有一个Path#addRoundRect()重载,它接受一个包含八个值的float数组,其中我们可以为四个角中的每一个指定x和y半径.这些值为[x,y]对,从左上角开始,顺时针绕其余部分.对于我们想要舍入的那些角,我们将该对的两个值都设置为半径值,并将它们保留为零,而不是那些.
作为一个说明性示例,一个简单的方法将返回可在您的代码段中使用的Path：
private Path getPath(float radius, boolean topLeft, boolean topRight,
boolean bottomRight, boolean bottomLeft) {
final Path path = new Path();
final float[] radii = new float[8];
if (topLeft) {
radii[0] = radius;
radii[1] = radius;
}
if (topRight) {
radii[2] = radius;
radii[3] = radius;
}
if (bottomRight) {
radii[4] = radius;
radii[5] = radius;
}
if (bottomLeft) {
radii[6] = radius;
radii[7] = radius;
}
path.addRoundRect(new RectF(0, 0, getWidth(), getHeight()),
radii, Path.Direction.CW);
return path;
}
根据您的示例说明,舍入左上角和右上角：
@Override
protected void onDraw(Canvas canvas) {
float radius = getContext().getResources().getDimension(R.dimen.round_corner_radius);
Path path = getPath(radius, true, true, false, false);
canvas.clipPath(path);
super.onDraw(canvas);
}
和往常一样,我建议尽可能地保持onDraw()方法,移动任何其他地方不必存在的东西.例如,可以在构造函数中检索radius的资源值,并将其保存在字段中.此外,只有在必要时才能构建路径;即,当视图的大小改变时,或当半径或选定的角改变时.
由于我将一个简单的自定义ImageView放在一起进行测试,我将在此处包含它,因为它演示了以上几点.此自定义视图还提供XML属性,允许在布局中设置角半径和圆角.
public class RoundishImageView extends ImageView {
public static final int CORNER_NONE = 0;
public static final int CORNER_TOP_LEFT = 1;
public static final int CORNER_TOP_RIGHT = 2;
public static final int CORNER_BOTTOM_RIGHT = 4;
public static final int CORNER_BOTTOM_LEFT = 8;
public static final int CORNER_ALL = 15;
private static final int[] CORNERS = {CORNER_TOP_LEFT,
CORNER_TOP_RIGHT,
CORNER_BOTTOM_RIGHT,
CORNER_BOTTOM_LEFT};
private final Path path = new Path();
private int cornerRadius;
private int roundedCorners;
public RoundishImageView(Context context) {
this(context, null);
}
public RoundishImageView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public RoundishImageView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.RoundishImageView);
cornerRadius = a.getDimensionPixelSize(R.styleable.RoundishImageView_cornerRadius, 0);
roundedCorners = a.getInt(R.styleable.RoundishImageView_roundedCorners, CORNER_NONE);
a.recycle();
}
public void setCornerRadius(int radius) {
if (cornerRadius != radius) {
cornerRadius = radius;
setPath();
invalidate();
}
}
public int getCornerRadius() {
return cornerRadius;
}
public void setRoundedCorners(int corners) {
if (roundedCorners != corners) {
roundedCorners = corners;
setPath();
invalidate();
}
}
public boolean isCornerRounded(int corner) {
return (roundedCorners & corner) == corner;
}
@Override
protected void onDraw(Canvas canvas) {
if (!path.isEmpty()) {
canvas.clipPath(path);
}
super.onDraw(canvas);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
setPath();
}
private void setPath() {
path.rewind();
if (cornerRadius >= 1f && roundedCorners != CORNER_NONE) {
final float[] radii = new float[8];
for (int i = 0; i < 4; i++) {
if (isCornerRounded(CORNERS[i])) {
radii[2 * i] = cornerRadius;
radii[2 * i + 1] = cornerRadius;
}
}
path.addRoundRect(new RectF(0, 0, getWidth(), getHeight()),
radii, Path.Direction.CW);
}
}
}
要使XML属性起作用,需要在< resources>中进行以下操作,您可以将此文件放在项目的res / values /文件夹中,或添加到可能已存在的文件中.
attrs.xml
cornerRadius是一个维度属性,应指定为dp或px值. roundedCorners是一个标志属性,可以使用竖线字符|来选择多个角.例如：
xmlns:app="/apk/res-auto"
android:id="@+id/riv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:adjustViewBounds="true"
android:scaleType="fitXY"
android:src="@drawable/magritte"
app:cornerRadius="@dimen/round_corner_radius"
app:roundedCorners="topLeft|topRight" />
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