Android自定義View實(shí)現(xiàn)葉子飄動(dòng)旋轉(zhuǎn)效果（四）

2019-12-12 03:18:18

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上一篇實(shí)現(xiàn)了葉子飄動(dòng)功能，《Android自定義葉子飄動(dòng)》現(xiàn)在實(shí)現(xiàn)旋轉(zhuǎn)效果

要實(shí)現(xiàn)這個(gè)效果，要在之前的功能上添加2個(gè)功能

1、通過matrix.postTranslate(int x, int y)在添加在Y軸上滑動(dòng)

2、通過matrix.postRotate(float degrees, float px, float py)實(shí)現(xiàn)葉子旋轉(zhuǎn)

代碼實(shí)現(xiàn)

1、獲取Y坐標(biāo)

 private float getMatrixY() {    float w = (float) ((float) 2 * Math.PI / width);    int y = (int) (18 * Math.sin(w * getMatrixX())) + (height-mLeafHeight)/2;    return y;  }

math.sin(Math.PI....)的取值范圍貌似是-1~1之間。通過X坐標(biāo)在整個(gè)width的比例，獲取到Y(jié)坐標(biāo)的比例。

這里方法有很多，我這邊葉子Y坐標(biāo)默認(rèn)在Y軸中間，然后上下+-18px實(shí)現(xiàn)在Y軸的滑動(dòng)，18滑動(dòng)浮動(dòng)比較大了

public LeafView(Context context, AttributeSet attrs) {    super(context, attrs);    mResources = getResources();    bgBitmap = ((BitmapDrawable) mResources.getDrawable(R.drawable.leaf_kuang, null)).getBitmap();    leafBitmap = ((BitmapDrawable) mResources.getDrawable(R.drawable.leaf, null))).getBitmap();   mLeafHeight = leafBitmap.getWidht();       bgPaint = new Paint();    bgPaint.setColor(mResources.getColor(R.color.bg_color));  }  @Override  protected void onSizeChanged(int w, int h, int oldw, int oldh) {    super.onSizeChanged(w, h, oldw, oldh);    width = w;    height = h;    bgDestRect = new Rect(0, 0 , width, height);  }  @Override  protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    bgRect = new RectF(0, 0 , width, height);    //添加黃色背景    canvas.drawRect(bgRect, bgPaint);    //添加背景圖片    canvas.drawBitmap(bgBitmap, null, bgDestRect, null);    //添加葉子    Matrix matrix = new Matrix();    matrix.postTranslate(getMatriX(), getMatrixY);    canvas.drawBitmap(leafBitmap, new Matrix(), new Paint());    //重復(fù)調(diào)用onDraw()    postInvalidate();  }  long cycleTime = 5000;  //葉子滑動(dòng)一周的時(shí)間5秒  long startTime = 0;   //葉子滑動(dòng)開始時(shí)間  private float getMatriX() {    float betweenTime = startTime - System.currentTimeMillis();    //周期結(jié)束再加一個(gè)cycleTime    if(betweenTime < 0) {      startTime = System.currentTimeMillis() + cycleTime;      betweenTime = cycleTime;    }    //通過時(shí)間差計(jì)算出葉子的坐標(biāo)    float fraction = (float) betweenTime / cycleTime;    float x = (int)(width * fraction);    return x;  }    private float getMatrixY() {    float w = (float) ((float) 2 * Math.PI / width);    int y = (int) (18 * Math.sin(w * getMatrixX())) + (height-mLeafHeight)/2;    return y;  }

看下效果就這樣，在Y軸上實(shí)現(xiàn)上下浮動(dòng)，如果要浮動(dòng)小點(diǎn)，可以把18改小

2、實(shí)現(xiàn)旋轉(zhuǎn)

主要通過matrix.postRotate(float degrees, float px, float py)

degrees就是角度（0~360），px，py就是圖片的中心點(diǎn)

  private int getRotate() {    float scale = ((startTime - System.currentTimeMillis())%cycleTime)/ (float)cycleTime;    int rotate = (int)(scale * 360);    return rotate;  }

同樣，通過當(dāng)前葉子在X軸的比例，來計(jì)算出旋轉(zhuǎn)的角度(0~360)

完整代碼：

public class LeafView extends View {  private Resources mResources;  private Bitmap mLeafBitmap, bgBitmap;  private int width, height;  private int mLeafWidth,mLeafHeight;  private Paint bgPaint;  private RectF bgRect;  private Rect bgDestRect;  public LeafView(Context context, AttributeSet attrs) {    super(context, attrs);    mResources = getResources();    mLeafBitmap = ((BitmapDrawable) mResources.getDrawable(R.drawable.leaf, null)).getBitmap();    mLeafWidth = mLeafBitmap.getWidht();    mLeafHeight = mLeafBitmap.getHeight();    bgBitmap = ((BitmapDrawable) mResources.getDrawable(R.drawable.leaf_kuang, null)).getBitmap();    bgPaint = new Paint();    bgPaint.setColor(mResources.getColor(R.color.bg_color));  }  @Override  protected void onSizeChanged(int w, int h, int oldw, int oldh) {    super.onSizeChanged(w, h, oldw, oldh);    width = w;    height = h;    bgDestRect = new Rect(0, 0 , width, height);  }  @Override  protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    bgRect = new RectF(0, 0 , width, height);    //添加黃色白金    canvas.drawRect(bgRect, bgPaint);    //添加背景圖片    canvas.drawBitmap(bgBitmap, null, bgDestRect, null);    canvas.save();    Matrix matrix = new Matrix();    //添加滑動(dòng)    matrix.postTranslate(getMatrixX(), getMatrixY());    //添加旋轉(zhuǎn)    matrix.postRotate(getRotate(), getMatrixX() + mLeafWidth / 2, getMatrixY() + mLeafHeight / 2);    canvas.drawBitmap(mLeafBitmap, matrix, new Paint());    canvas.restore();    postInvalidate();  }  long cycleTime = 5000;  //葉子滑動(dòng)一周的時(shí)間5秒  long startTime = 0;  private float getMatrixX() {    float betweenTime = startTime - System.currentTimeMillis();    //周期結(jié)束再加一個(gè)cycleTime    if(betweenTime < 0) {      startTime = System.currentTimeMillis() + cycleTime;      betweenTime = cycleTime;    }    //通過時(shí)間差計(jì)算出葉子的坐標(biāo)    float fraction = (float) betweenTime / cycleTime;    float x = (int)(width * fraction);    return x;  }  private float getMatrixY() {    float w = (float) ((float) 2 * Math.PI / width);    int y = (int) (18 * Math.sin(w * getMatrixX())) + (height-mLeafHeight)/2;    return y;  }  private int getRotate() {    float scale = ((startTime - System.currentTimeMillis())%cycleTime)/ (float)cycleTime;    int rotate = (int)(scale * 360);    return rotate;  }}

以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持武林網(wǎng)。

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