/**
* An interpolator where the rate of change starts and ends slowly but
* accelerates through the middle.
* 两边慢 中间快
*/
public class AccelerateDecelerateInterpolator extends BaseInterpolator
implements NativeInterpolatorFactory {
public AccelerateDecelerateInterpolator() {
}
public float getInterpolation(float input) {
return (float)(Math.cos((input + 1) * Math.PI) / 2.0f) + 0.5f;
}
}
/**
* An interpolator where the rate of change starts out slowly and
* and then accelerates.
* 先慢 后快
*/
public class AccelerateInterpolator extends BaseInterpolator implements NativeInterpolatorFactory {
private final float mFactor;
private final double mDoubleFactor;
public AccelerateInterpolator() {
mFactor = 1.0f;
mDoubleFactor = 2.0;
}
/**
* Constructor
*
* @param factor Degree to which the animation should be eased. Seting
* factor to 1.0f produces a y=x^2 parabola. Increasing factor above
* 1.0f exaggerates the ease-in effect (i.e., it starts even
* slower and ends evens faster)
*/
public AccelerateInterpolator(float factor) {
mFactor = factor;
mDoubleFactor = 2 * mFactor;
}
public float getInterpolation(float input) {
if (mFactor == 1.0f) {
return input * input;
} else {
return (float)Math.pow(input, mDoubleFactor);
}
}
}
/**
* An interpolator where the change starts backward then flings forward.
* 先向后 再向前
*/
public class AnticipateInterpolator extends BaseInterpolator implements NativeInterpolatorFactory {
private final float mTension;
public AnticipateInterpolator() {
mTension = 2.0f;
}
/**
* @param tension Amount of anticipation. When tension equals 0.0f, there is
* no anticipation and the interpolator becomes a simple
* acceleration interpolator.
*/
public AnticipateInterpolator(float tension) {
mTension = tension;
}
public float getInterpolation(float t) {
// a(t) = t * t * ((tension + 1) * t - tension)
return t * t * ((mTension + 1) * t - mTension);
}
}
/**
* An interpolator where the change starts backward then flings forward and overshoots
* the target value and finally goes back to the final value.
* 先向后运动 超过临界值，再快速向前运动超过临界值，最后慢慢回到临界值
*/
public class AnticipateOvershootInterpolator extends BaseInterpolator
implements NativeInterpolatorFactory {
private final float mTension;
public AnticipateOvershootInterpolator() {
mTension = 2.0f * 1.5f;
}
/**
* @param tension Amount of anticipation/overshoot. When tension equals 0.0f,
* there is no anticipation/overshoot and the interpolator becomes
* a simple acceleration/deceleration interpolator.
*/
public AnticipateOvershootInterpolator(float tension) {
mTension = tension * 1.5f;
}
/**
* @param tension Amount of anticipation/overshoot. When tension equals 0.0f,
* there is no anticipation/overshoot and the interpolator becomes
* a simple acceleration/deceleration interpolator.
* @param extraTension Amount by which to multiply the tension. For instance,
* to get the same overshoot as an OvershootInterpolator with
* a tension of 2.0f, you would use an extraTension of 1.5f.
*/
public AnticipateOvershootInterpolator(float tension, float extraTension) {
mTension = tension * extraTension;
}
private static float a(float t, float s) {
return t * t * ((s + 1) * t - s);
}
private static float o(float t, float s) {
return t * t * ((s + 1) * t + s);
}
public float getInterpolation(float t) {
// a(t, s) = t * t * ((s + 1) * t - s)
// o(t, s) = t * t * ((s + 1) * t + s)
// f(t) = 0.5 * a(t * 2, tension * extraTension), when t < 0.5
// f(t) = 0.5 * (o(t * 2 - 2, tension * extraTension) + 2), when t <= 1.0
if (t < 0.5f) return 0.5f * a(t * 2.0f, mTension);
else return 0.5f * (o(t * 2.0f - 2.0f, mTension) + 2.0f);
}
}
/**
* Repeats the animation for a specified number of cycles. The
* rate of change follows a sinusoidal pattern.
