Android中可以使用调色板Palette来获取图片中主要颜色，鲜艳或者柔和的颜色，或者其他的小色块Swatch。
Palette默认提取的颜色有：
Vibrant - 鲜艳色
Vibrant dark - 暗色
Vibrant light - 亮色
Muted - 柔和色
Muted dark - 暗色
Muted light - 亮色
Dominant - 主色
先上一张效果演示图片：
palette_swatch.png
1. 添加依赖库
可以直接在Project Structure中搜索库依赖：palette，选择com.android.support域名下的库即可。
compile 'com.android.support:appcompat-v7:25.1.0'
compile 'com.android.support:palette-v7:25.1.0'
2. 创建Palette对象
Palette对象的创建是一个耗时操作，应该使用异步方式或者在线程中调用同步方式创建。当前推荐使用Builder模式来创建Palette实例：
同步创建方式
// Synchronous
Palette p = Palette.from(bitmap).generate();
异步创建方式
// Asynchronous
Palette.from(bitmap).generate(new Palette.PaletteAsyncListener() {
@Override
public void onGenerated(Palette palette) {
// Use generated instance
}
});
3. Palette使用示例
这里使用异步方式来创建Palette调色板，在回调方法onGenerated(Palette)中可以得到Palette对象。Swatch小色块若使用XML方式定义则布局代码会很长，这里使用代码方式来创建布局样式。
private void setPaletteColor(TextView tv, int color) {
tv.setBackgroundColor(color);
tv.setText(ColorUtils.toRGBHexString(color));
tv.setTextColor(ColorUtils.parseBackgroundColor(color));
}
private void initPalette() {
Drawable drawable = mPictureIv.getDrawable();
Bitmap bitmap = drawableToBitmap(drawable);
// Synchronous
// mPalette = Palette.from(bitmap).generate();
// Asynchronous
Palette.from(bitmap).generate(new Palette.PaletteAsyncListener() {
@Override
public void onGenerated(Palette palette) {
// Use generated instance
int defaultColor = Color.parseColor("#b64242");
int mVibrantColor = palette.getVibrantColor(defaultColor);
int mDarkVibrantColor = palette.getDarkVibrantColor(defaultColor);
int mLightVibrantColor = palette.getLightVibrantColor(defaultColor);
int mMutedColor = palette.getMutedColor(defaultColor);
int mDarkMutedColor = palette.getDarkMutedColor(defaultColor);
int mLightMutedColor = palette.getLightMutedColor(defaultColor);
setPaletteColor(mVibrantColorTv, mVibrantColor);
setPaletteColor(mDarkVibrantColorTv, mDarkVibrantColor);
setPaletteColor(mLightVibrantColorTv, mLightVibrantColor);
setPaletteColor(mMutedColorTv, mMutedColor);
setPaletteColor(mDarkMutedColorTv, mDarkMutedColor);
setPaletteColor(mLightMutedColorTv, mLightMutedColor);
// dominant color (主色)
int mDominantColor = palette.getDominantColor(defaultColor);
setPaletteColor(mDominantColorTv, mDominantColor);
// Swatch - 色块 // 15种
List<Palette.Swatch> mSwatchList = palette.getSwatches();
Toast.makeText(MainActivity.this, "Swatch num: " + mSwatchList.size(), Toast.LENGTH_SHORT).show();
int index = -1;
LinearLayout mSwatchesContainer = null;
LinearLayout.LayoutParams params;
for (Palette.Swatch swatch : mSwatchList) {
int color = swatch.getRgb();
index++;
if (index % 3 == 0) {
mSwatchesContainer = new LinearLayout(getApplicationContext());
mSwatchesContainer.setOrientation(LinearLayout.HORIZONTAL);
params = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.MATCH_PARENT,
LinearLayout.LayoutParams.WRAP_CONTENT
);
params.topMargin = (int) DisplayUtils.dp2px(getApplicationContext(), 10);
mContainerLayout.addView(mSwatchesContainer, params); //
}
LinearLayout mSwatchContainer = new LinearLayout(getApplicationContext());
mSwatchContainer.setOrientation(LinearLayout.VERTICAL);
params = new LinearLayout.LayoutParams(0, LinearLayout.LayoutParams.WRAP_CONTENT);
params.weight = 1;
params.gravity = Gravity.CENTER;
if (mSwatchesContainer != null) {
mSwatchesContainer.addView(mSwatchContainer, params); //
}
TextView mColorTv = new TextView(getApplicationContext());
