編輯：關於android開發
實現了一個官方的demo：bitmap-plasma（水波紋）
源代碼就在samples文件夾下，可以自己去找。
界面：
建立項目的步驟和配置環境不明白的可以去看：http://www.cnblogs.com/jycboy/p/5393727.html
一、activity代碼：
package example.user.plasmatest;
import android.os.Bundle;
import android.app.Activity;
import android.os.Bundle;
import android.content.Context;
import android.view.View;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.view.Display;
import android.view.WindowManager;
public class MainActivity extends Activity
{
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
Display display = getWindowManager().getDefaultDisplay();
setContentView(new PlasmaView(this, display.getWidth(), display.getHeight()));
}
/* load our native library */
static {
System.loadLibrary("plasma");
}
}
class PlasmaView extends View {
private Bitmap mBitmap;
private long mStartTime;
/* implementend by libplasma.so */
private static native void renderPlasma(Bitmap bitmap, long time_ms);
public PlasmaView(Context context, int width, int height) {
super(context);
mBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
mStartTime = System.currentTimeMillis();
}
@Override
protected void onDraw(Canvas canvas) {
//canvas.drawColor(0xFFCCCCCC);
renderPlasma(mBitmap, System.currentTimeMillis() - mStartTime);
canvas.drawBitmap(mBitmap, 0, 0, null);
// force a redraw, with a different time-based pattern.
invalidate();
}
}
make project下，利用javah創建jni目錄、.h頭文件
在jni目錄下創建c代碼：
plasma.c:
/*
* Copyright (C) 2010 The Android Open Source Project
*
* 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.
*/
#include "example_user_plasmatest_PlasmaView.h"
#include <jni.h>
#include <time.h>
#include <android/log.h>
#include <android/bitmap.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define LOG_TAG "libplasma"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)
/* Set to 1 to enable debug log traces. */
#define DEBUG 0
/* Set to 1 to optimize memory stores when generating plasma. */
#define OPTIMIZE_WRITES 1
/* Return current time in milliseconds */
static double now_ms(void)
{
struct timeval tv;
gettimeofday(&tv, NULL);
return tv.tv_sec*1000. + tv.tv_usec/1000.;
}
/* We're going to perform computations for every pixel of the target
* bitmap. floating-point operations are very slow on ARMv5, and not
* too bad on ARMv7 with the exception of trigonometric functions.
*
* For better performance on all platforms, we're going to use fixed-point
* arithmetic and all kinds of tricks
*/
typedef int32_t Fixed;
#define FIXED_BITS 16
#define FIXED_ONE (1 << FIXED_BITS)
#define FIXED_AVERAGE(x,y) (((x) + (y)) >> 1)
#define FIXED_FROM_INT(x) ((x) << FIXED_BITS)
#define FIXED_TO_INT(x) ((x) >> FIXED_BITS)
#define FIXED_FROM_FLOAT(x) ((Fixed)((x)*FIXED_ONE))
#define FIXED_TO_FLOAT(x) ((x)/(1.*FIXED_ONE))
#define FIXED_MUL(x,y) (((int64_t)(x) * (y)) >> FIXED_BITS)
#define FIXED_DIV(x,y) (((int64_t)(x) * FIXED_ONE) / (y))
#define FIXED_DIV2(x) ((x) >> 1)
#define FIXED_AVERAGE(x,y) (((x) + (y)) >> 1)
#define FIXED_FRAC(x) ((x) & ((1 << FIXED_BITS)-1))
#define FIXED_TRUNC(x) ((x) & ~((1 << FIXED_BITS)-1))
#define FIXED_FROM_INT_FLOAT(x,f) (Fixed)((x)*(FIXED_ONE*(f)))
