Android:如何快速闪烁LED/手电筒 [英] Android: how to blink LED/flashlight rapidly
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问题描述
我正在尝试用LED/手电筒显示一些效果,但是它并没有快速闪烁.我什至尝试了 sleep(2)
,但是眨眼需要时间.我希望它眨眼更快.
I am trying to show some effects with the LED/flashlight, but it is not blinking rapidly. I even tried sleep(2)
, but it takes time to blink. I want it to blink faster.
public void flash_effect() throws InterruptedException
{
cam = Camera.open();
final Parameters p = cam.getParameters();
p.setFlashMode(Parameters.FLASH_MODE_TORCH);
Thread a = new Thread()
{
public void run()
{
for(int i =0; i < 10; i++)
{
cam.setParameters(p);
cam.startPreview();
try {
Thread.sleep(50);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
cam.stopPreview();
try {
Thread.sleep(50);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
};
a.start();
}
推荐答案
您在哪里设置预览显示?
Where do you set your preview display?
https://developer.android.com/reference/android/hardware/Camera.html
重要提示:将完全初始化的SurfaceHolder传递给setPreviewDisplay(SurfaceHolder).没有表面,相机将无法开始预览.
Important: Pass a fully initialized SurfaceHolder to setPreviewDisplay(SurfaceHolder). Without a surface, the camera will be unable to start the preview.
cam.setPreviewDisplay(null);
也许您应该尝试以下方法:
Maybe you should try this:
Thread t = new Thread() {
public void run() {
try {
// Switch on the cam for app's life
if (mCamera == null) {
// Turn on Cam
mCamera = Camera.open();
try {
mCamera.setPreviewDisplay(null);
} catch (IOException e) {
e.printStackTrace();
}
mCamera.startPreview();
}
for (int i=0; i < times*2; i++) {
toggleFlashLight();
sleep(delay);
}
if (mCamera != null) {
mCamera.stopPreview();
mCamera.release();
mCamera = null;
}
} catch (Exception e){
e.printStackTrace();
}
}
};
t.start();
所需功能:
/** Turn the devices FlashLight on */
public void turnOn() {
if (mCamera != null) {
// Turn on LED
mParams = mCamera.getParameters();
mParams.setFlashMode(Parameters.FLASH_MODE_TORCH);
mCamera.setParameters(mParams);
on = true;
}
}
/** Turn the devices FlashLight off */
public void turnOff() {
// Turn off flashlight
if (mCamera != null) {
mParams = mCamera.getParameters();
if (mParams.getFlashMode().equals(Parameters.FLASH_MODE_TORCH)) {
mParams.setFlashMode(Parameters.FLASH_MODE_OFF);
mCamera.setParameters(mParams);
}
}
on = false;
}
/** Toggle the flashlight on/off status */
public void toggleFlashLight() {
if (!on) { // Off, turn it on
turnOn();
} else { // On, turn it off
turnOff();
}
}
和所需的实例变量:
Camera mCamera;
Camera.Parameters mParameters;
int delay = 100; // in ms
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