/*

File: JavaColorWell.m

Abstract: Implementation file for the native side of the 

    NSColorWell-in-Java example.  See comments below for 

    explanation of how the NSColorWell communicates color 

    changes back to Java.

Version: 1.1

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*/ 

#import "JavaColorWell.h"

static JavaVM *jvm;

static jmethodID colorChange_mID;

// Cache the JavaVM when this library is loaded; it never changes (only one JVM per process)

JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved) {

    jvm = vm;

    return JNI_VERSION_1_4;

}

// jmethodIDs never go stale for the life of the class, so fetch them on classload and keep them around

// It is necessary to ensure the object bearing the method call is valid at call time

// From the build directory: javap -classpath JavaHeaders.jar -s apple.dts.samplecode.cwcocoacomponent.JavaColorWell

JNIEXPORT void JNICALL Java_apple_dts_samplecode_cwcocoacomponent_JavaColorWell_initMethodIDs (JNIEnv *env, jclass clazz) {

    // This potentially throws NoSuchMethodError, which we let propagate since the app is useless without it

    colorChange_mID = (*env)->GetMethodID(env, clazz, "cocoaColorChange", "(FFFF)V");

}

// Determines whether the current thread is already attached to the VM,

// and tells the caller if it needs to later DetachCurrentThread 

//

// CALL THIS ONCE WITHIN A FUNCTION SCOPE and use a local boolean

// for mustDetach; if you do not, the first call might attach, setting 

// mustDetach to true, but the second will misleadingly set mustDetach 

// to false, leaving a dangling JNIEnv

jint GetJNIEnv(JNIEnv **env, bool *mustDetach) {

    jint getEnvErr = JNI_OK;

    *mustDetach = false;

    if (jvm) {

        getEnvErr = (*jvm)->GetEnv(jvm, (void **)env, JNI_VERSION_1_4);

        if (getEnvErr == JNI_EDETACHED) {

            getEnvErr = (*jvm)->AttachCurrentThread(jvm, (void **)env, NULL);

            if (getEnvErr == JNI_OK) {

                *mustDetach = true;

            }

        }

    }

    return getEnvErr;

}

/*

 * Class:     apple_dts_samplecode_cwcocoacomponent_JavaColorWell

 * Method:    createNSViewLong

 * Signature: ()J

 */

JNIEXPORT jlong JNICALL Java_apple_dts_samplecode_cwcocoacomponent_JavaColorWell_createNSViewLong (JNIEnv *env, jobject caller) {

    return (jlong)[JavaColorWell colorWellWithCaller:caller env:env];

}

@implementation JavaColorWell

+ (id) colorWellWithCaller:(jobject) caller env:(JNIEnv *)env {

    return [[[JavaColorWell alloc] initWithCaller:caller env:env] autorelease];

}

// Obtain a JNI global reference to the enclosing Java object

// This will be used later to fire AWT events after a color change

- (id) initWithCaller:(jobject)caller env:(JNIEnv *)env {

    self = [super init];

    javaPeer = (*env)->NewGlobalRef(env, caller);

    return self;

}

// Override [NSColorWell activate] to show the opacity slider

- (void) activate:(BOOL)exclusive {

    [[NSColorPanel sharedColorPanel] setShowsAlpha:YES];

    [super activate:exclusive];

}

// Override [NSColorWell setColor] to fire a notification to Java when this ColorWell's color changes

// This is lighter-weight than observing a notification, and avoids the complexity of whether

// or not this ColorWell is active

- (void) setColor:(NSColor *)color {

    [self panelColorChange:color];

    [super setColor:color];

}

// This selector is performed by the observer on the sharedColorPanel whenever the selected color changes

// Call back to the enclosing Java instance so AWT events can be fired to respond to the color change

- (void) panelColorChange:(NSColor *)newColor {

    // The JavaVM can be cached; JNIEnvs are thread-specific and should be re-fetched every time

    JNIEnv *env = NULL;

    bool shouldDetach = false;

    if (GetJNIEnv(&env, &shouldDetach) != 0) {

        NSLog(@"panelColorChange: could not attach to JVM");

        return;

    }

            if (javaPeer != NULL && colorChange_mID != NULL) {

        // Convert the selected color to an RGB space that can be easily understood by Java

        NSColor *rgbColor = [newColor colorUsingColorSpaceName:NSCalibratedRGBColorSpace];

        if (rgbColor == nil) return;

        float r, g, b, a;

        [rgbColor getRed:&r green:&g blue:&b alpha:&a];

        // Call back into Java with the new color properties; the Java peer will fire ColorSelectionEvents to all its listeners     

        (*env)->CallVoidMethod(env, javaPeer, colorChange_mID, r, g, b, a);

        // IMPORTANT: if GetJNIEnv attached for us, we need to detach when done

        if (shouldDetach) {

            (*jvm)->DetachCurrentThread(jvm);

        }

            }

}

// Native target of the CocoaComponent.sendMessage method; see JavaColorWell.java

- (void) awtMessage:(jint)messageID message:(jobject)message env:(JNIEnv *)env { 

    switch (messageID) {

        // Delete the globalRef to the Java peer when the component is removed from its container

        case apple_dts_samplecode_cwcocoacomponent_JavaColorWell_REMOVE_NOTIFY:

            if (javaPeer != NULL) {

                (*env)->DeleteGlobalRef(env, javaPeer);

            }

            break;

        case apple_dts_samplecode_cwcocoacomponent_JavaColorWell_DEACTIVATE:

            // In case we need to deactivate the ColorWell directly

            // This is not called anywhere in the demo app

            [self deactivate];

            break;

        case apple_dts_samplecode_cwcocoacomponent_JavaColorWell_CLOSE_PANEL:

            // Close the NSColorPanel from Java

            // This could be a static method since the NSColorPanel is shared,

            // but sendMessage is more convenient

            [[NSColorPanel sharedColorPanel] close];

            break;

        default:

            break;

    }

}

@end