昨天刚好闪光灯弄过来，今天简单的做下总结。大概的说下，具体我也没有深入研究，不过效果确实是有了。
首先找到android拍照的时候所执行的函数代码在：
packages/apps/Camera/src/com/android/camera/Camera.java
找到这个地方：
mCameraDevice.setParameters(mParameters);
mCameraDevice.takePicture(mShutterCallback, mRawPictureCallback,
mPostViewPictureCallback, new JpegPictureCallback(loc));
mPreviewing = false;
据我理解，这里就是拍照的时候所执行的，而这里应该是调用的camera库里的takepicture下面我们找到库文件：
device/samsung/proprietary/libcamera
库文件就在这里，下面我们进入SeccameraHWInterface.cpp文件查找takepicture如下:
status_t CameraHardwareSec::takePicture()
{
LOGV("%s :", __func__);
stopPreview();
Mutex::Autolock lock(mStateLock);
if (mCaptureInProgress) {
LOGE("%s : capture already in progress", __func__);
return INVALID_OPERATION;
}
if (mPictureThread->run("CameraPictureThread", PRIORITY_DEFAULT) != NO_ERROR) {
LOGE("%s : couldn't run picture thread", __func__);
return INVALID_OPERATION;
}
mCaptureInProgress = true;
return NO_ERROR;
}
里面的mPictureThread->run就是拍照的东西了，具体我就不分析了。接下来我们找下闪光灯的接口
在SecCamera.h里你会发现下面三个函数接口：
bool getFlashSupport(void);
int setFlashMode(int flash_mode);
int getFlashMode(void);
其中setFlashMode即为设置闪光灯的接口，找到这个函数
在SecCamera.cpp里如下:
int SecCamera::setFlashMode(int flash_mode)
{
LOGV("%s(flash_mode(%d))", __func__, flash_mode);
if (flash_mode <= FLASH_MODE_BASE || FLASH_MODE_MAX <= flash_mode) {
LOGE("ERR(%s):Invalid flash_mode (%d)", __func__, flash_mode);
return -1;
}
if (m_params->flash_mode != flash_mode) {
m_params->flash_mode = flash_mode;
if (m_flag_camera_start) {
if (fimc_v4l2_s_ctrl(m_cam_fd, V4L2_CID_CAMERA_FLASH_MODE, flash_mode) < 0) {
LOGE("ERR(%s):Fail on V4L2_CID_CAMERA_FLASH_MODE", __func__);
return -1;
}
}
}
return 0;
}
这里又会调用fimc_v4l2_s_ctrl函数代码如下:
static int fimc_v4l2_s_ctrl(int fp, unsigned int id, unsigned int value)
{
struct v4l2_control ctrl;
int ret;
ctrl.id = id;
ctrl.value = value;
//LOGD("%s :--------------------------value is %d",__func__,value);//add dao
ret = ioctl(fp, VIDIOC_S_CTRL, &ctrl);
if (ret < 0) {
LOGE("ERR(%s):VIDIOC_S_CTRL(id = %#x (%d), value = %d) failed ret = %d\n",
__func__, id, id-V4L2_CID_PRIVATE_BASE, value, ret);
return ret;
}
return ctrl.value;
}
在这里进行了ioctl下面我们到内核里面去看看。
在内核下面的drivers/media/video/v4l2-ioctl.c有如下代码:
case VIDIOC_S_CTRL:
{
struct v4l2_control *p = arg;
struct v4l2_ext_controls ctrls;
struct v4l2_ext_control ctrl;
if (!ops->vidioc_s_ctrl && !ops->vidioc_s_ext_ctrls)
break;
dbgarg(cmd, "id=0x%x, value=%d\n", p->id, p->value);
if (ops->vidioc_s_ctrl) {
ret = ops->vidioc_s_ctrl(file, fh, p);
break;
}
if (!ops->vidioc_s_ext_ctrls)
break;
ctrls.ctrl_class = V4L2_CTRL_ID2CLASS(p->id);
ctrls.count = 1;
ctrls.controls = &ctrl;
ctrl.id = p->id;
ctrl.value = p->value;
if (check_ext_ctrls(&ctrls, 1))
ret = ops->vidioc_s_ext_ctrls(file, fh, &ctrls);
break;
}
很快我就想到了摄像头驱动里有这样的设置:
代码在drivers/media/video/samsung/ficm/ov2640.c