typedef int32_t Angle;
#define ANGLE_BITS 9
#if ANGLE_BITS < 8
# error ANGLE_BITS must be at least 8
#endif
#define ANGLE_2PI (1 << ANGLE_BITS)
#define ANGLE_PI (1 << (ANGLE_BITS-1))
#define ANGLE_PI2 (1 << (ANGLE_BITS-2))
#define ANGLE_PI4 (1 << (ANGLE_BITS-3))
#define ANGLE_FROM_FLOAT(x) (Angle)((x)*ANGLE_PI/M_PI)
#define ANGLE_TO_FLOAT(x) ((x)*M_PI/ANGLE_PI)
#if ANGLE_BITS <= FIXED_BITS
# define ANGLE_FROM_FIXED(x) (Angle)((x) >> (FIXED_BITS - ANGLE_BITS))
# define ANGLE_TO_FIXED(x) (Fixed)((x) << (FIXED_BITS - ANGLE_BITS))
#else
# define ANGLE_FROM_FIXED(x) (Angle)((x) << (ANGLE_BITS - FIXED_BITS))
# define ANGLE_TO_FIXED(x) (Fixed)((x) >> (ANGLE_BITS - FIXED_BITS))
#endif
static Fixed angle_sin_tab[ANGLE_2PI+1];
static void init_angles(void)
{
int nn;
for (nn = 0; nn < ANGLE_2PI+1; nn++) {
double radians = nn*M_PI/ANGLE_PI;
angle_sin_tab[nn] = FIXED_FROM_FLOAT(sin(radians));
}
}
static __inline__ Fixed angle_sin( Angle a )
{
return angle_sin_tab[(uint32_t)a & (ANGLE_2PI-1)];
}
static __inline__ Fixed angle_cos( Angle a )
{
return angle_sin(a + ANGLE_PI2);
}
static __inline__ Fixed fixed_sin( Fixed f )
{
return angle_sin(ANGLE_FROM_FIXED(f));
}
static __inline__ Fixed fixed_cos( Fixed f )
{
return angle_cos(ANGLE_FROM_FIXED(f));
}
/* Color palette used for rendering the plasma */
#define PALETTE_BITS 8
#define PALETTE_SIZE (1 << PALETTE_BITS)
#if PALETTE_BITS > FIXED_BITS
# error PALETTE_BITS must be smaller than FIXED_BITS
#endif
static uint16_t palette[PALETTE_SIZE];
static uint16_t make565(int red, int green, int blue)
{
return (uint16_t)( ((red << 8) & 0xf800) |
((green << 2) & 0x03e0) |
((blue >> 3) & 0x001f) );
}
static void init_palette(void)
{
int nn, mm = 0;
/* fun with colors */
for (nn = 0; nn < PALETTE_SIZE/4; nn++) {
int jj = (nn-mm)*4*255/PALETTE_SIZE;
palette[nn] = make565(255, jj, 255-jj);
}
for ( mm = nn; nn < PALETTE_SIZE/2; nn++ ) {
int jj = (nn-mm)*4*255/PALETTE_SIZE;
palette[nn] = make565(255-jj, 255, jj);
}
for ( mm = nn; nn < PALETTE_SIZE*3/4; nn++ ) {
int jj = (nn-mm)*4*255/PALETTE_SIZE;
palette[nn] = make565(0, 255-jj, 255);
}
for ( mm = nn; nn < PALETTE_SIZE; nn++ ) {
int jj = (nn-mm)*4*255/PALETTE_SIZE;
palette[nn] = make565(jj, 0, 255);
}
}
static __inline__ uint16_t palette_from_fixed( Fixed x )
{
if (x < 0) x = -x;
if (x >= FIXED_ONE) x = FIXED_ONE-1;
int idx = FIXED_FRAC(x) >> (FIXED_BITS - PALETTE_BITS);
return palette[idx & (PALETTE_SIZE-1)];
}
/* Angles expressed as fixed point radians */
static void init_tables(void)
{
init_palette();
init_angles();
}
static void fill_plasma( AndroidBitmapInfo* info, void* pixels, double t )
{
Fixed yt1 = FIXED_FROM_FLOAT(t/1230.);
Fixed yt2 = yt1;
Fixed xt10 = FIXED_FROM_FLOAT(t/3000.);
Fixed xt20 = xt10;
#define YT1_INCR FIXED_FROM_FLOAT(1/100.)
#define YT2_INCR FIXED_FROM_FLOAT(1/163.)
int yy;
for (yy = 0; yy < info->height; yy++) {
uint16_t* line = (uint16_t*)pixels;
Fixed base = fixed_sin(yt1) + fixed_sin(yt2);
Fixed xt1 = xt10;
Fixed xt2 = xt20;
yt1 += YT1_INCR;
yt2 += YT2_INCR;
#define XT1_INCR FIXED_FROM_FLOAT(1/173.)
#define XT2_INCR FIXED_FROM_FLOAT(1/242.)
