android使用方法---圖片的高斯模糊
今天這裡給大家介紹兩個高斯模糊的方法和一個優化的方法
1,RenderScript
RenderScript是在Android上的高效能執行密集型運算的框架,RenderScript主要用於資料平行計算,尤其對影象處理、攝影分析和計算機視覺特別有用。RenderScript是在Android3.0(API 11)引入的。而Android圖片高斯模糊處理,通常也是用這個庫來完成。它提供了我們Java層呼叫的API,實際上是在c/c++ 層來處理的,所以它的效率和效能通常是最高的。要使用RenderScript完成圖片高斯模糊只需要以下幾步:
(1) 初始化一個RenderScript Context:RenderScript 上下文環境通過create(Context)方法來建立,它保證RenderScript的使用並且提供一個控制後續所有RenderScript物件(如:ScriptIntrinsicBlur、Allocation等)生命週期的物件。
(2)通過Script至少建立一個Allocation:一個Allocation是提供儲存大量可變資料的RenderScript 物件。在核心中,Allocation作為輸入和輸出,在核心中通過rsGetElementAt_type ()和rsSetElementAt_type()方法來訪問Allocation當script全域性繫結的時候。使用createFromBitmap 和createTyped來建立Allocation。
(3)建立ScriptIntrinsic:它內建了RenderScript 的一些通用操作,如高斯模糊、扭曲變換、影象混合等等,更多的操作請看ScriptIntrinsic的子類,本文要用的高斯模糊處理就是用的它的子類ScriptIntrinsicBlur。
(4)填充資料到Allocations:除了使用方法createFromBitmap建立的Allocation外,其它的第一次建立時都是填充的空資料。
(5) 設定模糊半徑:設定一個模糊的半徑,其值為 0-25。
(6) 啟動核心,呼叫方法處理:呼叫forEach 方法模糊處理。
(7) 從Allocation 中拷貝資料:為了能在Java層訪問Allocation的資料,用Allocation其中一個copy方法來拷貝資料。
(8) 銷燬RenderScript物件:可以用destroy方法來銷燬RenderScript物件或者讓它可以被垃圾回收,destroy 之後,就能在用它控制的RenderScript物件了(比如在銷燬了之後,再呼叫ScriptIntrinsic或者Allocation的方法是要拋異常的)。
程式碼
/**
* RenderScript
* @param context
* @param source
* @param radius
* @return
*/
private static Bitmap rsBlur(Context context, Bitmap source, int radius){
Bitmap inputBmp = source;
//(1)
RenderScript renderScript = RenderScript.create(context);
Log.i("====","scale size:"+inputBmp.getWidth()+"*"+inputBmp.getHeight());
// Allocate memory for Renderscript to work with
//(2)
final Allocation input = Allocation.createFromBitmap(renderScript,inputBmp);
final Allocation output = Allocation.createTyped(renderScript,input.getType());
//(3)
// Load up an instance of the specific script that we want to use.