* sin正弦变化曲线
*/
@HasNativeInterpolator
public class CycleInterpolator extends BaseInterpolator implements NativeInterpolatorFactory {
private float mCycles;
public CycleInterpolator(float cycles) {
mCycles = cycles;
}
public float getInterpolation(float input) {
return (float)(Math.sin(2 * mCycles * Math.PI * input));
}
}
/**
* An interpolator where the rate of change starts out quickly and
* and then decelerates.
* 减速插值器变化曲线，其算法为AccelerateInterpolator的完全倒置。
*/
public class DecelerateInterpolator extends BaseInterpolator implements NativeInterpolatorFactory {
private float mFactor = 1.0f;
public DecelerateInterpolator() {
}
/**
* Constructor
*
* @param factor Degree to which the animation should be eased. Setting factor to 1.0f produces
* an upside-down y=x^2 parabola. Increasing factor above 1.0f exaggerates the
* ease-out effect (i.e., it starts even faster and ends evens slower).
*/
public DecelerateInterpolator(float factor) {
mFactor = factor;
}
public float getInterpolation(float input) {
float result;
if (mFactor == 1.0f) {
result = (float)(1.0f - (1.0f - input) * (1.0f - input));
} else {
result = (float)(1.0f - Math.pow((1.0f - input), 2 * mFactor));
}
return result;
}
}
/**
* An interpolator where the rate of change starts out quickly and
* and then decelerates.
* 为0~1之间匀速变化的一条直线。
*/
/**
* An interpolator where the rate of change is constant
*/
public class LinearInterpolator extends BaseInterpolator implements NativeInterpolatorFactory {
public LinearInterpolator() {
}
public float getInterpolation(float input) {
return input;
}
}
/**
* An interpolator where the change flings forward and overshoots the last value
* then comes back.
* 先超过临界值 再慢慢回到临界值
*/
public class OvershootInterpolator extends BaseInterpolator implements NativeInterpolatorFactory {
private final float mTension;
public OvershootInterpolator() {
mTension = 2.0f;
}
/**
* @param tension Amount of overshoot. When tension equals 0.0f, there is
* no overshoot and the interpolator becomes a simple
* deceleration interpolator.
*/
public OvershootInterpolator(float tension) {
mTension = tension;
}
public float getInterpolation(float t) {
// _o(t) = t * t * ((tension + 1) * t + tension)
// o(t) = _o(t - 1) + 1
t -= 1.0f;
return t * t * ((mTension + 1) * t + mTension) + 1.0f;
}
}
/**
* An interpolator that can traverse a Path that extends from <code>Point</code>
* <code>(0, 0)</code> to <code>(1, 1)</code>. The x coordinate along the <code>Path</code>
* is the input value and the output is the y coordinate of the line at that point.
* This means that the Path must conform to a function <code>y = f(x)</code>.
*
* <p>The <code>Path</code> must not have gaps in the x direction and must not
* loop back on itself such that there can be two points sharing the same x coordinate.
* It is alright to have a disjoint line in the vertical direction:</p>
* <p><blockquote><pre>
* Path path = new Path();
* path.lineTo(0.25f, 0.25f);
* path.moveTo(0.25f, 0.5f);
* path.lineTo(1f, 1f);
* </pre></blockquote></p>
* 构造一个普通Path路径或者贝塞尔曲线的插值器
*/
public class PathInterpolator extends BaseInterpolator implements NativeInterpolatorFactory {
// This governs how accurate the approximation of the Path is.
private static final float PRECISION = 0.002f;
private float[] mX; // x coordinates in the line
private float[] mY; // y coordinates in the line
/**
* Create an interpolator for an arbitrary <code>Path</code>. The <code>Path</code>
* must begin at <code>(0, 0)</code> and end at <code>(1, 1)</code>.
*
* @param path The <code>Path</code> to use to make the line representing the interpolator.
*/
public PathInterpolator(Path path) {
initPath(path);
}
public PathInterpolator(float controlX, float controlY) {
initQuad(controlX, controlY);
}
/**
* Create an interpolator for a cubic Bezier curve. The end points
* <code>(0, 0)</code> and <code>(1, 1)</code> are assumed.
