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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(guò)matrix.postTranslate(int x, int y)在添加在Y軸上滑動(dòng)
2、通過(guò)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(guò)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(guò)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(guò)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(guò)當(dāng)前葉子在X軸的比例,來(lái)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(guò)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; } }
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