The document discusses building native camera access in Codename One. It describes surveying existing solutions and choosing the Camera Kit Android API. It then details wrapping the native CameraNativeAccess interface in a high-level CameraKit class to abstract away the native implementation and allow changing the underlying native API. The CameraKit class implements common camera functions and allows adding listeners to handle camera events like errors, images and videos.

1. Building Native Camera Access - Part I

2. Introduction
© Codename One 2017 all rights reserved
✦Low level camera access has been a long time “wish
list” item
✦First Step: Survey Existing Solutions
✦Existing platforms don’t have something close
✦Camera Kit Android stood out as the best/simplest
option
https://github.com/CameraKit/camerakit-android/

3. Process
© Codename One 2017 all rights reserved
✦I went with the Android API “As Is”
✦Camera Kit Android already did the hard work of “design”
✦I started with an app that uses native interfaces, not a
cn1lib
✦API is mostly based on CameraView:
https://github.com/CameraKit/camerakit-android/blob/
master/camerakit-core/src/main/java/com/wonderkiln/
camerakit/CameraView.java

4. public interface CameraNativeAccess extends NativeInterface {
PeerComponent getView();
boolean isStarted();
void start();
void stop();
float getVerticalViewingAngle();
float getHorizontalViewingAngle();
int getFacing();
boolean isFacingFront();
boolean isFacingBack();
void setFacing(int facing);
void setFlash(int flash);
int toggleFacing();
int toggleFlash();
int getFlash();
void setFocus(int focus);
void setMethod(int method);
void setPinchToZoom(boolean zoom);
void setZoom(float zoom);
void setPermissions(int permissions);
void setVideoQuality(int videoQuality);
void setVideoBitRate(int videoBitRate);
void setLockVideoAspectRatio(boolean lockVideoAspectRatio);
CameraNativeAccess

5. public interface CameraNativeAccess extends NativeInterface {
PeerComponent getView();
boolean isStarted();
void start();
void stop();
float getVerticalViewingAngle();
float getHorizontalViewingAngle();
int getFacing();
boolean isFacingFront();
boolean isFacingBack();
void setFacing(int facing);
void setFlash(int flash);
int toggleFacing();
int toggleFlash();
int getFlash();
void setFocus(int focus);
void setMethod(int method);
void setPinchToZoom(boolean zoom);
void setZoom(float zoom);
void setPermissions(int permissions);
void setVideoQuality(int videoQuality);
void setVideoBitRate(int videoBitRate);
void setLockVideoAspectRatio(boolean lockVideoAspectRatio);
CameraNativeAccess

6. public interface CameraNativeAccess extends NativeInterface {
PeerComponent getView();
boolean isStarted();
void start();
void stop();
float getVerticalViewingAngle();
float getHorizontalViewingAngle();
int getFacing();
boolean isFacingFront();
boolean isFacingBack();
void setFacing(int facing);
void setFlash(int flash);
int toggleFacing();
int toggleFlash();
int getFlash();
void setFocus(int focus);
void setMethod(int method);
void setPinchToZoom(boolean zoom);
void setZoom(float zoom);
void setPermissions(int permissions);
void setVideoQuality(int videoQuality);
void setVideoBitRate(int videoBitRate);
void setLockVideoAspectRatio(boolean lockVideoAspectRatio);
CameraNativeAccess

7. public interface CameraNativeAccess extends NativeInterface {
PeerComponent getView();
boolean isStarted();
void start();
void stop();
float getVerticalViewingAngle();
float getHorizontalViewingAngle();
int getFacing();
boolean isFacingFront();
boolean isFacingBack();
void setFacing(int facing);
void setFlash(int flash);
int toggleFacing();
int toggleFlash();
int getFlash();
void setFocus(int focus);
void setMethod(int method);
void setPinchToZoom(boolean zoom);
void setZoom(float zoom);
void setPermissions(int permissions);
void setVideoQuality(int videoQuality);
void setVideoBitRate(int videoBitRate);
void setLockVideoAspectRatio(boolean lockVideoAspectRatio);
CameraNativeAccess

