给你Android实现的九宫格抽奖程序，2021百度Android岗面试真题收录解析
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super(context, attrs, defStyleAttr);
init();
}
/**
- 初始化数据
*/
private void init() {
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setStyle(Paint.Style.FILL);
mPaint.setStrokeWidth(mStrokWidth);
mRects = new ArrayList<>();
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mRectSize = Math.min(w, h)/3;//获取矩形的宽和高
mRects.clear();//当控件大小改变的时候清空数据
initRect();//重新加载矩形数据
}
/**
- 加载矩形数据
*/
private void initRect() {
//加载前三个矩形
for(int x = 0;x<3;x++){
float left = x * mRectSize;
float top = 0;
float right = (x + 1) * mRectSize;
float bottom = mRectSize;
RectF rectF = new RectF(left,top,right,bottom);
mRects.add(rectF);
}
//加载第四个
mRects.add(new RectF(getWidth()-mRectSize,mRectSize,getWidth(),mRectSize * 2));
//加载第五~七个
for(int y= 3;y>0;y–){
float left = getWidth() - (4-y) * mRectSize;
float top = mRectSize * 2;
float right = (y - 3) * mRectSize+getWidth();
float bottom = mRectSize * 3;
RectF rectF = new RectF(left,top,right,bottom);
mRects.add(rectF);
}
//加载第八个
mRects.add(new RectF(0,mRectSize,mRectSize,mRectSize * 2));
//加载第九个
mRects.add(new RectF(mRectSize,mRectSize,mRectSiz
e*2,mRectSize * 2));
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
drawRects(canvas);
}
/**
-
画矩形
-
@param canvas
*/
private void drawRects(Canvas canvas) {
for (int x = 0;x<mRects.size();x++){
RectF rectF = mRects.get(x);
if(x == 8){//中心的矩形背景为白色
mPaint.setColor(Color.WHITE);
canvas.drawRect(rectF, mPaint);
}else {
mPaint.setColor(mItemColor[x%2]);
canvas.drawRect(rectF, mPaint);
}
}
}
}
效果展示
2.添加奖品图片
我们在矩形的中心点画出图片，图片的宽高都为矩形宽高的1/2，其中矩形的中心点通过rectF.centerX()和rectF.centerY()获取。
代码展示（为了方便只展示部分代码）
public class NineLuckPan extends View {
private int [] mImgs = {R.drawable.ic_df,R.drawable.ic_jt,R.drawable.ic_mf,R.drawable.ic_scjx,R.drawable.ic_scng,R.drawable.ic_thl,R.drawable.ic_x,R.drawable.ic_xc,R.drawable.ic_j};
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
drawRects(canvas);//画矩形
drawImages(canvas);//画图片
}
/**
-
画图片
-
@param canvas
*/
private void drawImages(Canvas canvas) {
for (int x = 0;x<mRects.size();x++){
RectF rectF = mRects.get(x);
float left = rectF.centerX() - mRectSize / 4;
float top = rectF.centerY() - mRectSize / 4;
canvas.drawBitmap(Bitmap.createScaledBitmap(BitmapFactory.decodeResource(getResources(),mImgs[x]),mRectSize/2,mRectSize/2,false),left,top,null);
}
}
}
效果展示
3.实现抽奖动画
这里我们使用ValueAnimator使数字从0递增到我们的中奖位置比如3，然后改变递增所在的位置的矩形的背景以实现抽奖的效果，另外为了让用户感到逼真我们需要让抽奖色块多转几圈，同时我们需要将下一次的开始位置设为上一次的结束位置。
代码展示（为了方便只展示部分代码）
NineLuckPan:
public class NineLuckPan extends View {
private int mRepeatCount = 3;//转的圈数
private int mLuckNum = 3;//最终中奖位置
private int mPosition = -1;//抽奖块的位置
private int mStartLuckPosition = 0;//开始抽奖的位置
/**
-
画矩形
-
@param canvas
*/
private void drawRects(Canvas canvas) {
for (int x = 0;x<mRects.size();x++){
RectF rectF = mRects.get(x);
if(x == 8){
mPaint.setColor(Color.WHITE);
canvas.drawRect(rectF, mPaint);
}else {
mPaint.setColor(mItemColor[x%2]);
if(mPosition == x){
mPaint.setColor(Color.BLUE);
}
canvas.drawRect(rectF, mPaint);
}
}
}
public void setPosition(int position){
mPosition = position;
invalidate();
}
/**
- 开始动画
*/
public void startAnim(){
ValueAnimator valueAnimator = ValueAnimator.ofInt(mStartLuckPosition, mRepeatCount * 8 + mLuckNum).setDuration(5000);
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
int position = (int) animation.getAnimatedValue();
nim(){
ValueAnimator valueAnimator = ValueAnimator.ofInt(mStartLuckPosition, mRepeatCount * 8 + mLuckNum).setDuration(5000);
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
int position = (int) animation.getAnimatedValue();
标签：canvas,真题,int,void,九宫格,rectF,mRectSize,Android,mPaint 来源： https://blog.csdn.net/m0_65322636/article/details/122747600