#if OPTIMIZE_WRITES
/* optimize memory writes by generating one aligned 32-bit store
* for every pair of pixels.
*/
uint16_t* line_end = line + info->width;
if (line < line_end) {
if (((uint32_t)(uintptr_t)line & 3) != 0) {
Fixed ii = base + fixed_sin(xt1) + fixed_sin(xt2);
xt1 += XT1_INCR;
xt2 += XT2_INCR;
line[0] = palette_from_fixed(ii >> 2);
line++;
}
while (line + 2 <= line_end) {
Fixed i1 = base + fixed_sin(xt1) + fixed_sin(xt2);
xt1 += XT1_INCR;
xt2 += XT2_INCR;
Fixed i2 = base + fixed_sin(xt1) + fixed_sin(xt2);
xt1 += XT1_INCR;
xt2 += XT2_INCR;
uint32_t pixel = ((uint32_t)palette_from_fixed(i1 >> 2) << 16) |
(uint32_t)palette_from_fixed(i2 >> 2);
((uint32_t*)line)[0] = pixel;
line += 2;
}
if (line < line_end) {
Fixed ii = base + fixed_sin(xt1) + fixed_sin(xt2);
line[0] = palette_from_fixed(ii >> 2);
line++;
}
}
#else /* !OPTIMIZE_WRITES */
int xx;
for (xx = 0; xx < info->width; xx++) {
Fixed ii = base + fixed_sin(xt1) + fixed_sin(xt2);
xt1 += XT1_INCR;
xt2 += XT2_INCR;
line[xx] = palette_from_fixed(ii / 4);
}
#endif /* !OPTIMIZE_WRITES */
// go to next line
pixels = (char*)pixels + info->stride;
}
}
/* simple stats management */
typedef struct {
double renderTime;
double frameTime;
} FrameStats;
#define MAX_FRAME_STATS 200
#define MAX_PERIOD_MS 1500
typedef struct {
double firstTime;
double lastTime;
double frameTime;
int firstFrame;
int numFrames;
FrameStats frames[ MAX_FRAME_STATS ];
} Stats;
static void
stats_init( Stats* s )
{
s->lastTime = now_ms();
s->firstTime = 0.;
s->firstFrame = 0;
s->numFrames = 0;
}
static void
stats_startFrame( Stats* s )
{
s->frameTime = now_ms();
}
static void
stats_endFrame( Stats* s )
{
double now = now_ms();
double renderTime = now - s->frameTime;
double frameTime = now - s->lastTime;
int nn;
if (now - s->firstTime >= MAX_PERIOD_MS) {
if (s->numFrames > 0) {
double minRender, maxRender, avgRender;
double minFrame, maxFrame, avgFrame;
int count;
nn = s->firstFrame;
minRender = maxRender = avgRender = s->frames[nn].renderTime;
minFrame = maxFrame = avgFrame = s->frames[nn].frameTime;
for (count = s->numFrames; count > 0; count-- ) {
nn += 1;
if (nn >= MAX_FRAME_STATS)
nn -= MAX_FRAME_STATS;
double render = s->frames[nn].renderTime;
if (render < minRender) minRender = render;
if (render > maxRender) maxRender = render;
double frame = s->frames[nn].frameTime;
if (frame < minFrame) minFrame = frame;
if (frame > maxFrame) maxFrame = frame;
avgRender += render;
avgFrame += frame;
}
avgRender /= s->numFrames;
avgFrame /= s->numFrames;
LOGI("frame/s (avg,min,max) = (%.1f,%.1f,%.1f) "
"render time ms (avg,min,max) = (%.1f,%.1f,%.1f)\n",
1000./avgFrame, 1000./maxFrame, 1000./minFrame,
avgRender, minRender, maxRender);
}
s->numFrames = 0;
s->firstFrame = 0;
s->firstTime = now;
}
nn = s->firstFrame + s->numFrames;
if (nn >= MAX_FRAME_STATS)
nn -= MAX_FRAME_STATS;
s->frames[nn].renderTime = renderTime;
s->frames[nn].frameTime = frameTime;
if (s->numFrames < MAX_FRAME_STATS) {
s->numFrames += 1;
} else {
s->firstFrame += 1;
if (s->firstFrame >= MAX_FRAME_STATS)
s->firstFrame -= MAX_FRAME_STATS;
}
s->lastTime = now;
}
JNIEXPORT void JNICALL Java_example_user_plasmatest_PlasmaView_renderPlasma(JNIEnv * env, jobject obj, jobject bitmap, jlong time_ms)
{
AndroidBitmapInfo info;
void* pixels;
int ret;
static Stats stats;
static int init;
if (!init) {
init_tables();
stats_init(&stats);
init = 1;
}
if ((ret = AndroidBitmap_getInfo(env, bitmap, &info)) < 0) {
LOGE("AndroidBitmap_getInfo() failed ! error=%d", ret);
return;
}
if (info.format != ANDROID_BITMAP_FORMAT_RGB_565) {
LOGE("Bitmap format is not RGB_565 !");
return;
}
if ((ret = AndroidBitmap_lockPixels(env, bitmap, &pixels)) < 0) {
LOGE("AndroidBitmap_lockPixels() failed ! error=%d", ret);
}
stats_startFrame(&stats);
/* Now fill the values with a nice little plasma */
fill_plasma(&info, pixels, time_ms );
AndroidBitmap_unlockPixels(env, bitmap);
stats_endFrame(&stats);
}
//
// Created by user on 2016/4/14.