8. void setFlash(int flash);
int toggleFacing();
int toggleFlash();
int getFlash();
void setFocus(int focus);
void setMethod(int method);
void setPinchToZoom(boolean zoom);
void setZoom(float zoom);
void setPermissions(int permissions);
void setVideoQuality(int videoQuality);
void setVideoBitRate(int videoBitRate);
void setLockVideoAspectRatio(boolean lockVideoAspectRatio);
void setJpegQuality(int jpegQuality);
void setCropOutput(boolean cropOutput);
void captureImage();
void captureVideo();
void captureVideoFile(String videoFile);
void stopVideo();
int getPreviewWidth();
int getPreviewHeight();
int getCaptureWidth();
int getCaptureHeight();
}
CameraNativeAccess

9. void setFlash(int flash);
int toggleFacing();
int toggleFlash();
int getFlash();
void setFocus(int focus);
void setMethod(int method);
void setPinchToZoom(boolean zoom);
void setZoom(float zoom);
void setPermissions(int permissions);
void setVideoQuality(int videoQuality);
void setVideoBitRate(int videoBitRate);
void setLockVideoAspectRatio(boolean lockVideoAspectRatio);
void setJpegQuality(int jpegQuality);
void setCropOutput(boolean cropOutput);
void captureImage();
void captureVideo();
void captureVideoFile(String videoFile);
void stopVideo();
int getPreviewWidth();
int getPreviewHeight();
int getCaptureWidth();
int getCaptureHeight();
}
CameraNativeAccess

10. public boolean setTextDetectionListener(
CameraKitEventCallback<CameraKitTextDetect> callback);
public void captureImage(CameraKitEventCallback<CameraKitImage> callback);
public void captureVideo(CameraKitEventCallback<CameraKitVideo> callback);
public void captureVideo(File videoFile,
CameraKitEventCallback<CameraKitVideo> callback);
public void addCameraKitListener(
CameraKitEventListener CameraKitEventListener);
public void bindCameraKitListener(Object object);
Missing from the Native Interface

11. public interface Constants {
public static final int PERMISSION_REQUEST_CAMERA = 16;
public static final int FACING_BACK = 0;
public static final int FACING_FRONT = 1;
public static final int FLASH_OFF = 0;
public static final int FLASH_ON = 1;
public static final int FLASH_AUTO = 2;
public static final int FLASH_TORCH = 3;
public static final int FOCUS_OFF = 0;
public static final int FOCUS_CONTINUOUS = 1;
public static final int FOCUS_TAP = 2;
public static final int FOCUS_TAP_WITH_MARKER = 3;
public static final int METHOD_STANDARD = 0;
public static final int METHOD_STILL = 1;
public static final int PERMISSIONS_STRICT = 0;
public static final int PERMISSIONS_LAZY = 1;
public static final int PERMISSIONS_PICTURE = 2;
public static final int VIDEO_QUALITY_480P = 0;
public static final int VIDEO_QUALITY_720P = 1;
public static final int VIDEO_QUALITY_1080P = 2;
public static final int VIDEO_QUALITY_2160P = 3;
public static final int VIDEO_QUALITY_HIGHEST = 4;
public static final int VIDEO_QUALITY_LOWEST = 5;
public static final int VIDEO_QUALITY_QVGA = 6;
}
Constants

12. High Level Abstraction
© Codename One 2017 all rights reserved
✦Never expose a native interface to a user
✦Always wrap the native interface in a regular class
✦This lets you change the native API

13. public class CameraKit implements Constants {
private CameraNativeAccess cma;
private static CameraKit instance;
private ArrayList<CameraListener> listeners = new ArrayList<>();
static boolean thisIsForIOS;
private static void initBuildHint() {
Map<String, String> buildHints = Display.getInstance().
getProjectBuildHints();
if(!buildHints.containsKey("ios.NSCameraUsageDescription")) {
Display.getInstance().setProjectBuildHint(
"ios.NSCameraUsageDescription",
"We need camera access to grab pictures and videos");
}
}
public static CameraKit create() {
if(instance == null) {
if(isSimulator()) {
initBuildHint();
CameraKit