mColorTv.setTextSize(TypedValue.COMPLEX_UNIT_SP, 16);
setPaletteColor(mColorTv, color); //
mColorTv.setGravity(Gravity.CENTER);
params = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.MATCH_PARENT,
(int) DisplayUtils.dp2px(getApplicationContext(), 80)
);
params.gravity = Gravity.CENTER;
mSwatchContainer.addView(mColorTv, params); //
TextView mColorNameTv = new TextView(getApplicationContext());
mColorNameTv.setTextSize(TypedValue.COMPLEX_UNIT_SP, 16);
mColorNameTv.setText("Swatch " + index);
mColorNameTv.setGravity(Gravity.CENTER);
mColorNameTv.setTextColor(Color.parseColor("#333333"));
params = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT
);
params.gravity = Gravity.CENTER;
mSwatchContainer.addView(mColorNameTv, params);
}
}
});
}
Drawable转Bitmap的方法：
public static Bitmap drawableToBitmap(Drawable drawable) {
Bitmap bitmap = Bitmap.createBitmap(
drawable.getIntrinsicWidth(),
drawable.getIntrinsicHeight(),
drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565);
Canvas canvas = new Canvas(bitmap); // canvas -> bitmap
//canvas.setBitmap(bitmap);
drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());
drawable.draw(canvas); // drawable -> canvas
return bitmap; // drawable -> canvas -> bitmap
}
ColorUtils工具类中有如下几个方法：
public static String toRGBHexString(final int color) - 将int颜色值转成Hex颜色字符串(color -> #FF55FF)
public static int parseBackgroundColor(int color) - 通过分析背景色来决定当前文字的匹配颜色，使文字颜色自适应背景颜色
ColorUtils工具类是自己整理的用于颜色相关的操作方法，源代码如下：
public class ColorUtils {
public static int parseBackgroundColor2(int color) {
int counter = 0;
counter += Color.red(color) >= 128 ? 1 : 0;
counter += Color.green(color) >= 128 ? 1 : 0;
counter += Color.blue(color) >= 128 ? 1 : 0;
return counter >= 2 ? Color.BLACK : Color.WHITE;
}
// 通过分析背景色来决定当前文字的匹配颜色，使文字颜色自适应背景颜色
public static int parseBackgroundColor(int color) {
int red = Color.red(color);
int green = Color.green(color);
int blue = Color.blue(color);
if (red >= 128 && green >= 128 // 三选二
|| red >= 128 && blue >= 128
|| green >= 128 && blue >= 128) {
return Color.rgb(0, 0, 0);
}
return Color.rgb(255, 255, 255);
}
// #FF55FF => color
// int color = Color.parseColor("#b64242");
// color -> #FF55FF
public static String toRGBHexString(final int color) {
return toRGBHexString(Color.red(color), Color.green(color), Color.blue(color));
}
// (r,g,b) -> #FF55FF
public static String toRGBHexString(int red, int green, int blue) {
return toARGBHexString(-1, red, green, blue);
}
// default prefix: "#"
// (a,r,g,b) -> #FF55FF55
public static String toARGBHexString(int alpha, int red, int green, int blue) {
return toARGBHexString("#", alpha, red, green, blue);
}
public static String toARGBHexString(String prefix, int alpha, int red, int green, int blue) {
StringBuilder sb = new StringBuilder();
sb.append(prefix);
if (alpha != -1) {
String mAlphaStr = Integer.toHexString(alpha);
sb.append(mAlphaStr.length() == 1 ? "0" + mAlphaStr : mAlphaStr);
}
String mRedStr = Integer.toHexString(red);
sb.append(mRedStr.length() == 1 ? "0" + mRedStr : mRedStr);
String mGreenStr = Integer.toHexString(green);
sb.append(mGreenStr.length() == 1 ? "0" + mGreenStr : mGreenStr);
String mBlueStr = Integer.toHexString(blue);
sb.append(mBlueStr.length() == 1 ? "0" + mBlueStr : mBlueStr);
return sb.toString().toUpperCase();
}
}
4. 效果演示
palette_swatch.gif
5. Palette的UML类图关系
Swatch是定义在Palette中的内部类
palette_uml_class.png
