Bitmap 详解开发者社区

Bitmap 详解

<br />inSampleSize的值必须大于1时才会有效果，且采样率同时作用于宽和高；
当inSampleSize=1时，采样后的图片为图片的原始大小
当inSampleSize=2时，采样后的图片的宽高均为原始图片宽高的1/2，这时像素为原始图片的1/4,占用内存也为原始图片的1/4;
inSampleSize的取值应该总为2的整数倍，否则会向下取整，取一个最接近2的整数倍，比如inSampleSize=3时，系统会取inSampleSize=2
假设一张1024*1024，模式为ARGB_8888的图片,inSampleSize=2，原始占用内存大小是4MB，采样后的图片占用内存大小就是(1024/2) * (1024/2 )* 4 = 1MB

<br />将BitmapFacpry.Options的inJustDecodeBounds参数设为true并加载图片当inJustDecodeBounds为true时，执行decodeXXX方法时，BitmapFactory只会解析图片的原始宽高信息，并不会真正的加载图片
从BitmapFacpry.Options取出图片的原始宽高(outWidth,outHeight)信息
选取合适的采样率
将BitmapFacpry.Options的inSampleSize参数设为false并重新加载图片

<br />if (!bmp.isRecycle()) {
    bmp.recycle(); //回收图片所占的内存
    bitmap = null;
    system.gc(); //提醒系统及时回收

<br />    Bitmap bitmap = null;
    try {
        // 实例化Bitmap
        bitmap = BitmapFactory.decodeFile(path);
    } catch (OutOfMemoryError e) {
    if (bitmap == null) {
        return defaultBitmapMap; // 如果实例化失败 返回默认的Bitmap对象

<br />public Bitmap scaleMatrixImage(Bitmap oldbitmap, float scaleWidth, float scaleHeight) {
    Matrix matrix = new Matrix();
    matrix.postScale(scaleWidth,scaleHeight);// 放大缩小比例
    Bitmap ScaleBitmap = Bitmap.createBitmap(oldbitmap, 0, 0, oldbitmap.getWidth(), oldbitmap.getHeight(), matrix, true);
    return ScaleBitmap;

<br />public Bitmap cutImage(Bitmap bitmap, int reqWidth, int reqHeight) {
    Bitmap newBitmap = null;
    if (bitmap.getWidth() &gt; reqWidth &amp;&amp; bitmap.getHeight() &gt; reqHeight) {
        bitmap = Bitmap.createBitmap(bitmap, 0, 0, reqWidth, reqHeight);
    } else {
        bitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight());
    return bitmap;

<br />    public void savePic(Bitmap bitmap,String path) {
        File file = new File(path);
        FileOutputStream fileOutputStream = null;
        try {
            file.createNewFile();
            fileOutputStream = new FileOutputStream(file);
//以质量为100%的方式压缩图像，但是图片大小不变
            bitmap.compress(Bitmap.CompressFormat.PNG, 100, fileOutputStream);
            fileOutputStream.flush();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (fileOutputStream != null) {
                    fileOutputStream.close();
            } catch (IOException e) {
                e.printStackTrace();

<br />Resources res = getResources();
Bitmap bmp = BitmapFactory.decodeResource(res, R.drawable.ic_drawable);

<br />Resource res = gerResource();
Drawable drawable = res.getDrawable(R.drawable.ic_drawable);//获取drawable
BitmapDrawable bd = (BitmapDrawable) drawable;
Bitmap bm = bd.getBitmap();

<br />    public static Bitmap drawableToBitmap(Drawable drawable) {
        int w = drawable.getIntrinsicWidth();
        int h = drawable.getIntrinsicHeight();
        System.out.println("Drawable转Bitmap");
        Bitmap.Config config =
                drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
                        : Bitmap.Config.RGB_565;
        Bitmap bitmap = Bitmap.createBitmap(w, h, config);
        //注意，下面三行代码要用到，否则在View或者SurfaceView里的canvas.drawBitmap会看不到图
        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, w, h);
        drawable.draw(canvas);
        return bitmap;

<br />public static byte[] getBytes(Bitmap bitmap){
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);
        return baos.toByteArray();

<br />    public static Bitmap Bytes2Bimap(byte[] b) {
        if (b.length != 0) {
            return BitmapFactory.decodeByteArray(b, 0, b.length);
        } else {
            return null;

<br />public static Bitmap tintBitmap(Bitmap inBitmap , int tintColor) {
    if (inBitmap == null) {
        return null;
    Bitmap outBitmap = Bitmap.createBitmap (inBitmap.getWidth(), inBitmap.getHeight() , inBitmap.getConfig());
    Canvas canvas = new Canvas(outBitmap);
    Paint paint = new Paint();
    paint.setColorFilter( new PorterDuffColorFilter(tintColor, PorterDuff.Mode.SRC_IN)) ;
    canvas.drawBitmap(inBitmap , 0, 0, paint) ;
    return outBitmap ;

