/*
* Copyright 2014 Soichiro Kashima
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.github.ksoichiro.android.observablescrollview;
import android.os.Build;
import android.view.View;
import android.view.ViewTreeObserver;
/**
* Utilities for creating scrolling effects.
*/
public final class ScrollUtils {
private ScrollUtils() {
}
/**
* Return a float value within the range.
* This is just a wrapper for Math.min() and Math.max().
* This may be useful if you feel it confusing ("Which is min and which is max?").
*
* @param value the target value
* @param minValue minimum value. If value is less than this, minValue will be returned
* @param maxValue maximum value. If value is greater than this, maxValue will be returned
* @return float value limited to the range
*/
public static float getFloat(final float value, final float minValue, final float maxValue) {
return Math.min(maxValue, Math.max(minValue, value));
}
/**
* Create a color integer value with specified alpha.
* This may be useful to change alpha value of background color.
*
* @param alpha alpha value from 0.0f to 1.0f.
* @param baseColor base color. alpha value will be ignored.
* @return a color with alpha made from base color
*/
public static int getColorWithAlpha(float alpha, int baseColor) {
int a = Math.min(255, Math.max(0, (int) (alpha * 255))) << 24;
int rgb = 0x00ffffff & baseColor;
return a + rgb;
}
/**
* Add an OnGlobalLayoutListener for the view.
* This is just a convenience method for using {@code ViewTreeObserver.OnGlobalLayoutListener()}.
* This also handles removing listener when onGlobalLayout is called.
*
* @param view the target view to add global layout listener
* @param runnable runnable to be executed after the view is laid out
*/
public static void addOnGlobalLayoutListener(final View view, final Runnable runnable) {
ViewTreeObserver vto = view.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
view.getViewTreeObserver().removeGlobalOnLayoutListener(this);
} else {
view.getViewTreeObserver().removeOnGlobalLayoutListener(this);
}
runnable.run();
}
});
}
/**
* Mix two colors.
* {@code toColor} will be {@code toAlpha/1} percent,
* and {@code fromColor} will be {@code (1-toAlpha)/1} percent.
*
* @param fromColor first color to be mixed
* @param toColor second color to be mixed
* @param toAlpha alpha value of toColor, 0.0f to 1.0f.
* @return mixed color value in ARGB. Alpha is fixed value (255).
*/
public static int mixColors(int fromColor, int toColor, float toAlpha) {
float[] fromCmyk = ScrollUtils.cmykFromRgb(fromColor);
float[] toCmyk = ScrollUtils.cmykFromRgb(toColor);
float[] result = new float[4];
for (int i = 0; i < 4; i++) {
result[i] = Math.min(1, fromCmyk[i] * (1 - toAlpha) + toCmyk[i] * toAlpha);
}
return 0xff000000 + (0x00ffffff & ScrollUtils.rgbFromCmyk(result));
}
/**
* Convert RGB color to CMYK color.
*
* @param rgbColor target color
* @return CMYK array
*/
public static float[] cmykFromRgb(int rgbColor) {
int red = (0xff0000 & rgbColor) >> 16;
int green = (0xff00 & rgbColor) >> 8;
int blue = (0xff & rgbColor);
float black = Math.min(1.0f - red / 255.0f, Math.min(1.0f - green / 255.0f, 1.0f - blue / 255.0f));
float cyan = 1.0f;
float magenta = 1.0f;
float yellow = 1.0f;
if (black != 1.0f) {
// black 1.0 causes zero divide
cyan = (1.0f - (red / 255.0f) - black) / (1.0f - black);
magenta = (1.0f - (green / 255.0f) - black) / (1.0f - black);
yellow = (1.0f - (blue / 255.0f) - black) / (1.0f - black);
}
return new float[]{cyan, magenta, yellow, black};
}
/**
* Convert CYMK color to RGB color.
* This method doesn't check f cmyk is not null or have 4 elements in array.
*
* @param cmyk target CYMK color. Each value should be between 0.0f to 1.0f,
* and should be set in this order: cyan, magenta, yellow, black.
* @return ARGB color. Alpha is fixed value (255).
*/
public static int rgbFromCmyk(float[] cmyk) {
float cyan = cmyk[0];
float magenta = cmyk[1];
float yellow = cmyk[2];
float black = cmyk[3];
int red = (int) ((1.0f - Math.min(1.0f, cyan * (1.0f - black) + black)) * 255);
int green = (int) ((1.0f - Math.min(1.0f, magenta * (1.0f - black) + black)) * 255);
int blue = (int) ((1.0f - Math.min(1.0f, yellow * (1.0f - black) + black)) * 255);
return ((0xff & red) << 16) + ((0xff & green) << 8) + (0xff & blue);
}
}