14. public class CameraKit implements Constants {
private CameraNativeAccess cma;
private static CameraKit instance;
private ArrayList<CameraListener> listeners = new ArrayList<>();
static boolean thisIsForIOS;
private static void initBuildHint() {
Map<String, String> buildHints = Display.getInstance().
getProjectBuildHints();
if(!buildHints.containsKey("ios.NSCameraUsageDescription")) {
Display.getInstance().setProjectBuildHint(
"ios.NSCameraUsageDescription",
"We need camera access to grab pictures and videos");
}
}
public static CameraKit create() {
if(instance == null) {
if(isSimulator()) {
initBuildHint();
CameraKit

15. public class CameraKit implements Constants {
private CameraNativeAccess cma;
private static CameraKit instance;
private ArrayList<CameraListener> listeners = new ArrayList<>();
static boolean thisIsForIOS;
private static void initBuildHint() {
Map<String, String> buildHints = Display.getInstance().
getProjectBuildHints();
if(!buildHints.containsKey("ios.NSCameraUsageDescription")) {
Display.getInstance().setProjectBuildHint(
"ios.NSCameraUsageDescription",
"We need camera access to grab pictures and videos");
}
}
public static CameraKit create() {
if(instance == null) {
if(isSimulator()) {
initBuildHint();
CameraKit

16. public class CameraKit implements Constants {
private CameraNativeAccess cma;
private static CameraKit instance;
private ArrayList<CameraListener> listeners = new ArrayList<>();
static boolean thisIsForIOS;
private static void initBuildHint() {
Map<String, String> buildHints = Display.getInstance().
getProjectBuildHints();
if(!buildHints.containsKey("ios.NSCameraUsageDescription")) {
Display.getInstance().setProjectBuildHint(
"ios.NSCameraUsageDescription",
"We need camera access to grab pictures and videos");
}
}
public static CameraKit create() {
if(instance == null) {
if(isSimulator()) {
initBuildHint();
CameraKit

17. public class CameraKit implements Constants {
private CameraNativeAccess cma;
private static CameraKit instance;
private ArrayList<CameraListener> listeners = new ArrayList<>();
static boolean thisIsForIOS;
private static void initBuildHint() {
Map<String, String> buildHints = Display.getInstance().
getProjectBuildHints();
if(!buildHints.containsKey("ios.NSCameraUsageDescription")) {
Display.getInstance().setProjectBuildHint(
"ios.NSCameraUsageDescription",
"We need camera access to grab pictures and videos");
}
}
public static CameraKit create() {
if(instance == null) {
if(isSimulator()) {
initBuildHint();
CameraKit

18. public class CameraKit implements Constants {
private CameraNativeAccess cma;
private static CameraKit instance;
private ArrayList<CameraListener> listeners = new ArrayList<>();
static boolean thisIsForIOS;
private static void initBuildHint() {
Map<String, String> buildHints = Display.getInstance().
getProjectBuildHints();
if(!buildHints.containsKey("ios.NSCameraUsageDescription")) {
Display.getInstance().setProjectBuildHint(
"ios.NSCameraUsageDescription",
"We need camera access to grab pictures and videos");
}
}
public static CameraKit create() {
if(instance == null) {
if(isSimulator()) {
initBuildHint();
CameraKit

19. public class CameraKit implements Constants {
private CameraNativeAccess cma;
private static CameraKit instance;
private ArrayList<CameraListener> listeners = new ArrayList<>();
static boolean thisIsForIOS;
private static void initBuildHint() {
Map<String, String> buildHints = Display.getInstance().
getProjectBuildHints();
if(!buildHints.containsKey("ios.NSCameraUsageDescription")) {
Display.getInstance().setProjectBuildHint(
"ios.NSCameraUsageDescription",
"We need camera access to grab pictures and videos");
}
}
public static CameraKit create() {
if(instance == null) {
if(isSimulator()) {
initBuildHint();
CameraKit

20. public class CameraKit implements Constants {
private CameraNativeAccess cma;
private static CameraKit instance;
private ArrayList<CameraListener> listeners = new ArrayList<>();
static boolean thisIsForIOS;
private static void initBuildHint() {
Map<String, String> buildHints = Display.getInstance().
getProjectBuildHints();
if(!buildHints.containsKey("ios.NSCameraUsageDescription")) {
Display.getInstance().setProjectBuildHint(
"ios.NSCameraUsageDescription",
"We need camera access to grab pictures and videos");
}
}
public static CameraKit create() {
if(instance == null) {
if(isSimulator()) {
initBuildHint();
CameraKit