<br />/**
 * 设置模糊背景
private void setBlurBackground(int pos) {
    //获取轮播图索引pos处的图片
    Integer integer = pagerAdapter.getBitmapHashMap().get(pos);
    Resources res = this.getResources();
    Bitmap bitmap= BitmapFactory.decodeResource(res, integer);
    //压缩图片
    final Bitmap image = BitmapUtils.compressImage(bitmap);
    if (bitmap != null) {
        if (mBlurRunnable != null) {
            mIvBlurBackground.removeCallbacks(mBlurRunnable);
        mBlurRunnable = new Runnable() {
            @Override
            public void run() {
                //压缩图片，宽高缩放
                Bitmap blurBitmap = BlurBitmapUtils.getBlurBitmap(
                        mIvBlurBackground.getContext(), image, 15);
                ViewSwitchUtils.startSwitchBackgroundAnim(mIvBlurBackground, blurBitmap);
        mIvBlurBackground.postDelayed(mBlurRunnable, 100);

<br />/**
 * RenderScript图片高斯模糊
public class BlurBitmapUtils {
     * 建议模糊度(在0.0到25.0之间)
    private static final int SCALED_WIDTH = 100;
    private static final int SCALED_HEIGHT = 100;
     * 得到模糊后的bitmap
     * @param context 上下文
     * @param bitmap bitmap
     * @param radius 半径
     * @return
    public static Bitmap getBlurBitmap(Context context, Bitmap bitmap, int radius) {
        // 将缩小后的图片做为预渲染的图片。
        Bitmap inputBitmap = Bitmap.createScaledBitmap(bitmap, SCALED_WIDTH, SCALED_HEIGHT, false);
        // 创建一张渲染后的输出图片。
        Bitmap outputBitmap = Bitmap.createBitmap(inputBitmap);
        // 创建RenderScript内核对象
        RenderScript rs = RenderScript.create(context);
        // 创建一个模糊效果的RenderScript的工具对象
        ScriptIntrinsicBlur blurScript = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
        // 由于RenderScript并没有使用VM来分配内存,所以需要使用Allocation类来创建和分配内存空间。
        // 创建Allocation对象的时候其实内存是空的,需要使用copyTo()将数据填充进去。
        Allocation tmpIn = Allocation.createFromBitmap(rs, inputBitmap);
        Allocation tmpOut = Allocation.createFromBitmap(rs, outputBitmap);
        // 设置渲染的模糊程度, 25f是最大模糊度
        blurScript.setRadius(radius);
        // 设置blurScript对象的输入内存
        blurScript.setInput(tmpIn);
        // 将输出数据保存到输出内存中
        blurScript.forEach(tmpOut);
        // 将数据填充到Allocation中
        tmpOut.copyTo(outputBitmap);
        return outputBitmap;

<br />/**
 * 图片背景切换动画帮助类，设置View动画
public class ViewSwitchUtils {
    static void startSwitchBackgroundAnim(ImageView view, Bitmap bitmap) {
        Drawable oldDrawable = view.getDrawable();
        Drawable oldBitmapDrawable ;
        TransitionDrawable oldTransitionDrawable = null;
        if (oldDrawable instanceof TransitionDrawable) {
            oldTransitionDrawable = (TransitionDrawable) oldDrawable;
            oldBitmapDrawable = oldTransitionDrawable.findDrawableByLayerId(oldTransitionDrawable.getId(1));
        } else if (oldDrawable instanceof BitmapDrawable) {
            oldBitmapDrawable = oldDrawable;
        } else {
            oldBitmapDrawable = new ColorDrawable(0xffc2c2c2);
        if (oldTransitionDrawable == null) {
            oldTransitionDrawable = new TransitionDrawable(new Drawable[]{oldBitmapDrawable, new BitmapDrawable(bitmap)});
            oldTransitionDrawable.setId(0, 0);
            oldTransitionDrawable.setId(1, 1);
            oldTransitionDrawable.setCrossFadeEnabled(true);
            view.setImageDrawable(oldTransitionDrawable);
        } else {
            oldTransitionDrawable.setDrawableByLayerId(oldTransitionDrawable.getId(0), oldBitmapDrawable);
            oldTransitionDrawable.setDrawableByLayerId(oldTransitionDrawable.getId(1), new BitmapDrawable(bitmap));
        oldTransitionDrawable.startTransition(1000);

Bitmap 详解

Bitmap 详解

Bitmap 与 Drawable 区别

计算一张图片的大小

Bitmap的基本加载

高效的加载Bitmap

使用Bitmap时的一些注意事项

Bitmap recycler 相关

Bitmap一些其他用法

Bitmap与Drawable相互转换

Drawable 转换成 Bitmap

Bitmap 转换成 Drawable

Bitmap 转换成 byte[]

byte[] 转化成 Bitmap

Android 改变bitmap内部颜色

高斯模糊