Android 自定義View之咖啡杯動畫

摘要： 效果 CoffeeView CoffeeView 大概思路 自定義view，直接繼承view 複寫onSizeChanged()方法，在此計算杯墊，杯子，煙霧效果的path 在onDraw()方法中，描...

效果

大概思路

• 自定義view，直接繼承view
• 複寫onSizeChanged()方法，在此計算杯墊，杯子，煙霧效果的path
• 在onDraw()方法中，描繪杯墊，杯子
• 處理煙霧動畫效果

畫杯子

這裡需要畫兩部分內容，第一部分是杯子，第二部分是杯耳(提手的地方)

我們可以使用addRoundRect來描繪圓角矩形，並且可指定每個圓角的半徑即圓角的程度

/**
 * Add a closed round-rectangle contour to the path. Each corner receives
 * two radius values [X, Y]. The corners are ordered top-left, top-right,
 * bottom-right, bottom-left
 *
 * @param rect The bounds of a round-rectangle to add to the path
 * @param radii Array of 8 values, 4 pairs of [X,Y] radii
 * @param dirThe direction to wind the round-rectangle's contour
 */
public void addRoundRect(RectF rect, float[] radii, Direction dir) {
if (rect == null) {
throw new NullPointerException("need rect parameter");
}
addRoundRect(rect.left, rect.top, rect.right, rect.bottom, radii, dir);
}

以下程式碼註釋：

//計算view的中心點座標
mCenterX = w / 2;
mCenterY = h / 2;

//杯子的寬，為view的寬度的2/3
float cupWidth= w * 2 / 3f;

//杯子的高，為view的高度3/8
float cupHeight = (h / 2) * 3 / 4f;

//計算出杯子的中心點座標
float cupCenterX = mCenterX;
float cupCenterY = mCenterY + cupHeight / 2;

//計算杯子矩形的左上右上的圓角半徑
float cupTopRoundRadius = Math.min(cupWidth, cupHeight) / 20f;

//計算杯子矩形的左下右下的圓角半徑
float cupBottomRoundRadius = cupTopRoundRadius * 10;

//重置杯子path
mCupPath.reset();

//添加杯子(杯身)軌跡
mCupPath.addRoundRect(new RectF(cupCenterX - cupWidth / 2, cupCenterY - cupHeight / 2 - cupHeight / 10, cupCenterX + cupWidth / 2, cupCenterY + cupHeight / 2), new float[]{cupTopRoundRadius, cupTopRoundRadius, cupTopRoundRadius, cupTopRoundRadius,cupBottomRoundRadius, cupBottomRoundRadius, cupBottomRoundRadius, cupBottomRoundRadius}, Path.Direction.CW);

//計算杯耳寬度
float cupEarWidth= (w - cupWidth) * 3 / 4f;
//計算杯耳高度
float cupEarHeight = cupHeight / 3;

//計算杯耳的中心點座標
float cupEarCenterX = mCenterX + cupWidth / 2;
float cupEarCenterY = mCenterY + cupHeight / 2;

//計算杯耳的圓角半徑
float cupEarRoundRadius = Math.min(cupEarWidth, cupEarHeight) / 2f;

//設定杯耳畫筆的描邊寬度
mCupEarPaint.setStrokeWidth(Math.min(cupEarWidth, cupEarHeight) / 3f);

//重置杯耳path
mCupEarPath.reset();

//添加杯耳軌跡
mCupEarPath.addRoundRect(new RectF(cupEarCenterX - cupEarWidth / 2, cupEarCenterY - cupEarHeight / 2 - cupHeight / 10, cupEarCenterX + cupEarWidth / 2,
cupEarCenterY + cupEarHeight / 2),
new float[]{cupEarRoundRadius, cupEarRoundRadius, cupEarRoundRadius, cupEarRoundRadius,
cupEarRoundRadius, cupEarRoundRadius, cupEarRoundRadius, cupEarRoundRadius}, Path.Direction.CW);

在onDraw方法中

canvas.drawPath(mCupEarPath, mCupEarPaint);
canvas.drawPath(mCupPath, mCupPaint);

畫杯墊

首先計算杯墊path軌跡

//計算杯墊寬度
float coasterWidth = cupWidth;
//計算杯墊高度
float coasterHeight = (h / 2 - cupHeight) * 1 / 3f;

//計算杯墊中心點座標
float coasterCenterX = mCenterX;
float coasterCenterY = mCenterY + cupHeight + (h / 2 - cupHeight) / 2f;

//計算杯墊圓角半徑
float coasterRoundRadius = Math.min(coasterWidth, coasterHeight) / 2f;

//重置杯墊path
mCoasterPath.reset();

//添加杯墊軌跡
mCoasterPath.addRoundRect(new RectF(coasterCenterX - coasterWidth / 2, coasterCenterY - coasterHeight / 2,
coasterCenterX + coasterWidth / 2, coasterCenterY + coasterHeight / 2),
coasterRoundRadius, coasterRoundRadius, Path.Direction.CW);

