Clear previous points when using draw(from,to)

[huseyinkozan]

Thanks Uwe. It seems I can't draw out of the paintEvent() in windows. I tried it in winapi but needs some tune up.

void drawTest::plotData(void){
	int changing_size = 10;
	int start_index = index;
	for(int i=0; i<changing_size; ++i){
		data_y[index] = (qSin(index*0.1)*100+100) + (qrand() % 20);
		if(++index > plot_size) index = 0;
	}
 
	QwtPlotCanvas * canvas = plot->canvas();
	HWND hwnd = canvas->winId();
	HDC hdc = GetDC(hwnd);
	static HPEN hpen_white = CreatePen(PS_SOLID,1,RGB(0,0,0));
	SelectObject(hdc, hpen_white);
	RECT rec;
	rec.bottom = canvas->rect().height();
	rec.top = 0;
	rec.left = data_x[start_index];
	rec.right = data_x[start_index+changing_size];
	FillRect(hdc, &rec, (HBRUSH) (COLOR_WINDOW+1) );
	static HPEN hpen_black = CreatePen(PS_SOLID,1,RGB(0,0,0));
	SelectObject(hdc, hpen_black);
	if(start_index+changing_size > plot_size){
		for(int i=start_index; i<plot_size; ++i){ LineTo(hdc, data_x[i], data_y[i] ); }
		MoveToEx(hdc, data_x[0], data_y[0],NULL);
		for(int i=0; i<(start_index+changing_size)-plot_size; ++i){ LineTo(hdc, data_x[i], data_y[i] ); }
	}
	else{
		MoveToEx(hdc, data_x[start_index], data_y[start_index],NULL);
		for(int i=0; i<changing_size; ++i){ LineTo(hdc, data_x[start_index+i], data_y[start_index+i] ); }
	}
	ReleaseDC(hwnd, hdc);
}

void drawTest::plotData(void){
	int changing_size = 10;
	int start_index = index;
	for(int i=0; i<changing_size; ++i){
		data_y[index] = (qSin(index*0.1)*100+100) + (qrand() % 20);
		if(++index > plot_size) index = 0;
	}

	QwtPlotCanvas * canvas = plot->canvas();
	HWND hwnd = canvas->winId();
	HDC hdc = GetDC(hwnd);
	static HPEN hpen_white = CreatePen(PS_SOLID,1,RGB(0,0,0));
	SelectObject(hdc, hpen_white);
	RECT rec;
	rec.bottom = canvas->rect().height();
	rec.top = 0;
	rec.left = data_x[start_index];
	rec.right = data_x[start_index+changing_size];
	FillRect(hdc, &rec, (HBRUSH) (COLOR_WINDOW+1) );
	static HPEN hpen_black = CreatePen(PS_SOLID,1,RGB(0,0,0));
	SelectObject(hdc, hpen_black);
	if(start_index+changing_size > plot_size){
		for(int i=start_index; i<plot_size; ++i){ LineTo(hdc, data_x[i], data_y[i] ); }
		MoveToEx(hdc, data_x[0], data_y[0],NULL);
		for(int i=0; i<(start_index+changing_size)-plot_size; ++i){ LineTo(hdc, data_x[i], data_y[i] ); }
	}
	else{
		MoveToEx(hdc, data_x[start_index], data_y[start_index],NULL);
		for(int i=0; i<changing_size; ++i){ LineTo(hdc, data_x[start_index+i], data_y[start_index+i] ); }
	}
	ReleaseDC(hwnd, hdc);
}

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