//
修改build.gradle文件: 添加ndk{......}
defaultConfig {
applicationId "example.user.plasmatest"
minSdkVersion 15
targetSdkVersion 23
versionCode 1
versionName "1.0"
ndk{
moduleName "plasma"
ldLibs "log"
ldLibs "jnigraphics"//新增
}
}
修改Android.mk文件：
添加：LOCAL_LDLIBS := -llog -ljnigraphics
這是我的Android.mk:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := plasma
LOCAL_LDFLAGS := -Wl,--build-id
LOCAL_LDLIBS := \
-llog \
-ljnigraphics \
LOCAL_SRC_FILES := \
D:\as_workspace\NDKDemo2\plasmatest\src\main\jni\plasma.c \
D:\as_workspace\NDKDemo2\plasmatest\src\main\jni\util.c \
LOCAL_C_INCLUDES += D:\as_workspace\NDKDemo2\plasmatest\src\main\jni
LOCAL_C_INCLUDES += D:\as_workspace\NDKDemo2\plasmatest\src\debug\jni
include $(BUILD_SHARED_LIBRARY)
運行即可。。。
遇到的問題：
問題一：Error:(383) undefined reference to `__android_log_print'：
1 修改 Android.mk 文件相關:
1
LOCAL_LDLIBS := -llog
2 如果使用 android studio，需要修改 gradle 腳本：
1
2
3
4
5
6
7
8
android {
defaultConfig {
ndk {
moduleName "serial_port"
ldLibs "log"
}
}
}
也就是添加了一句：ldLibs "log"
問題二：Error:(377) undefined reference to `AndroidBitmap_getInfo'
修改Android.mk文件：
添加：LOCAL_LDLIBS := -llog -ljnigraphics
修改 gradle 腳本如下：
ndk {
moduleName "webcam"
ldLibs "log"
ldLibs "jnigraphics"
}
其實這句的意思就是增加動態鏈接庫 jnigraphics ，這樣就搞定了呢，是的，就是這樣。
問題三：找不到appcompatActivity
這時候你的activity應該繼承的是appcompatActivity，
解決方法一：修改成繼承Activity就可以
解決方法二：javah -d jni -classpath D:\ide\android-sdk\platforms\android-22\android.jar;D:\ide\android-sdk\extras\android\support\v7\appcompat\libs\android-support-v7-appcompat.jar;..\..\build\intermediates\classes\debug
在javah命令中加上android-support-v7-appcompat.jar這個的路徑，在安裝目錄下，一級級找就可以。
幾個很好的學習ndk的博客：
JNI官方規范中文版：http://blog.csdn.net/a345017062/article/category/1256568
Android 開發之 JNI入門 - NDK從入門到精通（說的很全）：http://www.hanshuliang.com/?post=3
http://blog.csdn.net/shulianghan/article/details/18964835（推薦）
NDK開發：http://blog.csdn.net/conowen/article/category/1127720
JNI實戰：http://blog.csdn.net/yanbober/article/details/45309049（推薦）
極客學院的：http://wiki.jikexueyuan.com/project/jni-ndk-developer-guide/overview.html（推薦）
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