下面的类是对已经发布的答案的改进。这使得从位图中读取和创建ColorFilter更加容易。
使用示例：
ImageView imageView = ...;
Drawable drawable = imageView.getDrawable();
ColorFilter colorFilter = ColorFilterGenerator.from(drawable).to(Color.RED);
imageView.setColorFilter(colorFilter);
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ColorFilter;
import android.graphics.ColorMatrix;
import android.graphics.ColorMatrixColorFilter;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.PictureDrawable;
import android.widget.ImageView;
public class ColorFilterGenerator {
private ColorFilterGenerator() {
throw new AssertionError();
}
public static From from(Drawable drawable) {
return new From(drawableToBitmap(drawable));
}
public static From from(Bitmap bitmap) {
return new From(bitmap);
}
public static From from(int color) {
return new From(color);
}
private static final double DELTA_INDEX[] = {
0, 0.01, 0.02, 0.04, 0.05, 0.06, 0.07, 0.08, 0.1, 0.11, 0.12, 0.14, 0.15, 0.16, 0.17, 0.18,
0.20, 0.21, 0.22, 0.24, 0.25, 0.27, 0.28, 0.30, 0.32, 0.34, 0.36, 0.38, 0.40, 0.42, 0.44,
0.46, 0.48, 0.5, 0.53, 0.56, 0.59, 0.62, 0.65, 0.68, 0.71, 0.74, 0.77, 0.80, 0.83, 0.86, 0.89,
0.92, 0.95, 0.98, 1.0, 1.06, 1.12, 1.18, 1.24, 1.30, 1.36, 1.42, 1.48, 1.54, 1.60, 1.66, 1.72,
1.78, 1.84, 1.90, 1.96, 2.0, 2.12, 2.25, 2.37, 2.50, 2.62, 2.75, 2.87, 3.0, 3.2, 3.4, 3.6,
3.8, 4.0, 4.3, 4.7, 4.9, 5.0, 5.5, 6.0, 6.5, 6.8, 7.0, 7.3, 7.5, 7.8, 8.0, 8.4, 8.7, 9.0, 9.4,
9.6, 9.8, 10.0
};
public static void adjustHue(ColorMatrix cm, float value) {
value = cleanValue(value, 180f) / 180f * (float) Math.PI;
if (value == 0) {
return;
}
float cosVal = (float) Math.cos(value);
float sinVal = (float) Math.sin(value);
float lumR = 0.213f;
float lumG = 0.715f;
float lumB = 0.072f;
float[] mat = new float[]{
lumR + cosVal * (1 - lumR) + sinVal * (-lumR),
lumG + cosVal * (-lumG) + sinVal * (-lumG),
lumB + cosVal * (-lumB) + sinVal * (1 - lumB), 0, 0,
lumR + cosVal * (-lumR) + sinVal * (0.143f),
lumG + cosVal * (1 - lumG) + sinVal * (0.140f),
lumB + cosVal * (-lumB) + sinVal * (-0.283f), 0, 0,
lumR + cosVal * (-lumR) + sinVal * (-(1 - lumR)),
lumG + cosVal * (-lumG) + sinVal * (lumG),
lumB + cosVal * (1 - lumB) + sinVal * (lumB), 0, 0, 0f, 0f, 0f, 1f, 0f, 0f, 0f, 0f,
0f, 1f
};
cm.postConcat(new ColorMatrix(mat));
}
public static void adjustBrightness(ColorMatrix cm, float value) {
value = cleanValue(value, 100);
if (value == 0) {
return;
}
float[] mat = new float[]{
1, 0, 0, 0, value, 0, 1, 0, 0, value, 0, 0, 1, 0, value, 0, 0, 0, 1, 0, 0, 0, 0, 0,
1
};
cm.postConcat(new ColorMatrix(mat));
}
public static void adjustContrast(ColorMatrix cm, int value) {
value = (int) cleanValue(value, 100);
if (value == 0) {
return;
}
float x;
if (value < 0) {
x = 127 + value / 100 * 127;
} else {
x = value % 1;
if (x == 0) {
x = (float) DELTA_INDEX[value];
} else {
x = (float) DELTA_INDEX[(value << 0)] * (1 - x)
+ (float) DELTA_INDEX[(value << 0) + 1] * x;
}
x = x * 127 + 127;
}
float[] mat = new float[]{
x / 127, 0, 0, 0, 0.5f * (127 - x), 0, x / 127, 0, 0, 0.5f * (127 - x), 0, 0,
x / 127, 0, 0.5f * (127 - x), 0, 0, 0, 1, 0, 0, 0, 0, 0, 1
};
cm.postConcat(new ColorMatrix(mat));
}
public static void adjustSaturation(ColorMatrix cm, float value) {
value = cleanValue(value, 100);
if (value == 0) {
return;
}
