/ShapeAppearanceOverlay.Avatar"/>
其中样式为ShapeAppearanceOverlay。Avatar驻留在res/values/styles.xml中:
<style name="ShapeAppearanceOverlay.Avatar" parent="ShapeAppearance.MaterialComponents.SmallComponent">
<item name="cornerFamily">rounded</item>
<item name="cornerSize">50%</item>
</style>
这只需要相等的layout_height和layout_width设置，否则将是一个药丸和没有圆。
在支持库的v21中，现在有了一个解决方案:它被称为RoundedBitmapDrawable。
它基本上就像一个普通的Drawable，除了你给它一个角半径的剪辑:
setCornerRadius(float cornerRadius)
所以，从Bitmap src和一个目标ImageView开始，它看起来像这样:
RoundedBitmapDrawable dr = RoundedBitmapDrawableFactory.create(res, src);
dr.setCornerRadius(cornerRadius);
imageView.setImageDrawable(dr);
我使用了一个自定义视图，我在其他视图的顶部布局，它只是画了4个小倒角，颜色与背景相同。
优点:
不分配位图。 适用于任何你想要应用圆角的视图。 适用于所有API级别;)
代码:
public class RoundedCornersView extends View {
private float mRadius;
private int mColor = Color.WHITE;
private Paint mPaint;
private Path mPath;
public RoundedCornersView(Context context) {
super(context);
init();
}
public RoundedCornersView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
TypedArray a = context.getTheme().obtainStyledAttributes(
attrs,
R.styleable.RoundedCornersView,
0, 0);
try {
setRadius(a.getDimension(R.styleable.RoundedCornersView_radius, 0));
setColor(a.getColor(R.styleable.RoundedCornersView_cornersColor, Color.WHITE));
} finally {
a.recycle();
}
}
private void init() {
setColor(mColor);
setRadius(mRadius);
}
private void setColor(int color) {
mColor = color;
mPaint = new Paint();
mPaint.setColor(mColor);
mPaint.setStyle(Paint.Style.FILL);
mPaint.setAntiAlias(true);
invalidate();
}
private void setRadius(float radius) {
mRadius = radius;
RectF r = new RectF(0, 0, 2 * mRadius, 2 * mRadius);
mPath = new Path();
mPath.moveTo(0,0);
mPath.lineTo(0, mRadius);
mPath.arcTo(r, 180, 90);
mPath.lineTo(0,0);
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
/*This just draws 4 little inverted corners */
int w = getWidth();
int h = getHeight();
canvas.drawPath(mPath, mPaint);
canvas.save();
canvas.translate(w, 0);
canvas.rotate(90);
canvas.drawPath(mPath, mPaint);
canvas.restore();
canvas.save();
canvas.translate(w, h);
canvas.rotate(180);
canvas.drawPath(mPath, mPaint);
canvas.restore();
canvas.translate(0, h);
canvas.rotate(270);
canvas.drawPath(mPath, mPaint);
}
}
试试这个
Bitmap finalBitmap;
if (bitmap.getWidth() != radius || bitmap.getHeight() != radius)
finalBitmap = Bitmap.createScaledBitmap(bitmap, radius, radius,
false);
else
finalBitmap = bitmap;
Bitmap output = Bitmap.createBitmap(finalBitmap.getWidth(),
finalBitmap.getHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final Paint paint = new Paint();
final Rect rect = new Rect(0, 0, finalBitmap.getWidth(),
finalBitmap.getHeight());
paint.setAntiAlias(true);
paint.setFilterBitmap(true);
paint.setDither(true);
canvas.drawARGB(0, 0, 0, 0);
paint.setColor(Color.parseColor("#BAB399"));
canvas.drawCircle(finalBitmap.getWidth() / 2 + 0.7f,
finalBitmap.getHeight() / 2 + 0.7f,
finalBitmap.getWidth() / 2 + 0.1f, paint);
paint.setXfermode(new PorterDuffXfermode(
android.graphics.PorterDuff.Mode.SRC_IN));
canvas.drawBitmap(finalBitmap, rect, rect, paint);
return output;
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