21. public static CameraKit create() {
if(instance == null) {
if(isSimulator()) {
initBuildHint();
if(thisIsForIOS) {
CameraCallbacks.onError(null, null, null);
CameraCallbacks.onImage(null);
CameraCallbacks.onVideo(null);
}
return null;
}
instance = new CameraKit();
instance.cma =
NativeLookup.create(CameraNativeAccess.class);
if(instance.cma != null && instance.cma.isSupported()) {
return instance;
}
instance = null;
CameraKit

22. public static CameraKit create() {
if(instance == null) {
if(isSimulator()) {
initBuildHint();
if(thisIsForIOS) {
CameraCallbacks.onError(null, null, null);
CameraCallbacks.onImage(null);
CameraCallbacks.onVideo(null);
}
return null;
}
instance = new CameraKit();
instance.cma =
NativeLookup.create(CameraNativeAccess.class);
if(instance.cma != null && instance.cma.isSupported()) {
return instance;
}
instance = null;
CameraKit

23. public static CameraKit create() {
if(instance == null) {
if(isSimulator()) {
initBuildHint();
if(thisIsForIOS) {
CameraCallbacks.onError(null, null, null);
CameraCallbacks.onImage(null);
CameraCallbacks.onVideo(null);
}
return null;
}
instance = new CameraKit();
instance.cma =
NativeLookup.create(CameraNativeAccess.class);
if(instance.cma != null && instance.cma.isSupported()) {
return instance;
}
instance = null;
CameraKit

24. initBuildHint();
if(thisIsForIOS) {
CameraCallbacks.onError(null, null, null);
CameraCallbacks.onImage(null);
CameraCallbacks.onVideo(null);
}
return null;
}
instance = new CameraKit();
instance.cma =
NativeLookup.create(CameraNativeAccess.class);
if(instance.cma != null && instance.cma.isSupported()) {
return instance;
}
instance = null;
}
return instance;
}
CameraKit

25. public PeerComponent getView() {
return cma.getView();
}
public boolean isStarted() {
return cma.isStarted();
}
public void start() {
cma.start();
}
public void stop() {
cma.stop();
}
CameraKit

26. public int toggleFacing() {
if(getFacing() == FACING_BACK) {
setFacing(FACING_FRONT);
return FACING_FRONT;
}
setFacing(FACING_BACK);
return FACING_BACK;
}
public int toggleFlash() {
switch (getFlash()) {
case FLASH_OFF:
setFlash(FLASH_ON);
break;
case FLASH_ON:
setFlash(FLASH_AUTO);
break;
case FLASH_AUTO:
case FLASH_TORCH:
setFlash(FLASH_OFF);
break;
}
return getFlash();
}
CameraKit

27. public int toggleFacing() {
if(getFacing() == FACING_BACK) {
setFacing(FACING_FRONT);
return FACING_FRONT;
}
setFacing(FACING_BACK);
return FACING_BACK;
}
public int toggleFlash() {
switch (getFlash()) {
case FLASH_OFF:
setFlash(FLASH_ON);
break;
case FLASH_ON:
setFlash(FLASH_AUTO);
break;
case FLASH_AUTO:
case FLASH_TORCH:
setFlash(FLASH_OFF);
break;
}
return getFlash();
}
CameraKit

28. public void addCameraListener(CameraListener listener) { listeners.add(listener); }
public void removeCameraListener(CameraListener listener) { listeners.remove(listener); }
public void fireCameraErrorEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraErrorEvent(ev));
return;
}
for(CameraListener l : listeners) {
l.onError(ev);
}
}
public void fireCameraImageEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraImageEvent(ev));
return;
}
for(CameraListener l : listeners) { l.onImage(ev); }
}
public void fireCameraVideoEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraVideoEvent(ev));
return;
}
for(CameraListener l : listeners) { l.onVideo(ev); }
}
CameraKit