ScriptIntrinsicBlur scriptIntrinsicBlur = ScriptIntrinsicBlur.create(renderScript, Element.U8_4(renderScript));
//(4)
scriptIntrinsicBlur.setInput(input);
//(5)
// Set the blur radius
scriptIntrinsicBlur.setRadius(radius);
//(6)
// Start the ScriptIntrinisicBlur
scriptIntrinsicBlur.forEach(output);
//(7)
// Copy the output to the blurred bitmap
output.copyTo(inputBmp);
//(8)
renderScript.destroy();
return inputBmp;
}
但是這隻對API17以上的好用,因為很多方法是API17以後加上去的
你需要在build.gradle檔案中新增那兩行加粗的程式碼:
android {
compileSdkVersion 23
buildToolsVersion "23.0.3"
defaultConfig {
minSdkVersion 8
targetSdkVersion 19
renderscriptTargetApi 18
renderscriptSupportModeEnabled true
}
}
這裡其實就是使用相容包,但還是有問題
- 雖然RenderScript效率不錯,但是處理尺寸大一點的圖片還是達不到16ms每一幀,需要優化
- 雖然結局了相容問題,但是upport.v8.renderscript有160k,對於現在提倡APP瘦身來說是不好的。
然後是fastBlur
/**
* fastBlur
* @param sentBitmap
* @param scale
* @param radius
* @return
*/
private static Bitmap fastBlur(Bitmap sentBitmap, float scale, int radius) {
int width = Math.round(sentBitmap.getWidth() * scale);
int height = Math.round(sentBitmap.getHeight() * scale);
sentBitmap = Bitmap.createScaledBitmap(sentBitmap, width, height, false);
Bitmap bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);
if (radius < 1) {
return (null);
}
int w = bitmap.getWidth();
int h = bitmap.getHeight();
int[] pix = new int[w * h];
Log.e("pix", w + " " + h + " " + pix.length);
bitmap.getPixels(pix, 0, w, 0, 0, w, h);
int wm = w - 1;
int hm = h - 1;
int wh = w * h;
int div = radius + radius + 1;
int r[] = new int[wh];
int g[] = new int[wh];
int b[] = new int[wh];
int rsum, gsum, bsum, x, y, i, p, yp, yi, yw;
int vmin[] = new int[Math.max(w, h)];
int divsum = (div + 1) >> 1;
divsum *= divsum;
int dv[] = new int[256 * divsum];
for (i = 0; i < 256 * divsum; i++) {
dv[i] = (i / divsum);
}
yw = yi = 0;
int[][] stack = new int[div][3];
int stackpointer;
int stackstart;
int[] sir;
int rbs;
int r1 = radius + 1;
int routsum, goutsum, boutsum;
int rinsum, ginsum, binsum;
for (y = 0; y < h; y++) {
rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
for (i = -radius; i <= radius; i++) {
p = pix[yi + Math.min(wm, Math.max(i, 0))];
sir = stack[i + radius];
sir[0] = (p & 0xff0000) >> 16;
sir[1] = (p & 0x00ff00) >> 8;
sir[2] = (p & 0x0000ff);
rbs = r1 - Math.abs(i);
rsum += sir[0] * rbs;
gsum += sir[1] * rbs;
bsum += sir[2] * rbs;
if (i > 0) {
rinsum += sir[0];
ginsum += sir[1];
binsum += sir[2];
} else {
routsum += sir[0];
goutsum += sir[1];
boutsum += sir[2];
}
}
stackpointer = radius;
for (x = 0; x < w; x++) {
r[yi] = dv[rsum];
g[yi] = dv[gsum];
b[yi] = dv[bsum];
rsum -= routsum;
gsum -= goutsum;
bsum -= boutsum;
stackstart = stackpointer - radius + div;
sir = stack[stackstart % div];
routsum -= sir[0];
goutsum -= sir[1];
boutsum -= sir[2];
if (y == 0) {
vmin[x] = Math.min(x + radius + 1, wm);
}
p = pix[yw + vmin[x]];
sir[0] = (p & 0xff0000) >> 16;
sir[1] = (p & 0x00ff00) >> 8;
sir[2] = (p & 0x0000ff);
rinsum += sir[0];
ginsum += sir[1];
binsum += sir[2];
rsum += rinsum;
gsum += ginsum;
bsum += binsum;
stackpointer = (stackpointer + 1) % div;
sir = stack[(stackpointer) % div];
routsum += sir[0];
goutsum += sir[1];
boutsum += sir[2];
rinsum -= sir[0];
ginsum -= sir[1];
binsum -= sir[2];
yi++;
}
yw += w;
