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An object of this class is used to paint a Grayscale plot of a 3D surface ranging from black at the lowest elevation to white at the highestelevation. The various shades of gray vary in a smooth gradient between the two extremes. The leftmost image in Figure 1 is an example of the type of plot produced by an object of this class.

Listing 14. Beginning of the class named CanvasType0surface.
class CanvasType0surface extends Canvas{ CanvasType0surface(){//constructorsetSize(dataWidth * blockSize, dataHeight * blockSize);getCenter(); }//end constructor

The constructor

The constructor for the class is straightforward. It accesses instance variables of the outer enclosing object to set the size of the canvas on thebasis of the size of the surface and the size of the square of pixels that will be used to represent each elevation value on the surface.

The constructor also calls the getCenter method to get the coordinates of the center of the surface in order to be able to draw theoptional red axes in the correct position later.

Overridden paint method for CanvasType0surface class

The real work is done by the overridden paint method, which begins in Listing 15 . Of the three classes used to plot the 3D surface, this is the simplest.

Listing 15. Beginning of overridden paint method.
public void paint(Graphics g){ Color color = null;for(int row = 0;row<dataHeight;row++){ for(int col = 0;col<dataWidth;col++){ //Add in red, green, and blue in// proportion to the value of the // surface height.int red = (int)data[row][col]; int green = red;int blue = red;

Purpose of overridden paint method

The purpose of this overridden paint method is to convert the elevation value of each point on the 3D surface into an appropriate shade ofgray, and to paint a square of pixels on the screen at that elevation value's location where every pixel in the square is the same shade of gray.

In order to produce a gray pixel in a 24-bit color system, you need to set the color values for red, green, and blue to the same value. If all three colorvalues are zero, the pixel color is black. If all three color values are 255, the pixel color is white. If all three color values fall somewhere in betweenzero and 255, the pixel color will be some shade of gray.

Recall that the elevation values were earlier normalized to fall in the range from zero to 255. The code in Listing 15 uses a nested for loop to access every elevation value in the array that describes the 3D surface. Thenit sets the red, green, and blue color values to the normalized surface valuefor each point on the 3D surface.

Instantiate a Color object

Continuing inside the nested for loops, the code in Listing 16 instantiates a new object of type Color based on the current red, green, and blue color values.

Listing 16. Instantiate a Color object.
color = new Color(red,green,blue);

Set colors and draw squares

The code in Listing 17 calls the setColor method of the Graphics class to set the current drawing color to the color described by the Color object referred to by the reference variable named color .

Questions & Answers

Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
hi
Loga
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
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Source:  OpenStax, Digital signal processing - dsp. OpenStax CNX. Jan 06, 2016 Download for free at https://legacy.cnx.org/content/col11642/1.38
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