static const struct v4l2_subdev_core_ops ov2640_core_ops = {
.init = ov2640_init, /* initializing API */
.s_config = ov2640_s_config, /* Fetch platform data */
.queryctrl = ov2640_queryctrl,
.querymenu = ov2640_querymenu,
.g_ctrl = ov2640_g_ctrl,
.s_ctrl = ov2640_s_ctrl,
};
这里有一个s_ctrl，事实证明确实是执行了ov2640_s_ctrl至于怎么调用过来的没有深入研究。
下面我们看到这个函数开始的部分
static int ov2640_s_ctrl(struct v4l2_subdev *sd, struct v4l2_control *ctrl)
{
struct i2c_client *client = v4l2_get_subdevdata(sd);
struct ov2640_state *state = to_state(sd);
int err = 0;
int value = ctrl->value;
switch (ctrl->id) {
case V4L2_CID_CAMERA_FLASH_MODE:
case V4L2_CID_CAMERA_BRIGHTNESS:
break;
第一个就是闪光灯的选项，文件系统里面设置闪光灯的就是传入的这个，可没作任何处理就直接跳出了。下面我在增加闪光灯驱动：
static int flash_ctrl(int mode)
{
int err;
err = gpio_request(S5PV210_GPD0(2), "GPD0"); //power
if (err) {
printk(KERN_ERR "failed to request GPD0 for "
"flashlight power control\n");
return err;
}
gpio_direction_output(S5PV210_GPD0(2), 1);
err = gpio_request(S5PV210_GPD0(3), "GPD0"); //mode
if (err) {
printk(KERN_ERR "failed to request GPD0 for "
"flashlight mode control\n");
return err;
}
/*
high is flash mode,low is torch mode
*/
switch(mode) {
case FLASH_MODE_ON:
gpio_direction_output(S5PV210_GPD0(3), 1);
break;
case FLASH_MODE_TORCH:
gpio_direction_output(S5PV210_GPD0(3), 0);
break;
default:
break;
}
mdelay(100);
gpio_direction_output(S5PV210_GPD0(2), 0);
gpio_free(S5PV210_GPD0(2));
gpio_free(S5PV210_GPD0(3));
return err;
}
电路我就不发出来了，流程搞清楚了，大家就好弄了。
修改ov2640_s_ctrl为：
case V4L2_CID_CAMERA_FLASH_MODE: err = flash_ctrl(value); break;
只修改相关设置，其它的不变。现在接口已经全部写好，在看到文件系统里。
在拍照之前加上闪光灯设置，这个可以在库里设置也可以在app里设置，我直接在库里设置的，路径我就不在打了，前面的相关函数已经全部给出了，如下：
status_t CameraHardwareSec::takePicture()
{
LOGV("%s :", __func__);
stopPreview();
Mutex::Autolock lock(mStateLock);
if (mCaptureInProgress) {
LOGE("%s : capture already in progress", __func__);
return INVALID_OPERATION;
}
mSecCamera->setFlashMode(FLASH_MODE_ON);//add by dao
if (mPictureThread->run("CameraPictureThread", PRIORITY_DEFAULT) != NO_ERROR) {
LOGE("%s : couldn't run picture thread", __func__);
return INVALID_OPERATION;
}
mCaptureInProgress = true;
return NO_ERROR;
}
在拍照之前设置FlashMode为FLASH_MODE_ON模式，结果发现这样不行，搞了半天终于发现问题所在，直接把setFlashMode改为如下:
int SecCamera::setFlashMode(int flash_mode)
{
LOGV("%s(flash_mode(%d))", __func__, flash_mode);
fimc_v4l2_s_ctrl(m_cam_fd, V4L2_CID_CAMERA_FLASH_MODE, flash_mode);
/*
if (flash_mode <= FLASH_MODE_BASE || FLASH_MODE_MAX <= flash_mode) {
LOGE("ERR(%s):Invalid flash_mode (%d)", __func__, flash_mode);
return -1;
}
if (m_params->flash_mode != flash_mode) {
m_params->flash_mode = flash_mode;
if (m_flag_camera_start) {
if (fimc_v4l2_s_ctrl(m_cam_fd, V4L2_CID_CAMERA_FLASH_MODE, flash_mode) < 0) {
LOGE("ERR(%s):Fail on V4L2_CID_CAMERA_FLASH_MODE", __func__);
return -1;
}
}
}
*/
return 0;
}
重新编译库和内核，下载，结果测试成功。