float x = 1 + ((value > 0) ? 3 * value / 100 : value / 100);
float lumR = 0.3086f;
float lumG = 0.6094f;
float lumB = 0.0820f;
float[] mat = new float[]{
lumR * (1 - x) + x, lumG * (1 - x), lumB * (1 - x), 0, 0, lumR * (1 - x),
lumG * (1 - x) + x, lumB * (1 - x), 0, 0, lumR * (1 - x), lumG * (1 - x),
lumB * (1 - x) + x, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1
};
cm.postConcat(new ColorMatrix(mat));
}
private static float cleanValue(float p_val, float p_limit) {
return Math.min(p_limit, Math.max(-p_limit, p_val));
}
private static float[] getHsv(int color) {
float[] hsv = new float[3];
Color.RGBToHSV(Color.red(color), Color.green(color), Color.blue(color), hsv);
return hsv;
}
private static Bitmap drawableToBitmap(Drawable drawable) {
if (drawable instanceof BitmapDrawable) {
return ((BitmapDrawable) drawable).getBitmap();
} else if (drawable instanceof PictureDrawable) {
PictureDrawable pictureDrawable = (PictureDrawable) drawable;
Bitmap bitmap = Bitmap.createBitmap(pictureDrawable.getIntrinsicWidth(),
pictureDrawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
canvas.drawPicture(pictureDrawable.getPicture());
return bitmap;
}
int width = drawable.getIntrinsicWidth();
width = width > 0 ? width : 1;
int height = drawable.getIntrinsicHeight();
height = height > 0 ? height : 1;
Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
drawable.draw(canvas);
return bitmap;
}
private static int[] getAverageColorRGB(Bitmap bitmap) {
int width = bitmap.getWidth();
int height = bitmap.getHeight();
int size = width * height;
int[] pixels = new int[size];
int r, g, b;
r = g = b = 0;
bitmap.getPixels(pixels, 0, width, 0, 0, width, height);
for (int i = 0; i < size; i++) {
int pixelColor = pixels[i];
if (pixelColor == Color.TRANSPARENT) {
size--;
continue;
}
r += Color.red(pixelColor);
g += Color.green(pixelColor);
b += Color.blue(pixelColor);
}
r /= size;
g /= size;
b /= size;
return new int[]{
r, g, b
};
}
private static int getAverageColor(Bitmap bitmap) {
int[] rgb = getAverageColorRGB(bitmap);
return Color.argb(255, rgb[0], rgb[1], rgb[2]);
}
public static final class Builder {
int hue;
int contrast;
int brightness;
int saturation;
public Builder setHue(int hue) {
this.hue = hue;
return this;
}
public Builder setContrast(int contrast) {
this.contrast = contrast;
return this;
}
public Builder setBrightness(int brightness) {
this.brightness = brightness;
return this;
}
public Builder setSaturation(int saturation) {
this.saturation = saturation;
return this;
}
public ColorFilter build() {
ColorMatrix cm = new ColorMatrix();
adjustHue(cm, hue);
adjustContrast(cm, contrast);
adjustBrightness(cm, brightness);
adjustSaturation(cm, saturation);
return new ColorMatrixColorFilter(cm);
}
}
public static final class From {
final int oldColor;
private From(Bitmap bitmap) {
oldColor = getAverageColor(bitmap);
}
private From(int oldColor) {
this.oldColor = oldColor;
}
public ColorFilter to(int newColor) {
float[] hsv1 = getHsv(oldColor);
float[] hsv2 = getHsv(newColor);
int hue = (int) (hsv2[0] - hsv1[0]);
int saturation = (int) (hsv2[1] - hsv1[1]);
int brightness = (int) (hsv2[2] - hsv1[2]);
return new ColorFilterGenerator.Builder()
.setHue(hue)
.setSaturation(saturation)
.setBrightness(brightness)
.build();
}
}
}
变成 