29. public void addCameraListener(CameraListener listener) { listeners.add(listener); }
public void removeCameraListener(CameraListener listener) { listeners.remove(listener); }
public void fireCameraErrorEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraErrorEvent(ev));
return;
}
for(CameraListener l : listeners) {
l.onError(ev);
}
}
public void fireCameraImageEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraImageEvent(ev));
return;
}
for(CameraListener l : listeners) { l.onImage(ev); }
}
public void fireCameraVideoEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraVideoEvent(ev));
return;
}
for(CameraListener l : listeners) { l.onVideo(ev); }
}
CameraKit

30. public void addCameraListener(CameraListener listener) { listeners.add(listener); }
public void removeCameraListener(CameraListener listener) { listeners.remove(listener); }
public void fireCameraErrorEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraErrorEvent(ev));
return;
}
for(CameraListener l : listeners) {
l.onError(ev);
}
}
public void fireCameraImageEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraImageEvent(ev));
return;
}
for(CameraListener l : listeners) { l.onImage(ev); }
}
public void fireCameraVideoEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraVideoEvent(ev));
return;
}
for(CameraListener l : listeners) { l.onVideo(ev); }
}
CameraKit

31. public void addCameraListener(CameraListener listener) { listeners.add(listener); }
public void removeCameraListener(CameraListener listener) { listeners.remove(listener); }
public void fireCameraErrorEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraErrorEvent(ev));
return;
}
for(CameraListener l : listeners) {
l.onError(ev);
}
}
public void fireCameraImageEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraImageEvent(ev));
return;
}
for(CameraListener l : listeners) { l.onImage(ev); }
}
public void fireCameraVideoEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraVideoEvent(ev));
return;
}
for(CameraListener l : listeners) { l.onVideo(ev); }
}
CameraKit

32. public void addCameraListener(CameraListener listener) { listeners.add(listener); }
public void removeCameraListener(CameraListener listener) { listeners.remove(listener); }
public void fireCameraErrorEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraErrorEvent(ev));
return;
}
for(CameraListener l : listeners) {
l.onError(ev);
}
}
public void fireCameraImageEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraImageEvent(ev));
return;
}
for(CameraListener l : listeners) { l.onImage(ev); }
}
public void fireCameraVideoEvent(final CameraEvent ev) {
if(!isEdt()) {
callSerially(() -> fireCameraVideoEvent(ev));
return;
}
for(CameraListener l : listeners) { l.onVideo(ev); }
}
CameraKit

33. public class CameraCallbacks {
public static void onError(String type, String message,
String exceptionMessage) {
CameraKit ck = CameraKit.create();
if(ck != null) {
ck.fireCameraErrorEvent(
new CameraEvent(type, message, exceptionMessage));
}
}
public static void onImage(byte[] jpeg) {
CameraKit ck = CameraKit.create();
if(ck != null) {
ck.fireCameraImageEvent(new CameraEvent(jpeg));
}
}
public static void onVideo(String file) {
CameraKit ck = CameraKit.create();
if(ck != null) {
ck.fireCameraVideoEvent(new CameraEvent(file));
}
}
}
CameraCallbacks

34. public class CameraCallbacks {
public static void onError(String type, String message,
String exceptionMessage) {
CameraKit ck = CameraKit.create();
if(ck != null) {
ck.fireCameraErrorEvent(
new CameraEvent(type, message, exceptionMessage));
}
}
public static void onImage(byte[] jpeg) {
CameraKit ck = CameraKit.create();
if(ck != null) {
ck.fireCameraImageEvent(new CameraEvent(jpeg));
}
}
public static void onVideo(String file) {
CameraKit ck = CameraKit.create();
if(ck != null) {
ck.fireCameraVideoEvent(new CameraEvent(file));
}
}
}
CameraCallbacks

35. public class CameraCallbacks {
public static void onError(String type, String message,
String exceptionMessage) {
CameraKit ck = CameraKit.create();
if(ck != null) {
ck.fireCameraErrorEvent(
new CameraEvent(type, message, exceptionMessage));
}
}
public static void onImage(byte[] jpeg) {
CameraKit ck = CameraKit.create();
if(ck != null) {
ck.fireCameraImageEvent(new CameraEvent(jpeg));
}
}
public static void onVideo(String file) {
CameraKit ck = CameraKit.create();
if(ck != null) {
ck.fireCameraVideoEvent(new CameraEvent(file));
}
}
}
CameraCallbacks