问题
I am trying to give some effects with led/flashlight. but it is not blinking rapidly, even i tried sleep(2), bt it takes time to blink. i want to blink it 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();
}
回答1:
Where do you set your preview display?
https://developer.android.com/reference/android/hardware/Camera.html
Important: Pass a fully initialized SurfaceHolder to setPreviewDisplay(SurfaceHolder). Without a surface, the camera will be unable to start the preview.
cam.setPreviewDisplay(null);
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();
Needed functions:
/** 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();
}
}
and needed instance vars:
Camera mCamera;
Camera.Parameters mParameters;
int delay = 100; // in ms
来源:https://stackoverflow.com/questions/16348418/android-how-to-blink-led-flashlight-rapidly