这次主要是练习一下Android的自定义view和path的相关使用，所以做了一个简单的demo：自定义一个view，并用path在上面画一个可以动态改变圆角大小的长方形。

自定义相关属性

自定义view首先需要在values文件夹下建一个attrs文件，并在其中定义view的相关属性，如下：

<resources> <declare-styleable name="CustomView"> <attr name="round_position"> <flag name="left-top" value="0x1"></flag> <flag name="right-top" value="0x4"></flag> <flag name="left-bottom" value="0x2"></flag> <flag name="right-bottom" value="0x8"></flag> </attr> <attr name="round_radius" format="dimension"></attr> </declare-styleable></resources>

其中round_position指的是圆角的位置，这里属性类型定为flag（位或运算）这样就可以在布局中同时使用多个属性了，类似于EditText中定义文字样式：android:textStyle="bold|italic";round_radius指圆角大小，类型为dimension。

自定义view类

新建一个类继承View，如下：

public class CustomView extends View { private Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG); private Path path; private int color = Color.GREEN; private final int LEFT_TOP = 0x1; private final int LEFT_BOTTOM = 0x2; private final int RIGHT_TOP = 0x4; private final int RIGHT_BOTTOM = 0x8; private boolean drawLeftTop; private boolean drawLeftBottom; private boolean drawRightTop; private boolean drawRightBottom; private float radius; public CustomView(Context context) { super(context); initDraw(); } public CustomView(Context context, @Nullable AttributeSet attrs) { super(context, attrs); TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.CustomView); int position = typedArray.getInt(R.styleable.CustomView_round_position, 0); radius = typedArray.getDimension(R.styleable.CustomView_round_radius, 0); drawLeftTop = (position & LEFT_TOP) == LEFT_TOP; drawLeftBottom = (position & LEFT_BOTTOM) == LEFT_BOTTOM; drawRightTop = (position & RIGHT_TOP) == RIGHT_TOP; drawRightBottom = (position & RIGHT_BOTTOM) == RIGHT_BOTTOM; typedArray.recycle(); initDraw(); } public CustomView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); initDraw(); } private void initDraw() { path = new Path(); paint.setColor(Color.GREEN); paint.setAntiAlias(true); paint.setStrokeWidth((float) 5); paint.setStyle(Paint.Style.STROKE); } @Override protected void onDraw(Canvas canvas) { path.reset();//这里很重要，如果不写这一行，则每次重绘view后先前绘制的还会存在 path.moveTo(radius, 0); if (drawRightTop) { path.lineTo(getWidth() - radius, 0);// path.cubicTo(radius + getWidth() / 3, 0, radius + getWidth() / 3 * 2, 0, getWidth() - radius, 0); path.cubicTo(getWidth() - radius / 2, 0, getWidth(), radius / 2, getWidth(), radius); } else { path.lineTo(getWidth(), 0);// path.cubicTo(radius + getWidth() / 3, 0, radius + getWidth() / 3 * 2, 0, getWidth(), 0); } path.lineTo(getWidth(), getHeight() - radius);// path.cubicTo(getWidth(), radius + getHeight() / 3, getWidth(), radius + getHeight() / 3 * 2, getWidth(), getHeight() - radius); if (drawRightBottom) { path.cubicTo(getWidth(), getHeight() - radius / 2, getWidth() - radius / 2, getHeight(), getWidth() - radius, getHeight()); } else { path.lineTo(getWidth(), getHeight()); } path.lineTo(radius, getHeight()); if (drawLeftBottom) { path.cubicTo(radius / 2, getHeight(), 0, getHeight() - radius / 2, 0, getHeight() - radius); } else { path.lineTo(0, getHeight()); } path.lineTo(0, radius); if (drawLeftTop) { path.cubicTo(0, radius / 2, radius / 2, 0, radius, 0); } else { path.lineTo(0, 0); path.lineTo(radius, 0); } canvas.drawPath(path, paint); super.onDraw(canvas); } public void setRadius(float radius) { this.radius = radius; } public void refreshView() { invalidate(); }}

这里使用了path和贝塞尔曲线的绘制方法来绘制可动态调整圆角大小的长方形，注意每次重绘时要先调用path.reset()清除之前绘制的path，然后再绘制新的path，不然旧的path还会一直存在。

布局中使用自定义view

<wjc.myrecyclerview.CustomView android:id="@+id/custom_view" android:layout_width="200dp" android:layout_height="200dp" android:layout_margin="100dp" app:layout_constraintLeft_toLeftOf="parent" app:layout_constraintRight_toRightOf="parent" app:layout_constraintTop_toTopOf="parent" app:round_position="left-bottom|right-bottom|right-top|left-top" />

这样就完成了一个简单的自定义可调整圆角的长方形，在MainActivity中进行动态控制：

view.setRadius(progress);view.refreshView();

实现的最终效果

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。