}
for (x = 0; x < w; x++) {
rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
yp = -radius * w;
for (i = -radius; i <= radius; i++) {
yi = Math.max(0, yp) + x;
sir = stack[i + radius];
sir[0] = r[yi];
sir[1] = g[yi];
sir[2] = b[yi];
rbs = r1 - Math.abs(i);
rsum += r[yi] * rbs;
gsum += g[yi] * rbs;
bsum += b[yi] * rbs;
if (i > 0) {
rinsum += sir[0];
ginsum += sir[1];
binsum += sir[2];
} else {
routsum += sir[0];
goutsum += sir[1];
boutsum += sir[2];
}
if (i < hm) {
yp += w;
}
}
yi = x;
stackpointer = radius;
for (y = 0; y < h; y++) {
// Preserve alpha channel: ( 0xff000000 & pix[yi] )
pix[yi] = ( 0xff000000 & pix[yi] ) | ( dv[rsum] << 16 ) | ( dv[gsum] << 8 ) | dv[bsum];
rsum -= routsum;
gsum -= goutsum;
bsum -= boutsum;
stackstart = stackpointer - radius + div;
sir = stack[stackstart % div];
routsum -= sir[0];
goutsum -= sir[1];
boutsum -= sir[2];
if (x == 0) {
vmin[y] = Math.min(y + r1, hm) * w;
}
p = x + vmin[y];
sir[0] = r[p];
sir[1] = g[p];
sir[2] = b[p];
rinsum += sir[0];
ginsum += sir[1];
binsum += sir[2];
rsum += rinsum;
gsum += ginsum;
bsum += binsum;
stackpointer = (stackpointer + 1) % div;
sir = stack[stackpointer];
routsum += sir[0];
goutsum += sir[1];
boutsum += sir[2];
rinsum -= sir[0];
ginsum -= sir[1];
binsum -= sir[2];
yi += w;
}
}
Log.e("pix", w + " " + h + " " + pix.length);
bitmap.setPixels(pix, 0, w, 0, 0, w, h);
return (bitmap);
}
使用這種方式不會有相容性問題,也不會引入jar包導致APK變大。但是這種方法的效率是非常低的,想想也知道,因為是在Java 層處理,速度當然慢。測試了一張800 x 450 的圖片,RenderScript平均25 ms 左右,fastBlur平均310ms 左右,相當於差了10倍。還有就是使用這種方式是把圖片全部載入到記憶體,如果圖片較大,容易導致OOM。
可以看到方法中的這兩句話
int width = Math.round(sentBitmap.getWidth() * scale);
int height = Math.round(sentBitmap.getHeight() * scale);
sentBitmap = Bitmap.createScaledBitmap(sentBitmap, width, height, false);
就是對這個的優化,其實就是先縮小然後進行模糊,看到這裡你就會想到RenderScript也應該可以 這樣那麼優化的程式碼如下
private static Bitmap rsBlur1(Context context,Bitmap source,int radius,float scale){
Log.i("===","origin size:"+source.getWidth()+"*"+source.getHeight());
int width = Math.round(source.getWidth() * scale);
int height = Math.round(source.getHeight() * scale);
Bitmap inputBmp = Bitmap.createScaledBitmap(source,width,height,false);
RenderScript renderScript = RenderScript.create(context);
Log.i("===","scale size:"+inputBmp.getWidth()+"*"+inputBmp.getHeight());
// Allocate memory for Renderscript to work with
final Allocation input = Allocation.createFromBitmap(renderScript,inputBmp);
final Allocation output = Allocation.createTyped(renderScript,input.getType());
// Load up an instance of the specific script that we want to use.
ScriptIntrinsicBlur scriptIntrinsicBlur = ScriptIntrinsicBlur.create(renderScript, Element.U8_4(renderScript));
scriptIntrinsicBlur.setInput(input);
// Set the blur radius
scriptIntrinsicBlur.setRadius(radius);
// Start the ScriptIntrinisicBlur
scriptIntrinsicBlur.forEach(output);
// Copy the output to the blurred bitmap
output.copyTo(inputBmp);
renderScript.destroy();
return inputBmp;
}
程式碼優化就這樣了,咱們再說說使用吧
RenderScript
- 使用程式碼少,優化方便,但是不相容api17以下的
- 使用相容包解決一的問題但增大了app的大小(160k左右)
fastBlur
- 不存在相容問題。
- 但是效率低,容易產生OOM
所以解決方案
一. 就是判斷API版本,17以上正常使用,17以下用fastBlur
二. 就是能忍受相容包只用RenderScript,加上相容包
當然都最好先縮小再模糊,但是不要設的比例過於小會出現邊框黑
(0-1)scale最好設定在0.6以上。
還有radius的範圍是0-25;