WindowHandle.cpp

/*
 * WindowHandle.cpp
 *
 * Author: Caleb Whiting
 */
#include "jni/org_jscrape_internal_WindowHandle.h"

#include <iostream>
#include <vector>
#include <Windows.h>

using namespace std;

#define JAVA_WRAPPER "org/jscrape/internal/WindowHandle"

struct JNI_ENUM_WINDOWS_PARAM {
	vector<jobject>* vect;
	JNIEnv* env;
};

template<typename T>
void invoke(JNIEnv* env, jobject o, jclass cls, const char* methodName,
		const char* signature, T arguments, ...) {
	jmethodID mid = env->GetMethodID(cls, methodName, signature);
	env->CallVoidMethod(o, mid, arguments);
}

void setBounds(JNIEnv* env, jobject o, jclass cls, const char* methodName,
		RECT b) {
	invoke(env, o, cls, methodName, "(IIII)V", b.top, b.right, b.bottom,
			b.left);
}

BOOL CALLBACK AddWindowToVector(HWND h, LPARAM ptr) {
	// Variables
	JNI_ENUM_WINDOWS_PARAM* param = reinterpret_cast<JNI_ENUM_WINDOWS_PARAM*>(ptr);
	JNIEnv* env = param->env;
	vector<jobject>* vect = param->vect;
	HDC hdc = GetDC(h);
	RECT windowRect;
	RECT clientRect;
	TITLEBARINFO ti;
	jclass cls = env->FindClass(JAVA_WRAPPER);
	// Check that the vector doesn't contain this process already
	DWORD pid;
	GetWindowThreadProcessId(h, &pid);
	for (vector<jobject>::size_type i = 0; i != vect->size(); i++) {
		jobject o = vect->at(i);
		int ppid = env->CallIntMethod(o, env -> GetMethodID(cls, "hashCode", "()I"));
		if (ppid == pid) {
			goto cleanup;
		}
	}
	// Create instance
	jmethodID construct = env->GetMethodID(cls, "<init>", "(I)V");
	jobject o = env->NewObject(cls, construct, pid);
	// Set properties
	GetWindowRect(h, &windowRect);
	setBounds(env, o, cls, "setWindowRect", windowRect);
	GetClientRect(h, &clientRect);
	setBounds(env, o, cls, "setClientRect", clientRect);
	// Set Title
	int titleLength = GetWindowTextLength(h) + 1;
	TCHAR* titleText = new TCHAR[titleLength];
	titleLength = GetWindowText(h, titleText, titleLength);
	jchar* title = new jchar[titleLength];
	for (int i = 0; i < titleLength; i++) {
		title[i] = titleText[i];
	}
	invoke(env, o, cls, "setTitle", "(Ljava/lang/String;)V",
			env->NewString(title, titleLength));
	// Get TitleBarInfo
	if (GetTitleBarInfo(h, &ti)) {
		RECT tb = ti.rcTitleBar;
		setBounds(env, o, cls, "setTitleRect", tb);
	}
	// Push
	vect->push_back(o);
	// Cleanup
	cleanup: {
		ReleaseDC(h, hdc);
		DeleteDC(hdc);
		return true;
	}
}

/*
 * Class:     org_jscrape_internal_WindowHandle
 * Method:    getHandles
 * Signature: ()[Lorg/jscrape/internal/WindowHandle;
 */
JNIEXPORT jobjectArray JNICALL
Java_org_jscrape_internal_WindowHandle_getHandles(JNIEnv * env, jclass c) {
	// Set environment for the callback
	// Iterate windows and add to vector
	vector<jobject>* vect = new vector<jobject>();
	JNI_ENUM_WINDOWS_PARAM param;
	param.vect = vect;
	param.env = env;
	EnumWindows(&AddWindowToVector, reinterpret_cast<LPARAM>(&param));
	// Copy to JNI array
	jobjectArray arr = env->NewObjectArray(vect->size(), c, nullptr);
	for (vector<jobject>::size_type i = 0; i != vect->size(); i++) {
		jobject o = vect->at(i);
		env->SetObjectArrayElement(arr, i, o);
	}
	// Cleanup
	vect->clear();
	delete vect;
	// Return
	return arr;
}