*
* @param controlX1 The x coordinate of the first control point of the cubic Bezier.
* @param controlY1 The y coordinate of the first control point of the cubic Bezier.
* @param controlX2 The x coordinate of the second control point of the cubic Bezier.
* @param controlY2 The y coordinate of the second control point of the cubic Bezier.
*/
public PathInterpolator(float controlX1, float controlY1, float controlX2, float controlY2) {
initCubic(controlX1, controlY1, controlX2, controlY2);
}
private void initQuad(float controlX, float controlY) {
Path path = new Path();
path.moveTo(0, 0);
path.quadTo(controlX, controlY, 1f, 1f);
initPath(path);
}
private void initCubic(float x1, float y1, float x2, float y2) {
Path path = new Path();
path.moveTo(0, 0);
path.cubicTo(x1, y1, x2, y2, 1f, 1f);
initPath(path);
}
private void initPath(Path path) {
float[] pointComponents = path.approximate(PRECISION);
int numPoints = pointComponents.length / 3;
if (pointComponents[1] != 0 || pointComponents[2] != 0
|| pointComponents[pointComponents.length - 2] != 1
|| pointComponents[pointComponents.length - 1] != 1) {
throw new IllegalArgumentException("The Path must start at (0,0) and end at (1,1)");
}
mX = new float[numPoints];
mY = new float[numPoints];
float prevX = 0;
float prevFraction = 0;
int componentIndex = 0;
for (int i = 0; i < numPoints; i++) {
float fraction = pointComponents[componentIndex++];
float x = pointComponents[componentIndex++];
float y = pointComponents[componentIndex++];
if (fraction == prevFraction && x != prevX) {
throw new IllegalArgumentException(
"The Path cannot have discontinuity in the X axis.");
}
if (x < prevX) {
throw new IllegalArgumentException("The Path cannot loop back on itself.");
}
mX[i] = x;
mY[i] = y;
prevX = x;
prevFraction = fraction;
}
}
/**
* Using the line in the Path in this interpolator that can be described as
* <code>y = f(x)</code>, finds the y coordinate of the line given <code>t</code>
* as the x coordinate. Values less than 0 will always return 0 and values greater
* than 1 will always return 1.
*
* @param t Treated as the x coordinate along the line.
* @return The y coordinate of the Path along the line where x = <code>t</code>.
* @see Interpolator#getInterpolation(float)
*/
@Override
public float getInterpolation(float t) {
if (t <= 0) {
return 0;
} else if (t >= 1) {
return 1;
}
// Do a binary search for the correct x to interpolate between.
int startIndex = 0;
int endIndex = mX.length - 1;
while (endIndex - startIndex > 1) {
int midIndex = (startIndex + endIndex) / 2;
if (t < mX[midIndex]) {
endIndex = midIndex;
} else {
startIndex = midIndex;
}
}
float xRange = mX[endIndex] - mX[startIndex];
if (xRange == 0) {
return mY[startIndex];
}
float tInRange = t - mX[startIndex];
float fraction = tInRange / xRange;
float startY = mY[startIndex];
float endY = mY[endIndex];
return startY + (fraction * (endY - startY));
}
}
/**
* An interpolator where the change flings forward and overshoots the last value
* then comes back.
* 先超过临界值 再慢慢回到临界值
*/
public class OvershootInterpolator extends BaseInterpolator implements NativeInterpolatorFactory {
private final float mTension;
public OvershootInterpolator() {
mTension = 2.0f;
}
/**
* @param tension Amount of overshoot. When tension equals 0.0f, there is
* no overshoot and the interpolator becomes a simple
* deceleration interpolator.
*/
public OvershootInterpolator(float tension) {
mTension = tension;
}
public float getInterpolation(float t) {
// _o(t) = t * t * ((tension + 1) * t + tension)
// o(t) = _o(t - 1) + 1
t -= 1.0f;
return t * t * ((mTension + 1) * t + mTension) + 1.0f;
}
}
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发布于：2021-08-30 20:55
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