今天看到一个银行的APP上面的loadingview 挺好的，就尝试着自己实现，觉得很简单，但自己实现起来还是发现了一些问题。

LoadingView和下图类似：

实现的代码也不是很复杂，就是小球的运动轨迹需要计算，我自己手画了个计算的图，很简单的就是三角函数的使用。

然后代码就是代码实现了，主要的内容都有注释，代码如下：

public class LoadingView extends View {

private final static String TAG = "LoadingView";

private final static int LEFT_BALL_DOWN = 1;

private final static int LEFT_BALL_UP = 2;

private final static int RIGHT_BALL_DOWN = 3;

private final static int RIGHT_BALL_UP = 4;

private Paint paint1, paint2, paint3, paint4, paint5;

private int mCurrentAnimatorValue;

private int circleRadius = 10; //小球的半径

private int distance = 60; //小球开始下落到最低点的距离

private int mCurrentState = LEFT_BALL_DOWN;

public LoadingView(Context context) {

super(context);

init(context);

}

public LoadingView(Context context, @Nullable AttributeSet attrs) {

super(context, attrs);

init(context);

}

public LoadingView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {

super(context, attrs, defStyleAttr);

init(context);

}

private void init(Context context) {

paint1 = getPaint(Color.RED);

paint2 = getPaint(Color.YELLOW);

paint3 = getPaint(Color.GREEN);

paint4 = getPaint(Color.BLUE);

paint5 = getPaint(Color.CYAN);

ValueAnimator animator = ValueAnimator.ofInt(0, 90);

animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {

@Override

public void onAnimationUpdate(ValueAnimator animation) {

mCurrentAnimatorValue = (int) animation.getAnimatedValue();

Log.e(TAG, "onAnimationUpdate : mCurrentAnimatorValue = " + mCurrentAnimatorValue);

invalidate();

}

});

animator.addListener(new Animator.AnimatorListener() {

@Override

public void onAnimationStart(Animator animation) {

}

@Override

public void onAnimationEnd(Animator animation) {

}

@Override

public void onAnimationCancel(Animator animation) {

}

@Override

public void onAnimationRepeat(Animator animation) {

Log.e(TAG, "onAnimationRepeat : mCurrentAnimatorValue = " + mCurrentAnimatorValue);

switch (mCurrentState) {

case LEFT_BALL_DOWN:

mCurrentState = RIGHT_BALL_UP;

break;

case RIGHT_BALL_UP:

mCurrentState = RIGHT_BALL_DOWN;

break;

case RIGHT_BALL_DOWN:

mCurrentState = LEFT_BALL_UP;

break;

case LEFT_BALL_UP:

mCurrentState = LEFT_BALL_DOWN;

break;

}

}

});

animator.setStartDelay(500);

animator.setDuration(600);

animator.setRepeatCount(ValueAnimator.INFINITE);

animator.setInterpolator(new DecelerateInterpolator());

animator.start();

}

private Paint getPaint(int color) {

Paint paint = new Paint();

paint.setColor(color);

paint.setAntiAlias(true);

paint.setStyle(Paint.Style.FILL);

return paint;

}

@Override

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

super.onMeasure(widthMeasureSpec, heightMeasureSpec);

}

@Override

protected void onDraw(Canvas canvas) {

super.onDraw(canvas);

int x, y;

double cosValue = Math.cos(PI * mCurrentAnimatorValue / 180);

double sinValue = Math.sin(PI * mCurrentAnimatorValue / 180);

drawFourBall(canvas);

switch (mCurrentState) {

case LEFT_BALL_DOWN://最左边小球往下撞击

x = circleRadius + (int) ((distance - circleRadius) * (1 - cosValue));

y = getHeight() - distance + (int) ((distance - circleRadius) * sinValue);

canvas.drawCircle(x, y, circleRadius, paint1);

break;

case RIGHT_BALL_UP://最右边小球往上撞击

x = distance + 8 * circleRadius + (int) ((distance - circleRadius) * sinValue);

y = getHeight() - distance + (int) (cosValue * (distance - circleRadius));

canvas.drawCircle(x, y, circleRadius, paint5);

break;

case RIGHT_BALL_DOWN://最右边小球往下撞击

x = distance + 8 * circleRadius + (int) ((distance - circleRadius) * (cosValue));

y = (getHeight() - distance) + (int) ((distance - circleRadius) * (sinValue));

canvas.drawCircle(x, y, circleRadius, paint5);

break;

case LEFT_BALL_UP://最左边小球往上撞击

x = distance - (int) ((distance - circleRadius) * sinValue);

y = getHeight() - distance + (int) ((distance - circleRadius) * cosValue);

canvas.drawCircle(x, y, circleRadius, paint1);

break;

}

}

private void drawFourBall(Canvas canvas) {

int y = getHeight() - circleRadius;

canvas.drawCircle(distance + 2 * circleRadius, y, circleRadius, paint2);

canvas.drawCircle(distance + 4 * circleRadius, y, circleRadius, paint3);

canvas.drawCircle(distance + 6 * circleRadius, y, circleRadius, paint4);

if (mCurrentState == LEFT_BALL_DOWN || mCurrentState == LEFT_BALL_UP) {//最左边球运动的时候，要绘制最右边的球

canvas.drawCircle(distance + 8 * circleRadius, y, circleRadius, paint5);

} else if (mCurrentState == RIGHT_BALL_UP || mCurrentState == RIGHT_BALL_DOWN) {//最右边球运动的时候，要绘制最左边的球

canvas.drawCircle(distance, y, circleRadius, paint1);

}

}

}

实现的效果如图一，有问题的话互相讨论。最后贴上想xml文件，后续会完善设置loadingview的大小和颜色之类的参数。

xml如下：

android:layout_marginTop="20px"

android:background="#999999"

android:layout_width="200px"

android:layout_height="200px" />

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脚本之家。