在onDraw方法中

canvas.drawPath(mCoasterPath, mCoasterPaint);

畫煙霧

煙霧原理

• 根據貝塞爾曲線新增波浪軌跡
• 根據LinearGradient實現顏色漸變效果

每條煙霧大概如下效果

當移動至煙霧底部的時候，重新將其移動至頭部，這樣迴圈動畫，就會顯示無線的滾動效果

程式碼註釋如下：

//計算煙霧的寬度
float vaporsStrokeWidth = cupWidth / 15f;

//計算煙霧相隔距離大小
float vaporsGapWidth = (cupWidth - VAPOR_COUNT * vaporsStrokeWidth) / 4f;
mVaporsHeight= cupHeight * 4 / 5f;

//設定煙霧畫筆描邊大小
mVaporPaint.setStrokeWidth(vaporsStrokeWidth);
float startX, startY, stopX, stopY;

//設定漸變效果
LinearGradient linearGradient = new LinearGradient(mCenterX, mCenterY, mCenterX, mCenterY - mVaporsHeight,
new int[]{mVaporColor, Color.TRANSPARENT},
null, Shader.TileMode.CLAMP);

//煙霧畫筆增加漸變效果的渲染器
mVaporPaint.setShader(linearGradient);

//增加每條煙霧的path的貝塞爾波浪
for (int i = 0; i < VAPOR_COUNT; i++) {
mVaporsPath[i].reset();

startX = (mCenterX - cupWidth / 2) + vaporsStrokeWidth / 2 + i * vaporsStrokeWidth + (i + 1) * vaporsGapWidth;
startY = mCenterY + mVaporsHeight;

stopX = startX;
stopY = mCenterY - mVaporsHeight;


mVaporsPath[i].moveTo(startX, startY);
mVaporsPath[i].quadTo(startX - vaporsGapWidth / 2, startY - mVaporsHeight / 4,
startX, startY - mVaporsHeight / 2);

mVaporsPath[i].quadTo(startX + vaporsGapWidth / 2, startY - mVaporsHeight * 3 / 4,
startX, mCenterY);

mVaporsPath[i].quadTo(startX - vaporsGapWidth / 2, mCenterY - mVaporsHeight / 4,
startX, mCenterY - mVaporsHeight / 2);

mVaporsPath[i].quadTo(startX + vaporsGapWidth / 2, mCenterY - mVaporsHeight * 3 / 4,
stopX, stopY);

//add twice the bezier curve
mVaporsPath[i].quadTo(startX - vaporsGapWidth / 2, stopY - mVaporsHeight / 4,
startX, stopY - mVaporsHeight / 2);

mVaporsPath[i].quadTo(startX + vaporsGapWidth / 2, stopY - mVaporsHeight * 3 / 4,
startX, stopY - mVaporsHeight);

mVaporsPath[i].quadTo(startX - vaporsGapWidth / 2, stopY - mVaporsHeight - mVaporsHeight / 4,
startX, stopY - mVaporsHeight - mVaporsHeight / 2);

mVaporsPath[i].quadTo(startX + vaporsGapWidth / 2, stopY - mVaporsHeight - mVaporsHeight * 3 / 4,
stopX, stopY - 2 * mVaporsHeight);
}

煙霧動畫處理：

每條煙霧都有一個path記錄其軌跡，利用path的transform方法可移動path

/**
 * Transform the points in this path by matrix, and write the answer
 * into dst. If dst is null, then the the original path is modified.
 *
 * @param matrix The matrix to apply to the path
 * @param dstThe transformed path is written here. If dst is null,
 *then the the original path is modified
 */
public void transform(Matrix matrix, Path dst) {
long dstNative = 0;
if (dst != null) {
dst.isSimplePath = false;
dstNative = dst.mNativePath;
}
nTransform(mNativePath, matrix.native_instance, dstNative);
}

ValueAnimator valueAnimator = ValueAnimator.ofFloat(0, -vaporHeight);
final int finalI = i;
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
mAnimatorValues[finalI] = (float) valueAnimator.getAnimatedValue();
invalidate();
}
});

valueAnimator.setDuration(1000);
valueAnimator.setInterpolator(new LinearInterpolator());
valueAnimator.setRepeatCount(ValueAnimator.INFINITE);
valueAnimator.setRepeatMode(ValueAnimator.RESTART);
mValueAnimators.add(valueAnimator);

在onDraw方法中，描繪煙霧

private void drawVapors(Canvas canvas){
for (int i = 0; i < VAPOR_COUNT; i++){
mCalculateMatrix.reset();
mCalculatePath.reset();

float animatedValue = mAnimatorValues[i];
mCalculateMatrix.postTranslate(0, animatedValue);
mVaporsPath[i].transform(mCalculateMatrix, mCalculatePath);

canvas.drawPath(mCalculatePath, mVaporPaint);
}
}

我這裡設定了每條煙霧的移動速度是一樣的，你們可以下載原始碼來修改，看看不同的移動速度的效果

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