dmcam Java extension overview¶

The Java extension provided by dmcam makes it easy for developers based on Java to perform rapid secondary development based on SmartToF cameras. This document mainly describes the installation of Java extensions and the associations and differences between Java API and C API.

Java extension installation¶

Window
- Supported systems：
  - Windows 7/8/10 32bit/64bit
  - JDK >= 1.8
- Java extended dynamic library includes：
  - dmcam.jar: Java extended dynamic library for importing Java projects.
  - dmcam_java.dll: Java dmcam extended suitable library configuration
  - libdmcam.dll: dmcam core lib
- Installation method
  - Add the above dll to the PATH or copy it to the executable file directory.
  - Java project references dmcam.jar
Linux
- Supported systems：
  - Linux 64bit (Ubuntu 14.04/16.04 tested)
  - Open JDK >= 7
- Java extended dynamic library includes：
  - dmcam.jar: Java extended dynamic library for importing Java projects.
  - libdmcam_java.so: Java dmcam extended suitable library configuration
  - libdmcam.so: dmcam core lib
- Installation method
  - Setting LD_LIBRAYR_PATH contains the above so/dll folder, or put the dynamic library in the system library directory, such as： /usr/local/lib/

Java API description¶

The module API in Java corresponds to the API defined in ** dmcam.h ** in the C library.。

The default namespace for Java extensions is: com.smarttof.dmcam. Can be imported via import:

import com.smarttof.dmcam.*;

public class sampleBasic{
    public static void main(String[] args) {
    dmcamDevArray devs = new dmcamDevArray(16);
            int cnt = dmcam.dev_list(devs.cast(), 16);
}

API name mapping(C->Java)： dmcam_xxxxx(…) -> dmcam.xxxxx(…) .For example dmcam_dev_open is mapped to dmcam.dev_open
Structure mapping(C->Java): dmcam_xxxxx -> xxxx() 。 . Structure is mapped to a class in Java. For example, create a dmcam_frame_info_t structure as follows:
```
finfo = new frame_info_t()
```
Caution

dmcam.init(null) is automatically called when the Java extension is loaded，dmcam.uninit() will be called automatically when released. So it is not necessary to use dmcam.init() and dmcam.uninit() in the program.
Accessing member variables of a structure： obj.field -> obj.getField()/setField. Member variable access needs to be performed by the get / set method corresponding to the member variable name. For example：
```
cap_cfg_t cfg = new cap_cfg_t();
cfg.setCache_frames_cnt(10);  // cfg.cache_frame_cnt = 10
cfg.setOn_error(null);        // cfg.on_error = NULL
/* ... */
```

NULL is mapped to null, for example:

dmcam.dev_open(null) // dmcam_dev_open(NULL)

The following are some differences between calling API in Java and C, need to pay attention.
dmcam.dev_list()
In Java, the device list is obtained as follows. The return value is the number of ready devices. Use example like below:
dmcamDevArray devs = new dmcamDevArray(16); int cnt = dmcam.dev_list(devs.cast(), 16); System.out.printf("found {0} device\n", cnt);
dmcam.param_batch_set()
Setting parameters in Java is a bit more complicated than C, and you need to construct a param_item_t instance. The specific usage example is as follows:
.. code-block:: Java
int pwr_percent = 100; param_item_t wparam = new param_item_t(); dmcamParamArray wparams = new dmcamParamArray(1); wparam.setParam_id(dev_param_e.PARAM_ILLUM_POWER); wparam.getParam_val().getIllum_power().setPercent((short) pwr_percent); wparams.setitem(0, wparam); if (!dmcam.param_batch_set(dev, wparams.cast(), 1)) {

System.out.printf(” set illu_power to %d %% failedn”, pwr_percent);}
dmcam.param_batch_get(dev, list)
Setting parameters in Java is a bit more complicated than C, and you need to construct a param_item_t instance. The specific usage example is as follows:
.. code-block:: Java
param_item_t r_fps = new param_item_t(); r_fps.setParam_id(dev_param_e.PARAM_FRAME_RATE); param_item_t r_intg = new param_item_t(); r_intg.setParam_id(dev_param_e.PARAM_INTG_TIME);

dmcamParamArray rparams = new dmcamParamArray(2); rparams.setitem(0, r_fps); rparams.setitem(1, r_intg);

if (dmcam.param_batch_get(dev, rparams.cast(), 2)) {
System.out.printf(“fps = %d, intg = %d”, (int)rparams.getitem(0).getParam_val().getFrame_rate().getFps(), (int)rparams.getitem(1).getParam_val().getIntg().getIntg_us());}
dmcam.set_callback_on_frame_ready and dmcam.set_callback_on_error
Java extensions do not support callback functions. When capturing, you can refer to the following settings:：
cap_cfg_t cfg = new cap_cfg_t(); cfg.setCache_frames_cnt(10); cfg.setOn_error(null); cfg.setOn_frame_ready(null); cfg.setEn_save_replay((short)0); cfg.setEn_save_dist_u16((short)0); cfg.setEn_save_gray_u16((short)0); cfg.setFname_replay(null); dmcam.cap_config_set(dev, cfg);