我必须创建一个小部件,它连续显示 3 个圆圈,并在其上应用动画来更改 alpha 值。我尝试扩展相对布局,但它没有正确显示。 我尝试通过在 Canvas 上绘制圆圈来扩展 View ,但我不知道如何在 Canvas 上设置动画。 我选择了第三个选项来创建圆形 View 并创建 View 组,然后将三个圆形 View 添加到 View 组并在其上应用动画。但我无法计算正确的 onMeasure 值。所以圆圈没有出现。要绘制圆,我需要一个中心点来绘制。但小部件可以放置在屏幕上的任何位置。此时我该如何添加圆圈。 我应该采取什么路线来画这三个圆圈: 这是我的代码
DotsView.java
public class DotsView extends View {
private final float xAxis,yAxis;
private final int radius;
Paint paint;
public DotsView(Context context,float xAxis, float yAxis, int radius) {
super(context);
this.xAxis = xAxis;
this.yAxis = yAxis;
this.radius = radius;
paint = new Paint();
paint.setColor(Color.BLACK);
paint.setStyle(Paint.Style.FILL);
}
@Override
protected void onDraw(Canvas canvas){
canvas.drawCircle(xAxis,yAxis,radius, paint);
}
}
三点.java
public class ThreeDots extends ViewGroup {
private static final int leftCircle = 0;
private static final int middleCircle = 1;
private static final int rightCircle = 2;
private Point center;
private int size;
DotsView left;
DotsView middle;
DotsView right;
public ThreeDots(Context context) {
super(context);
center = new Point();
createDots(context);
}
public ThreeDots(Context context, AttributeSet attrs) {
super(context, attrs);
center = new Point();
createDots(context);
}
@Override
protected void onMeasure(int widthSpec, int heightSpec) {
int measuredWidth = MeasureSpec.getSize(widthSpec);
int measuredHeight = MeasureSpec.getSize(heightSpec);
size = Math.min(measuredWidth, measuredHeight);
center.x = center.y = measuredWidth / 2;
int childSpec = MeasureSpec.makeMeasureSpec(size, MeasureSpec.EXACTLY);
// left.measure(widthMeasureSpec, heightMeasureSpec);
// left.measure(25, 25);
// middle.measure(25, 25);
// right.measure(25, 25);
setMeasuredDimension(measuredWidth, measuredHeight);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
this.left.layout(0, 0, 25, 25);
this.middle.layout(0, 0, 25, 25);
this.right.layout(0, 0, 25, 25);
}
public void createDots(Context context) {
int radius = 10;
int centerXAxis = center.x;
int centerYAxis = center.y;
LayoutParams circleParams = new LayoutParams(LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT);
left = new DotsView(context, centerXAxis - (radius * 3), centerYAxis, radius);
left.setLayoutParams(circleParams);
left.setId(leftCircle);
middle = new DotsView(context, centerXAxis, centerYAxis, radius);
middle.setLayoutParams(circleParams);
middle.setId(middleCircle);
right = new DotsView(context, centerXAxis + (radius * 3), centerYAxis, radius);
right.setLayoutParams(circleParams);
right.setId(rightCircle);
final AnimatorSet animSet = new AnimatorSet();
animSet.playSequentially(alphaAnimate(left), alphaAnimate(middle), alphaAnimate(right));
animSet.start();
animSet.addListener(new AnimatorListener() {
@Override
public void onAnimationStart(Animator animation) {
}
@Override
public void onAnimationRepeat(Animator animation) {
}
@Override
public void onAnimationEnd(Animator animation) {
animSet.start();
}
@Override
public void onAnimationCancel(Animator animation) {
}
});
this.addView(left, 0);
this.addView(middle, 1);
this.addView(right, 2);
}
private ValueAnimator alphaAnimate(DotsView view) {
ValueAnimator alphaAnim = ObjectAnimator.ofFloat(view, "alpha", 1f, 0.5f);
alphaAnim.setDuration(500);
return alphaAnim;
}
}
layout.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@color/white">
<com.android.champ.ThreeDots
xmlns:custom="http://schemas.android.com/apk/res-auto"
android:id="@+id/load_more_progress"
android:layout_width="100dp"
android:layout_height="100dp"
android:background="@color/blue_background"
/>
</RelativeLayout>
最佳答案
扩展View并在onDraw方法中绘制这三个圆圈。对于 Canvas 动画,请参阅我对此问题的回答:How to maintain multi layers of ImageViews and keep their aspect ratio based on the largest one?
关于java - Android自定义ViewGroup绘制圆行,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/19037826/